s

30/08/2003 8:54 PM

Dovetail bit not centered in baseplate

Hi,

I'm wondering if anyone can help me? I recently tried to use a
dovetail jig and found that my dovetail joints were consistently
sloppy on one side of the pin by about 1/16". Everything else fit
snuggly when viewed from the side but at the top of each pin there was
this 1/16" gap. (and, yes, I tried extending the bit a little but the
joint was still sloppy)

After checking everything out, I've concluded that because the bit is
off-center in the guide bushing, the bit is allowed to travel a little
deeper on one side of the cut. Looking at the bit in the bushing, it
is obvious that this is where my slop is coming in.

I removed the bushing and checked the distance from the bit to the
edge of the baseplate and then checked the opposite side. There is a
1/16" difference. I tried removing all the screws and rotating the
baseplate clockwise a couple of times, but the results are still
pretty much the same. (oh, sorry, didn't mention that I am using a
Porter-Cable 690 series router with the stock baseplate) I also tried
using a baseplate from my plunge router base. Almost the same
results. I would have thought that PC would have better tolerances
than that. Anyway, can you think of any way to correct this problem
so that I can use my dovetail jig?

Could I use a bearing in lieu of the guide bushing? My jig requires a
7/16" O.D. bushing so if a bearing is a possibility, do they come in
that size? What would hold the bearing on the shaft?

I'm a newbie to woodworking and not at all comfortable with the idea
of trying to make a new baseplate at this point. I'd just be happy to
be able to use my jig to make the drawers for the router table I'm
building. I know a little further on in the process I'll be pretty
much forced to make a baseplate for the table, but I'm just working on
little steps at a time. :)

Thanks,
Sandy


This topic has 8 replies

pR

[email protected] (Routerman P. Warner)

in reply to [email protected] on 30/08/2003 8:54 PM

31/08/2003 7:02 AM

Some information on the collar/cutter centricity issue at the
http://www.patwarner.com/collarguide.html link. A very common problem.
Suspect your error is more like a 1/32nd x 2. As bad as it may seem,
doing a 180 with the router when the work is indexed on the right side
of the jig may cancel all of the error. Try sample on scrap.
******************************************************************
> Hi,
>
> I'm wondering if anyone can help me? I recently tried to use a
> dovetail jig and found that my dovetail joints were consistently
> sloppy on one side of the pin by about 1/16". Everything else fit
> snuggly when viewed from the side but at the top of each pin there was
> this 1/16" gap. (and, yes, I tried extending the bit a little but the
> joint was still sloppy)
>
> After checking everything out, I've concluded that because the bit is
> off-center in the guide bushing, the bit is allowed to travel a little
> deeper on one side of the cut. Looking at the bit in the bushing, it
> is obvious that this is where my slop is coming in.
>
> I removed the bushing and checked the distance from the bit to the
> edge of the baseplate and then checked the opposite side. There is a
> 1/16" difference. I tried removing all the screws and rotating the
> baseplate clockwise a couple of times, but the results are still
> pretty much the same. (oh, sorry, didn't mention that I am using a
> Porter-Cable 690 series router with the stock baseplate) I also tried
> using a baseplate from my plunge router base. Almost the same
> results. I would have thought that PC would have better tolerances
> than that. Anyway, can you think of any way to correct this problem
> so that I can use my dovetail jig?
>
> Could I use a bearing in lieu of the guide bushing? My jig requires a
> 7/16" O.D. bushing so if a bearing is a possibility, do they come in
> that size? What would hold the bearing on the shaft?
>
> I'm a newbie to woodworking and not at all comfortable with the idea
> of trying to make a new baseplate at this point. I'd just be happy to
> be able to use my jig to make the drawers for the router table I'm
> building. I know a little further on in the process I'll be pretty
> much forced to make a baseplate for the table, but I'm just working on
> little steps at a time. :)
>
> Thanks,
> Sandy

LH

"Lowell Holmes"

in reply to [email protected] on 30/08/2003 8:54 PM

31/08/2003 8:54 AM

I did everything mentioned in this string. I ended up purchasing a DW 610
for my dovetail work. It solved all my problems. :-)
I only use my 690 in a router table these days, along with a foot switch for
safety.

<[email protected]> wrote in message
news:[email protected]...
> Hi,
>
> I'm wondering if anyone can help me? I recently tried to use a
> dovetail jig and found that my dovetail joints were consistently
> sloppy on one side of the pin by about 1/16". Everything else fit
>snip

Gs

"George"

in reply to [email protected] on 30/08/2003 8:54 PM

31/08/2003 11:29 AM

If that'll do it. I used a carving gouge, though you might do as well with
a Dremel-mounted rotary file.

<[email protected]> wrote in message
news:[email protected]...
> >The counterbores are usually enough oversize; a bit of scraping might be
> >necessary if they're not.
>
> It seems to me that those counterbores are what pull the baseplate out
> of alignment. What do you scrap them with? A small knife?
>
> Sandy
>

Sk

"Swingman"

in reply to [email protected] on 30/08/2003 8:54 PM

30/08/2003 9:48 PM

Are you rotating the router when you use it? Try to keep the orientation the
same at all times. It's a good idea to mark one side of the baseplate with a
marking pen and always keep the mark facing you. Also, you will want to
remove the three baseplate screws and try rotating the baseplate over one
set of holes at a time until you find the holes that get the bit closer to
center.

You rarely find a 690 that is dead-on concentric, but if you get it close,
and always orient the router the same way, you should be able to get better
cuts than you are getting on your jig.

--
www.e-woodshop.net
Last update: 8/24/03

wrote in message
> Hi,

> After checking everything out, I've concluded that because the bit is
> off-center in the guide bushing, the bit is allowed to travel a little
> deeper on one side of the cut. Looking at the bit in the bushing, it
> is obvious that this is where my slop is coming in.

s

in reply to [email protected] on 30/08/2003 8:54 PM

30/08/2003 10:21 PM

On Sat, 30 Aug 2003 21:48:51 GMT, "Swingman" <[email protected]> wrote:

>Are you rotating the router when you use it?

No

Also, you will want to
>remove the three baseplate screws and try rotating the baseplate over one
>set of holes at a time until you find the holes that get the bit closer to
>center.

Tried that with very little change in the results.

>
>You rarely find a 690 that is dead-on concentric, but if you get it close,
>and always orient the router the same way, you should be able to get better
>cuts than you are getting on your jig.

This advice will work well in general but when using a guide bushing
it doesn't help that much because when you are routing down a 1/2"
pair of dovetail fingers on a template, you can't really keep the same
edge against the pattern.

Thanks for your reply,
Sandy

s

in reply to [email protected] on 30/08/2003 8:54 PM

30/08/2003 10:22 PM

On Sat, 30 Aug 2003 22:14:55 GMT, "George"
<[email protected]> wrote:

>Most of us have been confronted by your problem, I'm sure. In my case, I
>did some modification of the holes in the plastic baseplate. Doesn't take
>much (1/32) to compensate. Makes it necessary to check concentricity every
>time thereafter, but you've seen that the results will justify the effort.
>The counterbores are usually enough oversize; a bit of scraping might be
>necessary if they're not.

It seems to me that those counterbores are what pull the baseplate out
of alignment. What do you scrap them with? A small knife?

Sandy

Rd

Rich

in reply to [email protected] on 30/08/2003 8:54 PM

31/08/2003 6:53 AM

Swingman wrote, wondering if this is really what he meant?

> You rarely find a 690 that is dead-on concentric, but if you get it close,
> and always orient the router the same way, you should be able to get
> better cuts than you are getting on your jig.

You'd think that one of the top of the line routers, (Porta Cable) could get
a measurement right! Sure doesnt say much about Porta Cable when it comes
to getting their baseplates in line. Makes me a little leary about my next
purchase.

Rich
--
You can lead them to LINUX
but you can't make them THINK.
Atten: Micro$oft Outlook users, please take me
off of your address books!
Email, remove the DOT

Gs

"George"

in reply to [email protected] on 30/08/2003 8:54 PM

30/08/2003 10:14 PM

Most of us have been confronted by your problem, I'm sure. In my case, I
did some modification of the holes in the plastic baseplate. Doesn't take
much (1/32) to compensate. Makes it necessary to check concentricity every
time thereafter, but you've seen that the results will justify the effort.
The counterbores are usually enough oversize; a bit of scraping might be
necessary if they're not.

<[email protected]> wrote in message
news:[email protected]...
> Hi,
>
> I'm wondering if anyone can help me? I recently tried to use a
> dovetail jig and found that my dovetail joints were consistently
> sloppy on one side of the pin by about 1/16". Everything else fit
> snuggly when viewed from the side but at the top of each pin there was
> this 1/16" gap. (and, yes, I tried extending the bit a little but the
> joint was still sloppy)
>
> After checking everything out, I've concluded that because the bit is
> off-center in the guide bushing, the bit is allowed to travel a little
> deeper on one side of the cut. Looking at the bit in the bushing, it
> is obvious that this is where my slop is coming in.
>
> I removed the bushing and checked the distance from the bit to the
> edge of the baseplate and then checked the opposite side. There is a
> 1/16" difference. I tried removing all the screws and rotating the
> baseplate clockwise a couple of times, but the results are still
> pretty much the same. (oh, sorry, didn't mention that I am using a
> Porter-Cable 690 series router with the stock baseplate) I also tried
> using a baseplate from my plunge router base. Almost the same
> results. I would have thought that PC would have better tolerances
> than that. Anyway, can you think of any way to correct this problem
> so that I can use my dovetail jig?
>
> Could I use a bearing in lieu of the guide bushing? My jig requires a
> 7/16" O.D. bushing so if a bearing is a possibility, do they come in
> that size? What would hold the bearing on the shaft?
>
> I'm a newbie to woodworking and not at all comfortable with the idea
> of trying to make a new baseplate at this point. I'd just be happy to
> be able to use my jig to make the drawers for the router table I'm
> building. I know a little further on in the process I'll be pretty
> much forced to make a baseplate for the table, but I'm just working on
> little steps at a time. :)
>
> Thanks,
> Sandy


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