WM18 spindle heat

The spindle on my WM18 always ran warm (since new) but I have noticed the heat problem is getting worse. I tried an IR thermometer and the spindle is reading 127°C next to the collet. The quill reads 47°C and the cutter and work piece about 54°C. The ambient temp in the shop is around 27°C. The motor does not run hot, so suspecting the bearings are overheating. I'm not sure for how long was the mill running... I normally spend a whole afternoon on and off using the mill.

Has anyone with a similar mill had similar issues with heat? From what I've read it is normal for the spindle to run warm, but mine is way too hot I think.

Is it time for a new set of bearings?

Ouch! My VMB runs quite hot when running for a long time at high speed but nothing like that. It may just be the bearings need (re-)packing with new grease, but if you have to strip the spindle to do that it might be as well to replace the bearings at the same time.

My WM18 ( not used a lot in the 18 months I've had it ) bearings run warm. Probably around 40 - 50C after about half an hour at 1500 RPM .

Beware your IR thermometer. Mine is wildly out on a reflective surface. Just tried it and I get 57C on a radiator but 103C on the chrome body of the thermostat which is about 4" away.

D.

You got a point there Dave, will check the temperature again with a probe thermometer. I'm sure it was getting very hot though, when changing tools, the endmill was warm but the R8 collet was hot, hot that you won't hold it. The quill was also hot, you could just about touch it for a little while.

From what I read and an interesting video on youtube, the spindle bearings do not really adjust as they are interference fit onto the spindle shaft, so it's meant to run hot.

I wonder if motor oil would help bearings like that

My earlty280 lathe which was know for a problem started to get quite hot after about 18months around the bearing nearest the chuck, there were marks on it and quite dry.. Swapped them for a couple of FAGS and not touched them since which is about 12yrs.

The KX3 can get quite hot after an hour or so running at 5000rpm can't hold your hand on the head but Ketan says that's down to how they are greased at the factory and not to worry and these are expensive matched pair bearings costing a couple of 100 sqid.

Any one replaced the bearings on their WM18 yet? I'm tempted to take it apart and at least inspect the bearings, but my gut tells me to leave it alone once it's not making any noises and rotates freely!

Over packing with grease has previously been blamed for hot running bearings.

It is common for mills to have taper roller bearings and if yours is this type, it will be very sensitive to the preload adjustment. Overheating is either overpacking of the grease, you need at least 50% airspace, or preload. I had another less common spindle overheating problem on the Tom Senior R8 conversion caused by the lower seal friction which fooled me for some time, but that is unlikely with the original dust cover on a mill. If the preload is adjustable, there will likely be two nuts, possibly with a lock washer that have left hand threads in the upper half of the spindle. The trick is to just get the loose play in the bearings removed before locking the nuts. Testing at maximum rpm for 20 minutes should get luke warm, but not any hotter. Too hot and you very slightly slacken the bearings (try about 10 degrees), let things cool down and repeat the test. Once set, the bearings will probably never need adjusting for years. I use lithium high melting point grease as used in older car wheel bearings.