So frustrated. why does this keep happening?

its like the machine loses its home coordinate mid job ad slowly starts going wonky each pass. the top part was fine and then it di the lower and it looks like it shifts position each time it plunges. and then when i hit cancel and the spindle returned home it crashes into the y rail.

this keeps happening just about every time i run a long job

Make sure your belts are tight at both ends, and make sure there are several teeth of the belt meshing just outside the clip. I used a little electrical tape on mine to make sure of it. Even if your belts feel tight, if the teeth aren’t meshing together at the clip ends, they’ll slip, and it will cause this kind of thing.

The other thing that may cause this is the potentiometers on the Grbl shield aren’t turned up far enough, so they’re not sending adequate voltage to drive the steppers, and they may bind or stall during a job, causing what you see here.

Another fault might be a loose connection in the terminal block. Check all the posts, make sure they haven’t come loose, and make sure there’s a good connection on both sides of the block.

Without sending any job, turn the spindle on from toggle switch and see if your stepper motors starts moving.

For some reason your machine is loosing steps. Are there rapid moves during the operation. One of the other causes can be noise from the spindle causing lose of steps.
I’m seeing a lot of folks with this same problem. The folks at Inventables need to find what the main cause of the problem is and tell people how to correct it.



I’m giving a battle for this for a month. Finally we decided to move on with DW611 and not to use same power supply for the spindle not to affect other electronic devices. So far I installed another 24V power supply for Spindle, only using ather power supply’s 24V output for Solid State Relay to activate new power supply for Spindle start, but of course temp solution until receive DW611 mouth.

If your belts are OK, adjusting the stepper motor current might be the solution. Below are two links that will explain the process.

belts are tight, zip tied and no slippage, eccentric wheels are not loose, checked all wires everything is connected firmly. turned on spindle no motor movement or green lights on gshield, ive adjusted my stepper driver currents. ive been fighting this problem basically since i got the cnc going three weeks ago. seems to only happen on long jobs and i thought it had something to do with UGS as up til today thats what i had been using on bigger jobs where this would happen but this happened using easel so that rules that out

im beginning to think its a spindle issue either a noise issue like mentioned here or a voltage drop like mentioned in other threads. hopefully the inventables folks see this

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It is most certainly a spindle issue. I had the exact same problem. A replacement spindle completely resolved the issue.

How did you go about getting a replacement?

also i remember tonight i did notice a change in the sound of the spindle while it was cutting. it sounded like a drop in rpm. it happened at a point where it wasnt cutting anything that would have bogged it down. it was very weird

Contact info for Inventables is here:

You could help verify that it’s the spindle by attaching a pen/pencil to your machine and having it run one of your projects with the spindle off, just a thought.

ill call them tomorrow

how would you account for the z travel with a pen?

I’d velco/zip tie it so that it was snug enough to draw, but could slide up when pressed as the z moves to another depth. It doesn’t have to be exact, just trying to get an idea if it’s going wildly off-path like your last project did.

ok i might give it a try tomorrow

Email and tell them your spindle is having issues with maintaining rpm and they will mail you a replacement along with a return label for the bad one.

There is a small percentage of spindles experiencing this issue and the cause is still under investigation.

You can read more about it from this thread

Also make sure your fan is blowing on the chips of the shield, not away. I made the same mistake.

i emailed help this morning, just waiting to hear back

Make sure the set screws on your pulleys are tight as well, if those are loose it would look like this.

ran the project with he spindle off and a pen attached and it came out just fine. no wandering lines or lost steps

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I wonder if it might be an “under cutting load” issue?