Single Axis multiple stepper with different steps/mm possible?
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Hello, my machine runs triple belted Z axis. This is my current driver mapping and steps/mm.
M584 X0 Y1 Z7:8:9 E3 M92 X80.00 Y80.00 Z80.00 E427.8My bed does drop when power is cut, currently I use counterweights to avoid this but I'd like to find another solution.
First thing I'd like to try is planetary geared (51/1) nema17 motor. However I'm on a budget and before ordering 3 of them I would prefer to try just one.
I don't think it is possible to assign driver numbers in M92, is there any way to achieve this? -
@Nordle i'm not aware of a way to run different steps per mm, i'm afraid.
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@Nordle 51:1 is quite a big ratio, that will slow down the z-axis a lot...
I've had good results with 4mm pitch ballscrews and 3:1 geared stepper, another user is happy with his rhino-drive a worm geared stepper. (not sure about it's gear ratio) -
Good morning @Nordle
You can assign different steps to different motors
Imagine you put the gearbox to driver 8, you should have the command like this, if I'm not confused, they go in order according to the assignment in the mapping (M584)
M92 Z80:4000:80
This applies to all the driver commands, but I don't know what will happen if you set different accelerations or jerk, I understand that it doesn't make sense or it's not possible.
On the other hand in my opinion without seeing your machine 50:1 seems too much, surely a 10:1 is more than enough or less as @O_LAMPE says.
Best regards
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@Aitor no, that won't work. you can't assign different steps per mm for different motors on the same axis
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Good morning @jay_s_uk
I have tested this on the E axle, what I can't say is if the rest of the axles behave the same, but I understood that they do.
Best regards
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@Aitor you can for extruders as its expected that people will have different tools etc. for a conventional movement axis, such as X, Y or Z etc it isn't supported
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Good morning @jay_s_uk
Ok, that's clear, a pity because it would have been a good solution for @NORDLE
And you are right, because I couldn't avoid doing a test, and although it doesn't show error when putting M92 Y100:150 it only keeps M92 Y100 and the axes move correctly.
Thanks for the clarification
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@Nordle have you considered using stepper motors with brakes?
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Thanks for all the helpful replies.
@o_lampe I would like to stay away from ball screws, as they tend to be rather expensive or a cheap hit/miss. And I'm already very impressed by the results of the belted Z. I did consider other gearing solutions like a worm gear but it is the same pita as acquiring quality ball screws, and a mediocre solution would probably give me more headache than my current counterweights.
I didn't think about the gearing ratio to much, went a little crazy probably should choose less ratio.
How is your ball screw setup geared? belt and pulleys?
I could probably do a 1/10 belted space wise.@jay_s_uk special thanks for the clarifications
@dc42 I didn't. something like this first I could find on aliexpress? Are they in holding position when no power is applied?
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You need different ratio of pulley , I run belt for my z axis . I have 2 60mm stepper motor tie to the following pulley 20 to 60-20 to 60-20, I have heavy bed and it doesn't move when power off , you can push it down but you need a decent amount of force with .9 deg stepper I have around 1400 step for one turn if memory correct
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@Nordle said in Single Axis multiple stepper with different steps/mm possible?:
@dc42 I didn't. something like this first I could find on aliexpress? Are they in holding position when no power is applied?
Normally the brake is engaged when power is not applied. Applying power to the brake solenoid releases the brake. RRF 3.4 and later support motors with brakes, see the M569.7 command.
Make sure that the brake solenoid voltage matches your VIN voltage. 24V is typical.
If your machine suffers a sudden loss of power, the brake may not engage quickly enough to prevent a slight drop. Using M18 in the M911 power fail script may speed up application of the brake, especially in RRF 3.5.
