Losing Z steps mach 3 on converted new hermes engraver

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05-16-2019, 05:56 PM
tom.jelly

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Losing Z steps mach 3 on converted new hermes engraver

I converted a New Hermes 3400 engraver using the OEM drives and steppers with a cheap ebay breakout board, and am consistently losing steps in the Z axis only, where the cutter ends up higher than it should. Note that this machine is designed so a spring loaded foot contacts the workpiece (to provide a consistent engraving depth even on somewhat flexible material by pushing down on floppy plastics) and the Z stepper, an Oriental Motor Vexta PH268-21-c68 2 phase, 1.8 degree 5.4vdc 1.5A is the same motor as the other axes which work fine. I think I've used very conservative values for motor tuning, (steps per 2000, velocity 30, acceleration 2, step pulse 5, dir pulse 5, same as the other axes) as speed is not that important to me. I thought maybe because the z motor was sometimes working against the spring that that might be causing the issue but the motor has no problem overcoming that force at the beginning of jobs, the problem happens in the middle of a job. I'm not sure what the step pulse or direction pulse settings do, should I adjust those to something other than 5 and 5 or is there some other adjustment I should make?
05-16-2019, 09:46 PM
awerby

Re: Losing Z steps mach 3 on converted new hermes engraver

According to this datasheet: https://datasheetspdf.com/pdf-file/9...xta/PH268-21/1 that motor has an inductance of 6 mH per phase, so it really wants about 78 volts of DC electricity supplied to run optimally. How much voltage are you giving it?
05-16-2019, 10:23 PM
tom.jelly

Quote:

Originally Posted by awerby

According to this datasheet: https://datasheetspdf.com/pdf-file/9...xta/PH268-21/1 that motor has an inductance of 6 mH per phase, so it really wants about 78 volts of DC electricity supplied to run optimally. How much voltage are you giving it?

It uses the OEM power supply and drives, so whatever the stock voltage was.
05-10-2020, 12:22 PM
kck63

Quote:

Originally Posted by tom.jelly

I converted a New Hermes 3400 engraver using the OEM drives and steppers with a cheap ebay breakout board, and am consistently losing steps in the Z axis only, where the cutter ends up higher than it should. Note that this machine is designed so a spring loaded foot contacts the workpiece (to provide a consistent engraving depth even on somewhat flexible material by pushing down on floppy plastics) and the Z stepper, an Oriental Motor Vexta PH268-21-c68 2 phase, 1.8 degree 5.4vdc 1.5A is the same motor as the other axes which work fine. I think I've used very conservative values for motor tuning, (steps per 2000, velocity 30, acceleration 2, step pulse 5, dir pulse 5, same as the other axes) as speed is not that important to me. I thought maybe because the z motor was sometimes working against the spring that that might be causing the issue but the motor has no problem overcoming that force at the beginning of jobs, the problem happens in the middle of a job. I'm not sure what the step pulse or direction pulse settings do, should I adjust those to something other than 5 and 5 or is there some other adjustment I should make?

Hi I am doing the same conversion , can you tell me how you went from the break out board to the oem driver. Any information would be greatly appreciated. Thank You