Strange jerking behavior

I was testing out my skirts and 12’ beam and cutting to the right edge of my ply. On the bottom right my sled start to be choppy and have a jerky motion. The Bit was bitting into the sides jerking the sled. I thought it was the location so I paused the program and z stepped to the next piece that was mid center. Same motion. I was about 2 hours into a cut. I shut it down and did a motor test, which worked. Then I right clicked to move to location and I got a sled not keeping up error after barely any movement. I checked connections all seemed to be good. I changed bits since it was slightly discolored and pressed on and it worked fine. Was using a 1/4" spiral upcut to a 1/4" straight. Any ideas?



Did the shield motor chip overheat? They will pulse if thermal shutoff occurs as the system moves, overheats, pauses, then continues until it overheats and pauses again, giving the jerking motion. A fan on the shield may help if heat is the issue.

Not sure. I’ve done 2+ hour cuts and it really wasn’t that hot yesterday. I’ll wire up a fan regardless.

I’m not saying that is absolutely what it is, but a possible suggestion to disprove in the process to learn what it could be.

since the bit was discolored and it worked after you changed the bit, I think
what happened is that the bit just overheated and got dull, it then requires
more force to cut, so as the chains let out it requies more slack before there
is enough weight on the sled for it to move (it could be that sanding/waxing the
bottom of the sled would help as well)

try to slow down the router to see if that helps the bit last longer (the maslow
has trouble moving fact wnough for good cutting, you want chips, not powder),
also going to a single flute bit may help.

David Lang

Also, if the bit is discoloured try cleaning it with engine degreaser, spray it on, wipe it off with a paper towel

Mine does the same at the lower right hand corner running vertically and on the X axis on the right side. The router wanders destroying the piece. These are large flat panels used in cabinet making, so a bad edge either has to be resawn or tossed. Can be expensive.

I placed another brick on the machine and that seem to help. I can get it to stay in line by pushing down on the router with my hand through the trouble spots. Do you think I have a motor issue as well?

sounds like the sled is sticking, a wider top beam can help, slowing the feed
rate can help, sanding/waxing the bottom of the sled can help, slowing the speed
of the router so that the bit doesn’t burn out as much can help.

David Lang

Getting good chips from Bits Bits 1/4 Compression Bit.
What are the spec’s of a set up that doesn’t have this issue?

It seems to have been an overheating problem. Today everything ran smoothly.

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