Hello- I'm working on getting my C-Beam machine and running. I've followed the videos, have been able to jog the machine and get code to run, but when I run the Hello World code from the C-Beam folder, I am getting weird results. I'm hoping someone might have some thoughts. I'm using grbl on an Arduino with a Protoneer CNC shield. I've updated the grbl codes to match those in the C-Beam folder. The "W" seemed to cut fine, but then things seemed to go off the rails. I'd appreciate any suggestions.
Hi Scott. I am probably going to be the first, of many, to say it looks like a mechanical thing. It would seem it started okay, but then the stress of doing it's thing has made something come lose. Initial checks should be the grub screws are still tight in the screw connectors. A very common cause for problems like this. Generally tug and heave on all the parts and check for ANY movement. Did you just have one attempt, or did the same thing happen several times? Get back to us if no luck there. Gray
Hi GrayUK- Thanks for your response. I've only done it the one time with the spindle going, but in dry runs without the spindle, the movement hasn't been what I've expected (like the D in the image ending up way over on the right hand side, partially outside the build area). I've checked the mechanicals and everything feels pretty tight to me. I am beginning suspect one or more of the stepper driver chips might be bad. It looks to me like when the machine tries to step down, it isn't aligning the new cuts and many of the letters are the correct shape, but in the wrong place. Can bad stepper chips behave well some of the time? There are times while running the Hello World code when I hear sounds coming from the steppers, but there is no movement or there are long pauses between movements. . . .I'm still getting me feet wet so I don't know what's normal and what's a sign things are amiss.
You'll need to give us some details of your setup. Power supply - drivers - steppers etc. Voltages and Amps. Any cooling? Gray
Just to throw this in. For diagnostics you may want to try sending some G-Code G0 commands and make sure the spindle is going where you'd expect it to. For example try a G0x100 then a G0x0 and make sure the spindle ends up back where you started. Try plenty of moves and make sure it's always doing what you expect. Try the same on the Y. It does look (and from your description sound) like both X and Y steppers are losing steps either due to binding (wheels too tight in the frame type stuff) or a driver issue.
Thank you for your replies. I think I've made some progress. I had purchased a synthetos grblShield in addition to the Protoneer board a while back, so I tried wiring it up to see if I got the same results and everything suddenly seemed to work much better. So it does seem to be an issue with the stepper drivers. I have since found a link to the Polulo drivers and a discussion of setting the power output of those chips. I'll report back once I've had a chance to tune the chips.
After following the directions for tuning the DVR8825 chips, the Protoneer shield seems to be working well. It seems that DVR8825 chips as they arrived were set to deliver current too high for the steppers and thus I was loosing steps. After tuning the chips following the directions on the earlier link, everything worked well and I had a successful run of Hello World. It does look though like I will either need to tune the chips to even lower current or get a fan to keep everything cool.
