I know this has been covered a couple times but I have to ask. I have tightened everything. Checked my steps and such and am still having the issue. I do seem to have a slight play in the x axis which is where the error is. Would that be a Backlash block issue. It is very slight but even when I try to compensate for it , it is still there. I will post a picture. This is very frustrating as till only a short while ago everything was going great. Thank you in advance. Randy
Assuming that the "circle" toolpath joins up, it probably is backlash. Could be several things, not just the nut blocks. Starting at the bit wiggle things looking for anything moving that shouldn't. Main things to look for - adjust the nut blocks - loosen one slightly, squeeze the nut blocks GENTLY together and re-tighten. The aim is to have one nut block touching each side of the leadscrew thread but not gripping it tightly. Adjust the eccentrics - you should JUST be able tum a wheel with your finger. Check lock collars and bearings are properly seated. Check that there is no possibility of the motor coupler shifting on the leadscrew or the motor shaft. Check all the above on the Z axis and that your router/spindle is securely mounted. Your sense of touch is more sensitive than your eyes so it is likely that only you will be able to spot what is loose. Alex.
Thanks. there is a slight movement in the x axis when I try to move it by hand. Not much but resetting the nut blocks did not help. There should be no play correct? I rechecked everything else and tightened as required.
If there is play, something is looser than it should be. Nut blocks are the least common source of backlash (because they are so easy to adjust) - I can only refer you back to my previous post. Alex.
Well I am not sure what else to do. Everything else is tight. Only thing left is to pull the whole thing apart.
When you move the X axis by hand I am assuming that the leadscrew is moving with it (as you have adjusted the nut blocks) - check the ends of the leadscrew - are the bearings properly seated. Can you detect any movement of the lock collars? Is the motor coupler REALLY secure on the leadscrew and the motor shaft - one grub screw on the flat of the motor shaft. From what you have described I would suspect that the lock collars are not firmly against plates, allowing a very small amount of movement. You could also have a faulty bearing. Alex.
Ok Alex got it fixed. I appreciate your help. I went through the entire machine and re-adjusted everything. Circles are perfect now. There were indeed a couple collars that moved a little so there may have been just enough play to cause the issue. The other interesting thing I found is that when calibrating the X and Y axis using the wizard is that it measured 101mm . I am curious why that would be. It used to move 100 at the time of purchase.
When calibrating (over as long a distance as you can measure accurately) it is a good idea to do a very small move in the direction you intend to measure first - that takes any backlash out of the equation. Alex.
Ok good to know thanks. I thought using the default was how it was supposed to be done but your method makes more sense. Thanks again I will recheck it using a smaller value .
Err, if I understood you correctly, no - calibrate over as long a distance as possible. Calibrating your cnc Alex.
I use a meter stick and send it 1000mm to calibrate. When doing this, my machine traveled 1000.3 mm. I would have never noticed the error by only calibrated at 100 mm.
