Workbench top. Pylwood or MDF?

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I'm rebuilding and re-sizing my workbench. It was originally a home made drafting table that was 48 x 96. I took it home and cut it down to 40 x 72. It is still too big for my use and now it is 32 x 72 and I can even reach the wall in back of it.
The original top is 3/4" plywood that has been beat on for many years. My plan was to put an addition 3/4" MDF on top. Now, I'm thinking plywood can look nicer that MDF but it is not as dense. Will it be a major difference?
I mounted a 7" vice I bought from Lee Valley and just have to put the top in place and drill some dog holes. Any comments? Ed
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MDF. It will hold up better in the long run. JMHO.
Edwin Pawlowski wrote:

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proposed a theory ......and in reply I say!:
remove ns from my header address to reply via email

This puzzles me. Ply has always seemed stronger to me. What about MDF makes it hold up better?

???????
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vaguely

It won't. It does not take abuse without denting, chipping and crumbling, and it does not withstand moisture as well as plywood. MDF is a poor substitute for plywood.
--

-Mike-
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On Mon, 3 Jan 2005 06:24:51 -0500, "Mike Marlow"
......and in reply I say!:
remove ns from my header address to reply via email
I tend to agree with you, Mike. But there is a lot of posting apart from the one I queried saying MDF will be as good or better. One post, and I may not have asked.
As far as I am concerned, thickness for thickness, ply craps on MDF. Weight for weight, it's no contest. I even wonder about dollar for dollar!
But I am thinking of more "free" designs (boxes etc). I wondered if benchtops were an exception.

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Somewhere along the line I recall hearing that plywood, while stiffer and lighter than MDF, tended to give more of a 'bounce' rather than absorb the impact and/or vibrations, which might not be desirable on a workbench top.
Any truth to this from y'alls experience?
TIA,
nuk
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I know more than enough *nix to do some very destructive things,
and not nearly enough to do very many useful things.
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Don't know about that, but it becomes a moot point if you properly brace the benchtop. For a benchtop, the span from front to back is so small and if you brace it every two feet to support it along its length, any bounce is so negligible that you'll never experience it. MDF is not going to absorb any amount of impact or vibrations that you'll benefit from. Except of course, when it breaks...
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MDF, but seal it with 3 or 4 coats of poly before using it.
Malcolm Webb
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I'm just curious. How come there's so much talk about using MDF for work bench tops but nothing about using MDO? I would seem to me that MDO would et away from a lot of the problems with MDF.

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72.
can
difference?
in
Why not skin the top with masonite? That will give you a nice smooth finish. If you don't like the dark brown, overlay the masonite with Formica. For a few more dollars you can get the Formica with the color all the way through so any scratches are the same color.
--

Roger Shoaf

About the time I had mastered getting the toothpaste back in the tube, then
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I have made three work tables over the years, two with plywood tops and the latest with MDF. I used normal pine ply for the first two.
Of the ones I made, the plywood is not as flat, even after being coated with varnish.
The MDF is as flat as I can get at home for such a large surface. I also varnished the MDF, which is highly recommended to minimize absorbing all sorts of stains with the kind of tasks I do on this bench.
For the latest work table I cut a 4ft x 8ft sheet of MDF into two 2ft x 8 ft pieces. One piece was 1.5 in narrower. I then glued the narrow piece on top of the other piece and finished off the edge with pieces of 1.5 in x 2.75 in fir (a 2x6 cut in half) mounted with long side vertical. I made a 3/4 in groove in the edge to accomodate the wider piece of MDF.
I considered screwing the top piece of MDF so I could replace, but decided I wanted the stabiliy of the glue. I promised myself to make a better top if ever I need to replace this one.
I would recommend putting some real wood edging on an MDF top. This will prove more practical since it is less prone to chipping.
If I were to build another top out of plywood, I would probably use underlay. This is designed for high compression loads and so has the knot holes filled it. I am not sure of the type of wood for the surface layer, but it seems to have a finer grain than pine.
Dave Paine.

72.
can
difference?
in
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Did similar. Two pieces of 3/4 MDF face glued, with screws to lock the faces together for the glue. Hardwood edging around. Built a solid frame separately, then screwed down the top which allows me to replace it when/if needed. Sealed with several coats of poly, just letting it soak in without much of a surface film. Did same process on several other benches, and they last well. By making sure the frame is flat first, screwing down the top helps flatten it a bit more.
Every so often I sand lightly with an orbital, then apply another coat of poly. Either poly or varnish do nicely, as they're resistant to most droppings.
GerryG

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On Sun, 02 Jan 2005 12:30:34 -0500, Tyke wrote:

I did something similar, using a ripped 4x8 of 3/4" MDF. Decided after having it ripped at the orange box that I wanted a slightly wider workbench, so I ripped two additional 6" strips to make it 30" wide. The seams are on opposite sides on the top and bottom layers, with the top seam in back. The bottom layer was screwed and glued to a rectangular apron of tuba sixes, then the top layer was screwed (from below) and glued to the bottom layer. The legs are doubled-up tuba fours, screwed with big honking #12 screws into the corners of the apron. Just above the floor is a shelf made of tuba fours and a single layer of MDF.
After it was finished, I realized that it was a couple inches higher than my table saw, which would make ripping large pieces somewhat tricky (in my tiny little shop, the saw and workbench are about 2 feet apart). The design enabled me to unscrew one leg at a time and cut it down a bit.
Had to chisel a rectangular hole in the apron in order to mount a vise, a problem I didn't think of when I designed it.
My only complaint is it tends to move a little bit when I do things like hand planing (which I do less often than I perhaps ought to admit). Might add some diagonal bracing to deal with that.
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The bench I built is free standing with a three layer top. The outside layers are 3/4" MDF and the center core is 3/4" ply. It is blind screwed from the bottom as well as glued. If I had it to do over, I would have added a layer of masonite to the top surface. I can still do that when the MDF becomes worn beyond serviceability. But not yet...there are other things that are more pressing in my agenda.
I might mention that this is the first "real" workbench that I have ever built and it has served me very well.
Did I mention that it is very heavy? I did not want it to move and it doesn't. :-) Bill Waller New Eagle, PA
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Tempered masonite for the last 1/8. Rest up to you.
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Any secondhand office supply places nearby? You can buy 2 inch thick counter and table tops completely finished for 20% of the cost of the materials in my neck of the woods. I bought 3 30"x72" tables arborite, 1.5 inch MDF, each with 4 solid oak turned legs for a grand total of $20 each. Not only that the legs are set in two steel full length tracks that would cost this much alone.

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Edwin Pawlowski wrote:

If you're going to combine plywood and MDF then make a sandwich either of MDF between two layers of ply or ply between two layers of MDF. Otherwise it's likely to end up warping on you--while MDF and ply are both fairly stable they are not completely so and so you can run into two different issues--variable moisture content across the thickness because one side is shielded and different expansion rates due to the different properties and compositions of the two materials. Making a sandwich gives you a balanced structure in which this is much less an issue.

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--John
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Hi Ed, My main workbench is plywood too. It gets banged on, glued on, paint dripped on. IIRC MDF is a nice surface...Do you really want that kind of work surface? Have fun. Joe
Edwin Pawlowski wrote:

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All good idea.
The general consensus is that MDF is OK, no big advantage to plywood. Considering hte potential to warp or otherwise misbehave if mating the two mateial, I'm goin gto screw them together from underneath. If it does move it will be easy to remove it and go to plan B. The sandwich is a good idea, but I'm kind of commited size wise right now and the extra 3/4" will prove to ba a PITA.
My bench top now is painted white. I'm probably going to poly the top but will consider white paint or something remvable and easily replaced.
Thanks for the comments.
--
Ed
http://pages.cthome.net/edhome/



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<snip>
At Thanksgiving time, we needed some temporary tables, so I went to the door shop of the local, really good contractor's lumber yard.
For $30, I got three really nice, birch veneer fire-rated doors, which had suffered minor installation errors.
By Friday after the feast, one of them had become a new bench top in my garage/shop. The second, a narrower one, is now the bench top in my dad's garage. I'd give you the third one, but you might not want to come to California to pick it up.
Lotsa mass. Looks really pretty, at least for now. Cheaper than I could buy the stock to build it from. The door shop was really happy to move something off of their bonepile. They would likely have been happier if I'd had exact change, and could have avoided the register... ;-)
Patriarch
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