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When the x-carve is on the stepper motors should be powered and “locked” into position.
That is why the motors get hot even when not moving, they are actually on and holding position at that “step”.
Many CNC controllers use a different current settings for “Holding” and “Cutting” operations.
The idea being that it takes less force to hold the motor in place than it does to do a cutting operation.
So by reducing the current during a Hold operation it lets both the stepper driver and motor run cooler.
If you can cause the gantry to move when the motors are “on” then the “Holding current” is not high enough.
There are 2 settings that will effect this:
The main current potentiometer changing this will change the current to the stepper for everything and is usually what you will be adjusting
There is also a software setting in grbl, to adjust the “Holding Current” value.
If I remember correctly it is set to Max by default. So you should not have to mess with it.
You probably will need to bump the pot on your controller until you can change the bit without the gantry shifting.
James, thank you for the videos. i’ve watched quite a few of them, not only in this thread. keep up the good work.
keep an eye (or finger) on those steppers as they’re working through your job to make sure that they’re not getting too hot. too hot may not kill the stepper, but it might burn out your motor controller (G-Shield?). turning up those towards the top means that it’s sending more voltage (more current) through each line. but, hey, looks like you found your solution. do you think it was a combination of motor voltage AND loosening the strain of the Dewalt power cable? or are you leaning more towards one than the other.
I think it was a combination of both items. The voltage increase definitely cured the words spacing problem and the to tight power cord resolved the word write over problem on the right extreme of the carriage travel.
Zach, I have my machine up and running with my new computer and I am still having problems with the dual cut. As Alan Davis suggested, I left the p/s interface on during the bit change and it was still almost impossible for me not to move the router. I have the stepper motor voltage set to 1/8 turn from the maximum settings on each stepper motor. I tried two test runs, first one for some reason the cnc would not recognize my com port when it came to the finish part of the run. After speaking with John, I turned off the p/s interface and turned it back on and it accepted my port # but it still carved off a small amount and left a small edge around the box and letter. Then I tried it a second time and again I was unable to change out the bit without moving the router and I was being very cautious of doing this. When it started the finish carve (it recognized my port this time) but it was off to the right about 1/8". So I stopped the process and don’t know what to do now?
WOOHOO! Success at last! Talking with John at Inventables and he made a couple of suggestions for me to try and it worked. I was able to get my dual test carving to come out looking correctly. I mean who knew what them lock/unlock rotor tabs were for??? Thanks John! Now on to the real thing, with a piece of high dollar oak no less.
Well things were going along just great and the machine stopped about 40% into the finish carve? Don’t know what happened unless my internet crapped out, which it does from time to time (thank you so much Comcast). So I re-started the carve from the rough cut and was carving until I realized I had not gotten the ‘zero’ set point in the same place and I was getting a ‘phunny’ looking carving, so I stopped it again, turned the board over and started anew on the reverse side of the board. It is currently running and I get real bored watching saw dust accumulate. Will follow up and let you all know how it came out the third time. That’s the charm, right?
This is for John at Inventables. Thought we had all the kinks out of the dual carve process, but obviously not. As you will see from the video I set the rough carve for a .075 depth and it carved then the finish carve came up, checked it was set the same and you can see it carves deeper around the letters for some reason. Don’t really know what’s going on here, but maybe you guys at inventables can get together and let me know.
I mean who knew what them lock/unlock rotor tabs were for??? Thanks John! Now on to the real thing, with a piece of high dollar oak no less.