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
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Google is your friend.
http://www.lungster.com/l/speakers/mdffaq/mdf.html

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
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
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
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"

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
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:

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
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
wrote:

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
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
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
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"

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
<snippage>

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 490-736
Patriarch
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
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

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
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

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

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
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

sheets
cheaper
more
power
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
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Site Timeline

Related Threads

    HomeOwnersHub.com is a website for homeowners and building and maintenance pros. It is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.