Dadoes in both sides of 3/4" ply?

Greg Guarino <[email protected]> wrote:
> , is it OK
> to make dadoes in both sides of the center divider, as long as none of
> them are in line with each other?

Perfectly OK to make dadoes in both sides of the center divider, even if
they are in line with each other, as long as you fill them with shelf.
--
www.ewoodshop.com (Mobile)

On Wednesday, December 12, 2012 3:02:53 AM UTC-8, Swingman wrote:
> Greg Guarino <[email protected]> wrote:
>
> > , is it OK
>
> > to make dadoes in both sides of the center divider, as long as none of
>
> > them are in line with each other?

> Perfectly OK to make dadoes in both sides of the center divider, even if
> they are in line with each other, as long as you fill them with shelf.

I'd add a caveat, there ought to be LONG GRAIN extension of the central
ply through the thinned region. It's possible to orient the plywood
so that thinning it leaves only/mainly one ply, with grain parallel to the shelf.
That's gonna break REAL easy. Maybe won't survive attempted assembly.

"Greg Guarino" wrote in message news:[email protected]...

On 12/11/2012 10:35 PM, Mike Marlow wrote:
> Greg Guarino wrote:
>
>>
>> All shelves would be fixed. There would be a face frame, and a back.
>> I'm wondering if I should simply make the cabinet as two separate
>> boxes, joining them together after both are assembled. That would give
>> me a double-thickness center divider, but there would be a 1x2
>> covering the seam anyway. This idea appeals to me because I think it
>> will be easier to handle two smaller, simpler units than one large
>> one. But if do decide to make the cabinet as a single unit, is it OK
>> to make dadoes in both sides of the center divider, as long as none of
>> them are in line with each other?
>
> Yes - it would be fine to dado both sides of a board. Make sure your
> shelves fit snugly into your dados and once they're glued up it will be as
> if it were a solid piece.
>
So there's my next question. My only option for making dadoes is a
router, and I'd love to avoid making extra passes. If I buy a 23/32 bit,
will I be OK? Or is plywood thickness too unpredictable these days?
========================================================================
A router jig can be easily made that cuts exact size of your material.

On Dec 14, 3:35=A0pm, Swingman <[email protected]> wrote:
> On 12/14/2012 2:03 PM, Greg Guarino wrote:
>
>
>
>
>
>
>
>
>
> > On 12/14/2012 1:54 PM, Peter Bennett wrote:
> >> On Thu, 13 Dec 2012 21:38:15 -0600, -MIKE- <[email protected]>
> >> wrote:
>
> >>> On 12/13/12 8:19 PM, Peter Bennett wrote:
> >>>> My router dado jig doesn't need guide bushings or a top bearing bit =
-
> >>>> it guides the router base.
>
> >>>> each side of the guide consists of two pieces - a wide piece of 1/4"
> >>>> plywood that the router rides on, and a (straight!) piece of 1/2"
> >>>> plywood, or similar piece of solid wood glued on top.
>
> >>>> Before the first use, run the router along the jig with the base
> >>>> against the 1/2" board, so the router bit can trim the 1/4" plywood =
to
> >>>> the correct size.
>
> >>> The jigs we're discussing adjust for the thickness of the board that
> >>> will go into the dado.
> >>> If I understand correctly, all your jig does is allow you to line up
> >>> perfectly with a marked line, like a circular saw rip guide.
>
> >> No - my dado jig uses two pieces as described, joined similarly to the
> >> Woodwhisperer's dado jig, but it uses the router base as the guide,
> >> rather than requiring a guide bushing or a bearing on the bit. (maybe
> >> I should take a picture of it, and post it somewhere...)
>
> > Now that sounds like the idea I had. The two guides are separated by a
> > distance equal to the diameter of the router base plus the thickness of
> > the stock to go in the dado, right? The router base rides along one
> > guide first, then the other? I figured if I did this the first pass
> > would cut a dado in the pieces that join the two guides together,
> > thereby giving me registration marks to line up the cut with. The
> > pattern bit idea sounds even more foolproof though, at least to my
> > untutored ear.
>
> All basically the same principle ... the edge of the router plate in
> this one takes the place of the bearing in the top bearing bit method,
> or the edge of the guide bushing in the other method.
>
> IMO, the problem with the all the router methods boils down to the use
> of a wooden jig, which is prone to the dimensional instability of wood;
> and/or the concentricity of a router plate; either with the potential to
> effect accuracy over time.

How often do we get to use the word "concentricity" in a sentence?
Google groups even puts a squiggly line under it. :)

I don't have the table saw option. But I was wondering about both of
those potential problems too. I think that the small imperfection
would probably not be out of place when compared with my general level
of work (sigh), but I'd be perfectly happy to avoid it. I wonder if I
couldn't make the edges that the bearing rides on out of something
more "dimensionally stable"; maybe strips of aluminum set into slots
(or rabbets) in both guide edges, just a little proud of the wood
edge.

On 12/13/2012 9:00 AM, Greg Guarino wrote:
> On 12/12/2012 4:31 PM, Leon wrote:
>> On 12/12/2012 9:15 AM, Greg Guarino wrote:
>
>>>>
>>> So there's my next question. My only option for making dadoes is a
>>> router, and I'd love to avoid making extra passes. If I buy a 23/32 bit,
>>> will I be OK? Or is plywood thickness too unpredictable these days?
>>
>>
>> The simplest solution is to clamp a board where you want the board/panel
>> to fit. Place the board/panel that will fit into that dado against the
>> clamped board. Clamp another board on the other side. Basically you
>> are clamping 2 boards the exact width of the piece that will go into the
>> dado.
>>
>> With a top bearing 1/2" flush cut bit use the clamped rails as your
>> guide and remove everything in between. Should be a perfect fit.
>
> A "top-bearing" bit. You see, that's why I ask questions here. I had no
> idea such bits existed. I had only seen (and have one or two of) what I
> thought was the only kind, for laminate trimming and such. Excellent. I
> still think I'll make a jig something like what I had in mind, but with
> a narrow slot in the middle instead. Thanks.


I came up with a jig that several years ago that is similar to the one
in the wood whisperer video. Mine closes in width and length and holds
its settings. Any way most all of these type dado jigs call for a
bushing to keep the bit from hitting the jig. I hate those things as
they have to be perfectly centered with the router or you get wider and
or narrower cuts if you rotate the router as you feed it along.

With the top bearing flush trim bit you get a perfect cut along your
guide whether you rotate the router or not and you do not have to deal
with a bushing.

I use something like this,

http://www.amazon.com/Freud-50-102-2-Inch-Bearing-Flush/dp/B0000225XQ/ref=sr_1_1?ie=UTF8&qid=1355429718&sr=8-1&keywords=top+bearing+flush+trim+bit

On Wed, 12 Dec 2012 10:15:44 -0500, Greg Guarino <[email protected]>
>So there's my next question. My only option for making dadoes is a
>router, and I'd love to avoid making extra passes. If I buy a 23/32 bit,
>will I be OK? Or is plywood thickness too unpredictable these days?

Plywood thickness is *EXTREMELY* unpredictable these days and has been
for a number of years. You might get lucky and be able to find a
router bit perfectly sized for the plywood on hand, but the chances of
that happening are almost nil.

Sorry, but multiple router passes are usually the norm if you want
your dados sized properly.

On thing you might consider, is an adjustable dado blade for the table
saw. Get that sized properly and *then* you can do your single passes.

On 12/13/2012 2:53 PM, -MIKE- wrote:
> On 12/13/12 2:16 PM, Leon wrote:
>> On 12/13/2012 9:00 AM, Greg Guarino wrote:
>>> On 12/12/2012 4:31 PM, Leon wrote:
>>>> On 12/12/2012 9:15 AM, Greg Guarino wrote:
>>>
>>>>>>
>>>>> So there's my next question. My only option for making dadoes is a
>>>>> router, and I'd love to avoid making extra passes. If I buy a 23/32
>>>>> bit,
>>>>> will I be OK? Or is plywood thickness too unpredictable these days?
>>>>
>>>>
>>>> The simplest solution is to clamp a board where you want the
>>>> board/panel
>>>> to fit. Place the board/panel that will fit into that dado against the
>>>> clamped board. Clamp another board on the other side. Basically you
>>>> are clamping 2 boards the exact width of the piece that will go into
>>>> the
>>>> dado.
>>>>
>>>> With a top bearing 1/2" flush cut bit use the clamped rails as your
>>>> guide and remove everything in between. Should be a perfect fit.
>>>
>>> A "top-bearing" bit. You see, that's why I ask questions here. I had no
>>> idea such bits existed. I had only seen (and have one or two of) what I
>>> thought was the only kind, for laminate trimming and such. Excellent. I
>>> still think I'll make a jig something like what I had in mind, but with
>>> a narrow slot in the middle instead. Thanks.
>>
>>
>> I came up with a jig that several years ago that is similar to the one
>> in the wood whisperer video. Mine closes in width and length and holds
>> its settings. Any way most all of these type dado jigs call for a
>> bushing to keep the bit from hitting the jig. I hate those things as
>> they have to be perfectly centered with the router or you get wider and
>> or narrower cuts if you rotate the router as you feed it along.
>>
>> With the top bearing flush trim bit you get a perfect cut along your
>> guide whether you rotate the router or not and you do not have to deal
>> with a bushing.
>>
>
> That's the problem I had with his video. Well, the other problem. The
> first problem is him getting waaaaaay too detailed on each step.
>
> We're talking about trying to cut dadoes the exact width of a piece of
> wood. And he's using a bushing... those things never get perfectly
> centered. So you essentially have a technique with a margin of error
> greater than what I could cut dadoes sans jig. :-)
>
>

As soon as he mentioned the bushing I quit watching.

"Greg Guarino" wrote:


> We still haven't settled on our book storage plans. Now I'm
> considering a design that would involve shelves on both sides of a
> wide cabinet divided in the middle, but not in line with each other.
> The cabinet would be 54" high by 48" wide, with a vertical divider a
> little off-center. To one side of the divider there would be 4 shelf
> spaces each 12" high. On the other side would be 3 shelf spaces,
> each
> 18" high. (all numbers approximate, I know the thickness of the wood
> will change the exact dimensions). The dadoes on opposite sides of
> the
> divider would then be about six inches apart.
>
> All shelves would be fixed. There would be a face frame, and a back.
> I'm wondering if I should simply make the cabinet as two separate
> boxes, joining them together after both are assembled. That would
> give
> me a double-thickness center divider, but there would be a 1x2
> covering the seam anyway. This idea appeals to me because I think it
> will be easier to handle two smaller, simpler units than one large
> one. But if do decide to make the cabinet as a single unit, is it OK
> to make dadoes in both sides of the center divider, as long as none
> of
> them are in line with each other?
----------------------------------------------------------------
No problem structurally; however, you are going to be busier than a
one armed paper hanger in a wind storm trying to get everything
aligned
before your adhesive fires.

You are going to want the longest open time adhesive you can find.

I'd use epoxy with a slow hardener which will give you about 30
minutes
open time at 75F.

A good helper will be a big help.

Have fun.

Lew

"Greg Guarino" wrote:

>> You are going to want the longest open time adhesive you can find.
>> I'd use epoxy with a slow hardener which will give you about 30
>> minutes open time at 75F.
-------------------------------------------------------------------------------------
> I've only used regular yellow wood glue, for wood anyway. I have
> used two part epoxy for other things. Is there epoxy especially for
> woodworking?
------------------------------------------------------------
There are lots of epoxy suppliers out there.

There are only 3-5 manufacturers of part A; however, there are
litterly
hundreds of part B suppliers which is where all the black art of
formulation
gets involved.

WEST Systems probably has the widest distribution.

I have a preference for System3.

http://tinyurl.com/bx584yx

Epoxy is basically an adhesive, it works very well gluing wood
together.

You want standard laminating part A resin and the slowest
part B hardener for this project.

You will make life easier at assembly time by toe nailing shelves into
grooves
at assembly time, then clamping at final assembly.

When using a router for dado grooves, easiest solution is to make
two passes using a jig.

Leon has a jig he developed for the purpose.

Maybe he will post details again.

Lew

"Greg Guarino" wrote:

> I knew one of you killjoys were going to say that. So now I suppose
> you'll be recommending I get a guide collar for the router or some
> such.
-----------------------------------------------------------------
Also go to Pat Warner's site and get his little gizmo that insures
base
plate and guide bushing are centered with bit.
--------------------------------------------------------------
> I have some ideas. Let's see how stupid they are.
---------------------------------------------------------------
Not stupid at all.

Either build the jig shown on U-tube or ping Leon and get his plan.

No need to reinvent the wheel.

Lew

"Greg Guarino" wrote:

> Wow. I finally got a moment to look at this (I skipped to the end)
> and it is remarkably similar to what I had envisioned, minus the
> adjustability and the collar. I don't have a collar, nor do I think
> my router will easily accept one without an adapter. I'd probably
> give the top-guide bit a whirl.
---------------------------------------------------
A pattern bit (top bearing) has severe limitations for cutting dadoes
compared to a guide bushing.

A full set of brass guide bushings was less than $30 the last time
I looked.

What ever the price, they represent a good investment if you use a
router.

Lew

"chaniarts" wrote:


> the problem with this is that the bit usually isn't dead center in
> the base. if you twist the router on it's trip across the board,
> you'll get a wavy edge to the dado.
-----------------------------------------------------------
That's why you get Pat Warner's gizmo.

Pat has solved that problem.

Lew

chaniarts <[email protected]> wrote in
news:[email protected]:

>
> and if you put the router down in a slightly skewed position on the
> next one than the previous one, you don't get a repeatable width dado
> because the router base may not be circular.
>

If you can replace your router's baseplate, you can get (make?) one with a
flat edge. If you have two parallel flat edges, then you can just adjust
your jig to accomdate.

Puckdropper
--
Make it to fit, don't make it fit.

"Swingman" wrote:

> You missing the point?
>
> Those who take the time and effort to cut a dado with the precision
> under discussion in this thread, are fooling themselves if they
> consider/take into account, and understand, ALL factors that can
> effect the precision they are pursuing.
>
> Anyone sneering at the effects of a lack of "concentricity" when
> using a router jig that relies on a reference edge, better first go
> cut a bunch of dovetails with one and see how long that attitude
> lasts.
---------------------------------------------
See what the man has to say about the subject.

www.patwarner.com


Lew

On 12/12/2012 9:15 AM, Greg Guarino wrote:

> So there's my next question. My only option for making dadoes is a
> router, and I'd love to avoid making extra passes. If I buy a 23/32 bit,
> will I be OK? Or is plywood thickness too unpredictable these days?

http://www.youtube.com/watch?v=7j4vGS4HY-8

Or Leon has one that he designed a few years back and might have a
Sketchup model?

--
eWoodShop: www.eWoodShop.com
Wood Shop: www.e-WoodShop.net
https://plus.google.com/114902129577517371552/posts
KarlCaillouet@ (the obvious)

On 12/12/2012 9:15 AM, Greg Guarino wrote:
> On 12/11/2012 10:35 PM, Mike Marlow wrote:
>> Greg Guarino wrote:
>>
>>>
>>> All shelves would be fixed. There would be a face frame, and a back.
>>> I'm wondering if I should simply make the cabinet as two separate
>>> boxes, joining them together after both are assembled. That would give
>>> me a double-thickness center divider, but there would be a 1x2
>>> covering the seam anyway. This idea appeals to me because I think it
>>> will be easier to handle two smaller, simpler units than one large
>>> one. But if do decide to make the cabinet as a single unit, is it OK
>>> to make dadoes in both sides of the center divider, as long as none of
>>> them are in line with each other?
>>
>> Yes - it would be fine to dado both sides of a board. Make sure your
>> shelves fit snugly into your dados and once they're glued up it will
>> be as
>> if it were a solid piece.
>>
> So there's my next question. My only option for making dadoes is a
> router, and I'd love to avoid making extra passes. If I buy a 23/32 bit,
> will I be OK? Or is plywood thickness too unpredictable these days?


The simplest solution is to clamp a board where you want the board/panel
to fit. Place the board/panel that will fit into that dado against the
clamped board. Clamp another board on the other side. Basically you
are clamping 2 boards the exact width of the piece that will go into the
dado.

With a top bearing 1/2" flush cut bit use the clamped rails as your
guide and remove everything in between. Should be a perfect fit.

On 12/15/2012 3:24 PM, Lew Hodgett wrote:
> "Swingman" wrote:
>
>> You missing the point?
>>
>> Those who take the time and effort to cut a dado with the precision
>> under discussion in this thread, are fooling themselves if they
>> consider/take into account, and understand, ALL factors that can
>> effect the precision they are pursuing.

"if they DON'T ... " is missing,

>> Anyone sneering at the effects of a lack of "concentricity" when
>> using a router jig that relies on a reference edge, better first go
>> cut a bunch of dovetails with one and see how long that attitude
>> lasts.
> ---------------------------------------------
> See what the man has to say about the subject.
>
> www.patwarner.com


To be more precise, the second paragraph:

http://www.patwarner.com/collarguide.html


--
eWoodShop: www.eWoodShop.com
Wood Shop: www.e-WoodShop.net
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KarlCaillouet@ (the obvious)

On 12/15/2012 1:45 PM, dadiOH wrote:

> Somewhere out there exists a great forest. The trees are getting in the
> way.

You missing the point?

Those who take the time and effort to cut a dado with the precision
under discussion in this thread, are fooling themselves if they
consider/take into account, and understand, ALL factors that can effect
the precision they are pursuing.

Anyone sneering at the effects of a lack of "concentricity" when using a
router jig that relies on a reference edge, better first go cut a bunch
of dovetails with one and see how long that attitude lasts.

--
eWoodShop: www.eWoodShop.com
Wood Shop: www.e-WoodShop.net
https://plus.google.com/114902129577517371552/posts
KarlCaillouet@ (the obvious)

On 12/15/2012 4:54 PM, whit3rd wrote:
> On Wednesday, December 12, 2012 3:02:53 AM UTC-8, Swingman wrote:
>> Greg Guarino <[email protected]> wrote:
>>
>>> , is it OK
>>
>>> to make dadoes in both sides of the center divider, as long as none of
>>
>>> them are in line with each other?
>
>> Perfectly OK to make dadoes in both sides of the center divider, even if
>> they are in line with each other, as long as you fill them with shelf.
>
> I'd add a caveat, there ought to be LONG GRAIN extension of the central
> ply through the thinned region.

OK, which ply is the "central" ply?

Most, if not all plywood has an odd number of plys by design,
specifically to mitigate warping.

It's possible to orient the plywood
> so that thinning it leaves only/mainly one ply, with grain parallel to the shelf.
> That's gonna break REAL easy.

Not so sure about that, especially if the dado fits what's going into it.

> Maybe won't survive attempted assembly.

That's a pretty strong statement ... got anything to back it up with?

Literally thousands of this type joint under my belt and have never
seen, or heard of any instance, of that happening.

All that means nothing in the greater scheme of things, basically, I'll
continue to take my chances that, providing everything fits as spec'ed,
it ain't gonna happen. :)

--
eWoodShop: www.eWoodShop.com
Wood Shop: www.e-WoodShop.net
https://plus.google.com/114902129577517371552/posts
KarlCaillouet@ (the obvious)

On Thu, 13 Dec 2012 14:16:44 -0600, Leon <lcb11211@swbelldotnet>
>With the top bearing flush trim bit you get a perfect cut along your
>guide whether you rotate the router or not and you do not have to deal
>with a bushing.
>
>I use something like this,
>
>http://www.amazon.com/Freud-50-102-2-Inch-Bearing-Flush/dp/B0000225XQ/ref=sr_1_1?ie=UTF8&qid=1355429718&sr=8-1&keywords=top+bearing+flush+trim+bit

And, the Lee Valley version
http://www.leevalley.com/en/Wood/page.aspx?p=30166&cat=1,46168,69435,46171&ap=1

Greg Guarino wrote:

>
> All shelves would be fixed. There would be a face frame, and a back.
> I'm wondering if I should simply make the cabinet as two separate
> boxes, joining them together after both are assembled. That would give
> me a double-thickness center divider, but there would be a 1x2
> covering the seam anyway. This idea appeals to me because I think it
> will be easier to handle two smaller, simpler units than one large
> one. But if do decide to make the cabinet as a single unit, is it OK
> to make dadoes in both sides of the center divider, as long as none of
> them are in line with each other?

Yes - it would be fine to dado both sides of a board. Make sure your
shelves fit snugly into your dados and once they're glued up it will be as
if it were a solid piece.

--

-Mike-
[email protected]

On 12/11/12 9:26 PM, Greg Guarino wrote:
> We still haven't settled on our book storage plans. Now I'm
> considering a design that would involve shelves on both sides of a
> wide cabinet divided in the middle, but not in line with each other.
> The cabinet would be 54" high by 48" wide, with a vertical divider a
> little off-center. To one side of the divider there would be 4 shelf
> spaces each 12" high. On the other side would be 3 shelf spaces, each
> 18" high. (all numbers approximate, I know the thickness of the wood
> will change the exact dimensions). The dadoes on opposite sides of the
> divider would then be about six inches apart.
>
> All shelves would be fixed. There would be a face frame, and a back.
> I'm wondering if I should simply make the cabinet as two separate
> boxes, joining them together after both are assembled. That would give
> me a double-thickness center divider, but there would be a 1x2
> covering the seam anyway. This idea appeals to me because I think it
> will be easier to handle two smaller, simpler units than one large
> one. But if do decide to make the cabinet as a single unit, is it OK
> to make dadoes in both sides of the center divider, as long as none of
> them are in line with each other?
>

Dadoes on both sides of a sheet of plywood would be fine.

However, if it's easier to build two cases, do it. It's not that much
more material and there's nothing wrong with it, if the design calls for
a center divider. IMO a bookcase that is wider than it is tall looks odd
and.... sideways.... so a divider is nice, esthetically.

I'm starting a build-in bookcase project that will be 64" wide x floor
to ceiling.
I'm breaking it up into two 32" wide cases for two reasons-- sheet goods
are 48" and who in their right mind would try to build a single case
that big. :-)


--

-MIKE-

"Playing is not something I do at night, it's my function in life"
--Elvin Jones (1927-2004)
--
http://mikedrums.com
[email protected]
---remove "DOT" ^^^^ to reply

Greg Guarino wrote:
> We still haven't settled on our book storage plans. Now I'm
> considering a design that would involve shelves on both sides of a
> wide cabinet divided in the middle, but not in line with each other.
> The cabinet would be 54" high by 48" wide, with a vertical divider a
> little off-center. To one side of the divider there would be 4 shelf
> spaces each 12" high. On the other side would be 3 shelf spaces, each
> 18" high. (all numbers approximate, I know the thickness of the wood
> will change the exact dimensions). The dadoes on opposite sides of the
> divider would then be about six inches apart.
>
> All shelves would be fixed. There would be a face frame, and a back.
> I'm wondering if I should simply make the cabinet as two separate
> boxes, joining them together after both are assembled. That would give
> me a double-thickness center divider, but there would be a 1x2
> covering the seam anyway. This idea appeals to me because I think it
> will be easier to handle two smaller, simpler units than one large
> one. But if do decide to make the cabinet as a single unit, is it OK
> to make dadoes in both sides of the center divider, as long as none of
> them are in line with each other?

Sure, you have our permission to do that. Mine at least.

For that matter - should you want the shelves in the same plane - you can
cut the dado all the way through except for a few inches at each end and
notch the shelves appropriately.

A variation on notching the shelves would be to make rabbets...on one shelf,
make a 3/4 x 3/8 rabbet on the top; same on the other shelf but at the
bottom. Rabbet size depends on ply thickness but the goal is to have one
shelf rabbet resting on the other.

Still another variation that comes to mind would be to make a series of half
through slots, each maybe 2" long from each side but staggered so that none
go all the way through. Then cut fingers on the shelfs.

One of the joys of woodworking is that with a fertile mind one can come up
with all sorts of ways to complicate things. :)

--

dadiOH
____________________________

Winters getting colder? Tired of the rat race?
Maybe just ready for a change? Check it out...
http://www.floridaloghouse.net

On 12/11/2012 10:35 PM, Mike Marlow wrote:
> Greg Guarino wrote:
>
>>
>> All shelves would be fixed. There would be a face frame, and a back.
>> I'm wondering if I should simply make the cabinet as two separate
>> boxes, joining them together after both are assembled. That would give
>> me a double-thickness center divider, but there would be a 1x2
>> covering the seam anyway. This idea appeals to me because I think it
>> will be easier to handle two smaller, simpler units than one large
>> one. But if do decide to make the cabinet as a single unit, is it OK
>> to make dadoes in both sides of the center divider, as long as none of
>> them are in line with each other?
>
> Yes - it would be fine to dado both sides of a board. Make sure your
> shelves fit snugly into your dados and once they're glued up it will be as
> if it were a solid piece.
>
So there's my next question. My only option for making dadoes is a
router, and I'd love to avoid making extra passes. If I buy a 23/32 bit,
will I be OK? Or is plywood thickness too unpredictable these days?

On 12/11/2012 10:59 PM, -MIKE- wrote:
> However, if it's easier to build two cases, do it. It's not that much
> more material and there's nothing wrong with it, if the design calls for
> a center divider.

My "design" (more of a half-assed idea so far) was based on two factors:
the size and the weight of the books to be stored. These bookshelves
will hold books mostly, rather than the usual bric-a-brac. The spaces
available are 4' wide, but I don't feel quite right about shelves 48"
long. Plus, some of the books are very tall, but most are not. Thus I'll
need some tall shelf spaces and some less so.

I was originally going to make the lowest shelf tall and the rest
shorter, but if I need a divider anyway, I think it will add some visual
interest to break it up the way I described.

IMO a bookcase that is wider than it is tall looks odd
> and.... sideways.... so a divider is nice, esthetically.

These bookcases will actually sit atop a set of existing cubbyhole units
that span a whole wall. The two new bookcases will be placed at either
end, with a TV in the middle. Assuming all goes well (and I live long
enough, given my less-than-efficient woodworking methods) I may complete
a faux built-in with a "bridge" over the TV between the two units.
Anticipating the obvious question, yes, I will be anchoring the units
into the wall as well.

That is, until the plan changes entirely. We'll see.

On 12/12/2012 2:16 AM, Lew Hodgett wrote:
> No problem structurally; however, you are going to be busier than a
> one armed paper hanger in a wind storm trying to get everything
> aligned before your adhesive fires.

That's an oldie. My Dad's version was "a one-armed paper hanger with an
itch". And yes, I now recognize that the choice is between building
separate units and bursting a blood vessel in my temple. I'm leaning
toward the former.

> You are going to want the longest open time adhesive you can find.
> I'd use epoxy with a slow hardener which will give you about 30
> minutes open time at 75F.

I've only used regular yellow wood glue, for wood anyway. I have used
two part epoxy for other things. Is there epoxy especially for woodworking?

On 12/12/2012 5:27 AM, dadiOH wrote:
> One of the joys of woodworking is that with a fertile mind one can come up
> with all sorts of ways to complicate things.:)

Definitely. A novice like me can come up with some really "special"
ideas. Trust me.

Greg Guarino wrote:
> On 12/11/2012 10:35 PM, Mike Marlow wrote:
>> Greg Guarino wrote:
>>
>>>
>>> All shelves would be fixed. There would be a face frame, and a back.
>>> I'm wondering if I should simply make the cabinet as two separate
>>> boxes, joining them together after both are assembled. That would
>>> give me a double-thickness center divider, but there would be a 1x2
>>> covering the seam anyway. This idea appeals to me because I think it
>>> will be easier to handle two smaller, simpler units than one large
>>> one. But if do decide to make the cabinet as a single unit, is it OK
>>> to make dadoes in both sides of the center divider, as long as none
>>> of them are in line with each other?
>>
>> Yes - it would be fine to dado both sides of a board. Make sure your
>> shelves fit snugly into your dados and once they're glued up it will
>> be as if it were a solid piece.
>>
> So there's my next question. My only option for making dadoes is a
> router, and I'd love to avoid making extra passes. If I buy a 23/32
> bit, will I be OK? Or is plywood thickness too unpredictable these
> days?

I honestly don't know. Haven't dadoed a piece of plywood into a board in
too long. Well - I have, but in those cases I had to make multiple passes
anyway, so it didn't matter. I use my router too. I don't do enough dados
to warrant buying a dado blade and farting around getting it setup and all.
I just chuck a router bit and go at it. That process has never caused me a
problem.

I wouldn't sweat making multiple passes if that's what's necessary. Just
make all of your passes that use the same fence setting before moving your
fence to make any next passes, and then do them all at once.

--

-Mike-
[email protected]

Greg Guarino wrote:

> So there's my next question. My only option for making dadoes is a
> router, and I'd love to avoid making extra passes. If I buy a 23/32
> bit, will I be OK? Or is plywood thickness too unpredictable these
> days?

IMO you'd be better off making your dados 1/2" and cutting tongues to fit on
the shelf ends. The shoulder of the tongue will then limit the depth the
shelf can be inserted and hide any unevenness on the dado. Double shoulders
(top and bottom) are even better. Again, IMO, YMMV.

--

dadiOH
____________________________

Winters getting colder? Tired of the rat race?
Maybe just ready for a change? Check it out...
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Greg Guarino wrote:
> On 12/12/2012 2:16 AM, Lew Hodgett wrote:
>> No problem structurally; however, you are going to be busier than a
>> one armed paper hanger in a wind storm trying to get everything
>> aligned before your adhesive fires.
>
> That's an oldie. My Dad's version was "a one-armed paper hanger with
> an itch". And yes, I now recognize that the choice is between building
> separate units and bursting a blood vessel in my temple. I'm leaning
> toward the former.
>
>> You are going to want the longest open time adhesive you can find.
>> I'd use epoxy with a slow hardener which will give you about 30
>> minutes open time at 75F.
>
> I've only used regular yellow wood glue, for wood anyway. I have used
> two part epoxy for other things. Is there epoxy especially for
> woodworking?

No but there are various hardeners which cause the epoxy to set up
slower/faster.

--

dadiOH
____________________________

Winters getting colder? Tired of the rat race?
Maybe just ready for a change? Check it out...
http://www.floridaloghouse.net

On 12/12/2012 10:23 AM, Dave wrote:
> On Wed, 12 Dec 2012 10:15:44 -0500, Greg Guarino <[email protected]>
>> So there's my next question. My only option for making dadoes is a
>> router, and I'd love to avoid making extra passes. If I buy a 23/32 bit,
>> will I be OK? Or is plywood thickness too unpredictable these days?
>
> Plywood thickness is *EXTREMELY* unpredictable these days and has been
> for a number of years. You might get lucky and be able to find a
> router bit perfectly sized for the plywood on hand, but the chances of
> that happening are almost nil.
>

I knew one of you killjoys were going to say that. So now I suppose
you'll be recommending I get a guide collar for the router or some such.

I have some ideas. Let's see how stupid they are.

My first thought was to use two parallel guides clamped to the work,
spaced apart just far enough so that two passes (one pass touching one
guide, one touching the other) would produce the proper dado width. I
have one of those self-clamping straightedge gizmos, and I have some
non-self-clamping extruded aluminum guides. I'd use some combination.

So next I thought, hey, that'll be a drag to set up 36 times. Maybe I'll
cut a couple of pieces of scrap just the right length to set the span
between the two guides. That would work, I think, but all you guys would
snicker about how clumsy it was. We can't have that, can we?

So now I wonder if I couldn't make a rectangular jig of some sort,
consisting of two wooden guides joined by two other pieces to set the
correct distance. Those pieces would ride along the edges of the work to
be cut, sitting flush with the top. (all of the pieces that will need
these dadoes will be the same width, probably 12")On the first cut, the
"joining" pieces would themselves receive a dado groove, which I could
then use to line up each new dado to be cut in the work pieces.

I think this would work, and could be easily clamped to each new
position. But I worry that my abilities may not allow me to produce a
jig as square and straight as would be needed.

I'm also wondering if I could get away with dadoing a pair of "mating"
uprights in one pass by lining them up next to each other. That way the
dadoes would be sure to line up on both sides of each shelf, but it
would mean reaching farther with the router too, and would make for a
longer jig, more prone to be out of square.

On 12/12/2012 4:31 PM, Leon wrote:
> On 12/12/2012 9:15 AM, Greg Guarino wrote:

>>>
>> So there's my next question. My only option for making dadoes is a
>> router, and I'd love to avoid making extra passes. If I buy a 23/32 bit,
>> will I be OK? Or is plywood thickness too unpredictable these days?
>
>
> The simplest solution is to clamp a board where you want the board/panel
> to fit. Place the board/panel that will fit into that dado against the
> clamped board. Clamp another board on the other side. Basically you
> are clamping 2 boards the exact width of the piece that will go into the
> dado.
>
> With a top bearing 1/2" flush cut bit use the clamped rails as your
> guide and remove everything in between. Should be a perfect fit.

A "top-bearing" bit. You see, that's why I ask questions here. I had no
idea such bits existed. I had only seen (and have one or two of) what I
thought was the only kind, for laminate trimming and such. Excellent. I
still think I'll make a jig something like what I had in mind, but with
a narrow slot in the middle instead. Thanks.

Greg Guarino wrote:

>
> A "top-bearing" bit. You see, that's why I ask questions here. I had
> no idea such bits existed. I had only seen (and have one or two of)
> what I thought was the only kind, for laminate trimming and such.
> Excellent. I still think I'll make a jig something like what I had in
> mind, but with a narrow slot in the middle instead. Thanks.

A top bearing bit will certainly work and represents another way to skin a
cat, but that will not change they type or size of slot you need/want. To
make your jig more universal, you'll still want to make an adjustable jig
like what's on the internet. It takes a bit longer to make, but it saves a
ton of time in properly sizing your dado to the workpiece you are using, and
it does not care about irregular workpiece dimensions.

--

-Mike-
[email protected]

On 12/13/12 2:16 PM, Leon wrote:
> On 12/13/2012 9:00 AM, Greg Guarino wrote:
>> On 12/12/2012 4:31 PM, Leon wrote:
>>> On 12/12/2012 9:15 AM, Greg Guarino wrote:
>>
>>>>>
>>>> So there's my next question. My only option for making dadoes is a
>>>> router, and I'd love to avoid making extra passes. If I buy a 23/32
>>>> bit,
>>>> will I be OK? Or is plywood thickness too unpredictable these days?
>>>
>>>
>>> The simplest solution is to clamp a board where you want the board/panel
>>> to fit. Place the board/panel that will fit into that dado against the
>>> clamped board. Clamp another board on the other side. Basically you
>>> are clamping 2 boards the exact width of the piece that will go into the
>>> dado.
>>>
>>> With a top bearing 1/2" flush cut bit use the clamped rails as your
>>> guide and remove everything in between. Should be a perfect fit.
>>
>> A "top-bearing" bit. You see, that's why I ask questions here. I had no
>> idea such bits existed. I had only seen (and have one or two of) what I
>> thought was the only kind, for laminate trimming and such. Excellent. I
>> still think I'll make a jig something like what I had in mind, but with
>> a narrow slot in the middle instead. Thanks.
>
>
> I came up with a jig that several years ago that is similar to the one
> in the wood whisperer video. Mine closes in width and length and holds
> its settings. Any way most all of these type dado jigs call for a
> bushing to keep the bit from hitting the jig. I hate those things as
> they have to be perfectly centered with the router or you get wider and
> or narrower cuts if you rotate the router as you feed it along.
>
> With the top bearing flush trim bit you get a perfect cut along your
> guide whether you rotate the router or not and you do not have to deal
> with a bushing.
>

That's the problem I had with his video. Well, the other problem. The
first problem is him getting waaaaaay too detailed on each step.

We're talking about trying to cut dadoes the exact width of a piece of
wood. And he's using a bushing... those things never get perfectly
centered. So you essentially have a technique with a margin of error
greater than what I could cut dadoes sans jig. :-)


--

-MIKE-

"Playing is not something I do at night, it's my function in life"
--Elvin Jones (1927-2004)
--
http://mikedrums.com
[email protected]
---remove "DOT" ^^^^ to reply

On 12/13/2012 2:16 PM, Lew Hodgett wrote:
>> I have some ideas. Let's see how stupid they are.
> ---------------------------------------------------------------
> Not stupid at all.
>
> Either build the jig shown on U-tube

Wow. I finally got a moment to look at this (I skipped to the end) and
it is remarkably similar to what I had envisioned, minus the
adjustability and the collar. I don't have a collar, nor do I think my
router will easily accept one without an adapter. I'd probably give the
top-guide bit a whirl.

As for adjustability, I've got to think on that. I'm an occasional
weekend dabbler with much less time than I would like. I could screw the
thing together at a a fixed width much more quickly (although I have to
say, using a clamp while setting the width looks like a great idea).
Shortsighted? I guess so. And I'll have to kick myself if I don't get it
right the first time.

I'll think about it.

Thanks.

On 12/13/12 8:19 PM, Peter Bennett wrote:
> My router dado jig doesn't need guide bushings or a top bearing bit -
> it guides the router base.
>
> each side of the guide consists of two pieces - a wide piece of 1/4"
> plywood that the router rides on, and a (straight!) piece of 1/2"
> plywood, or similar piece of solid wood glued on top.
>
> Before the first use, run the router along the jig with the base
> against the 1/2" board, so the router bit can trim the 1/4" plywood to
> the correct size.
>

The jigs we're discussing adjust for the thickness of the board that
will go into the dado.
If I understand correctly, all your jig does is allow you to line up
perfectly with a marked line, like a circular saw rip guide.


--

-MIKE-

"Playing is not something I do at night, it's my function in life"
--Elvin Jones (1927-2004)
--
http://mikedrums.com
[email protected]
---remove "DOT" ^^^^ to reply

On 12/14/12 12:54 PM, Peter Bennett wrote:
> On Thu, 13 Dec 2012 21:38:15 -0600, -MIKE- <[email protected]>
> wrote:
>
>> On 12/13/12 8:19 PM, Peter Bennett wrote:
>>> My router dado jig doesn't need guide bushings or a top bearing bit -
>>> it guides the router base.
>>>
>>> each side of the guide consists of two pieces - a wide piece of 1/4"
>>> plywood that the router rides on, and a (straight!) piece of 1/2"
>>> plywood, or similar piece of solid wood glued on top.
>>>
>>> Before the first use, run the router along the jig with the base
>>> against the 1/2" board, so the router bit can trim the 1/4" plywood to
>>> the correct size.
>>>
>>
>> The jigs we're discussing adjust for the thickness of the board that
>> will go into the dado.
>> If I understand correctly, all your jig does is allow you to line up
>> perfectly with a marked line, like a circular saw rip guide.
>
> No - my dado jig uses two pieces as described, joined similarly to the
> Woodwhisperer's dado jig, but it uses the router base as the guide,
> rather than requiring a guide bushing or a bearing on the bit. (maybe
> I should take a picture of it, and post it somewhere...)
>

No, I think I understand.
The 1/4" plywood on both sides is what "clamps" tightly around the
material to be inserted into the dado to insure a perfect size.
Correct?

If so, that's a great alternative.


--

-MIKE-

"Playing is not something I do at night, it's my function in life"
--Elvin Jones (1927-2004)
--
http://mikedrums.com
[email protected]
---remove "DOT" ^^^^ to reply

On 12/14/2012 1:54 PM, Peter Bennett wrote:
> On Thu, 13 Dec 2012 21:38:15 -0600, -MIKE- <[email protected]>
> wrote:
>
>> On 12/13/12 8:19 PM, Peter Bennett wrote:
>>> My router dado jig doesn't need guide bushings or a top bearing bit -
>>> it guides the router base.
>>>
>>> each side of the guide consists of two pieces - a wide piece of 1/4"
>>> plywood that the router rides on, and a (straight!) piece of 1/2"
>>> plywood, or similar piece of solid wood glued on top.
>>>
>>> Before the first use, run the router along the jig with the base
>>> against the 1/2" board, so the router bit can trim the 1/4" plywood to
>>> the correct size.
>>>
>>
>> The jigs we're discussing adjust for the thickness of the board that
>> will go into the dado.
>> If I understand correctly, all your jig does is allow you to line up
>> perfectly with a marked line, like a circular saw rip guide.
>
> No - my dado jig uses two pieces as described, joined similarly to the
> Woodwhisperer's dado jig, but it uses the router base as the guide,
> rather than requiring a guide bushing or a bearing on the bit. (maybe
> I should take a picture of it, and post it somewhere...)
>
>
Now that sounds like the idea I had. The two guides are separated by a
distance equal to the diameter of the router base plus the thickness of
the stock to go in the dado, right? The router base rides along one
guide first, then the other? I figured if I did this the first pass
would cut a dado in the pieces that join the two guides together,
thereby giving me registration marks to line up the cut with. The
pattern bit idea sounds even more foolproof though, at least to my
untutored ear.

On 12/14/2012 1:03 PM, Greg Guarino wrote:
> On 12/14/2012 1:54 PM, Peter Bennett wrote:
>> On Thu, 13 Dec 2012 21:38:15 -0600, -MIKE- <[email protected]>
>> wrote:
>>
>>> On 12/13/12 8:19 PM, Peter Bennett wrote:
>>>> My router dado jig doesn't need guide bushings or a top bearing bit -
>>>> it guides the router base.
>>>>
>>>> each side of the guide consists of two pieces - a wide piece of 1/4"
>>>> plywood that the router rides on, and a (straight!) piece of 1/2"
>>>> plywood, or similar piece of solid wood glued on top.
>>>>
>>>> Before the first use, run the router along the jig with the base
>>>> against the 1/2" board, so the router bit can trim the 1/4" plywood to
>>>> the correct size.
>>>>
>>>
>>> The jigs we're discussing adjust for the thickness of the board that
>>> will go into the dado.
>>> If I understand correctly, all your jig does is allow you to line up
>>> perfectly with a marked line, like a circular saw rip guide.
>>
>> No - my dado jig uses two pieces as described, joined similarly to the
>> Woodwhisperer's dado jig, but it uses the router base as the guide,
>> rather than requiring a guide bushing or a bearing on the bit. (maybe
>> I should take a picture of it, and post it somewhere...)
>>
>>
> Now that sounds like the idea I had. The two guides are separated by a
> distance equal to the diameter of the router base plus the thickness of
> the stock to go in the dado, right? The router base rides along one
> guide first, then the other? I figured if I did this the first pass
> would cut a dado in the pieces that join the two guides together,
> thereby giving me registration marks to line up the cut with. The
> pattern bit idea sounds even more foolproof though, at least to my
> untutored ear.

the problem with this is that the bit usually isn't dead center in the
base. if you twist the router on it's trip across the board, you'll get
a wavy edge to the dado.

On 12/14/12 2:20 PM, chaniarts wrote:
> On 12/14/2012 1:03 PM, Greg Guarino wrote:
>> On 12/14/2012 1:54 PM, Peter Bennett wrote:
>>> On Thu, 13 Dec 2012 21:38:15 -0600, -MIKE- <[email protected]>
>>> wrote:
>>>
>>>> On 12/13/12 8:19 PM, Peter Bennett wrote:
>>>>> My router dado jig doesn't need guide bushings or a top bearing bit -
>>>>> it guides the router base.
>>>>>
>>>>> each side of the guide consists of two pieces - a wide piece of 1/4"
>>>>> plywood that the router rides on, and a (straight!) piece of 1/2"
>>>>> plywood, or similar piece of solid wood glued on top.
>>>>>
>>>>> Before the first use, run the router along the jig with the base
>>>>> against the 1/2" board, so the router bit can trim the 1/4" plywood to
>>>>> the correct size.
>>>>>
>>>>
>>>> The jigs we're discussing adjust for the thickness of the board that
>>>> will go into the dado.
>>>> If I understand correctly, all your jig does is allow you to line up
>>>> perfectly with a marked line, like a circular saw rip guide.
>>>
>>> No - my dado jig uses two pieces as described, joined similarly to the
>>> Woodwhisperer's dado jig, but it uses the router base as the guide,
>>> rather than requiring a guide bushing or a bearing on the bit. (maybe
>>> I should take a picture of it, and post it somewhere...)
>>>
>>>
>> Now that sounds like the idea I had. The two guides are separated by a
>> distance equal to the diameter of the router base plus the thickness of
>> the stock to go in the dado, right? The router base rides along one
>> guide first, then the other? I figured if I did this the first pass
>> would cut a dado in the pieces that join the two guides together,
>> thereby giving me registration marks to line up the cut with. The
>> pattern bit idea sounds even more foolproof though, at least to my
>> untutored ear.
>
> the problem with this is that the bit usually isn't dead center in the
> base. if you twist the router on it's trip across the board, you'll get
> a wavy edge to the dado.
>

That's the same for any router, any jig, and it's compounded with guide
bushings.
Most experienced router users know to keep the router in the same
relative position and not rotate during the length of a cut.


--

-MIKE-

"Playing is not something I do at night, it's my function in life"
--Elvin Jones (1927-2004)
--
http://mikedrums.com
[email protected]
---remove "DOT" ^^^^ to reply

Greg Guarino wrote:

> Now that sounds like the idea I had. The two guides are separated by a
> distance equal to the diameter of the router base plus the thickness
> of the stock to go in the dado, right? The router base rides along one
> guide first, then the other? I figured if I did this the first pass
> would cut a dado in the pieces that join the two guides together,
> thereby giving me registration marks to line up the cut with. The
> pattern bit idea sounds even more foolproof though, at least to my
> untutored ear.

You've got it correct Greg, but do yourself a favor and look at the YouTube
videos on these things. You will easily find the type of jig you've
described here as well as other types. I'm not a fan of the pattern bit or
the collar idea, although both represent different approaches to the same
problem. I like the idea of registering the router base agains the guide
rails myself, but I guess that's just opinion.

--

-Mike-
[email protected]

On 12/14/2012 1:24 PM, -MIKE- wrote:
> On 12/14/12 2:20 PM, chaniarts wrote:
>> On 12/14/2012 1:03 PM, Greg Guarino wrote:
>>> On 12/14/2012 1:54 PM, Peter Bennett wrote:
>>>> On Thu, 13 Dec 2012 21:38:15 -0600, -MIKE- <[email protected]>
>>>> wrote:
>>>>
>>>>> On 12/13/12 8:19 PM, Peter Bennett wrote:
>>>>>> My router dado jig doesn't need guide bushings or a top bearing bit -
>>>>>> it guides the router base.
>>>>>>
>>>>>> each side of the guide consists of two pieces - a wide piece of 1/4"
>>>>>> plywood that the router rides on, and a (straight!) piece of 1/2"
>>>>>> plywood, or similar piece of solid wood glued on top.
>>>>>>
>>>>>> Before the first use, run the router along the jig with the base
>>>>>> against the 1/2" board, so the router bit can trim the 1/4"
>>>>>> plywood to
>>>>>> the correct size.
>>>>>>
>>>>>
>>>>> The jigs we're discussing adjust for the thickness of the board that
>>>>> will go into the dado.
>>>>> If I understand correctly, all your jig does is allow you to line up
>>>>> perfectly with a marked line, like a circular saw rip guide.
>>>>
>>>> No - my dado jig uses two pieces as described, joined similarly to the
>>>> Woodwhisperer's dado jig, but it uses the router base as the guide,
>>>> rather than requiring a guide bushing or a bearing on the bit. (maybe
>>>> I should take a picture of it, and post it somewhere...)
>>>>
>>>>
>>> Now that sounds like the idea I had. The two guides are separated by a
>>> distance equal to the diameter of the router base plus the thickness of
>>> the stock to go in the dado, right? The router base rides along one
>>> guide first, then the other? I figured if I did this the first pass
>>> would cut a dado in the pieces that join the two guides together,
>>> thereby giving me registration marks to line up the cut with. The
>>> pattern bit idea sounds even more foolproof though, at least to my
>>> untutored ear.
>>
>> the problem with this is that the bit usually isn't dead center in the
>> base. if you twist the router on it's trip across the board, you'll get
>> a wavy edge to the dado.
>>
>
> That's the same for any router, any jig, and it's compounded with guide
> bushings.
> Most experienced router users know to keep the router in the same
> relative position and not rotate during the length of a cut.
>
>

and if you put the router down in a slightly skewed position on the next
one than the previous one, you don't get a repeatable width dado because
the router base may not be circular.

On 12/15/12 9:30 AM, Greg Guarino wrote:
> On Dec 14, 3:35 pm, Swingman <[email protected]> wrote:
>> On 12/14/2012 2:03 PM, Greg Guarino wrote:
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>> On 12/14/2012 1:54 PM, Peter Bennett wrote:
>>>> On Thu, 13 Dec 2012 21:38:15 -0600, -MIKE- <[email protected]>
>>>> wrote:
>>
>>>>> On 12/13/12 8:19 PM, Peter Bennett wrote:
>>>>>> My router dado jig doesn't need guide bushings or a top bearing bit -
>>>>>> it guides the router base.
>>
>>>>>> each side of the guide consists of two pieces - a wide piece of 1/4"
>>>>>> plywood that the router rides on, and a (straight!) piece of 1/2"
>>>>>> plywood, or similar piece of solid wood glued on top.
>>
>>>>>> Before the first use, run the router along the jig with the base
>>>>>> against the 1/2" board, so the router bit can trim the 1/4" plywood to
>>>>>> the correct size.
>>
>>>>> The jigs we're discussing adjust for the thickness of the board that
>>>>> will go into the dado.
>>>>> If I understand correctly, all your jig does is allow you to line up
>>>>> perfectly with a marked line, like a circular saw rip guide.
>>
>>>> No - my dado jig uses two pieces as described, joined similarly to the
>>>> Woodwhisperer's dado jig, but it uses the router base as the guide,
>>>> rather than requiring a guide bushing or a bearing on the bit. (maybe
>>>> I should take a picture of it, and post it somewhere...)
>>
>>> Now that sounds like the idea I had. The two guides are separated by a
>>> distance equal to the diameter of the router base plus the thickness of
>>> the stock to go in the dado, right? The router base rides along one
>>> guide first, then the other? I figured if I did this the first pass
>>> would cut a dado in the pieces that join the two guides together,
>>> thereby giving me registration marks to line up the cut with. The
>>> pattern bit idea sounds even more foolproof though, at least to my
>>> untutored ear.
>>
>> All basically the same principle ... the edge of the router plate in
>> this one takes the place of the bearing in the top bearing bit method,
>> or the edge of the guide bushing in the other method.
>>
>> IMO, the problem with the all the router methods boils down to the use
>> of a wooden jig, which is prone to the dimensional instability of wood;
>> and/or the concentricity of a router plate; either with the potential to
>> effect accuracy over time.
>
> How often do we get to use the word "concentricity" in a sentence?
> Google groups even puts a squiggly line under it. :)
>
> I don't have the table saw option. But I was wondering about both of
> those potential problems too. I think that the small imperfection
> would probably not be out of place when compared with my general level
> of work (sigh), but I'd be perfectly happy to avoid it. I wonder if I
> couldn't make the edges that the bearing rides on out of something
> more "dimensionally stable"; maybe strips of aluminum set into slots
> (or rabbets) in both guide edges, just a little proud of the wood
> edge.
>

I think, as others have also suggested, the best bet is a bearing bit
with a plywood jig.
A strip of hardwood for the nearing to ride against insures a smoother
surface. This type of jig only needs to be dimensionally stable from the
time you clamp it down until the time your cut the dadoes. :-)

Of course there's always the option of using a couple of these guide
clamps with a bearing bit....
http://www.rockler.com/product.cfm?page=25134
Use the first one to clamp along a marked line on one side of the dado,
using squaring attachment blocks. Use the second one to "sandwich" the
material that will go into the dado, clamping against the squaring
blocks of the first guide clamp. Cut the dadoes, running the router
along the flat tops of both guide clamps.


--

-MIKE-

"Playing is not something I do at night, it's my function in life"
--Elvin Jones (1927-2004)
--
http://mikedrums.com
[email protected]
---remove "DOT" ^^^^ to reply

-MIKE- wrote:

> Of course there's always the option of using a couple of these guide
> clamps with a bearing bit....
> http://www.rockler.com/product.cfm?page=25134

I see that those are "new & improved". I hope so. I bought a couple years
ago, used them once and have never used them again. Why? Because they
deflected. Even with modest sideways pressure from the router base.

--

dadiOH
____________________________

Winters getting colder? Tired of the rat race?
Maybe just ready for a change? Check it out...
http://www.floridaloghouse.net

Greg Guarino wrote:

>> IMO, the problem with the all the router methods boils down to the
>> use of a wooden jig, which is prone to the dimensional instability
>> of wood; and/or the concentricity of a router plate; either with the
>> potential to effect accuracy over time.
>
> How often do we get to use the word "concentricity" in a sentence?
> Google groups even puts a squiggly line under it. :)
>
> I don't have the table saw option. But I was wondering about both of
> those potential problems too. I think that the small imperfection
> would probably not be out of place when compared with my general level
> of work (sigh), but I'd be perfectly happy to avoid it. I wonder if I
> couldn't make the edges that the bearing rides on out of something
> more "dimensionally stable"; maybe strips of aluminum set into slots
> (or rabbets) in both guide edges, just a little proud of the wood
> edge.

Somewhere out there exists a great forest. The trees are getting in the
way.

Greg, your jig will work just fine as is. I would worry more about being
abducted by aliens from outer space than I would about the dimensional
stability of the ply in your jig. Hell, you are making a dado *IN* plywood.
How about the stability of that? We are working wood and there is a pretty
fair amount of leeway.

Ditto any lack of concentricity in the router base plate. If it is out of
round, make one that *does* have the bit centered. Or a square one.

There is something to be said for square as each side can be at a different
distance from the center. If one side is, say, 1/16 different it becomes
easy to make a cut that is 7/16 or 9/16 or whatever without having to have a
bit that size. Same thing for 1/8. And if you need a way to take off just
a skosh from something, 1/64. Or less.

--

dadiOH
____________________________

Winters getting colder? Tired of the rat race?
Maybe just ready for a change? Check it out...
http://www.floridaloghouse.net

On 12/15/12 1:00 PM, Swingman wrote:
> On 12/15/2012 10:57 AM, -MIKE- wrote:
>>
>> I think, as others have also suggested, the best bet is a bearing bit
>> with a plywood jig.
>> A strip of hardwood for the nearing to ride against insures a smoother
>> surface. This type of jig only needs to be dimensionally stable from the
>> time you clamp it down until the time your cut the dadoes. :-)
>
> Don't ignore Murphy ... she always strikes somewhere around the next to
> the last one.
>
> (That's right, "she" ... nothing but a female could be that heartless to
> your last piece of irreplaceable $tock)
>

+1


--

-MIKE-

"Playing is not something I do at night, it's my function in life"
--Elvin Jones (1927-2004)
--
http://mikedrums.com
[email protected]
---remove "DOT" ^^^^ to reply

On 12/15/12 1:35 PM, dadiOH wrote:
> -MIKE- wrote:
>
>> Of course there's always the option of using a couple of these guide
>> clamps with a bearing bit....
>> http://www.rockler.com/product.cfm?page=25134
>
> I see that those are "new & improved". I hope so. I bought a couple years
> ago, used them once and have never used them again. Why? Because they
> deflected. Even with modest sideways pressure from the router base.
>

Yes, not all of those are the same. I just used that page as an example
of what I was talking about.
I had issues with them developing a "memory" at locations one might
often, repeatedly clamp, like say, 24" and 36", making it difficult to
adjust slightly away from the often used spot.

I've seen some from other suppliers that are much more rigid, sideways.


--

-MIKE-

"Playing is not something I do at night, it's my function in life"
--Elvin Jones (1927-2004)
--
http://mikedrums.com
[email protected]
---remove "DOT" ^^^^ to reply

On Fri, 14 Dec 2012 13:09:45 -0600, -MIKE- <[email protected]>
wrote:

>On 12/14/12 12:54 PM, Peter Bennett wrote:
>> On Thu, 13 Dec 2012 21:38:15 -0600, -MIKE- <[email protected]>
>> wrote:
>>
>>> On 12/13/12 8:19 PM, Peter Bennett wrote:
>>>> My router dado jig doesn't need guide bushings or a top bearing bit -
>>>> it guides the router base.
>>>>
>>>> each side of the guide consists of two pieces - a wide piece of 1/4"
>>>> plywood that the router rides on, and a (straight!) piece of 1/2"
>>>> plywood, or similar piece of solid wood glued on top.
>>>>
>>>> Before the first use, run the router along the jig with the base
>>>> against the 1/2" board, so the router bit can trim the 1/4" plywood to
>>>> the correct size.
>>>>
>>>
>>> The jigs we're discussing adjust for the thickness of the board that
>>> will go into the dado.
>>> If I understand correctly, all your jig does is allow you to line up
>>> perfectly with a marked line, like a circular saw rip guide.
>>
>> No - my dado jig uses two pieces as described, joined similarly to the
>> Woodwhisperer's dado jig, but it uses the router base as the guide,
>> rather than requiring a guide bushing or a bearing on the bit. (maybe
>> I should take a picture of it, and post it somewhere...)
>>
>
>No, I think I understand.
>The 1/4" plywood on both sides is what "clamps" tightly around the
>material to be inserted into the dado to insure a perfect size.
>Correct?
>
>If so, that's a great alternative.

Yes - photos now posted:
http://www3.telus.net/peterbb/dado_jig1.jpg
http://www3.telus.net/peterbb/dado_jig4.jpg

There may be a slight problem with this if the bit is not centered in
the base - but if you don't turn the router as you slide it along,
this shouldn't be a problem. The B&D router I use with this jig has
two flat sides on the base, so I can't turn it too far without ruining
everything anyway...


--
Peter Bennett, VE7CEI
peterbb (at) telus.net
GPS and NMEA info: http://vancouver-webpages.com/peter
Vancouver Power Squadron: http://vancouver.powersquadron.ca

On Thu, 13 Dec 2012 16:02:25 -0500, Greg Guarino <[email protected]>
wrote:

>On 12/13/2012 2:16 PM, Lew Hodgett wrote:
>>> I have some ideas. Let's see how stupid they are.
>> ---------------------------------------------------------------
>> Not stupid at all.
>>
>> Either build the jig shown on U-tube
>
>Wow. I finally got a moment to look at this (I skipped to the end) and
>it is remarkably similar to what I had envisioned, minus the
>adjustability and the collar. I don't have a collar, nor do I think my
>router will easily accept one without an adapter. I'd probably give the
>top-guide bit a whirl.
>
>As for adjustability, I've got to think on that. I'm an occasional
>weekend dabbler with much less time than I would like. I could screw the
>thing together at a a fixed width much more quickly (although I have to
>say, using a clamp while setting the width looks like a great idea).
>Shortsighted? I guess so. And I'll have to kick myself if I don't get it
>right the first time.
>
>I'll think about it.
>
>Thanks.

My router dado jig doesn't need guide bushings or a top bearing bit -
it guides the router base.

each side of the guide consists of two pieces - a wide piece of 1/4"
plywood that the router rides on, and a (straight!) piece of 1/2"
plywood, or similar piece of solid wood glued on top.

Before the first use, run the router along the jig with the base
against the 1/2" board, so the router bit can trim the 1/4" plywood to
the correct size.


--
Peter Bennett, VE7CEI
peterbb (at) telus.net
GPS and NMEA info: http://vancouver-webpages.com/peter
Vancouver Power Squadron: http://vancouver.powersquadron.ca

On 12/15/2012 10:57 AM, -MIKE- wrote:
>
> I think, as others have also suggested, the best bet is a bearing bit
> with a plywood jig.
> A strip of hardwood for the nearing to ride against insures a smoother
> surface. This type of jig only needs to be dimensionally stable from the
> time you clamp it down until the time your cut the dadoes. :-)

Don't ignore Murphy ... she always strikes somewhere around the next to
the last one.

(That's right, "she" ... nothing but a female could be that heartless to
your last piece of irreplaceable $tock)

--
eWoodShop: www.eWoodShop.com
Wood Shop: www.e-WoodShop.net
https://plus.google.com/114902129577517371552/posts
KarlCaillouet@ (the obvious)

On Thu, 13 Dec 2012 21:38:15 -0600, -MIKE- <[email protected]>
wrote:

>On 12/13/12 8:19 PM, Peter Bennett wrote:
>> My router dado jig doesn't need guide bushings or a top bearing bit -
>> it guides the router base.
>>
>> each side of the guide consists of two pieces - a wide piece of 1/4"
>> plywood that the router rides on, and a (straight!) piece of 1/2"
>> plywood, or similar piece of solid wood glued on top.
>>
>> Before the first use, run the router along the jig with the base
>> against the 1/2" board, so the router bit can trim the 1/4" plywood to
>> the correct size.
>>
>
>The jigs we're discussing adjust for the thickness of the board that
>will go into the dado.
>If I understand correctly, all your jig does is allow you to line up
>perfectly with a marked line, like a circular saw rip guide.

No - my dado jig uses two pieces as described, joined similarly to the
Woodwhisperer's dado jig, but it uses the router base as the guide,
rather than requiring a guide bushing or a bearing on the bit. (maybe
I should take a picture of it, and post it somewhere...)


--
Peter Bennett, VE7CEI
peterbb (at) telus.net
GPS and NMEA info: http://vancouver-webpages.com/peter
Vancouver Power Squadron: http://vancouver.powersquadron.ca

On 12/14/2012 2:03 PM, Greg Guarino wrote:
> On 12/14/2012 1:54 PM, Peter Bennett wrote:
>> On Thu, 13 Dec 2012 21:38:15 -0600, -MIKE- <[email protected]>
>> wrote:
>>
>>> On 12/13/12 8:19 PM, Peter Bennett wrote:
>>>> My router dado jig doesn't need guide bushings or a top bearing bit -
>>>> it guides the router base.
>>>>
>>>> each side of the guide consists of two pieces - a wide piece of 1/4"
>>>> plywood that the router rides on, and a (straight!) piece of 1/2"
>>>> plywood, or similar piece of solid wood glued on top.
>>>>
>>>> Before the first use, run the router along the jig with the base
>>>> against the 1/2" board, so the router bit can trim the 1/4" plywood to
>>>> the correct size.
>>>>
>>>
>>> The jigs we're discussing adjust for the thickness of the board that
>>> will go into the dado.
>>> If I understand correctly, all your jig does is allow you to line up
>>> perfectly with a marked line, like a circular saw rip guide.
>>
>> No - my dado jig uses two pieces as described, joined similarly to the
>> Woodwhisperer's dado jig, but it uses the router base as the guide,
>> rather than requiring a guide bushing or a bearing on the bit. (maybe
>> I should take a picture of it, and post it somewhere...)
>>
>>
> Now that sounds like the idea I had. The two guides are separated by a
> distance equal to the diameter of the router base plus the thickness of
> the stock to go in the dado, right? The router base rides along one
> guide first, then the other? I figured if I did this the first pass
> would cut a dado in the pieces that join the two guides together,
> thereby giving me registration marks to line up the cut with. The
> pattern bit idea sounds even more foolproof though, at least to my
> untutored ear.

All basically the same principle ... the edge of the router plate in
this one takes the place of the bearing in the top bearing bit method,
or the edge of the guide bushing in the other method.

IMO, the problem with the all the router methods boils down to the use
of a wooden jig, which is prone to the dimensional instability of wood;
and/or the concentricity of a router plate; either with the potential to
effect accuracy over time.

With the router methods, and having tried them all, the top bearing bit
gave me the most accurate (but I'd want to joint those two guide edges
for starters when making the jig) and, because of wood's eventual
instability, or Murphy biting me in the ass, I found myself having to
re-make said jigs over time.

The latter being why I much prefer doing dadoes and rabbets on the TS
with my Freud Dial-a-Width dado stack, particularly if doing more than a
one-off piece. :)

--
eWoodShop: www.eWoodShop.com
Wood Shop: www.e-WoodShop.net
https://plus.google.com/114902129577517371552/posts
KarlCaillouet@ (the obvious)