Hi all. I have just built an Ox CNC router with black box controller and having an issue on a cut. I am trying to cut a slot 10 mm wide and 80 mm long. The starting point is mid line and makes the first arc great but after it completes the second arc it does not go all the way to make the width 10mm (about 3 mm short on the x axis). All the subsequent plunge cuts follow a straight line (Narrow slot). This does this on pockets, inside and outside profile cuts, but only on the first pass. I have tried using a different computer as well as a dfx file created by solid edge and Freecad as well as the cut file using sheetcam and Freecad, all with the same result. I have reset the controller but no change. I have attached an image of the issue as well as my cut file Any help would be appreciated
As its an Ox, first thing to check is the Grubscrews on all the pulleys - they can go loose over time, pulley slips on shaft, during direction changes particularly
I have checked those and they are all good. It is a very repeatable issue as it happens every time. It seems to be related to the circle component. I tried a 25 mm diameter circle this morning and the x axis is only 22 mm wide so looking more like an oval. Double checked the calibration of the machine and that is good. Not sure if it with the code, controller or the machine.
That jump looks like its at the entry point - have you tried a very slow plunge rate as a test? The gcode looks correct, the symptoms still looks mechanical
I have tried with .5 mm cut with same results but will slow the plunge rate. Reading some other posts I will check current adjustment to the steppers and possible wiring connections as well. The widest portion of the cut is correct at 10mm. It is the bottom of the photo when the bit exits the arc it is now only a 7mm wide slot instead of 10mm. Every additional pass follows the 7mm cut lines. If it was mechanical I would think that each pass would be slightly different.
X is slipping, mechanically or just missing steps due to overload. it is coming down in Y then curling clockwise going left in X. since it is conventional cutting it is then experiencing maximum pushback from the tool in the corner and slipping or skipping steps. if you run the code with the tool in the air what happens? maybe attach a sharpie to draw the tool path so you can confirm. if that operates correctly then this diagnosis is confirmed. several possible fixes for skipping steps: (some or all of) increase current to the X motor decrease speed decrease acceleration climb cut
After going through everything again I have the issued solved. Thanks everyone for your suggestions. I believe the biggest culprit was the gantry wheels being too tight. Great support Thanks
