Homemade hydralic press?

My 20-ton hydraulic press is built mostly of 4" channel. That's beefed up on the top crosspiece with an I-beam welded below it, and the H-bar in the middle (the one that is held on with pins) is reinforced on both sides by 3x1/2" flat bar, but the guy who built it says he has really stressed it and it took it fine. It's also built quite a bit heavier than the import 20 ton presses. So I vote for 20 ton as long as you do some judicious reinforcing. Within the last 2 months, I bought a 20 ton air-over-hydraulic jack at Harbor Freight for $79.99, you just have to watch for their sale price. Amazing jack for the money.

GWE

Depends entirely on the span of the press. With a 6-8" opening you could use almost any jack. If you want 2 ft. of opening it will need some beefing up. Bugs

I've built a few and now buy them but, go for it! The biggest thing to keep in mind it that everything stay square under pressure. How thick is the 4" channel? How much pressure do you want? You can put a 60 ton cylinder in there and only use 10 ton of it. Put the biggest cylinder that you can find in it just for the few times that you really want that much power, most of the time you'll only use a fraction of it. The down side is the loss of speed. One of my hyd. presses has 2 cylinders just for that reason. I'm thinking of my next one being powder actuated... I might be the first kid on the block! Gunner probably beat me to it.

I knew you'd get a kick out of that...now I just HAVE to build one! (I will set up a video camera)

Google "explosive forming"

Gunner

"Considering the events of recent years, the world has a long way to go to regain its credibility and reputation with the US." unknown

I've been looking at some designs for my shop press and come to a couple different styles. I'm not sure which is the better design.

Since my scrap pile is small, I would like to build the A-Frame style, instead of the H-frame style. Does anybody have any comments on either style?

I'm looking at a 20 ton press, I have some 4" channel, not sure on the thickness, perhaps .25", On the A-frame style (Harbourfreight), there is some strapping, again I cant figure out what thickness they are using, that attaches the upper mount for the bottle jack to the side frames, (think cap A). Any recommendation as what thickness of strapping to use? .25"? When bolting this press together, .5" grade 8 bolts?

What is the shear rating of .5 grade 8 bolts?

Many thanks.

If you have a failure in a welded frame press, all that happens is the weld breaks. Fairly unexciting. If you have a frame bolted together and one of the bolts should shear, it can spit out of the hole like a bullet (or like a fast, heavy watermelon seed), far more dangerous. Now lots of folks make bolted together frames, but you should consider this.

Your holes should be nice snug fit to the bolts. I'd suggest maybe some reading about shear strength would be a good idea. Getting a value from someone else doesn't provide nearly the understanding that figuring it out yourself does. Same applies to the frame.

Just my thoughts, Steve

"Steve Smith" wrote in message news: snipped-for-privacy@corp.supernews.com... | Your holes should be nice snug fit to the bolts. I'd suggest maybe some | reading about shear strength would be a good idea. Getting a value from | someone else doesn't provide nearly the understanding that figuring it | out yourself does. Same applies to the frame. | | Just my thoughts, | Steve

Great point. I will also add that the place most bolts fail in tension is where the shank meets the threads. High stress there, and bolts in shear will fail at that spot or under the bolt head, where the bending forces are at the worst, thus leading to the explosive failure noted. Best bolt practice says no threads in bearing, which means the bolt has to just the right length. SAE bolts have lots of threads, which means you usually have a lot hanging out, but that very requirement is why most aviation fasteners have so little thread. The tighter the hole the better as well. Interference fit is actually the very best, but harder to actually do in practice. A way to make up for it is to use a hollow spacer whose length is just the smallest amount shorter than the length of the bolted joint. The spacer takes up the load and the bolt merely holds it all together. Needless to say the spacer shouldn't be soft seamed pipe, but then again a larger fastener equivalent is better than a smaller one, providing you have sufficient hole edge margin. Again, the snug fit is better.

There's a web site out there called bolt science.... I think. Hang on... here it is: