Inaccuracy issue

[Tamarbarr]

Hey there,
I'm having issues with my 6 meter long axis(y3).
This machine in an integrated sheets and tube cutting.
Runs of acorn 4 axis controller.

X - left and right on the gantry.
Y1 + Y2 - forward and backwards gantry
Z - laser head up and down

Y3 - tube backwards and forwards (rear chuck)
B - tube rotation

I marked on the linear rails on the long y3 axis each 1000mm .
According to the marking the axis itself is very accurate(with the tube clamped on).

In addition I marked the same marking on the tube itself, every 1000mm.
According to the marking on the tube there in an inaccuracy of 3.5mm+- that is only happening on the first 300mm of travel on the y3 axis.

This is not making any sense to me, because from the marking on the Linear rails it is accurate, but on the marking on the tube is not.

I'm attaching two videos that showing the problem.

Motor settings

[Joey]

Attach a fresh report please.
What motors and drives do you have?

Getting the Extra 5th axis is a little un orthodox. Can you explain how this is done?

Possibly take a clear video showing how you turn the Gantry off and turn the Pipe axes on.

[Tamarbarr]

All of my motors are close loop steppers / hybrid servo
Nema 34 12nm.

I can post a fresh report but I don't think that is relevant because the whole machine moves correctly and accurate including the y3 of the tube cutter.

[Joey]

All of my motors are close loop steppers / hybrid servo
Nema 34 12nm.

I can post a fresh report but I don't think that is relevant because the whole machine moves correctly and accurate including the y3 of the tube cutter.

I thought the point of the post and what you show in the video is that the grantry works perfectly. But when you switch to the pipe feeding axis is or "Y3" the movement is off by 3.4mm? Or cm

Are the movements for the y3 off by the same amount for all movements? If you make some movements on y3 and not reset zero can it return to zero after the movements? Or is it losing steps?

[Tamarbarr]

It's returning to 0 and it's not losing steps.

[Joey]

Looks like the Overall Turns ration for the Rotary Y axis has a different Overall turns ratio.

Can you post some pictures of this axis. and how the Rotary Y is connected and switched ON/OFF

[tblough]

Just because the DRO returns to zero, does not mean you are not losing steps. Unless you have connected the drive alarm signals to Acorn (and configured the inputs accordingly) , the Acorn has no way of knowing if your drives and motors may have missed steps.

You need to set up an indicator on the axis, and verify the axis returns to the same position the DRO says it is.