Help with my Z raising during 3d carving

**KurtRosenzweig** · 06-12-2018, 01:48 PM

HI guys. I've had a 4x8 Chinese machine for about 3 years now. I do a lot of 2d cutting and everything is spot on in that aspect. The only glitch is when I do 3d carving. I'll start a 3d carve and rough out and then start a finish pass. As the finish goes along the Z slowly rises to the point within 15 min into the cut it's no longer in contact with the model. The z is tight as well as the new belt. The bit isn't slipping and the collet is new. Everything is lubed as it should be and there is no binding. My thought was EMI but I've done everything possible i believe to assure that wasn't happening. Just replaced the spindle wiring with a foil and braided cable as well. It has an XHC controller running Mach 3 and seem to run great just till I get into the 3d and Z motion. Any input would be greatly appreciated.As always thank you in advance.

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**Sterob** · 06-13-2018, 02:38 AM

Hi Kurt,
Did the problem start after you replaced the spindle cable or before?
When you say 'no binding' I assume , with no power ont ehstepeprs, that you can wind the axis up and down, by hand, freely?
I'm not sure 'foil braiding' is the best to use. I have always used 'braided screen' cable...might be worth a look...
Did you earth the screen at both ends? You are supposed to according to Danfoss. This is the only case where you do, as far a I know.
Are your motor cables screened? Maybe the Z axis is being affected because it is the closest to the spindle cable?
Where is your VFD mounted? In the control box or in its own box?

These problems are tricky....All I can suggest change one thing at a time until you discover what the cause is....

Steve

**KurtRosenzweig** · 06-13-2018, 07:52 AM

Ty for the reply Sterob. This has been from day 1 with just the 3d stuff. 95% of my stuff is 2d and there is no problem there at all. I replaced the spindle cable in hopes it would solve my problem. The spindle cable has both foil and braid. When I remove the belt the Z slides up and down smoothly.

**KurtRosenzweig** · 06-13-2018, 07:54 AM

Maybe a picture will help as well. As you can see it cruised right through the flat part but it seems to raise just a little on each pass once the Z action starts.