ACME 1/2-10 vs 5/8-5

[DroopyPawn]

Is there any reason to choose one over the other in ACME 1/2-10 vs 5/8-8?
The 1/2-10 rod (and nuts) seems to be a little more available than the others. What about other options too? Like 5/8-5 for example?

[djr76]

Pitch difference is the obvious, the 5/8 will be stronger. What are you using it for?

[flyinchips]

If you were to put dials on the end of these, one would be graduated so that a full turn was 1/10 of an inch (100 thousandths), while the other would be 125 thousandths. So, if you were driving the axis of a machine, you might choose one over the other for convenience of counting the distance traveled.

[DroopyPawn]

I'm not "using it" for anything. Just wondering if there was good reason to choose one diameter/pitch over another for hobby CNC purposes.

Would the 8tpi vs 10tpi possible allow faster rapids? Would the extra mass of the larger diameter cause a problem with stepper acceleration?

[ger21]

Would the 8tpi vs 10tpi possible allow faster rapids? Would the extra mass of the larger diameter cause a problem with stepper acceleration?

Yes, and Yes.
Fewer turns per inch gives more speed, but may require more power to get that speed. And the bigger the diameter, the more inertia, so the motor has more work to do to accelerate.

[DroopyPawn]

By my math, going from 10tpi to 8tpi would give a 20% max speed increase. To do that, you'd have to go from .5" diameter to .625" which is a 25% increase in mass. Is all of this even worth bothering with? 10tpi seems like it could be very slow on a 2'x3' machine (or bigger).

[ger21]

That's why everybody building routers uses 1/2-10 2 start, 1/2-8 4 start, or 1/2-10 5 start.

[Shane123]

in theory you would think the more threads, the more accurate you could be with your movements.......