cutting circles with new linear bearing

[Toby Hope]

Hi all,

i replaced my linear x axis bearing as there was wobble on the head, new one has no slack which is great, but it is slightly stiffer running when moved manually.

i started cutting some test circles which were awful, tightens the belt tension and they have got a lot better.

trouble is i don’t want to over tighten and with a couple of half turns tightening i can seem to get an improvement on the flat spot on the circle .
i have checked the gears are tight on the motors, any other ideas ?

pic shows the flat/ skew across the horizontal diameter indicting the x axis isn’t moving as it should (i think)
the latest circle after tightening has the fish next to it you can see before tightening above the circles were much worse

thanks in advance !

9D88C5DA-02AD-440C-8FB0-9688CFF4A090.jpeg

[Toby Hope]

here’s a speed test same thing as different mm/s
you can see the anomaly highlighted in green almost a symmetrical kink diagonal opposite , and doesn’t seem to change with speed .

EA15CD74-B33C-4ED8-96C9-564948C40B88.jpeg

and this pic i cranked it up to 200 on the left and 60 on the right , 120 in the middle, my machine doesn’t like high speed it tends to shake a bit too much, but the flattening of the circle is still there

35F6ED3B-4E7E-4AC7-945E-CFA9DF0AEAC1.jpeg

[Pete Cyr]

1. did you lubricate the bearings
2. Did you re-calibrate you movement - viewtopic.php?f=105&t=3528

[Toby Hope]

1. did you lubricate the bearings
2. Did you re-calibrate you movement - viewtopic.php?f=105&t=3528

thanks Pete, the bearing came lubricated already so i shouldn’t have to worry on that score.

i haven’t recalibrated in terms of x and y as i’m not getting ovals i’m getting flat spots which aren’t symmetrical.

I guess it’s worth doing tho! just in case.

is there any other type of calibration apart from the xy i should be checking ?

thanks

[Rodney Edington]

It might be backlash in the belt. There is a setting for it, but I don't remember where it is.

[Toby Hope]

It might be backlash in the belt. There is a setting for it, but I don't remember where it is.

thanks, i did run the backlash test of two squares with a small break on the x axis on one square and then one break in the top axis on the other square and they lined up perfectly.

[Pete Cyr]

1. did you lubricate the bearings
2. Did you re-calibrate you movement - viewtopic.php?f=105&t=3528

thanks Pete, the bearing came lubricated already so i shouldn’t have to worry on that score.

i haven’t recalibrated in terms of x and y as i’m not getting ovals i’m getting flat spots which aren’t symmetrical.

I guess it’s worth doing tho! just in case.

is there any other type of calibration apart from the xy i should be checking ?

thanks

Yes - a backlash test - i know you said you did that but try this one

https://cartonus.com/how-to-improve-eng ... r-machine/

[Toby Hope]

thanks Pete, the bearing came lubricated already so i shouldn’t have to worry on that score.

i haven’t recalibrated in terms of x and y as i’m not getting ovals i’m getting flat spots which aren’t symmetrical.

I guess it’s worth doing tho! just in case.

is there any other type of calibration apart from the xy i should be checking ?

thanks

Yes - a backlash test - i know you said you did that but try this one

https://cartonus.com/how-to-improve-eng ... r-machine/

thanks Pete, i’ll try that i have now calibrated , gone around checking fastness if all bolts on motor mount and x axis head etc , i did actually think i had found the issue as i hadn’t tightened the clamp nuts on the belt tensioner, but it made no odds.

one thing i have found is the idle pulley isn’t perfectly round , in trying to work out if that would create the flat spot in seeing, but struggle to work out why the flat spots would appear in the same spot on different diameter circles .

i’ll report back on the backlash settings

thanks for the help

[Toby Hope]

I placed a strip of 3mm acrylic over the bracket just to show how much the idle pulley is out of circle

4F23C411-0726-4B59-8A4D-F0F034186B5A.MOV

[Dave Vigness]

I'm not seeing any rise / fall in the belt itself. I can see a bit in the outside flange, but that wouldn't affect the belt position. Or am I just not seeing the belt movement?