Gg

GerryG

15/09/2004 4:35 AM

Plywood - mdf or lumber core

I've only used lumber core plywood before, but will be needing about 15 sheets
of 3/4 ash for a rather large project. The question is do I use the cheaper
mdf core or pay more for the lighter lumber core. I believe the mfd is more
stable in size and should be free of voids, but may have less holding power
for screws. Also interested in just how much of a weight difference I'll have.
GerryG


This topic has 12 replies

AB

"Alan Bierbaum"

in reply to GerryG on 15/09/2004 4:35 AM

15/09/2004 8:04 AM

I used to do kitchens for a living (still work there part time). After
several hundred kitchens with MDF ply; we switched to veneer core because of
the weight of MDF. The MDF core is flatter and more uniform in thickness.
The extra weight is a killer, both in raw stock and finished product. We
did not use screws for primary joining; so can not comment on screw holding
power.

--
Alan Bierbaum

Web Site: http://www.calanb.com
Current project: http://home.comcast.net/~cabierbaum/

"GerryG" <[email protected]> wrote in message
news:[email protected]...
> I've only used lumber core plywood before, but will be needing about 15
sheets
> of 3/4 ash for a rather large project. The question is do I use the
cheaper
> mdf core or pay more for the lighter lumber core. I believe the mfd is
more
> stable in size and should be free of voids, but may have less holding
power
> for screws. Also interested in just how much of a weight difference I'll
have.
> GerryG

Gg

GerryG

in reply to GerryG on 15/09/2004 4:35 AM

16/09/2004 4:27 PM

Just got a response elsewhere with 60-70 for lumber core, and 100 for MDF, so
that's consistant with your figures. For ash ply, we're looking at prices of
about 71 for lumber core, and 61 for MDF. I'm tending towards lumber core, but
need to find out which of several types they have, and maybe see a sample to
get a better idea about the voids and dimension. Have yet to check if it's
rotary cut or not, and that could be a big issue with ash in matching the
lumber pieces.

I think the next project's going to be a sheet goods lumber rack to hold this
stuff. If I get lucky, my new shop may be ready in time, and I'll actually
have the room to cut all this stuff. At least this project's big enough that
it was worth buying a copy of CutList to handle the cutting patterns.

Thanks for the help Pat (and Alan and Patriarch),
GerryG

On Thu, 16 Sep 2004 14:47:44 GMT, Pat Barber <[email protected]>
wrote:

>A 3/4" panel of mdf comes in "about" 90lbs. The veneer would
>add a "wee bit" to that.
>
>A 3/4" panel of oak veneer plywood comes in "about"
>70 lbs.
>
>That will vary according to the species used
>as the "inner veneers". SYP plywood is a little heavier
>than plywood made from poplar. Birch plywood is in
>the 60-70 lbs category.
>
>
>
>GerryG wrote:
>
>> Any idea how much of a difference there is? I've heard both, but am trying to
>> get an idea of how much. Is the weight maybe double? Any idea how much
>> thickness variation?
>>
>> Not having a panel saw, it's going to be tough getting exact dimensions
>> cutting it on the floor with a circular saw and guide, but even the lumber
>> core's probably too heavy to handle on a table saw. Even if cut in half, I'm
>> wondering if the mdf core's still to heavy for the table saw. Some of the
>> panels are 84x26".
>>
>> GerryG
>>
>>
>> On Wed, 15 Sep 2004 08:04:09 -0600, "Alan Bierbaum"
>> <[email protected]> wrote:
>>
>>
>>>I used to do kitchens for a living (still work there part time). After
>>>several hundred kitchens with MDF ply; we switched to veneer core because of
>>>the weight of MDF. The MDF core is flatter and more uniform in thickness.
>>>The extra weight is a killer, both in raw stock and finished product. We
>>>did not use screws for primary joining; so can not comment on screw holding
>>>power.

SI

"Slowhand"

in reply to GerryG on 15/09/2004 4:35 AM

15/09/2004 9:04 AM


"GerryG" <[email protected]> wrote in message
news:[email protected]...
> I've only used lumber core plywood before, but will be needing about 15
sheets
> of 3/4 ash for a rather large project. The question is do I use the
cheaper
> mdf core or pay more for the lighter lumber core. I believe the mfd is
more
> stable in size and should be free of voids, but may have less holding
power
> for screws. Also interested in just how much of a weight difference I'll
have.

I typically use the lumber core for stuff over 1/2" mostly because of
weight. For the stuff under 1/2", I like the mdf core because it seems to
be flatter and more dimensionally routine.
SH

AB

"Alan Bierbaum"

in reply to GerryG on 15/09/2004 4:35 AM

16/09/2004 10:31 AM

Looks like Pat has the exact figures on weight. The weight problem is that
you move or lift that extra 20-30 pounds many times during the process of
building and installing the cabinets. I would build the cabinets one week
and then rip out the old cabinets and install the new ones the next week
(that is a lot of lifting and moving) for a complete kitchen. I did use a
panel cutter (industrial vertical/horizontal cuts), table saw with a 10' x
10' table area for support and a panel router. In my personal shop, I would
not be able to produce at this rate. Any cabinet saw (with some kind of
rollers/supports) can support the weight of 3/4" plywood for cutting. Build
support tables/rollers and make sure that you have room to move the sheet
around without bumping into anything and you should not have problems other
than guiding the sheet through the saw.

--
Alan Bierbaum

Web Site: http://www.calanb.com
Current project: http://home.comcast.net/~cabierbaum/

"Pat Barber" <[email protected]> wrote in message
news:[email protected]...
> A 3/4" panel of mdf comes in "about" 90lbs. The veneer would
> add a "wee bit" to that.
>
> A 3/4" panel of oak veneer plywood comes in "about"
> 70 lbs.
>
> That will vary according to the species used
> as the "inner veneers". SYP plywood is a little heavier
> than plywood made from poplar. Birch plywood is in
> the 60-70 lbs category.
>
>
>
> GerryG wrote:
>
> > Any idea how much of a difference there is? I've heard both, but am
trying to
> > get an idea of how much. Is the weight maybe double? Any idea how much
> > thickness variation?
> >
> > Not having a panel saw, it's going to be tough getting exact dimensions
> > cutting it on the floor with a circular saw and guide, but even the
lumber
> > core's probably too heavy to handle on a table saw. Even if cut in half,
I'm
> > wondering if the mdf core's still to heavy for the table saw. Some of
the
> > panels are 84x26".
> >
> > GerryG
> >
> >

PB

Pat Barber

in reply to GerryG on 15/09/2004 4:35 AM

16/09/2004 8:44 PM

I have a HUGE outfeed table that allows a full sheet
to be cut and all of it to be on the table but I
am not man enough to lift and control a full sheet.
(OK ..I can do a sheet of 1/4" and maybe a 1/2")

I trim my sheets on a set of horses and a straight edge
guide with a circular saw. I cut oversize and trim it
back on the table saw.

Here is my saw with the end extension folded down. There is
another 36" of outfeed.

http://home.att.net/~mboceanside/wsb/html/view.cgi-photo.html--SiteID-638867.html

Here is the "full monty":

http://home.att.net/~mboceanside/wsb/html/view.cgi-photo.html--SiteID-639331.html

I would "kill" for a full blown panel saw.


Alan Bierbaum wrote:

Any cabinet saw (with some kind of
> rollers/supports) can support the weight of 3/4" plywood for cutting. Build
> support tables/rollers and make sure that you have room to move the sheet
> around without bumping into anything and you should not have problems other
> than guiding the sheet through the saw.

pp

patriarch <[email protected]>

in reply to GerryG on 15/09/2004 4:35 AM

16/09/2004 3:02 PM

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

> Any idea how much of a difference there is? I've heard both, but am
> trying to get an idea of how much. Is the weight maybe double? Any
> idea how much thickness variation?
>
> Not having a panel saw, it's going to be tough getting exact
> dimensions cutting it on the floor with a circular saw and guide, but
> even the lumber core's probably too heavy to handle on a table saw.
> Even if cut in half, I'm wondering if the mdf core's still to heavy
> for the table saw. Some of the panels are 84x26".
>
IIRC, the difference in weight is maybe 20%, not half. Shopnotes or
Woodsmith had something on this, but I don't recall when. (I often run
across older ones, and lose track of when they were published.)

I don't know that you could make a generalisation as to thickness
variation. Lots of sources, thicknesses and grades. A professional
supplier should be your friend here.

As to cutting on the floor: I don't bend that way as well as I used to.
So I built a frame of 2x4's, topped with 1/2" ply, and set it up on
sawhorses in my driveway, for my last large cabinet assembly project. When
done, everything was unscrewed for storage. Next time, I'll likely forego
the plywood 'decking', and have more clamping available.

You may also want to ask about the availability of material in sizes other
than 48"x96". These might make life easier for you.

Patriarch

pp

patriarch <[email protected]>

in reply to GerryG on 15/09/2004 4:35 AM

16/09/2004 9:10 PM

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

<snippage>
>
> At this point, as my knees are no better than Patriarch's back, I may
> go to an abbreviated panel saw: a shelf to hold the wood, and a
> squared guide, similar to what you'd use horizontally. You can build
> it from a few 2x4s, and square with a measure. When you don't have to
> reach or crawl over the board, it's much easier to keep the saw steady
> against the guide. GerryG

Think clamping guide, similar to the one in Rockler's ad this week. I've
seen them 8' long, with the ability to join smaller ones together. The saw
sled is up to you. Or better yet,

http://www.festools.com/festool_product.asp?ProductID=FD490-736

Patriarch

Gg

GerryG

in reply to GerryG on 15/09/2004 4:35 AM

16/09/2004 10:39 PM

Pat,
I've got a smaller saw, but similar outfeed and extension tables. From
experience, I'll completely-utterly-fully agree with your comments.

Patriarch,
That's nice but designed for Festool only. The problem with most of the simple
guides is they only give you a single edge, and it's hard to keep even
pressure over that distance. That Festool seems to address that issue. There's
also a more general kit at
http://www.sawtrax.com/Page3.html though it's twice as much. The best/cheapest
I've seen is http://www.woodsmithstore.com/panelsawkit.html , and their
quality is usually pretty good.This project is large enough that I'm trying to
talk SWMBO into a 20% tool budget which would cover that panel saw kit, and
resolve most of the cutting issues.

GerryG

On Thu, 16 Sep 2004 21:10:34 GMT, patriarch
<<patriarch>[email protected]> wrote:

>GerryG <[email protected]> wrote in
>news:[email protected]:
>
><snippage>
>>
>> At this point, as my knees are no better than Patriarch's back, I may
>> go to an abbreviated panel saw: a shelf to hold the wood, and a
>> squared guide, similar to what you'd use horizontally. You can build
>> it from a few 2x4s, and square with a measure. When you don't have to
>> reach or crawl over the board, it's much easier to keep the saw steady
>> against the guide. GerryG
>
>Think clamping guide, similar to the one in Rockler's ad this week. I've
>seen them 8' long, with the ability to join smaller ones together. The saw
>sled is up to you. Or better yet,
>
>http://www.festools.com/festool_product.asp?ProductID=FD490-736
>
>Patriarch

><< Pat Barber wrote:>>
>I have a HUGE outfeed table that allows a full sheet
>to be cut and all of it to be on the table but I
>am not man enough to lift and control a full sheet.
>(OK ..I can do a sheet of 1/4" and maybe a 1/2")
>
>I trim my sheets on a set of horses and a straight edge
>guide with a circular saw. I cut oversize and trim it
>back on the table saw.

JB

Jim Behning

in reply to GerryG on 15/09/2004 4:35 AM

15/09/2004 1:06 PM

Google is your friend.

http://www.lungster.com/l/speakers/mdffaq/mdf.html

GerryG <[email protected]> wrote:

>I've only used lumber core plywood before, but will be needing about 15 sheets
>of 3/4 ash for a rather large project. The question is do I use the cheaper
>mdf core or pay more for the lighter lumber core. I believe the mfd is more
>stable in size and should be free of voids, but may have less holding power
>for screws. Also interested in just how much of a weight difference I'll have.
>GerryG

Gg

GerryG

in reply to GerryG on 15/09/2004 4:35 AM

16/09/2004 1:55 PM

Any idea how much of a difference there is? I've heard both, but am trying to
get an idea of how much. Is the weight maybe double? Any idea how much
thickness variation?

Not having a panel saw, it's going to be tough getting exact dimensions
cutting it on the floor with a circular saw and guide, but even the lumber
core's probably too heavy to handle on a table saw. Even if cut in half, I'm
wondering if the mdf core's still to heavy for the table saw. Some of the
panels are 84x26".

GerryG


On Wed, 15 Sep 2004 08:04:09 -0600, "Alan Bierbaum"
<[email protected]> wrote:

>I used to do kitchens for a living (still work there part time). After
>several hundred kitchens with MDF ply; we switched to veneer core because of
>the weight of MDF. The MDF core is flatter and more uniform in thickness.
>The extra weight is a killer, both in raw stock and finished product. We
>did not use screws for primary joining; so can not comment on screw holding
>power.

Gg

GerryG

in reply to GerryG on 15/09/2004 4:35 AM

16/09/2004 8:29 PM

Alan, it's not holding the weight itself that's the table saw issue, but more
a torque problem. I had extension and outfeed tables of melamine, with infeed
support and an outfeed roller. The 4x8-3/4 sheet slid around pretty easily.
However, when cutting more than 1/4 of the sheet, it was very difficult to
hold against the fence. As hard as I could push, I still ended up with burn
and tooth marks, and bound up the blade twice. The only thing I can see might
help is a fence extension, since you're first standing nearly 4' in front of
the table. In any case, making multiple cuts to 15 sheets is not something I'd
be looking forward to doing.

At this point, as my knees are no better than Patriarch's back, I may go to an
abbreviated panel saw: a shelf to hold the wood, and a squared guide, similar
to what you'd use horizontally. You can build it from a few 2x4s, and square
with a measure. When you don't have to reach or crawl over the board, it's
much easier to keep the saw steady against the guide.
GerryG
On Thu, 16 Sep 2004 10:31:34 -0600, "Alan Bierbaum"
<[email protected]> wrote:

>Looks like Pat has the exact figures on weight. The weight problem is that
>you move or lift that extra 20-30 pounds many times during the process of
>building and installing the cabinets. I would build the cabinets one week
>and then rip out the old cabinets and install the new ones the next week
>(that is a lot of lifting and moving) for a complete kitchen. I did use a
>panel cutter (industrial vertical/horizontal cuts), table saw with a 10' x
>10' table area for support and a panel router. In my personal shop, I would
>not be able to produce at this rate. Any cabinet saw (with some kind of
>rollers/supports) can support the weight of 3/4" plywood for cutting. Build
>support tables/rollers and make sure that you have room to move the sheet
>around without bumping into anything and you should not have problems other
>than guiding the sheet through the saw.

PB

Pat Barber

in reply to GerryG on 15/09/2004 4:35 AM

16/09/2004 2:47 PM

A 3/4" panel of mdf comes in "about" 90lbs. The veneer would
add a "wee bit" to that.

A 3/4" panel of oak veneer plywood comes in "about"
70 lbs.

That will vary according to the species used
as the "inner veneers". SYP plywood is a little heavier
than plywood made from poplar. Birch plywood is in
the 60-70 lbs category.



GerryG wrote:

> Any idea how much of a difference there is? I've heard both, but am trying to
> get an idea of how much. Is the weight maybe double? Any idea how much
> thickness variation?
>
> Not having a panel saw, it's going to be tough getting exact dimensions
> cutting it on the floor with a circular saw and guide, but even the lumber
> core's probably too heavy to handle on a table saw. Even if cut in half, I'm
> wondering if the mdf core's still to heavy for the table saw. Some of the
> panels are 84x26".
>
> GerryG
>
>
> On Wed, 15 Sep 2004 08:04:09 -0600, "Alan Bierbaum"
> <[email protected]> wrote:
>
>
>>I used to do kitchens for a living (still work there part time). After
>>several hundred kitchens with MDF ply; we switched to veneer core because of
>>the weight of MDF. The MDF core is flatter and more uniform in thickness.
>>The extra weight is a killer, both in raw stock and finished product. We
>>did not use screws for primary joining; so can not comment on screw holding
>>power.


You’ve reached the end of replies