Optimum BF20 Milling Machine Axis travel issues

[Pietskiet247]

Hi Everyone

Hope this is the correct area to post this.

I have a Optimum BF 20 CNC Milling machine with a Acorn Controller
It is still as per the original Optimum CNC upgrade Stepper motors with Balls crews and Belts on the Stepper Motors

On the STD Optimum Stepper Control box I picked up that if I move longer distances for example 125mm the axis only move 100mm or so cant remember the exact distance

I then upgraded to the Acorn Controller as I have one on my Lathe for a few years

I have calibrated everything on the milling when I installed the Acorn controller

Today I saw if I move for example 125mm it only moves about 110mm or so

With small distance all seems to be ok
I have a Touch probe and when measuring a pin of 5.5mm it measures it correctly

What could be the problem maybe for not moving the correct distance?

I was wondering if I need to change the belt to direct connection.

Any help or advice would be appreciated

Thank you

[CentroidFrog]

Hello, welcome to the forums.
To help us get some more info on your system please post a fresh report.

[suntravel]

Some pictures of the machine, especially the steppers and how they are mounted on the machine would be helpful too.

Acorn is very reliable, I suppose the steppers are loosing steps, or there is something slipping.

Uwe

[tblough]

If you can move out and back and it returns physically to the sane spot, the you have an error in your turns/inch calibration. If it doesn't return to the same spot, then you have a noise issue.

[Pietskiet247]

Hello, welcome to the forums.
To help us get some more info on your system please post a fresh report.

Thank you

Please find the attached ZIP as requested

[Pietskiet247]

Some pictures of the machine, especially the steppers and how they are mounted on the machine would be helpful too.

Acorn is very reliable, I suppose the steppers are loosing steps, or there is something slipping.

Uwe

Please find attached images

All three Stepper Motors are the same size and all are belt driven

The Connection have a GRN wired but on the controller side its not wired
Do I need to wire it to the 220V Supply GND?

If not how should it be wired please

[suntravel]

Hi,

you have several problems.

A lot of communication resends could indicate a noise issue.

Backlash 0,15 and 0,2mm must be fixed mechanical

3.2mm pitch on X and Y is not common, are there ball screws and a belt reduction?

The old steppers are weak, I would use at least 4Nm XY and 12Nm Z

Uwe

[cnckeith]

as Uwe pointed out, you need to fix these com errors first!

Here is how. viewtopic.php?f=61&t=1451


2025 10:23:09 944 MPU requested resend # 99
(4) 03-17-2025 10:23:09 946 PC resending # 1676
(4) 03-17-2025 10:23:32 944 MPU requested resend # 100
(4) 03-17-2025 10:23:32 946 PC resending # 1678
(4) 03-17-2025 10:23:39 944 MPU requested resend # 101
(4) 03-17-2025 10:23:39 946 PC resending # 1680
(4) 03-17-2025 10:23:46 944 MPU requested resend # 102
(4) 03-17-2025 10:23:46 946 PC resending # 1682
(4) 03-17-2025 10:24:06 944 MPU requested resend # 103
(4) 03-17-2025 10:24:06 946 PC resending # 1684
(4) 03-17-2025 10:24:37 944 MPU requested resend # 104
(4) 03-17-2025 10:24:37 946 PC resending # 1686
(4) 03-17-2025 10:24:56 944 MPU requested resend # 105
(4) 03-17-2025 10:24:56 946 PC resending # 1688
(4) 03-17-2025 10:25:30 944 MPU requested resend # 106
(4) 03-17-2025 10:25:30 946 PC resending # 1690
(4) 03-17-2025 10:26:02 944 MPU requested resend # 107
(4) 03-17-2025 10:26:02 946 PC resending # 1692
(4) 03-17-2025 10:26:21 944 MPU requested resend # 108
(4) 03-17-2025 10:26:21 946 PC resending # 1694
(4) 03-17-2025 10:27:03 944 MPU requested resend # 109
(4) 03-17-2025 10:27:03 946 PC resending # 1696

[Pietskiet247]

as Uwe pointed out, you need to fix these com errors first!

Here is how. https://centroidcncforum.com/viewtopic.php?f=61&t=1451


2025 10:23:09 944 MPU requested resend # 99
(4) 03-17-2025 10:23:09 946 PC resending # 1676
(4) 03-17-2025 10:23:32 944 MPU requested resend # 100
(4) 03-17-2025 10:23:32 946 PC resending # 1678
(4) 03-17-2025 10:23:39 944 MPU requested resend # 101
(4) 03-17-2025 10:23:39 946 PC resending # 1680
(4) 03-17-2025 10:23:46 944 MPU requested resend # 102
(4) 03-17-2025 10:23:46 946 PC resending # 1682
(4) 03-17-2025 10:24:06 944 MPU requested resend # 103
(4) 03-17-2025 10:24:06 946 PC resending # 1684
(4) 03-17-2025 10:24:37 944 MPU requested resend # 104
(4) 03-17-2025 10:24:37 946 PC resending # 1686
(4) 03-17-2025 10:24:56 944 MPU requested resend # 105
(4) 03-17-2025 10:24:56 946 PC resending # 1688
(4) 03-17-2025 10:25:30 944 MPU requested resend # 106
(4) 03-17-2025 10:25:30 946 PC resending # 1690
(4) 03-17-2025 10:26:02 944 MPU requested resend # 107
(4) 03-17-2025 10:26:02 946 PC resending # 1692
(4) 03-17-2025 10:26:21 944 MPU requested resend # 108
(4) 03-17-2025 10:26:21 946 PC resending # 1694
(4) 03-17-2025 10:27:03 944 MPU requested resend # 109
(4) 03-17-2025 10:27:03 946 PC resending # 1696

Thank you Cnckeith

I will have a look and see if I can sort this out first

If I can ask which file show this information then I can monitor it when making changes

Thanks

[Pietskiet247]

I have tested the continuity from the machine to the stepper motor and to the control box PSU casing

And there are continuity between everything

I have a Lathe with ACORN board as well next to the milling machine and the continuity goes between the two machines as well

I think it might be the VFD 220V GRND thats doing that