I am getting some strange results trying to cut a simple circle. I have tried everything I can think of including making a whole new file. When cutting the circle the router head is moving out at three different spots during the cut. Each slightly more or less pronounced. I have attached a pic. I have run the job a few times shrinking the circle a little but so there are two attempts show here both the with same strange bump.
If I start it above the material so the bit is contacting nothing I can see the head move over. Its also doing it in 3 spots consistently so I dont think anything is binding.
With the power on and the spindle OFF, grab the nose of the spindle and try to move it around. Don’t push so hard that you over-power the stepper motors.
It should be locked in place. If it moves at all, you have mechanical problems.
With the machine on and the spindle off I cannot move anything.
I ran a new job with a much smaller circle and the problem is much easier to see. I took a pencil and colored in the groove so it was visible on this mdf.
On this little 1.6 inch radius circle this makes the problem look more mechanical whereas on the big 20 inch circle its so consistent where the head makes a move it seems more like a software problem. I only went .1 inches deep with this one.
Ok, this is even more perplexing. I changed the size of the circle to 1.25 and moved to the far opposite corner of the machine. Reran it and I get basically the same shape.
Then I reran this same one but put it back to a 1/8th inch bit. It barely even altered my pencil lines and didnt change the shape of either the inner or outer portion of the ring at all. I would think if it was mechanical that the “wobble” or whatever causing it would be at a differing radius/angle with a bit 1/2 the size. I am guessing but this really seems to me like the software is not cutting a proper circle.
I am on the newest (non-beta) create and motion that I downloaded when I first had this problem. I may or may not have already been on the newest create as I just didnt pay attention but my motion was a little behind.
There is nothing wrong with your file. This is 100% a mechanical issue with the machine. Can you share more details about your machine, its age, and what parts of the machine you’ve inspected so far so we can help you narrow your search?
Its a Shapeoko Pro that I got new in March of 2022. I use it regularly but not a ton, like two or three times a month mostly for smaller stuff.
As far as inspecting things, I have wiped down all the rails, made sure there is nothing obstructing anything, made sure there is no play when the power is on and the spindle is off, and driven the head all over the bed and up and down. I have not noticed anything out of the ordinary.
The truth is this is the first problem I have really had with it so I am not really sure what else I should check.
I guess its worth noting that I have been away for a while so this is probably the first time I have used it in about 2 months, so it sat for a little bit.
I would try turning the machine off, and slowly moving the the X and Y axes by hand to see if there are any spots where the machine repeatedly binds. You may need to lubricate the rails.
Another things to check: Flip the drive belts over. Sometimes the fiberglass reinforcement will give out over time and the belt will stretch, creating points where the teeth will skip. (This is in addition to just making sure the belts are tight…)
I will do all those things, probably be in the morning now but will try first thing.
I also notice there is a Shapeoko Pro Maintenance kit that I will just go ahead and order. Even if I dont need it now it would not be bad to have extra belts on hand.
As an SO4 Pro it is still belt driven. So check that all your stepper motor pulleys have one set screw on the flat and both are tight. Many people get them aligned and put a magic marker across the pulley end and shaft so they can quickly see if a pulley has slipped off the flat spot. A loose pulley will cause your problem as well as others mentioned mechanical binds. That could be your drag chains, dust collection hose or even your linear rails need lubrication.
That can be one of two things with your machine. Either you are getting tool flex, whether its in the tool itself, or the spindle or spindle holder. The other could be that you are pushing your stepper motors too hard and they are jumping out of step, meaning, they are not smoothly moving because of high build up of sawdust or the bearings need oiled/maintenance done.
Also, check all of your screws on the Z axis head and the spindle/router holding brackets. Something is moving and its not your part. So, that means your machine it moving wrong and the cut is evidence of this issue. If the program simulation is correct and these cuts are not what you designed, then the machine needs to be checked for issues, or you need to do maintenance.
Power down, remove both Y-axis belts, put a bit of tape on the Y-axis pulleys so as to more easily see their rotation, then power up and try initializing — the Z-axis should home as normal, then the X- and Y-axes should try to home — the X-axis should also finish normally, while the Y-axis motors should turn until they time out. Do they turn evenly and in synch?
If not, check in at support. If they do, inspect the belts and re-install flipped end-for-end and side-for-side.
Lastly, you are trying to cut a slot as narrow as the tool to a depth more than four times greater than the diameter and greater than the length of the cutting flutes:
Thanks to everyone for all the feedback. I am gonna go look over all this stuff now and hopefully find the problem. Will report back when I am done but wanted to say thanks.
Sorry this took a few hours because I was bouncing between work and messing with this machine but, I do seem to be at least 99% resolved. Not sure which part fixed it (probably a little of everything) but I did just about everything that was suggested in this thread. I took off cleaned and reversed my belts, cleaned and lubricated all the rails, and took the head off and lubricated the fill holes on the top and bottom bearings. I also took the gear off the end of the stepper motors and did find one of them that had this set pin misaligned from the flat of the shaft.
I say I am 99% resolved because now my circle is 1000x better but there is still a little bit of wobble in two spots. I ordered new belts which will take a few days to get here but I am feeling like they will finish fixing things. I didn’t see anything wrong with the teeth but there is a spot on both of them where it looks a little funny. I think its from when I left it sit for a couple months. There is also a few strands coming off the sides of one of the belts so its likely swapping them will mop this up.
I guess I should point out one thing. The whole time I was using an Amana 46415 bit which is a 1/8 spiral plunge which is plenty long enough to cut through the 1/2 inch MDF. I have just always set it to the #102 in Create. If there is something better to set it to I would love to know what it is but I have never had problems like that.
