Frame Press

[Kevin Jenness]

Yes, you could say I am talking about a torsion box. So the 1/2" platen top will have a grid of 1/8" wide by 3/16 deep groves to evacuate the air. and the torsion frame that the MDF is succured to is 2.5" thick. Thoughts?

I wouldn't do it that way. A true torsion box will have a top and bottom skin to develop full strength and as John said at that scale the skins can be on the order of 1/4" thick. Nominal 1/4" lauan makes a nice light stiff box.

You can use breather fabric but I favor a separate grooved platen on top of the torsion box that both provides air evacuation channels and prevents my wood membrane frame from bending inward. The commercial aluminum extrusion frames are stiff enough to avoid that problem. You will need a good sealing surface on the top of your torsion box such as smooth plastic laminate or a good build of finish. You will be pulling a lot of air through unfinished mdf and your frame gasket needs a smooth surface to compress to.

[John TenEyck]

I wouldn't do it that way. A true torsion box will have a top and bottom skin to develop full strength and as John said at that scale the skins can be on the order of 1/4" thick. Nominal 1/4" lauan makes a nice light stiff box.

You can use breather fabric but I favor a separate grooved platen on top of the torsion box that both provides air evacuation channels and prevents my wood membrane frame from bending inward. The commercial aluminum extrusion frames are stiff enough to avoid that problem. You will need a good sealing surface on the top of your torsion box such as smooth plastic laminate or a good build of finish. You will be pulling a lot of air through unfinished mdf and your frame gasket needs a smooth surface to compress to.

Kevin, do I interpret it correctly that the lid of your unit fits over the grooved platen snugly enough that the vacuum doesn't pull it towards the center? That was a huge problem with mine. Adding a mid-span crossbar didn't completely stop it. I went back to using a bag because of that, but I still have it.

John

[Kevin Jenness]

Kevin, do I interpret it correctly that the lid of your unit fits over the grooved platen snugly enough that the vacuum doesn't pull it towards the center? That was a huge problem with mine. Adding a mid-span crossbar didn't completely stop it. I went back to using a bag because of that, but I still have it.

John

Yes, that's right. I suspect part of the reason (maybe the whole reason) commercial units don't have that problem is because the membranes are typically formed in a box shape and the vertical pleats take up the slack, whereas my simple flat polyurethane sheet pulls the frame in as it is sucked down to the platen. I too tried a crossbar initially without much success.

[Mike King]

https://www.joewoodworker.com/veneer...rame-press.htm

[John TenEyck]

https://www.joewoodworker.com/veneer...rame-press.htm

As he warns, it's not a good design if you want a large unit, which I proved correct. Not complaining; I knew I was in unchartered waters, and found out the earth, indeed, is flat.

John

[Mike King]

As he warns, it's not a good design if you want a large unit, which I proved correct. Not complaining; I knew I was in unchartered waters, and found out the earth, indeed, is flat.

John

There is the commercial/industrial route. Has support, at least.

https://www.felder-group.com/en-us/p...-flex-p2186651