Hello. I’m kind of new to this, have got a bit of experiance. So long story short I started to build my laser engraver. I got recommended for starters to try Arduino Uno with Cnc shield. So I saw a bundle on ebay, someone sold it as sitting on shelf and collecting dust. So I bought it, over a period of time collecting all bits apart from the actual structure of the laser, I wired everything, got it running. Everything was fine, run lasergrbl and the axis responded fine, the laser module was working fine.
Then couple months later I assembled the laser structure, hooked things up and all of a sudden the Y axis is not performing. So the X axis is moving forward and back fine, Y axis is only going one way. I tried different cable for stepper on Y axis, tried different stepper, tried different drivers. If I try to run the stepper and cable thats meant for Y axis, on X axis its working fine, so I decided to try the same with Z axis and even cloning Y or Z, turns oit to be the same thing. So X axis is fine on cnc shield, Y and Z only runs one way. personally Id say maybe something on either shield or uno is faulty, but havent that much experiance or knowledge to be sure. but when I did original test runs couple months ago, had no issues whatsoever.
Any ideas or recommendations?
Thanks.
Axis moving only one way often occurs because the direction signal isn't getting to the stepper driver; or its timing is wrong relative to the step signal - usually because the wrong polarity pulse is selected so the pulse edge is in the wrong place. On some cnc controls the relative timing can be set per axis, not sure if GRBL is the same, a while since I needed to configure it. Anyway some things to look at.
Ive tried different software to control the shield, lasergrbl, ugs, some other grbl controller, nothing seems to change. Aswell i tried to reupload grbl to arduino to reset everything. so far, ive tried software change, different cables, different steppers, different drivers on that axis and its doing the same thing. so does Z axis too. X axis is completely fine.
Well those tests have at least confirmed that it isn't a software problem though it could still be misconfiguration. But it could still be the shield, it could be that the direction connection to the drivers is missing or broken. I assume that the drivers are on the shield itself? Which shield are you using?
Regarding configuration, this page explains how grbl commands can set up the step and direction pulses:
As I mentioned, it can happen that if the direction pulse sense is wrong relative to step then the direction signal won't be seen correctly by the driver.
I will look at grbl bits when Im home. Its CNC shield v3. The drivers go on the shield. I tried swapping them over. Its fine on X axis header but not on others. I moght get another arduino and shield of my mate to try. On other forums where people had similar issue they said their arduino was faulty, once replaced it all worked.
Some drivers depending on the type may need to be orientated differently.
ALL drivers need to have the current set with the potentiometer and a DMM.
Don't guess with either of those two things as it may result in blown drivers.
Another issue that causes one-directional motion is if your coils are cross-wired, which causes some half-fed phasing:
(but if the motor works correctly on one driver but not the other, it is probably the direction signal not getting to the driver.)
So after a while of troubleshooting and testing, I had access to my work colleagues parts etc. So originally I was building my laser with a modified old PC power supply. When I connected first time the steppers were pulsing. I had no idea what’s happening. Then I got another power supply from my buddy that I tested my setup with in the past and it was working. This time it wasn’t pulsing but axis went only one direction. I swapped out the drivers and jackpot. All up and running.
I don’t have much experience or knowledge to give a smart answer but what I do suspect is, that when I connected the old PC power supply, it was pulsing 6-12v all the time and it burned the drivers.( checked power supply with multimeter later )
Now I have new drivers, a proper 12v power supply and the laser is happily engraving.
Thanks to everyone who chipped in with things to try and look at. Thanks a lot.
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