What is the best press to make for the least $?
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I spoke to a friend of mine who is a mechancial engineer. He said that he thought that I shouldn't multiply the cloth width by two. He also said that it is necessary to account for the surface area of your hose pressing both up and down. Ie. none of the calculations I posted earlier are even remotely accurate. The force from the hose should be doubled from what I figured and the strength from the fabric should be halved from what I figured. But we've also concluded that the grab tensile strength (the numbers I used) aren't accurate so really all my figures are rubbish.
Anyways, I might actually go the webbing route. We'll see. I like the fact that there are real numbers for its strength.
Anyways, I might actually go the webbing route. We'll see. I like the fact that there are real numbers for its strength.
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MontuckyMadman
- Posts: 2395
- Joined: Fri Jun 20, 2008 9:41 pm
Cable press?
How about a press using metal cables instead of bolts? With 20 cables, sleeved when contacting the wood, the pressure should be fairly evenly spread. I'l upload a drawing of my idea. Cable is cheap around where I live, and two used glue-lams could be used to make the top and bottom, and the mold goes between them. The press is kept open when the bag is not inflated by supports along the sides of press, and bottom of press has supports attached so it rests on the floor.
A full size mold with cat track (top and bottom) is slid inside with laid-up board between the two.
A full size mold with cat track (top and bottom) is slid inside with laid-up board between the two.
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doughboyshredder
- Posts: 1354
- Joined: Mon Sep 17, 2007 7:37 pm
Yea, that sounds like a good idea. I was thinking about making half-circle grooves across for the sleeved cables to fit into. I would be using metal sleeves, so I'm not sure if they would eat away at the would? I'm trying to calculate the size rope I would need, and since you make snowboards what are the dimensions of the hose you use in your press if you don't mind me asking?
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doughboyshredder
- Posts: 1354
- Joined: Mon Sep 17, 2007 7:37 pm
I use (3) 6" lay flat hoses (I think, they may be 5's), which I only allow a couple inches at most to inflate in to. I press at 70psi. Wood is soft and even with steel guides like you're talking about, I think they will work their way in. Remember the forces generated are ridiculous.
rough numbers you're probably going to be generating around 120,000 lbs of pressure. The weak link in a steel wire system would be the crimp joint, or attachment point and the tendency of the wire to push in to the mold.
rough numbers you're probably going to be generating around 120,000 lbs of pressure. The weak link in a steel wire system would be the crimp joint, or attachment point and the tendency of the wire to push in to the mold.