How much "support" for MDF

[Brian Dormer]

A few more "shop projects" left to go, then I have a rather large one. I'm going to build a 8' x 3' miter saw station (similar to the NYW plan).

If I use 2 sheets of 3/4" MDF and have to span openings that are no more than 3' x 2' 6" - how much intermediate support should it need. I'd like it to stay dead flat for a long, long time.

Also - would it be better to use Titebond, Probond or Gorilla Glue for the laminiation?

TIA-

bd

[Lee DeRaud]

If I use 2 sheets of 3/4" MDF and have to span openings that are no more than 3' x 2' 6" - how much intermediate support should it need. I'd like it to stay dead flat for a long, long time.I like overkill as much as the next person, but I think the answer to that question is "none".

[Doug Shepard]

Dont know about the sag question, but I just glued up some 12 layer 9"x12" blocks of 3/4" MDF with Probond (just cuz it's what I had handy) and it glued up really well. I imagine Titebond would work just as well. I just laid down a few beads then used some scrap plastic laminate to spread a thin coat on all the layers.

[Chris Padilla]

Are you laminating the two sheets of MDF together? If so, consider using thinner sheets to get more laminations. The strength is in the glue and I'd use something like Unibond 800 for such things.

If you want it to stay flat for a long time, you should seriously consider additional support. Some hardwood edgebanding might be all you need but I'd go further and look to putting some hardwood on edge under the top.

You are in a humid area and unless you seal that MDF well (I suggest laminating BOTH exposed sides and all edges), it will soak up moisture over time and sag.

[Brian Dormer]

In my haste, I guess I did omit the fact that the MDF will be laminated. So total thickness would be 1 1/2". I was going to use 3/4" - but I have a (less critical) counter in the shop that's already got a sag in it (despite some creative shimming) and has to be redone (so, I'm going to double it up).

I was intending to either put some laminate top and bottom or use WATCO Oil on the raw MDF. I'll edge band it with either oak or maple (whatever I can get for le$$).

bd

[Jim Becker]

Brian, take a look at the "Cantilevered Miter Station" article/pictorial on my site. You can see what kind of support I have under a single sheet of 3/4" MDF and judge from there what you will need. My supports are about 12" OC if I recall clearly, but it was quite a long time ago that I built it.