Lead screw mech adv

[WilliamD]

I was wondering if they diameter of the lead screw made any difference as to the mechanical advantage. Also, how do you calculate mechanical advantage. If I have 50 oz at the motor, on a 10:1 ACME, is that 500 oz, minus half for efficiency, so 250 oz at the spindle? Just trying to finalize me router setup and tune it to what I need. Thanks in advance!

[WhiteTiger]

www.roton.com has reference and advisory pages for acme and ballscrew. You can find pretty much all of what you want there, I think.

Btw, if the pitch is the same then yes a larger diameter will have a lower thread angle and greater mech adv. Unrolled, it's a shallower ramp, so more travel, less force for the same lift.



Tiger

[mike hide]

Just wondering are buttress threads ever used ? that way the cutter head could cut on the way out and the way in .I think acme threads are for thrust loads in one direction.

[WhiteTiger]

Just bass ackwards. Buttress are for loads one direction only while acmes are symetrical at 14.5 degree pressure angle. Buttress look like the teeth on a handsaw: near vertical load face and ramped away on the back side.

I've used buttress more than once in building custom rifle actions. Hard to beat for one direction loads, especially where radial distances are tight.


Tiger

[Geof]

Originally Posted by mike hide Just wondering are buttress threads ever used ? that way the cutter head could cut on the way out and the way in .I think acme threads are for thrust loads in one direction.

You have it backwards.