What should I be looking at to diagnose this?
It was weaving around when in the left and particularly the upper left of the board. So not resisting the cutter force and swerving around way off the cut line. After a few serious swerves the cutter really grabs and the >15mm error happens and the emergency stop is triggered.
The thing is it works quite accurately elsewhere on the sheet.
Upper left was having trouble retracting. I had to help it get turning by hand but then it sucked all the way in just fine.
Here are photos of the cut starting to fail when in upper left region. It’s a simple grid of blocks with slots. Next one over starts the slot and quickly goes off course and trips the emergency stop.
125” cut depth and speed of 60. Router on 1 or 2.
This sounds to me like the tension in the belts is too high. The top left belt has the most angle to it so it makes sense that we would see the issue there. Is this in the upright configuration?
You can try running calibration with the amount of force used to retract the belts when taking the measurements reduced which will reduce the tension in the belts, but it also might just be a geometry issue that you can only really get so close to the anchor points reliably especially the top left one and especially in the vertical orientation
Yes it’s upright. Belts too tight? That’s interesting, I did wonder if it was flexing the frame but this happened after reinforcing it. It has worked in this area a few monthes ago.
It really seems like that upper left is just not reeling in smoothly. Is that a thing? It is the highest and does have the biggest tilt down to the mount. I wondered if there was something mechanical with the arm. Since it often needed help to begin retracting. Could chips or dust in the gears start to need too much force to operate? I got some graphite powder in some a few months ago and they totally jammed. Had to disassemble and clean.
The arms squeak a lot now when retracting. Like the belt spool has some friction.
I’ve found that sometimes (especially if the belts are really tight) the belt can get wound on the spool funny which creates extra friction. A couple of cycles of extending and retracting can help.
The 4.1 update also generally has several fixes that should help make the arms run more smoothly and be lower maintenance.
I’m pretty sure this isn’t an issue, that’s a totally reasonable amount to cut unless the bit is super dull or something and even then it wouldn’t be an issue just in one corner.
The issue is usually the way the belt piles up on the spool. If it is spooled in a way that it’s rubbing on the top of the arm it can create extra friction
Right, I guess I’ll take the arm apart and just see if anything is wierd with it.
I looked at the cuts more closely it seems it has the most problems heading left. Almost no problems cutting to the right . But it’s not totally consistent.
It definitely seems that belt is moving in jerks not smoothly. Hence the zigzag. It returns to the line but then goes off again. Is that something with a known cause?
I’m pretty sure that you don’t need to take it apart, I think that the issue isn’t in the arm.
What is causing the zig zagging is the top left motor not having enough power to pull the machine to where it wants to in that top left corner.
There are a couple things which could cause that like funky calibration, frame flex, or just the geometry of the frame. There is some point where it won’t work well as you get closer to the anchor points (especially the top left one) so it might be that in the top left corner you are hitting the limits of how close to that anchor point you can safely cut in which case there isn’t really anything you can do other than to cut further form that anchor point (move the spoil board down a little) or more the anchor points further apart (make the frame bigger)
I got it working better. I think it was frame flex as the original problem! I had to modify the basic frame to fit in my shop so I added some 2x4s where I had cut it away but it wasn’t until I redid Calibration after this renforcement that it really started to operate smoothly.
I did take the arm apart just be sure. So I can’t say for sure if it was not working but I did clean some accumulated junk out of the gaps in the gear teeth (which, depending on tolerances can make them too hard to turn)
