help loss steps on inversions

fr4nc3sco

I have a problem measuring with a comparator I have loss of steps with microstep aquando inverto the axis for example:
g1y10 shifts by 10mm then gives g1y10.1 and he goes correctly to 10.1 as he reverses g1y10 he goes in behind at about 10.05 if he then gives g1y9.9 he goes to 9.95 doing correctly 0.1 of step, as he reverses back to g1y10 he still loses 0.05mm from what can it depend? I changed straps, motor, cable, but not always solve the problem disappears if I use step full this problem does not occur but already with 1/2 makes it

zapta

Are these lost steps or backlash? E.g. if you move many times between y10 to y11, does it lose more and more steps and drifts?

Thingiverse has a good model to test x/y backlash https://www.thingiverse.com/thing:10524

fr4nc3sco

https://vimeo.com/user98280453/review/343792510/2e2bd0d7d6
this is the problem I was saying, if you have an idea, they are more than willing to solve

Veti

link does not work

fr4nc3sco

https://youtu.be/Ej2VGE_aFAg

dc42

It looks like you have backlash of about 0.06mm. What is your steps/mm in that direction, and at what microstepping?

fr4nc3sco

@dc42
M350 X16 Y16 Z8 E16:16 I1
M92 X80.00 Y80.00 Z800.00 E412.88:412.88
M566 X300.00 Y300.00 Z12.00 E300.00:300.00
M203 X15000.00 Y15000.00 Z300.00 E1500.00:1500.00
M201 X500.00 Y500.00 Z10.00 E1000.00:1000.00
M906 X1700.00 Y1700.00 Z1700.00 E1700.00:1700.00 I90
tested motor
17hs19-2004s1 and 17hm19-2004-s and longer 42bygh40h-2-19d he does it with everyone

dc42

You have 80 x1/16 microsteps per mm. so each microstep is 0.0125um. It looks like when you reverse direction, it takes 4 microsteps to put enough tension in the belt on the other size of the pulley to overcome friction. Tightening the belt may help, if it's not already tight enough. It's also possible that the belt is slipping on the motor pulley, if it's not a perfect fit.

50um backlash should be OK for 3D printing, but perhaps not for CNC work.

fr4nc3sco

@dc42 said in help loss steps on inversions:

You have 80 x1/16 microsteps per mm. so each microstep is 0.0125um. It looks like when you reverse direction, it takes 4 microsteps to put enough tension in the belt on the other size of the pulley to overcome friction. Tightening the belt may help, if it's not already tight enough. It's also possible that the belt is slipping on the motor pulley, if it's not a perfect fit.

50um backlash should be OK for 3D printing, but perhaps not for CNC work.

could his hypothesis be real and is there a parameter to correct this error? it's possible ?

Veti

maybe change from belts to ball screws if you need that kind of precision.

fr4nc3sco

I ordered the 9mm gates should be more rigid etc .. let's see what accuracy can bring, well let's say that the print itself brings so many errors and if we start with a bad base ... certainly will not know what, for the screws I thought but there are no such long recirculation steps to keep up with the straps

Veti

as an example see here
https://www.thingiverse.com/thing:2929869

fr4nc3sco

Hi possibly to eliminate loss of steps mount a MKS SERVO42 Nema 17 closed loop with the Duet Expansion Breakout Board but then it is possible to recover the pins to make a bltouch coexist and work?

Veti

it is not lost steps. its backlash.

fr4nc3sco

hi,
I changed the strap with a better 9mm gates
[IMG]http://i63.tinypic.com/34zc28w.jpg[/IMG]

this is the problem at 1/16
https://drive.google.com/file/d/1-6TC1k9jVaZar40PE5DxQoyw79dfP6_Z/view?usp=sharing

while at 1/2 the problem disappears
https://drive.google.com/file/d/1--GEUBKAdP7hRF3CA10b_3lvMfIiLgF-/view?usp=sharing

the strange thing and that however also happens this setting 0.1mm of movement to time
https://drive.google.com/file/d/10v1igg_cmjlgtJU7rxxotNrS7KxMH9Cg/view?usp=sharing