Strange noise and stuck while milling‏ Aluminum (solved)

Weekend is close and i got no response from Carbide3D so far, so maybe anybody else can help me with my current issue:

After some smaller cuts I start to make “bigger” parts out of T6061 Aluminum.
If have done a lot of test cuts for speed and feed rate and feel now very comfortable with my setting.
(0.125 End Mill, 200-400 mm/Min, 0.12 mm/Cut, Plunge 10 mm/sek, @8000 RPM, with a coated End Mill (2 Flutes).
At the weekend I discover some strange noise from my nomand. After about 30-60 minutes the spindle (maybe the motor, or belt drive)
sounds like a baby bird (high pitch, short period like:
If I let the nomad run, the noise will return in shorter periods until the spindle stops complete.
I discover that it is possible to prevent the spindle from stopping with a little bit of WD-40 (just a little bit, on top of the spindle).
(BTW I use an active cooled spindle/motor/z-axis to keep the temperature below 40-50 °C).
Since the Spindle stops at a run with only 120 mm/Min, I m pretty sure that there is something wrong with my Nomad.
What do you thing? Any suggestions?

Sounds like a bad motor bearing to me.

WD-40 is not really a good lubricant. I would get some light electric motor oil and add a few drops to see if it helps.

Even the 3-in-1 multipurpose would be better than WD-40.


Sounds like a bearing is heating up and seizing. WD40 is not a lubricant. In fact it will wash out any lubricant that was in the bearing if they aren’t sealed. You might want to try a light bearing oil until you can figure out which bearing is bad and replace it.

If the motor bearing is bad you may have to replace the motor. I doubt it is meant to be rebuilt but I’m not sure. That motor is probably not very expensive to replace.

1 Like

Thank you for your responses.

Sounds logical to me, i will look for an SAE 20 equivalent. Should be similar to an ISO-46 oil (very similar boiling point index and viscosity) (like:

Any suggestions for the lubrication process? It is necessary to disassemble anything, or just add some oil on top of the spindle?

I didn’t see twforeman’s reply when I wrote mine. Great minds think alike :wink:

I would just put a drop as close to the top bearing as you can get it. I would think they designed this with sealed bearings but if a bearing is seizing the seal must me compromised so the oil should get in. However, I would troubleshoot to try to find which bearing is seizing and make sure that one gets replaced. Its cheap insurance.

Generally you don’t want any oil residue on the outside of the bearing because it just holds dust and becomes abrasive so once you get the bearing(s) replaced don’t oil them. I would double check with C3D but make sure the bearings you get are sealed and shielded and are rated for at least 10,000 rpm. Higher would be better. I would imagine C3D sells replacements which will take a lot of risk out of trying to spec your own bearing.

I think I solved the problem for now. Yesterday Evening i cleaned up the upper part of the spindle (with weaponry oil).
Than I put some drops high performance oil for bearing on top of the bearing and start the spindle of the jog dialogue.
From that point I replaced the oil drop every 30 Minutes for about 4 hours.
Now it runs like a charge again. I may got an idea why this happens in the first time. I use a nearly closed case for my Nomad. Since WD-40 is made of low weight hydrocarbons a serious amount of oil could be transport via air into the bearing. The to reduce the volatile organic compound amount of air in the machine, I replaced my cutting fluid (was WD-40) with sunflower oil.
By the way it is much cheaper :wink:
Thanks again for your help, hopefully this solves the problem for a long time.

Make sure you wipe off any excess oil from the outside of the bearing to keep it from catching dust. If you start seeing any strange cutting behavior or tolerances getting worse, put a indicator on the spindle and wiggle on it to make sure the bearing didn’t wear enough to cause allow runout.

I’m wondering if it might be a good idea to enclose the belt and top bearing volume so that ambient dust doesn’t get to the belt, pulleys and bearings as easily. I can’t think of any downsides to it other than possible heat buildup. I think I’ll try that and just monitor the temperature with and without a shroud.

A little update on my problem. After 5 hours of milling the spindle stops again (this time without noise). Now I’m definitely waiting for the reply from Carbide3D.

I will keep you informed

And another update to complete the story.
After receiving (and replacing) a new new driver board and spindle cartridge the Nomad shows no more sings of the problem.
I noticed that the driver board got a very different design from the original one.
One the positive side i had to open my Nomad and make my cooling solution permanent. At the moment i use an 100 mm fan for the spindle and the mount of the z axis (stores a lot of energy). And a small chipset cooler for the motor ( The small cooler fits perfects between motor and cable, without interfering any movement.
Hopefully i able to finish my modifications today and be able to continue with my little project at the weekend.

Thanks to everybody for the support
keep milling

btw: if you got a similar problem, you may have a look here: Spindle stalls almost immediately - SOLVED