1. Guys whats the best way to find out the pitch of the Z screw?

2. Originally Posted by JAZZCNC
Mark it and rotate one ful revolution and measure distance moved.. . . Simplizzzzz

3. Ah ok

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4. Measure it would be the obvious answer, but I'm going to guess it's buried out of sight.

Do you know if it's got any gearing between it and motor?

If it's all totally unknown, I'd set the steps/mm to 10 or 100. I'd probably try 10, and if you don't get much movement jogging, up it to 100, or maybe even 1000. You want to be able to jog at a reasonable speed. Too low a setting and it'll hardly move, too high and it'll be hard to control.

Then jog over a reasonable distance that you can measure accurately.
Then divide the commanded movement by the actual movement, and finally multiply the steps/mm by that figure.

So say you use 100 steps/mm. You jog 20mm, yet the machine moves 35mm. 20/35 = 0.571439 Now multiply that by 100, and your steps/mm should be 57.1439.

5. Originally Posted by m_c
Measure it would be the obvious answer, but I'm going to guess it's buried out of sight.

Do you know if it's got any gearing between it and motor?

If it's all totally unknown, I'd set the steps/mm to 10 or 100. I'd probably try 10, and if you don't get much movement jogging, up it to 100, or maybe even 1000. You want to be able to jog at a reasonable speed. Too low a setting and it'll hardly move, too high and it'll be hard to control.

Then jog over a reasonable distance that you can measure accurately.
Then divide the commanded movement by the actual movement, and finally multiply the steps/mm by that figure.

So say you use 100 steps/mm. You jog 20mm, yet the machine moves 35mm. 20/35 = 0.571439 Now multiply that by 100, and your steps/mm should be 57.1439.
It's a tad tight but the gearing is 1/1

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6. I can just get in to measure it when I lower it, what am I measuring? I know the screw dia just need the pitch for the steps per

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7. You could get a rough indication with a pair of dividers, if you set them to the narrow groves between the ball ways, ie on the OD of the screw. Then do as M-C instructed and use a dial gauge to get the actual distance traversed.
Last edited by mekanik; 18-03-2017 at 04:57 PM.

8. Originally Posted by D-man
I can just get in to measure it when I lower it, what am I measuring? I know the screw dia just need the pitch for the steps per
For a metric screw, you measure the distance between each thread/ball track.
For an imperial screw, you measure the number of threads/ball tracks over an inch.

9. measuring gaps won't help if it's multi start which often are. Best way is try to mark the screw and rotate 1 rev and measure distance. Chances are it will 5mm or 10mm pitch so easy to see which.

However if your still using mach3 then it's simple really just let mach work it out for you using Set steps per in the settings tab.

10. Originally Posted by JAZZCNC
measuring gaps won't help if it's multi start which often are. Best way is try to mark the screw and rotate 1 rev and measure distance. Chances are it will 5mm or 10mm pitch so easy to see which.

However if your still using mach3 then it's simple really just let mach work it out for you using Set steps per in the settings tab.
Bang on my mate! 5mm I took a chance and it was bob on!

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