Post by dwkdnvr on Mar 28, 2018 4:10:32 GMT
I picked up my M3 quite a while ago, but after getting it assembled and verifying that it basically 'worked' life got in the way. I'm finally getting back to fine-tuning recently; I've tightened up the belts and gotten the eccentric spacers at least close so the basic mechanics are pretty reasonable. After that, I figured I'd try calibrating and am not quite sure what I'm seeing.
I created a dxf file with a 100mm square, and centered inside that I created a 50mm diameter circle. In Estlcam I set up an outside cut on the square, and an inside cut on the circle. I used a 3mm bit upcut bit for the test, and cut at a 6mm depth so I didn't cut all the way through the material. The test was done in cheap 1/2" ply so there was a fair bit of fuzz on the edges of the cut, but other than that it looked ok. I squared the bit to the workpiece as well as I could with my try-square; I'm sure it's not exact, but visual inspection indicates that it doesn't seem to be wildly off.
When I ran the file, the good news is that things are fairly close and X and Y are in pretty close agreement. The problem is that the square is too small, but the circle is too big. The 'outer' square measured at about 99.3mm, while the circular 'hole' measured at about 50.4mm. So, it doesn't look like I'm dealing with a simple problem of the steps per mm being off, since if that were the case I'd expect everything to be off in the same direction.
My first guess was that the bit diameter was off, but according to my calipers it's very close to the nominal 3mm configured in the CAM tool - maybe 3.03 or so. Second guess is runout (I'm using a Dewalt 660, although with the 611 being $99 on amazon at the moment I suspect I'll switch over). The paths cut around the circle measure about 3.3mm which is a bit more than I'd expect so that may be part of the problem - but even if that represents runout it doesn't fully account for the measurements I'm seeing.
So I'm asking for other suggestions - what should I be looking at to get more accurate cuts? And, if the 3.3mm cut width does represent runout, can I account for this runout by altering the bit definition in CAM to try to compensate?
thanks for any suggestions
Doug.
I created a dxf file with a 100mm square, and centered inside that I created a 50mm diameter circle. In Estlcam I set up an outside cut on the square, and an inside cut on the circle. I used a 3mm bit upcut bit for the test, and cut at a 6mm depth so I didn't cut all the way through the material. The test was done in cheap 1/2" ply so there was a fair bit of fuzz on the edges of the cut, but other than that it looked ok. I squared the bit to the workpiece as well as I could with my try-square; I'm sure it's not exact, but visual inspection indicates that it doesn't seem to be wildly off.
When I ran the file, the good news is that things are fairly close and X and Y are in pretty close agreement. The problem is that the square is too small, but the circle is too big. The 'outer' square measured at about 99.3mm, while the circular 'hole' measured at about 50.4mm. So, it doesn't look like I'm dealing with a simple problem of the steps per mm being off, since if that were the case I'd expect everything to be off in the same direction.
My first guess was that the bit diameter was off, but according to my calipers it's very close to the nominal 3mm configured in the CAM tool - maybe 3.03 or so. Second guess is runout (I'm using a Dewalt 660, although with the 611 being $99 on amazon at the moment I suspect I'll switch over). The paths cut around the circle measure about 3.3mm which is a bit more than I'd expect so that may be part of the problem - but even if that represents runout it doesn't fully account for the measurements I'm seeing.
So I'm asking for other suggestions - what should I be looking at to get more accurate cuts? And, if the 3.3mm cut width does represent runout, can I account for this runout by altering the bit definition in CAM to try to compensate?
thanks for any suggestions
Doug.
