Hey folks, I have a consistent error when I mill double sided object. When probing with the openbuilds probe and software (advanced menu), I consistently have an error of +2mm+diameter of the bit i'm using. I have to manually reset the zero on the X axis every time and that leads to errors (when I forget to push that bloody zero button) that are SUPER frustrating, because they happen at the end of a long milling process. Any idea on how to correct this on a more systematic basis? To be more specific, that's the process: - after milling the front part, I turn my piece - I zero my bit with the probe, in the advance section I choose lower right corner instead of the lower left corner and add the dimension of the stock. Y is always fine, X is always wrong Did anyone face this issue? best!
And your X dimension is out? Sounds like it could be a discrepancy between actual stock dimensions and the ones assumed for CAM.
Yes, it happens every single time I flip a piece to mill its back. I follow the instructions of the probe and always get this error.
You need to mill holes into your piece and your spoil board for locating pins. Then when you flip it, it will always be accurate. Here is a video that explains it better than I can. You do not need to have Vectric products to do this, they just make it easy. At about the 20 minute mark they show how you place the holes and copy to the other side. If you can't copy to the other side with your CAM software, always put the holes dead center above and below the model (or centered on each side). They have to be in the exact same positions for both sides. If you only use two, you have to be consistent with which way you flip your model. I always use three that way there is no way I can flip it the wrong way.
Also, broken endmills work great as locating pins. Because they can be pretty long, I put the endmill shaft in a vise and snap it in half. Then I have two per broken endmill. Sadly a couple of my nice Sharkbits 1/4 inch endmills are now locating pins. The nice thing is that when I drill the holes in the work piece and spoil board with the new replacement endmill the locating pins are an exact fit. Here is a picture illustrating the work piece after completing one side and inserting the locating pins so it can be flipped into place on the spoil board. The nice thing about locating pins is that you only need to probe your very first side because after that all cuts on the back will be referenced to the holes on the front (first side). In fact, you can restart the second side anywhere on the spoil board you want because everything will be based off the holes, which are always the first tool path of the second side. This is handy for when you realize that a reference hole would have been drilled right into a threaded insert or t-track if you use those things. Just set a new XY zero point in a location where the holes can safely be drilled.
I always use one of the locating pins as x0y0, and table surface as Z0 for the second side, then material thickness no longer matters so long as it is thick enough for the carve
Argh, exactly it was just the machine that needed better calibration Calibrated to the full length of the bed, to get maximum precision, now it works like a charm!
