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Z-axis Pitch calculated at 99!

Hi, I’ve just cut my first piece on my just assembled MetalMaslow. It’s cutting great and surprisingly accurate. The only trouble I had was getting the pitch of the Z-axis correct. I set the Z-axis pitch at 8, as suggested in the forum. However when I moved it 0.5mm down it actually moved 6.4mm. A factor of 12 times more! So after some calculations I ended up with a pitch of 99!
I changed the Z axis pitch setting in GC to 99 and got the correct displacement. Of course I can live with this setting if it works, but how is it possible that I have to use a pitch of 99 where everybody else is below 10!

Sint

Wow! That does seem really high. Hmmm, I have no idea how that could work…but if it’s working…:grinning:

remember, the movement is the pitch * steps per rev, so is steps per rev don’t
match the encoder, you could need a very high pitch to make things right.

when configuring it, it may be useful to have a box that shows the calculated
result (either in steps per inch/mm or distance per step or both)

David Lang

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As @dlang alluded to, there are two settings that determine how much a zaxis will move. One is the Z-Axis Pitch and the other is Z-Axis Encoder Steps Per Revolution. If you had to make the Z-Axis Pitch 99 to get close/correct, then it’s likely that the Z-Axis Encoder Steps Per Revolution is off (i.e., low). I know on stock setup, that value is 7560.0. If @Metalmaslow is using the same stock zaxis motor, you may want to check that value.

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I believe they are using the same stock z-axis motor

@madgrizzle I checked the setting of the Z-Axis Encoder Steps Per Revolution and it was set at 7560. So that’s correct. Today I checked once again the displacement and it’s spot on with a pitch set at 99. I made my first Gcode and cut a tiny stratocaster, I am amazed by the result, so precise and clean cut. Well like Bar wrote if it works…. So for now I let it rest and focus on my dust collection system in order to outlife my Maslow!

Sint

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so that means that you have a 1:1 ratio from the stock motor to your shaft? If
you have a different ratio, either that steps per rev or the pitch will need to
be changed.

@dlang Yes the ratio from the motor to the shaft is 1:1, (equal diameters). I also measured the pitch of the spindle. I put a mark on the spindle shaft and rotated the shaft via GC in small steps until I had one revolution. Then I measured the displacement of the sled. It was 8mm. That means that I have indeed a spindle with a pitch of 8mm/rev.

Also the belt sprockets are not slipping, and displacement is consistent. If I lower the sled in GC by 8mm and then measure the actual displacement I have a spread of about 0.1-0.2mm. Good enough right?

For now I keep the pitch set at 101.5 (more accurate than the 99) and the Z axis steps 7560, and hope that this will keep giving me the same and consistent displacements. Although it does worry me a bit, it’s a mystery.

Sint

Can you post pictures of your z axis setup?

Here are some pictures. I mounted the router on a wooden fixture. It’s a temporary solution. I ordered the wrong clamp for my Maikita router, while I am waiting for a clamp from China I can already use my Maslow.

Sint.

Where did th zaxis motor come from? I wonder if it’s different than the stock motor…

I bought it from MetalMaslow. Here is a link:

But I think you are right about the Z-axis motor.
At the time I bought it I didn’t pay attention to it but they do mention: 200mm C-Beam Axis with 8x faster Z axis motor mount and clamp for above router.

It’s 8 times faster, that explains it. Probably also the Z-axis step number is not stock. The arduino had already the 1.26 firmware installed. With the incorrect setting for the Z-axis.

Anyhow mystery solved, Thanks!

Sint.