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I Forge Iron

Fly press screw?


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i was wondering if anyone could tell me the pitch of some of the larger fly presses, or if theres some formula for the wight of the head vs screw diameter vs thread pitch. i am looking into the possibility of making a fly press, welding up a base, arm, and ram guide are no problem. but i have not clue what type of screw to use, i imagine i would have to have it turned out on a lathe, along with the receive for the arm. i know that is quight steep. could the screw be perched from McMaster ccarr?

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Flypress screws have been listed with two- three- and four-pitch threads. The listings have also made mention of straight-cut and Acme threads. Both threads can be a bear to cut on the lathe, with the straight-cut being more challenging. The difficult part of that exercise is cutting threads for the nut or female part of the structure. As for thread pitch, yes there probably is a formula somewhere though I have no idea where. A larger number of thread pitch (four) would be a faster advancing ram per revolution than a dual pitch. As for making one on your own, understand this is not a weekend or four weekend project to make one that does more than go up and down; everything better be right on.
I suggest getting a video on one and visiting a website or two.
I still have six feet of two inch diameter, two-pitch straight-thread with nuts (can't remember where I got it), plus much three and four inch solid bar, and after doing much planning a year ago, I still haven't started because it is fairly intimidating.

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You can get ACME thraded rod from McMaster.. but if you want something that will last.. you need to remember that a 1", 2 start, 2 turn per inch rod will cost you $75 for 3 feet. The only nut I can seem to find on there that would work with that would be $62 and bronze.

You could go smaller.. but no clue on the durability of it. I suggest you keep an eye out for a used one.

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Don't forget that a flypress is trying to tear itself apart in use with the forces rapidly spiking *very* *high* if you run it down and have it bounce up. I'd suggest 2" thich steel for the frame and full penetration welds heat treated to avoid any problem with brittleness.

A friend of mine in AR has bought about a dozen fly presses for coining; he gets them reasonable from a used machinery newspaper; most of them from the NE as they were very common in the clock/silversmithing trades up there at one time.

Shoot I have a friend here who has one in FL he hasn't drug back here in several years. I'll ask him what he wants for it.

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