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Y axis calibration issue, goes down 300mm and up 306mm

So I have just finished setting up my M2. Im using makerverse software with the DUE controller and im stuck on a calibration issue. I marked an X in the centre of my waste board and X’s 300mm up,down,left and right of the centre. I set home as the centre and when I move the M2 300mm to the left, right or down it hits the X’s almost perfectly but when I move it up it goes to 306mm.

Any adjustment i make to the Y axis scaling means that it goes up correctly but then is wrong in the down direction. It seems impossible to get the Y axis to move 300mm up and down.

Any help would be greatly appreciated.
Tom.

adjust your y offset or your motor spacing. the system is a triangle and if it moves up too far, it is off on one of the settings.

Thanks heaps for the quick reply,

I have measured the motor spacing and motor offset perfectly and I have tried 10 or 15 other combinations of measurements (+or- 2mm at a time) and then re setting home to the centre and re measuring. I still get a different measurement in the up direction on the Y axis as I do in the down direction. Is there any other setup/ calibration steps that I could have missed or gotten wrong that would cause this issue?

are you using makerverse 1.1.2?

No, I was using 1.0.6 but when I tried 1.1.2 it said I needed new firmware. I found some instructions on how to update it but I couldn’t follow them. Im using Windows 10 and the example video was done on a Mac.

I tried adjusting all my motor offsets and distance between motors with no luck. No matter what I do it goes up further than it goes down by at least 3mm.

make sure that you don’t have the chain jumping on a sprocket. that’s the only
reason it should not move back to the same place (if that place is the correct
distance is a different problem, but repeatably going to the same place for the
same coordinates should be very good)

David Lang

Thanks dlang.

I should re phrase the problem. I have my centre of board marked with an “X” and an “X” marked 300mm up,down,left and right of the centre. The machine moves perfectly to the marks on the x axis but it moves up 306mm from home and comes back perfectly to home and down 300mm and comes back perfectly to home. If the calibration is good on the bottom half of the board its 4-6mm out on the top half.

Ok, that is a very different problem.

What you are running into is a result of calibration problems. The errors caused
by calibration are nowhere near consistant, they are curves that are going to be
different in different places on the workpiece. If you were to make a grid of
holes at a nominal 300mm spacing across your entire workpiece, you will find
that the errors are very different in different areas of the workpiece.

there are a LOT of things that can result in location errors (there’s a topic I
created a while ago, something like “sources of errors” that covers a lot of
them)

The fundamental problem is that we don’t have a good way to measure small errors
over large distnces, and a 1mm error in the measurement of the distance between
motors can result in a 2mm error of vertical position in some places (and far
less error in other places) a 1mm error over the standard motor spacing is 0.1%

tape measures are not that accurate (see
Tape Measure Accuracy (class 1 / class 2) ) for
a discussion on tape measure accuracy)

So the calibration routine tries to setup cuts that you can measure that result
in maximizing and isolating specific errors in motor spacing and ring rotation
radius (as they are the most common sources of error) and correct for them. But
if there are other sources of error (say the machine flexing, which was a much
bigger problem on the 1st generation of machines that had a much worse
calibration routine) the result is not that accurate

Holey calibration takes more measurements and does more complex calculations, so
it seems to result in a more accurate machine.

1st check that your machine is not flexing as it moves to the different
locations (and as noted above, even a mm or so of flex is significant). This
includes checking that your motors are not moving on the beam.

Then get a decent tape measure (class 2 tape measures are not that expensive,
and even class 1 tape measures are dropping in price) and measure very carefully
(we really need to setup a routine to measure chain stretch, but that’s a
long-term problem). Try holey calibration, see if it works better for you.

Some people throw their machine together and report good accuracy, others
agonize over the details and struggle to get acceptable accuracy, we really do
not understand why there is so much of a difference.

David Lang

Thanks alot for the advice. I will definitely run the holey calibration this weekend. Is there any instructions for running the holey calibration on an M2 with makerverse? I can’t seem to find anything.

Thanks again.

M2 has a version of holey built in its calibration routine called precision, but it does not measure hole to hole, it is a measurement from the edges of the work space. Look in the wiki for makerverse basics post and there is a calibration youtube video link that goes through it.