z stepper driver replacement help

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Wibb
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Joined: Wed Mar 30, 2016 5:07 pm

z stepper driver replacement help

Postby Wibb » Mon Jul 25, 2016 9:16 pm

My old stepper driver had died so i replaced it with a generic A4988 driver.

I have noticed some strange behavoir. when manually jogging the Z stage it moves fine, but when starting a print, the z stage drops a few cm to prime the nozzle but when the head travels to the build area and brings the Z stage up - there is a loud grinding noise and the z stage looks like it is jammed (only moving up very slightly) and then begins to air print.

My question is do i need to adjust the pot on the replacement driver? if so how do i do it? i have a multimeter but need to know which pins to read off and what values im looking for.

Also there are 3 tiny toggle switches under the stepper driver socket, they are all flipped toward the right as you look at them. what do these switches do and do they need changing?

Any suggestions on what to try would be appreciated
thanks
Simon

P.s. i do have a spare TMC2100 driver which i would like to use for the Z but im told i have to change some settings to reverse the travel direction

firesped
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Joined: Mon Mar 21, 2016 9:23 pm
Location: Tucson, AZ

Re: z stepper driver replacement help

Postby firesped » Mon Jul 25, 2016 11:18 pm

I needs to be set to 1. The switches are the step configuration. I think all the stock steppers are hardwired to the correct steps. You will need to configure this to 1/16 steps. If it is not configured right it will either move very small distances or very large distances.

they are set to ON by default. the A4988 is all set to High for 1/16. however I would find the specific documentation for that driver to know how it should be configured.
RL name: Michael Nolen
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Wibb
Posts: 70
Joined: Wed Mar 30, 2016 5:07 pm

Re: z stepper driver replacement help

Postby Wibb » Tue Jul 26, 2016 8:40 pm

I had a look at what voltage the A4899 was set at from the factory - it turned out it was 0.6v which is why the motor struggled during use. i turned it up to 1.0v and this solved the issue straight away :)

I will also try this again with the TMC2100 with the voltage turned up to 1.0 next.

thanks for the help Michael!
Simon

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Vicky@Raise3D
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Re: z stepper driver replacement help

Postby Vicky@Raise3D » Wed Jul 27, 2016 2:20 am

Hi Simon,

Is your Z stepper driver the adjustable one like Extruder driver?
We have two kinds of stepper drivers for Z. One is a normal, fixed voltage a4988. One is adjustable a4988. Not sure the reason, but the default voltage in our factory adjusted for Z hould be 0.8V-0.85V. I suggest you turned your Z stepper driver's voltage down to 0.85V for safety.
Don't recommend to use TMC2100 to Z. You need to change the wiring order and switch the dial switch.


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