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CNC Machine Maintenance
http://www.luthiersforum.com/forum/viewtopic.php?f=10106&t=39743		 Page 1 of 1
Author:  Scott McKee 2 [ Sat Mar 16, 2013 4:03 pm ]
Post subject:  CNC Machine Maintenance
I'm wondering what sort of regular maintenance everyone does on their CNC machines? How often do you lubricate the bearings and ball screws, what kind of lubricant do you use, etc.

I have a persistent issue on my XZero machine with the X axis ball screw becoming clogged with dust and missing steps.

Thanks

Scott
Author:  ZekeM [ Sun Mar 17, 2013 10:19 am ]
Post subject:  Re: CNC Machine Maintenance
My machines are commercial machines so they auto lube the ball screws and ways automatically as the machine runs. So I can't give you any advise as to when you should lube yours. I will tell you that I use Mobil Vactra #2 way oil though. Do you have way covers on your machine? If not you may want to consider some to keep the dust out.
Author:  Andy Birko [ Sun Mar 17, 2013 2:09 pm ]
Post subject:  Re: CNC Machine Maintenance
I have the same problem with my Xzero. I grease the X screw about every 6 months or so and also oil the ballscrew itself with motor oil about once a month or so. The oil seems to help a lot but it may also be leading to dust sticking to it.

I've also had to decrease my acceleration a little bit to improve reliability.

Some sort of cover for the ballscrew is a good idea too but everywhere I've looked, the bellows are very expensive. Anyone know of a reasonably priced source?
Author:  Bob Garrish [ Sun Mar 17, 2013 2:31 pm ]
Post subject:  Re: CNC Machine Maintenance
+1 on way covers and Vactra #2, I put that stuff on everything.

My maintenance was similar, having an industrial machine: fill up the waylube every few weeks, shovel out the enclosure. There'd be work to do when things broke or started acting funny, but that wasn't really routine.

You can make bellows or sliding covers if you're having a hard time finding them online. I'd suspect eBay might have something usable. Sliding covers are easier to make, much less gluing.
Author:  ZekeM [ Sun Mar 17, 2013 2:56 pm ]
Post subject:  Re: CNC Machine Maintenance
+1 on sliding covers. Much nicer than bellows IMO.
Author:  Sheldon Dingwall [ Mon Mar 18, 2013 1:51 pm ]
Post subject:  Re: CNC Machine Maintenance
Where'd you find the Vactra in Canada Bob? I've been using Hangsterfers #2 because that's all anyone carries around here.
Author:  Bob Garrish [ Thu Mar 21, 2013 6:56 pm ]
Post subject:  Re: CNC Machine Maintenance
Sheldon Dingwall wrote:
Where'd you find the Vactra in Canada Bob? I've been using Hangsterfers #2 because that's all anyone carries around here.


I was using a Shell equivalent, but now I don't remember the name because I gave both jugs to the guy who bought my Fadal! There was a Shell outlet across the street from my shop, so it wasn't hard to find!
Author:  ZekeM [ Thu Mar 21, 2013 7:37 pm ]
Post subject:  Re: CNC Machine Maintenance
Bob Garrish wrote:
Sheldon Dingwall wrote:
Where'd you find the Vactra in Canada Bob? I've been using Hangsterfers #2 because that's all anyone carries around here.


I was using a Shell equivalent, but now I don't remember the name because I gave both jugs to the guy who bought my Fadal! There was a Shell outlet across the street from my shop, so it wasn't hard to find!

if you want the name of the shell stuff let me know and I'll post it tomorrow. I have an old jug of it laying around somewhere.
Author:  ZekeM [ Fri Mar 22, 2013 6:27 am ]
Post subject:  Re: CNC Machine Maintenance
Found it! I got some of this years ago when a local distributor couldn't get the vactra #2. It worked well but I've since found another local Mobil dealer and have switched back. Anyhow it's called Tonna v oil 68
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Author:  Sheldon Dingwall [ Fri Mar 22, 2013 11:30 am ]
Post subject:  Re: CNC Machine Maintenance
Thanks Bob And Zeke.

What about Dow Frost. That's another "don't use anything else or you'll screw up your machine" type product that's not available in Canada. I was at the local machine dealer yesterday and he clearly wasn't familiar with spindle coolant.
Author:  Scott McKee 2 [ Thu Apr 04, 2013 9:36 pm ]
Post subject:  Re: CNC Machine Maintenance
I kind of abandoned this thread when I put my back out. I think it was lifting the table off the CNC machine that tweaked it. Now that I can walk upright again, I've been spending time with the CNC again and I just can't seem to get the thing working accurately. If do a multi-level pocket, there will some inaccuracy that always shows up in the same place on each level. I've greased the ball screw and oiled the ball nut (first with WD-40 to loosen things up and then with chain oil) and have cut the velocity and acceleration in half.

Some history: A while back the machine started missing steps and then eventually the X axis completely stalled. I had been cutting a lot of MDF and we all know how dusty that can be. WD-40 got things moving again but it hasn't been the same since. It is a lot better but I'm trying to do some fairly delicate inlays and a .005" problem is really visible.

I'm at a bit of a loss as to what to do next. While the issue I am having could be caused by a lot of things, I'm pretty sure that the ball nut is still not doing its job properly. But you can't really take these things apart...don't ask me how I know that!
Author:  Sheldon Dingwall [ Thu Apr 04, 2013 11:25 pm ]
Post subject:  Re: CNC Machine Maintenance
Thrust bearings?

Is the ball nut expensive to replace?
Author:  Bob Garrish [ Fri Apr 05, 2013 11:55 am ]
Post subject:  Re: CNC Machine Maintenance
Sheldon Dingwall wrote:
Thrust bearings?

Is the ball nut expensive to replace?


Sounds like thrust bearings to me, too. The only two options I can see are thrust bearings or the ballnut is still so gummed up that it stalls your stepper a bit when it turns around.
Author:  arie [ Fri Apr 12, 2013 11:27 am ]
Post subject:  Re: CNC Machine Maintenance
Vactra #2 is technically ISO 68.
Author:  Bob Garrish [ Sat Apr 13, 2013 5:36 pm ]
Post subject:  Re: CNC Machine Maintenance
arie wrote:
Vactra #2 is technically ISO 68.


Now that's useful to know! It would have been nice if they'd just put that in the spec rather than a list of trade names!
Author:  arie [ Tue Apr 16, 2013 2:24 pm ]
Post subject:  Re: CNC Machine Maintenance
Bob Garrish wrote:
arie wrote:
Vactra #2 is technically ISO 68.


Now that's useful to know! It would have been nice if they'd just put that in the spec rather than a list of trade names!


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the "VG" stands for "viscosity grade" ie: "68" @ 40c (mm2/s). average of min 61.2 to 74.8 max as per DIN 51 519
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