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Post by holmz on Jul 4, 2016 15:30:18 GMT -5
Why not go both... Aluminium 1/8" or so on the top so where the foot is at it will be stiff, because the foot is there. Then at the edge of the foot bond on ply or some other wood with Silaflex. You could use another 1/8" of alloy on the other side, and then the ply layer is only to space out the alloy for stiffness, and the only stress is shear. At that point you exchange ply for end-grain balsa. You pretty much have a ski, snowboard etc composite structure.
I am thinking I could replace the alloy with glass or other fibre.
Or just mount the foot on the bottom of a factory leaf.
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Post by reflector on Jul 4, 2016 19:32:29 GMT -5
That's a good idea. I'll explore that option since there's a some metal suppliers near me. Or I can order some sheets online and do minimal cutting (TCG blade in the MT55 probably) if they're close in size and just laminate the top of some baltic birch.
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Post by holmz on Jul 5, 2016 3:00:45 GMT -5
That's a good idea. I'll explore that option since there's a some metal suppliers near me. Or I can order some sheets online and do minimal cutting (TCG blade in the MT55 probably) if they're close in size and just laminate the top of some baltic birch. www.onlinemetals.com/i would probably use something that will not run off, so anodised aluminium or ... a local supplier seems easier. Once it is bonded to some wood it will not have very far to be able to flex, with the foot also on it. One could also have something like 1" x 6" and recess it into the ply, leaving enough of a lip to get a solid bond, and then even go 3/16"
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Post by reflector on Jul 5, 2016 5:18:22 GMT -5
Even faster idea since I am scratching my head at anything but epoxy and specialized glues for laminating aluminum onto plywood: What about that aluminum-plastic-aluminum laminate material that the MF26cc video shows it cutting? That stuff I assume can be easily cut with a TCG blade still. Buying a sheet of that and cutting a panel out of it would work pretty well for an insert plate.
Edit: At this point I might as well check a local signmaker to see if they're willing to sell me an offcut of the 1/4" thickness stuff, apparently it is extremely rigid. A 1/8" sheet doesn't deflect (visibly) when thumb pressure is applied to it according to some online anecdotal evidence. I'm going to look up some specsheets on it later... Looks like the stuff machines readily with a saw or even if you just scour it with a knife and hit it over a table.
Edit: 1/8 thickness approx provides 10% of the OSB equivalent, 1/4 thickness provides 35% of the OSB equivalent, if I got all the conversions corrected. I will just call up some local signshops to see if they'll let me see the offcuts before I buy them.
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Post by holmz on Jul 5, 2016 15:41:14 GMT -5
I would not use plywood as the grain runs flat, so it will fight the alloy in expansion/contraction. It may not matter. But ideally you run the grain up/down like a cutting board.
The sign board is not very stiff. The stuff I have is maybe 0.3 on the face sheets, and the total thickness is ~3-mm. Stiffness goes as the ^3 of the thickness I think. I could stack 3 to 5 together and it would be stiff.
Anyhow the West systems works for that stuff, or Silaflex .
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