Right after homing the machine I move the machine to a particular machine coordinate where I made a little mark. Sometimes the mill doesn’t lie on top of the mark instead has about a 1mm error.
My understanding is that the endstops can precisely zero the machine, so I am confused about what causing this divergence.
Thank you,
Ignacio
Please check the machine mechanically:
If you don’t find anything to address there and continue to have difficulties please let us know at support@carbide3d.com and we’ll do our best to help you puzzle things out.
Hi William,
Thanks for your quick response.
Pulley set screws - are tight.
V wheels are tight.
Repeatability issues are only on X and Y. X-axis motor is tight.
The belts are tight on my opinion:
It takes 0.22 kg to displace it 1cm at the center of the x-axis and y-axis. In contrast, the z-axis took 3kg to be displaced about 1 cm. I also can't hear any belt skipping when the machine moves.
I did some more experimentation, if the machine is kept on, it can reliably go from homing to the specified machine coordinates. The problem happens when the machine is turn off, after homing and move to the specified machine coordinates there is an error of 1mm on x and y. I think this is evidence that the belt system is working correctly because when on it can repeatedly move in a precise way but that something fishy is going on with the first homing.
How can we run some gcode that repeatedly homes the machines and compares the believed position with the actual and plot that distribution?
Thanks,
Ignacio
We’ve got your ticket referencing this at support@carbide3d.com and we’ll do our best to work this out with you there and to share what we learn with the community.
I did some more precise testing and there doesn’t seem to be any problem.
I set a machine position where indicator marked 3.02 mm.
Then move the machines around and made it go back to that machine coordinates.
The measurements I took where
Random moves
Then I did home and go back to those machine coordinates and I measured
After homing
I then turn the machine on and off, home, and go to where the instrument was and I measured
The machine error is likely to be less than .02 mm given that I was measuring against the mill which can move slightly. But for sure much less than the 1mm error I thought there was after homing.
Some of us have gone to using powered non contact proximity switches for a little better repeatability.
In my case, stock limit switches could vary as much as 0.010" or more. This was seen on three separate machines with stock switches and the problem went away with the new ones.
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