I can't seem to search and find a definitive answer on what is happening. I would say I'm circle trouble shooting, but that's not the correct term here. I am getting a lump on my carvings whenever there is a plunge movement to go deeper. IE: I cut a center section of a letter out of plywood and it's entry or plunge point in that part will have a lump, defect or point that is repeatably cut wrong according to the drawing. Same thing with the outside of the carving, there is a lump at one point where the cnc is plunging deeper. My Lead 1010 is controlled by a Blackbox and Openbuild control software, I create GRBL code in VCarve Pro. I have checked calibration by using a dial caliper on each axis to measure movement, then verified again at the tool.
Measured two points of the circle, 90 degrees apart and away from the lump, the circle appears to be a consistent circle.
This was a 1/8" downcut bit, I was running it at 0.08" and 25 in/min (plunge) to be conservative while I learn. 55 in/min feed rate.
It only does that on circles? I just recently purchased V-Carve and am not real familiar with it. Have you tried ramping into the cut? Although .08" is not real aggressive so it probably isn't from plunging, but end mills are not great for plunging. Also, the error would probably show up on other shapes if the plunging was the problem. I usually ramp in unless I am using a V bit. I have had similar errors when I accidentally plunged on harder materials especially aluminum. If the option is there, try some test cuts by ramping into your material.
No, just used the circle as a reference. I do have the option to ramp, so I will give that a try. I will also try using Openbuilds software to create code and run it to see if my settings in Vcarve may be awry. This issue can definitely be software based now that I think about it. There is no play in the router, Z axis or twist in the X. If there was, I believe the symptoms would be different.
If it is, the preview would show it likely (does it?, you can post the file too) Try it, but my money is mechanical play of some sorts
I think your money is in the right place, but I'm having trouble finding it. Is there a good source somewhere to follow for troubleshooting? I added .5" ramp into the plunge and nothing changed. I added in the files to see I missed something.. It doesn't matter what shape it is, as long as there is a curve in a profile cut where the plunge into the material is at.
Yip, no bump in the gcode, must be something mechanical Hold the endmill, give it a wiggle, something has to give a little if you push hard enough, that first cut is full cutter engagement (hardest forces)
I can get it to move by 0.008 in parallel with the waste board, measured by dial calipers. I really need a dial indicator to get better results, but don't have those on hand. I definitely can't measure the vertical movement of the router with a dial caliper, but it feels about the same. Feel isn't exact, but I can say that with more experience than most, I am a metrologist, working in physical dimensional and electro-optic areas.
That's pretty good, almost less than the normal deflection numbers - sure you were pushing hard enough against it? How to calculate V-Slot® deflection Then next up is rechecking drive system (couplers, stop collars, leadnuts)
This morning I was running back over what motions are happening and possible errors within the CNC machine. If the Y axis motors had a different preload or backlash on one side it can cause this. I'll check the Y axis tonight and see.
Fairly positive, wasn't trying to break the 1/8" endmill. I could retry with a 1/4" and feel better about using more pressure. Couplers and stop collars are easily checked, I'm guessing leadnuts would show play along the threaded rod. Is there an easy way to adjust the Y axis leadnuts without taking the X axis off the rail?
If i judge the scale on the cut correctly i dont think leadnut adjustment would be the issue (dialing in last couple microns) - more like nut is just barely hanging onto the plate.
There was a small amount of play on the right side of the Y axis, took it out with the collar nearest the motor. Ran it again and it's mostly gone, I'll have to continue to search a little more. Thanks for helping me narrow this down!
That's great! I would also recommend that you double check that all of the X to Y axis frame connections are also nice and tight and also double check all your wheel nuts are seated tight.
