Hi guys…I built my LR2 last spring and with the help of this great forum I’ve been able to resolve every problem which has come up so far, but his one has me stumped:
When cutting out a part it seems to cut “inside the line” on the first pass, but only on the right side of the part. The remaining passes are right on the money and I’d have a perfect part if not for the unsightly rabbet on the top right edge. This hasn’t mattered for most of my projects to date, but the time has come to fix it.
A bit about my setup - LR2 on 4’ x 6’ table, mini rambo, Estlcam, the following example was cut with a 1/4" 2 flute endmill (though I’ve had the same issue with other bits), 8mm/s, 0.10" DOC. Now some pics:
I would really appreciate any thoughts you have on what could be causing it. And for the record I double (and triple) checked the tightness of my grub screws.
I don’t have a Low Rider nor any particular idea about what is going on, but I suggest a few tests to collect some information. First for a test cut, I’d define the material thickness thicker than the actual material in the CAD program, say 1/4" thicker, and then I’d set the bit 1/4" above the stock when starting the cut. Another test might be to place a board under stock stock before you clamp it to see if the problem occurs at a different level. Both tests are to determine if the issue occurs at a specific height, or if the issue is caused by the forces of the bit first cutting the stock. If the problem happens at a specific height, then there is probably some sort of mechanical obstruction that is pushing the router. But if I had to guess, the problem sounds more like a deflection issue caused by something being too loose. So if the problem occurs at the top of the stock no matter what the height, then with the stepper engaged, pull your router different directions to see how much play there is.
Have you tried to power all your steppers and then grab the router and move it side to side and forward and back to see if there is any play anywhere? Looks like something shifted after your first cut because you seem to have the error on all the features on the same side?
Thanks for the suggestions guys. I will have some time to tinker with it later today. First, I’ll lock the steppers and try to feel for play anywhere. Then I’ll try cutting a part on stock of different thicknesses to see if the effect is proportional to height.
I’ve never observed the wheels wandering, but I suppose I could test this by squaring the machine, manually plunging the machine to drill a hole in some stock, jog it down the length of the table and back to zero, then plunging it again to see if it hits the same hole.
I have a mpcnc primo. Today I cut my first two pieces on 1/4” ply wood and I had a similar situation happen to me. I can tell you that on the second test I made changes on my tool list on the bit I used (1/4 spiral cut bit (upward cut) and made changes to the plunge rate (z direction) and it seemed to be less (sections) and less noticeable. I am using a dewalt dwp611 router. This was the second test and I didn’t think anything would be out of alignment or loose but since I got a similar result I’m going to also check for any play in the x and y axis and change the setting to make even smaller cuts and see if that gives me better results.
