Author Options:

have i got 1 good driver or 3 bad ones Answered

Hi all, nice to be here

I have just finished building my first cnc router and about to start actually doing something with it, during my build I somehow managed to blow up 2 grbl boards and 6 drivers, hey note to myself, don't connect voltages when tired late at night

also I have a problem, I think,

thanks to YouTube I found how to set the voltage using the trimmer pots on the driver boards, I set all 4 drivers initially to 0.75 volt and it all works and tests fine, apart from having to buy 2 more driver boards when the trim pots fell off

that is apart from

one of the stepper drivers powers one motor (Y axis) and when it finishes working it goes absolutely solid locked up and sounds like it is groaning, the other 3 are firm but not locked up

I tried increasing the voltage on the 3 looser stepper motors to 1.0 volt and it didn't seem to make a lot of difference, but to get the solid stepper driver down to the same stiffness I have had to drop the voltage down to 0.4 volt and it did stop groaning and loosened a bit

I swapped over the motors, same result, moved the driver to another spot on the grbl board exactly the same effect on a different motor, so it looks to me like it is the DRV8825 driver board

is this a case of I have 1 bad board and 3 good boards? or 1 good board and 3 bad boards ? any help would be more than welcome

info on my cnc build and components below

basically the cnc has a bed of 900mm x 900mm and is pure self build made up of parts found laying around my workshop, rails bearings lead screws etc, and I added in a new Arduino uno (of which I am novice) and a new GRBL board and ended up using DRV8825 drivers, stepper motors are used (eBay) 4 x identical minebea 23LM-C343-14V wired from 6 wire down to 4 wire with pairs being red & yellow and pair 2 being blue & orange, which I believe is correct LINK TO STEPPER MOTOR SPEC SHEET please correct me if I have made a mistake

I have used links to set all drivers to 1/32 micro stepping, also set the mm rate so it is exact at 500mm travel, and set max speed at a sensible 400mm per minute as I am not really expecting supersonic speed and all is nice and quiet, nothing straining

I have paired 2 of the stepper motors via the grbl to drive the X axis and used the clone spare on the GRBL to make that work, which it does marvellous

The CNC structure does need strengthening up as mostly built on ply at the moment, but everything works as expected, the spindle is a nice almost new RotaZip high speed tool that I bought new about 4 years ago and only used it on one job so keeping stuff does come in handy even if wifey says it doesn't

Look forward to sharing info on here as I learn more

2 Replies

Downunder35m (author)2018-01-18

If you can't effictively adjust the motor current anymore than I would say the board is done.
Especially if swapping it around makes the error move with it.
I suspect you use a standard screwdriver to adjust the potentiometer?
If so then consider buying a ceramic one meant for these jobs.
Difference is the proper fit so you only get the twisting motion transfered to the potentiometer.
Also make sure to keep it straight and without wobble when turning ;)

Select as Best AnswerUndo Best Answer

IanT107 (author)Downunder35m2018-01-19

Hi and thanks for answering, I have ordered another driver board, they are dirt cheap anyway so no real worries, I have a ceramic trimmer from when I used to have to trim 415 voltage so I did use that one, guess I am just a tad heavy handed these days, could you look at the data on the stepper motors if you get a chance and direct me to the correct voltage I should be setting the drivers to


Select as Best AnswerUndo Best Answer