I have a Workbee 1510 CNC Mill. I put it together last week and tried to cut a grid in the spoil board with my company's logo on it. The grid should be 45X25 with a line every inch. The far left and right lines on said grid are off by about 1/8 of an inch and the overall dimensions are 44.875X25. This would be fine, but the logo also came out incorrectly. It looks fine in the preview, but on the board many of the lines are straight when they should be diagonal and some lines that should connect on the ends do not. After I ran the logo and saw this, I ran it again to see if it would cut on the same lines, and sure enough, it did. At first I thought it was something loose, but from watching it cut the exact same way through very soft wood with an engraver bit I'm thinking it may be something else. Does anyone know what might cause this?
Was this the very first cut you did on it? If yes, it may be a good idea to cut a "calibration" cut like a circle within a square or something very similar. It may indicate if you have a mechanical problem and/or on what axis it is.
We calibrated and re-tried. The motors were less than half a mm off before calibration. When we re-cut the logo we got the same issues. I now believe it to be a belt issue. We thought we got them tight enough but the way it's hesitating when going back and forth in the Y direction makes me think that our 1500mm belts are loose. We did try to cut circular aluminum mounts before this. They were also off in the Y-axis, but we put that down to slop in the motor mount because when we pull on the motor it rotates slightly in the Y-direction. Now I believe that it could be the belt too. Will try some simple shapes in wood next. Thanks for the suggestions!
Sounds more like loose setscrews on the pulley. Some nonpermanent locktite between motor shaft and pulley also prevents it rattling loose
Hey, an update on what I've done: I took apart both Y-axis assemblies and locktited the set screw as well as tightened the belts. I tried the calibration cuts as Justin suggested. Here are the results: As you can see, the quality has certainly improved, but is still not quite perfect. There are still some flat-ish sides to the circles on the far left and right sides, particularly the smaller ones. Also, I tried the logo again: Again, improvement, but not quite perfection. Are these results to be expected with the belt-driven steppers or could it be some other mechanical issue? Thanks for your input!
1500mm belts just aren't a great idea all the way around- we just went through this a couple of weeks ago here: Poor Circles Not sure if anything in there helps, it's usually the same issues, but it might be worth reading through since it's only a page. No real conclusion, unfortunately. If your pulleys are tight and your belts are tight- really tight, not just feel tight- then you might have just reached the limit of what the machine can resolve. It's possible that you have other issues like loose wheels or plates though. The way those two lines completely miss each other is rather odd. It's always the WorkBee 1510, though.
I pull my belts tight with a spring balance, that way I know they are all the same, and also know that they are not too little. I pull to 12kg. your longer belts may need more.
Hey, I have a similar problem on my custom made cnc machine. It makes curvy lines where the diagonal straight line has to be, and it screws up circles in the same way each time. I don't know what could be a problem. The screws and belts are all tightened up and the mistakes still happen. Do you have idea why this happens?
Check grubscrews on pulleys. Make sure you have grubs on the Flat face of the D-shaped motor shaft and properly tight.
