Cutting in the UK! Electrical noise problem solved! - Darwen, UK
 

Hi Gerald
Finished the machine and its running well, we have made several name placks using diff fonts, all ok.
However we came to run a program to level the table bed and for some reason the Z axis seems to drop when the spindle motor is running. we put it in one position and started the spindle, you can hear the Z axis and it does move but very slowly, stop the spindle and its ok. do you think this could be pickup from the high frequency spindle motor?
I look forward to your reply.
Kind Regards
Barrie.
UK

Hi Barrie

First thing; Congratulations on having possible the first cutting MM in the UK!

A creeping Z axis is unfortunately a common problem with CNC routers. In our case, and with many ShopBotters, it is caused by grounding problems. We solved it by running a thick wire ground from frame to frame, all the way back to the control box. See Grounding or Earthing

The spindle motor also needs its own ground/earth wire to run in a cable with its power wires.

Can you tell us more about your grounding/earthing?

Where is your VFD located? How close to everything else?

A photo inside your control box could help.

Earthing / Z Axis Problem
 

Hi Gerald
Thanks again for the quick reply and the things to look for regarding earthing.
I checked all my earth connections and they are all fine, every earth point gives 0.5 Ohms back to the main earth. I still had the same problem so I wired the spindle motor direct (not going through the cable track, still yhe same I then disconected the screen from the motor (only 1 end connected) and the problem went away I checked the screen to earth with the motor running and had a reading of 36v ac which was being generated from the high frequency from the inverter, every time i touched this point to earth it caused problems to the Z axis. so I have not connected the screen but all the machine and motor are still earth via the main bonding.
Thanks again for your help. we have now leveled the full bed and run several deisigns all without problems.
Kind regards
Barrie

Hey Barrie,

Congratulations on getting your MechMate running!:) Tying only one end of the screen to ground is a STRONG recommendation of Mike Richards. I don't pretend to understand it, but given Mike's expertise, I certainly follow it.

Is it time for pictures to document your build?

Sounds like it might be time to get a Serial Number...the first in the UK! The requirements are a painted MM with the MechMate Logo's applied that is actually cutting.

Regards,
John

Thanks for the feedback Barrie and glad to hear that you are on your way again.

(Will copy the above posts to the troubleshooting thread in a quiet moment)

Hey Barrie,
If you have some blue paint and logos on your machine, why not send us some pics so Gerald can send out the first UK serial number?