I went to Home Depot last night and priced various types of lumber for the benchtop. I really like the feel and structure of MDF as compared to all others (except birch and oak, which are prohibitively expensive). It’s a decent price, not much more than the various types of plywood, and it’s pre-cut into the sizes I want. BUT I have been reading that it doesn’t take screws very well. I was planning on using Gorilla Glue for the flat parts of the bench and screws for the legs (want to be able to take them apart later if I move).
Can anyone else recommend/share horror stories about MDF? Thanks.
MDF is not very rigid, so it will need support closer together below it than, say, 1/2" plywood. It does not take screws well at all on the smooth side, but pre-drilling and countersinking will give you a nice finish and it will be tight, especially if you also glue.
If you send screws into the rough edge of the MDF, prepare for failures…it will split and spawl, and generally not work well at all. Same for nails.
I used 1/4" MDF for spline roadbed, and it worked very nicely indeed. However, I pre-dilled each and every time I wanted to use fasteners.
I feel that it could benefit from some sort of sealant, too. It absorbs moisture something fierce, so it will not be dimensionally stable.
MDF is not very stable as far as humidity is concerned. You can seal it with paint, and that helps, but it’s basically a pressed fiber board and is not as stable as plywood. An alternative to traditional plywood (and what I chose to use) was luan with foam insulation board glued over the top. The luan gives you something to mount things to, like switch machines, and the foam allows you to carve scenery out below the track level with ease.
I took a different approach: 1x3 framing with a layer of pink insulation board topped with a layer of birch plywood that is 3/32" thick (I know it’s less than 1/4") This give a top that can accept either glue or screws and the foam makes it rigid.
I use straight 2-inch foam, no wood at all. I’m very happy with it. I do NOT use Tortoises, though, so if you plan to use them then consider this fair warning. You can’t use screws in the foam at all. You could glue on a small wood plate and use that to mount a Tortoise, though.
MDF is heavy and if you do use screws use a course thread. This leaves lots of wood for bite, treat it as you would soft wood. OSB is strong has a fairly smooth surface and is stable and a lot cheaper than plywood and compaired to 3 ply CDX stronger in my opinion. The luan back foam is quite attractive and on my next layout is the way I’ll go.
Mr. B, I have successfully used those large white plastic wall anchors in foam. Once you have them in, a regular screw holding a Tortoise should work just fine.
I used 1/2" MDF and found it to be excellent. The lumber yard suggested it and comparing it to plywood it was much firmer and straighter. I had absolutely no problems with using dry wall screws to attach it to the benchwork My layout is on the first floor in a spare bedroom and the MDF has performed very well.
See my web site on how I used Tortoises and foam. Not my idea, I got it from the North California Freemo Group. But I found an even better way. That same good old latex caulk I used for my roadbed and track - it sticks a Tortoise to the underside of the foam but good. It’s workable for a decent amount of time so it’s easy to lien things up. Once the caulk dries - I ripped a chunk out of the foam pulling the Tortoise loose. It’s NOT going to go anywhere.
Do not use MDF flat. It’s heavy yet will sag without an unreasonable number of supports. And it’s a real pain to cut.
Mine is made from 2x4’s and 1/2 ply for the top, then I use some foam ontop of that to make it easier laying track. then my legs are 4X4"s bolted to the benchtop, yes it it major overkill but it’s also very durable.
I used OSB and glued it all together with yellow Elmer’s Wood Glue. You can see it here: http://the-hammills-nhrr.blogspot.com I did end up using dimensional lumber for the wall supports, legs and supports underneath, but that’s because I already had it on-hand (and some of it was already attached to the wall). The only thing I would purchase dimensional lumber for is legs in the future. The construction is extremely strong, easy to build, and cheap. The benchwork including the spline, and enough OSB for all of the benchwork (including the parts that I used old lumber for) was less than $40.00. I highly recommend it. Oh, and pick up a bag or two of clamps. The ones you see in the pictures were from Wal-Mart - a bag of 16 clamps of assorted sizes for $4.44. Randy