Awrksmokey

Flypress efficiency questions and turning a pipe vise into a flypress

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I don't quite understand how flypresses work in terms of efficiency. I understand the mechanism and how to use one, but I don't get why or how it becomes more effective then hitting it with a hammer. Why do flypresses squish metal really well? 

My other question that's related the the first one is whether it would make sense to convert a pipe vise into a small flypress. I'm not if sure this would make any sense at all, but they work in similar ways as far as i understand.

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Because of the weights on opposing sides of the large wheel plus the angle of the threads it's almost like a hit versus just pressure if my assessment of what I was seeing was correct. I've only seen one used for forging once and it seemed like it hit the stock as much as squished it. He bumped the stock by spinning the wheel is maybe a better description. I hope this makes some sense. 

Pnut

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My screwpress has a 200#+ toroid that is spinning down a couple of screw threads with the mechanical advantage they have. When it bottoms out all that inertia goes into deforming the workpiece so much so that it may even spin back up a ways.  Personally I can't swing a hammer that large.  I am amused to see the two 2.5"x4"x16" cold steel blocks flex under the impact of my screw press.

Does you pipe vise have a multiple lead screw?  Note I mentioned a 2 lead screw for my screwpress, a fly press will have 3-5 leads.

Is the pipe vise engineered for the massive pressure spike when it bottoms out---why flypresses are good for striking coins the "squirt" helps fill the die.

As far as I know, having experience with both, a fly press and pipe vise are not similar at all in use or construction!

Now not knowing what you need a flypress for; it's impossible to to say if it would make sense to try to make one that way.  

I can say that your area used to be the best place in the entire USA to get used flypresses due to the historic clock and jewelry making industries in that area.  Used tool publications used to list tons of them there.

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36 minutes ago, ThomasPowers said:

When it bottoms out all that inertia goes into deforming the workpiece so much so that it may even spin back up a ways.

That's what I meant when I said it seemed to hit, or bump it more than just squish it like a normal press. 

Pnut

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What we need is a pressure graph of a screwpress and a hydraulic press in action.

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This my approximation of what it would would look like if it works the way I think

Pnut 1580763181893.thumb.jpg.e24a93f17962bf62fdd15e273cd20a9d.jpg

 

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Probably something along those lines, but you'll get some variation depending on the size and speed of the press. The big difference is that the hydraulic press continues to apply pressure so long as the control valve is open, while the fly press's blow is limited to the inertia at the initial impact.

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4 minutes ago, JHCC said:

The big difference is that the hydraulic press continues to apply pressure so long as the control valve is open, while the fly press's blow is limited to the inertia at the initial impact.

The simplest way I can think to say it is a flypress is more of a hit versus a hydraulic press' steady squish. 

Pnut

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I think I get it now. I've never actually seen a flypress in real life, but I think i understand why they're different and why it wouldn't really work. My screwpress is on the relatively smaller side and it has 2 lead screws. Definitely an interesting concept. Thanks for the help!

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1 hour ago, Awrksmokey said:

I've never actually seen a flypress in real life

I hadn't either, until I got to try out Latticino's a little while back. Now I want one!

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