4th axis for milling machine

**DIYer** · Jun 6, 2021, 01:22 AM

Thanks markgyver! We've added your 4th Mill Axis to our Milling category,
as well as to your builder page: markgyver's Homemade Tools. Your receipt:

4th Mill Axis by markgyver

tags: CNC, mill

**markgyver** · Jun 7, 2021, 01:43 PM

Originally Posted by Saltfever

Many thanks for the excellent video as well as the completeness of your design. I especially enjoyed seeing your HEM (or adaptive) machining strategies. It appears that you have a vacuum plate, however, I never saw an o-ring in your video. How are you holding down your work? Are you using the super glue & tape method or is it vacuum? I couldn’t see well enough when you created the small holes. Were you boring holes instead of drilling? And were you thread milling? Also, that was an excellent job of grinding the spindle! I am very interested in this design but need to think about the backlash issue.

I'm glad you like my video.
I use a vacuum plate and a foam rubber cord to clamp the parts under vacuum.
The foam rubber cord is not visible because it sits inside the part and is completely flattened when the vacuum is created.
All the holes that could be made without reclamping (in the 1st milling pass) are milled, all the others I drilled only during assembly because of the difficulty of finding a perfect zero point and the perfect right-angled arrangement. I think that with a little effort all the holes can be milled.
I cut all the threads by hand, which was quite an effort - I think it was about 50.
I'm not quite sure where the backlash is coming from.
It could also be the software, although I have set the stepper motor to 51200 microsteps, but the resolution at mach4 is 0.1 degrees. maybe it could also be that when I only ever approach whole values such as 15 45 30 60, I could not detect any play. I still have to do a few tests to be able to say more precisely. If it is mechanical, i think i could get it under control by making only positive or only negative movements.

**Saltfever** · Jun 9, 2021, 12:45 AM

Thanks for answering, Mark. I couldn't see the vacuum port holes (as well as the foam ring) so that is why I was confused. Where are the holes for the vacuum? I can see the plumbing but I can't see any holes in the base-plate slots . Also, all the holes you drilled did not go completely through the part because that would have created a vacuum leak, correct?

With that 25 mm wide belt under tension, I doubt the backlash is coming from it. As you say, it could be the stepper motor software issue.
THANKS for posting your design.

**markgyver** · Jun 14, 2021, 01:20 PM

Originally Posted by Saltfever

Thanks for answering, Mark. I couldn't see the vacuum port holes (as well as the foam ring) so that is why I was confused. Where are the holes for the vacuum? I can see the plumbing but I can't see any holes in the base-plate slots . Also, all the holes you drilled did not go completely through the part because that would have created a vacuum leak, correct?

With that 25 mm wide belt under tension, I doubt the backlash is coming from it. As you say, it could be the stepper motor software issue.
THANKS for posting your design.

Sorry for the late reply. The holes for the vacuum are on the left side of the plate at the bottom. Yes, the holes and the cut do not go through, there is still 0.2mm of material at the bottom.
With the first cuts, it was always exciting whether the zero point would fit or whether the vacuum would loosen and I would mill into the vacuum plate. Fortunately everything went well :-) . In the end, I turn the plates over and mill over them again, then the holes go all the way through the plate.

I hope it's not from the belt - according to the manufacturer, the HTD 5M should have almost no play and can be neglected.