Ultralight MDF for Assembly Table?

[Roland Chung]

I am just about ready to start on an assembly table. I've studied the video at WoodWhisperer and the step by step instructions at DIY- it has helped ease my anxiety levels enough to actually go out and pick up the materials.

My Question-Is there a problem with using Ultralight MDF? I have been researching torsion boxes for quite a while now, but have not found any comments adressing the use of ultralight. Everyone complains about how crazy heavy the torsion boxes are, but I don't think that anyone has tried Ultralight. I plan to follow just about all of your steps - but just want to use the lighter stuff and don't want any nasty surprises down the road. What do you think?

I am also planning to incorporate many of the features from Brian Gray's Jumbo MFT. I realize that drilling a bunch of 20mm holes and access holes below will compromise some of the strength of the torsion box, but I really like his idea and would like to try a version. With L type clamps occasionally going in and out of the 20mm holes, would the regular MDF hold up better?

[Jamie Buxton]

Light MDF, IMHO, doesn't have much value. True, it is lighter than standard MDF. However, at my suppliers it is more expensive than standard MDF. It is essentially the same price as plywood. It is also about the same weight as plywood. Plywood is stronger and doesn't sag as much. All in all, I go with plywood.


As an aside, torsion boxes can be light. In fact, that's really the point to the torsion box approach: it is stiff while being light. I have a torsion box for an assembly table. It is about 40"x80"x6". It weighs about 20 pounds -- so light that I easily hang it on the wall high above my head when I'm not using it. I can support it on sawhorses at the ends, sit in the middle, and measure a deflection of something less than a thirty-second of an inch. The spacer grid inside is 1/8" ply on 8" centers. The top is 1/4" ply, and the bottom is 1/8" ply.

[Noah Katz]

If I was going to make a torsion box, I'd bond facings and edgings to rigid insulation board.

[Gary Keedwell]

Light MDF, IMHO, doesn't have much value. True, it is lighter than standard MDF. However, at my suppliers it is more expensive than standard MDF. It is essentially the same price as plywood. It is also about the same weight as plywood. Plywood is stronger and doesn't sag as much. All in all, I go with plywood.


As an aside, torsion boxes can be light. In fact, that's really the point to the torsion box approach: it is stiff while being light. I have a torsion box for an assembly table. It is about 40"x80"x6". It weighs about 20 pounds -- so light that I easily hang it on the wall high above my head when I'm not using it. I can support it on sawhorses at the ends, sit in the middle, and measure a deflection of something less than a thirty-second of an inch. The spacer grid inside is 1/8" ply on 8" centers. The top is 1/4" ply, and the bottom is 1/8" ply.
Jamie Now that is something I can sink my teeth into. Do you have any pictures? I'm with you...I always imagined a tortion box to be super light.

Gary K.