I’m pretty much a noob, but I did some searching and YouTubing without much luck.
I was able to pocket a shaker style sample piece pretty successfully, but I wanted to see what it would look like with a bevel on it. So I tried a 60 degree vee with a vcarve exactly on the outline, and ended up with rounded corners.
I tried a new piece (without having done the pocketing) with an advanced vcarve, and it’s much better, but there’s kind of a flare in the corner. If somebody could look at the pics and tell me where I’m going wrong that would be great!
It looks like there could be some slop in your machine. With the power on, and the spindle off, grab the tool & try to move it right-left, front-back. If it moves, even a tiny amount, that is your issue.
Plywood has a lot of variation in density & hardness, so the forces, particularly lateral forces on the tool fluctuate quite a bit.
My guess would be that the corner is correct, but the path leading away from it moved a bit.
Use a depth of cut that is slightly less than a factor of the total depth. This will result in a ‘finish’ pass for the last cut. i.e. Your total depth is 0.250. You want 3 passes. Divide 0.250 by 2 (0.125) and set your depth of cut to 0.120. Now you should have two passes at -0.120 & -0.240, leaving 0.010 for the last pass.
If the issue is specific to the 60 degree bit and shows up regardless of material being cut, you might try defining it as a custom V bit with a smaller angle (maybe 57 degrees or even less). This is a guess based on the following picture where I cut gcode (generated for a 60 degree bit) five times, three times by varying zero height and two additional times by intentionally using a bit of an incorrect angle. When I used a 30 degree bit, I got odd corners which might be exaggerated examples of yours. This was an error of -30 degrees in the bit used vs the bit the code was generated for.
Investigate what aspect of the machine allows the movement — if loose hardware tighten, if loose belt, tension, if a bad bearing in a spindle, replace, &c.
