Will a ball screw work for a fly press or will it blow apart? I found a few that are the size I am looking for I just am unsure if they will last.

Also am I shooting for 2" per revolution for a screw? The ball screw I found traveled about 1.250" per revolution.

Thank you for your help...

Chopper Where in the country are you? You can build a flypress, I guess, but I don't see how it could possibly be cost effective. If you really are going to make all the effort needed, it would be nuts not to use a three or four lead screw. Meaning that 3 or 4 seperate threads are cut on the same bar. This can be done on a good running thread cutting lathe, and isn't that bad of a job, just takes a while especialy if you have a threading dial. I am guessing that you could find one already made somewhere if you really look. Location would help a lot.

My best guess is that ball screws don't like impact too much.

yeah Im thinking a ball screw would be a poor choice... you use a ball screw for precision... you want a 4 lead screw....

I've never considered ball screws to be a good idea in situations were they will see high impact, but thats just my opinion.

An engineering/fab company built a new piece of paper roll handling equipment for a company I used to work for. They used large ball screws (>2" dia.) everywhere versus the hydraulic and pneumatic cylinders the old system they were replacing utilized. The first ball screw failed after the first day or so, lucky they had an extra on-site on another piece of equipment they could canabalize.

Only very specialized lathes have the ability to do the sort of lead required. Best my lathe will do is 4tpi. And you need/want 1/3 - 1/4 tpi.That means my lathe can do a 1/4" lead and you need a 3-4" lead!

If you have a ball screw hanging around that you don`t know what to do with and feel like sacrificing it then go for it!
If you`re thinking about buying one I`d put the money toward a fly press instead.Here`s why;a ball screw was designed to do what something like an acme or buttress thread screw did but with tighter tolerances,less slop and less resistance.What the conventional screws had going for them is that they spread the wear and impact over a wider area,the mating surfaces of the screw.
A ball screw`s mating surface consists of the combined contact surfaces of all those points where the balls contact the race,far less surface to transmit and distribute the impact.The ball screw will actually be focusing that impact onto a small point on a hardened ball and that same small point where the ball contacts the softer race.
Judging from the failures I`ve seen in both internal combustion engines and industrial transmissions I`d not put a lot of faith in ball bearings under extreme impact conditions.There`s a good reason roller bearings are used predominantly for this type of application.

I`d still go for it though if I had a mega-heavy one kicking around with no other useful application.
It`s physically impossible for bumblebees to fly after all. ;)

Only very specialized lathes have the ability to do the sort of lead required. Best my lathe will do is 4tpi. And you need/want 1/3 - 1/4 tpi.That means my lathe can do a 1/4" lead and you need a 3-4" lead!

Ah, you got me this time Grant. My 16" southbend only goes down to 4 also. Glad I bought a flypress instead of trying to make one.

I have milled that type of screw on a K&T universal mill I wasnt making a screw press just a decrotive pattern for a steel container. I know my mill will cut threads like that with the powered dividing head and the thread milling attachment, but to actually make them to a tolerance would be real hard at least for me. I looked into making a fly press but they are so cheap it is not worth it.

How improbable is it to make the threads using a cnc bridgeport? I have a freind who is setting up my cnc to thread a bunch of shafts for robotics research. I could make a few shafts if it's practical.

Thread cutting on a mill is done with a horizontal universal mill that has a power takeoff to drive the dividing head in conjunction with the table feed so that you can generate a spiral. I could make drill bits and milling cutters if I could figure out all the gearing and feeds and speeds to make it happen, I dont think a cnc BP will do it alone you need the dividing head and a way to power it with the table feed at a predetermined rate.

Thread cutting on a mill is done with a horizontal universal mill that has a power takeoff to drive the dividing head in conjunction with the table feed so that you can generate a spiral. I could make drill bits and milling cutters if I could figure out all the gearing and feeds and speeds to make it happen, I dont think a cnc BP will do it alone you need the dividing head and a way to power it with the table feed at a predetermined rate.

I realize that. I don't have my K+T universal anymore, so I am trying to figure out if I can do it on the bridgeport. I am pretty sure the computer is capable of running a forth axis, I have a hand divider, but need to find a powered one.

Thread cutting on a mill is done with a horizontal universal mill that has a power takeoff to drive the dividing head in conjunction with the table feed so that you can generate a spiral. I could make drill bits and milling cutters if I could figure out all the gearing and feeds and speeds to make it happen, I dont think a cnc BP will do it alone you need the dividing head and a way to power it with the table feed at a predetermined rate.

I realize that. I don't have my K+T universal anymore, so I am trying to figure out if I can do it on the bridgeport. I am pretty sure the computer is capable of running a forth axis, I have a hand divider, but need to find a powered one.