Acme Lead Screws & Nuts

[sinardet]

Hi everybody,
I've got a Shark pro plus for 5 years and I'm very pleased about this purchasing.
I would like to know some measurments regarding Acme Lead Screws & Nuts , threaded rod sizes and thread for X and Y.
I'm not really good in mechanics so I look for somebody who is able to tell me if I made mistakes.
For me X is 3/8 8 TPI (pitch : 0125)
Y is 1/2 8 TPI (pitch : 0125)
Please is there somebody to let me know if it's right ?.
Thanks for your help

[Rando]

Sinardet:

Are you trying to replace them?

It's important to remember that the lead-screws actually have TWO threads, so for example, one complete turn on the lead-screw moves the axis 1/4", even though the thread pitch measures to be 1/8".

I'm not sure what your question is beyond "are these the right sizes". Yes, those are the right sizes of lead screws.

The thing to remember is that the lead-screws and nuts have a set pitch, as you found. The stepper motors are 220 steps per revolution, or 1.5 degrees per step. So, for example, it takes 220 steps to move the Z-axis lead one full revolution, for 1/4 inch of vertical movemement. Same is true of X and Y: 220 steps = 1 revolution = 1/4". Inside the control panel, the software decides how many pulses to send for each mm/inch of movement. It's a really odd number, but let's just assume it's right . You can actually change it in a "hidden" dialog box, but I don't recommend accessing that unless you'd doing something crazy like swapping X and Y axes (I did this on my machine).

Hope that helps, Sinardet.

Regards,

Thom