X2 Mini Mill Spindle Heat Problems

[Adamj12b]

I recently converted my mill to belt drive, with the LMS belt system. I ran the mill on and off for an hour and the spindle was so hot that I could not even touch it. Even the draw bar was too hot to touch. I am using a 1/4" solid carbide so I am turning it at the max 4300 RPM. Is this normal for the for the bearings to create this heat while operating? If somebody could shed some light on this for me I would really appreciate it. -Adam

[BrassBuilder]

Adam,
I just ordered the belt conversion from LMS. I had a few concerns of the spindle getting hot because of the higher speed. I'm interested in following along on this and seeing what others have had for experience on this topic.
Mike

[Adamj12b]

The benefits still out weigh the the use of the gears. I'm thinking that it will cause the bearings to prematurely fail. Anybody else had this problem? -Adam

[philbur]

Its probably wrong lubrication and/or wrong preload. At least that's the place to start.

Phil

Originally Posted by Adamj12b I recently converted my mill to belt drive, with the LMS belt system. I ran the mill on and off for an hour and the spindle was so hot that I could not even touch it. Even the draw bar was too hot to touch. I am using a 1/4" solid carbide so I am turning it at the max 4300 RPM. Is this normal for the for the bearings to create this heat while operating? If somebody could shed some light on this for me I would really appreciate it. -Adam

[LeeWay]

I am not sure what might be causing the heat for you. I have a bigger motor driving an X2 head at 3740 RPM. I have done some flycutting on the new table and I have used a 1/2" 2 flute end mill to cut some of the new parts for the new table. My spindle head barely gets the chill off. This is an older head that came on my X2. I actually bought another head for this project, but wound up dismantling the X2. There really should not be that kind of heat on it.

Things to check? Make sure neither belt pulley is rubbing top or bottom or even between each other. Those tolerance are fairly close. I don't know if you removed the old speed changing gear, but if that is engaged, it might help to heat things up. If all these things are good, then you may have poor or worn bearings. Did it get hot when it was running @ 2500 with the gear drive? I have found some new bearings @ McMaster that may work okay for higher RPM. These were rated @ 7000 RPM. Near that would be a great speed to be able to use especially with some smaller carbide bits.

[Rodm1954]

I had the same problem after I fitted the LMS kit. The spindle runs faster with the kit so natural that there is more heat in the bearings. I did have the bearing pre-load a bit firm so I backed it off a bit and the spindled cooled down. There is no play in the spindle but I can just hear a bit of noise in the spindle while it is running but it did improve the heat problem.

[LeeWay]

Another thing you might consider is running coolant through the head itself. Only if you use a good coolant setup though. I had considered this when changing the motor, but this head doesn't get warm. I don't think it would take a lot of coolant either.
If you have a foamy type coolant, it wouldn't do so well. You could also rig it so that the coolant drain would go into a directional tube and you could use it on the tool then. Something like this may just save your bearings on the cheap if you already have coolant.

[blades]

My guess would be excessive bearing preload, either via. too much belt pressure or too much preload from the nut or both. The heat can only be generated to the spindle by way of the bearings or through the cutter, since they're the only items actually touching the spindle. If you loosen the belt, do the bearings feel smooth, or do they feel rough when turned by hand?

[cjdavis618]

Yep, loosen the belt a bit. I had a similar problem on my belt kit when I got it installed. Turned out one of the noises I had was the keystock that the main shaft pulley has. It was slightly stuck out and would hit the shaftway as it turned with a heavy load. I adjusted that out and the system went mostly silent. (save motor and cutting noise)

As for heat, I haven't had that problem but would suspect that the gears are engaged, or the spindle needs lube.

[philbur]

A spindle like this running at 4300 rpm shouldn't need coolant. It would be treating the symptom not the fault.

Phil

Originally Posted by LeeWay Another thing you might consider is running coolant through the head itself. Only if you use a good coolant setup though. I had considered this when changing the motor, but this head doesn't get warm. I don't think it would take a lot of coolant either. If you have a foamy type coolant, it wouldn't do so well. You could also rig it so that the coolant drain would go into a directional tube and you could use it on the tool then. Something like this may just save your bearings on the cheap if you already have coolant.

[LeeWay]

Originally Posted by philbur A spindle like this running at 4300 rpm shouldn't need coolant. It would be treating the symptom not the fault. Phil

I agree. It should not need coolant. That is only a stop gap measure to prevent burning up the bearings that are in there, assuming they aren't in bad shape already. I haven't actually done it myself, but have been considering the pro's and con's should I try to increase the speed through the use of pulleys. The motor that is on mine now is capable of pretty good torque so far. Shows no signs of bogging.
In any effort to increase speed on an X2 head, the spindle bearings speed ratings are the weak link. The OEM motor is probably running max as well.
In the case of the OP, I don't think he was looking to increase speed as much as efficiency and noise reduction. Not chewing up gears anymore is another benefit.
The coolant idea is just one that has been flowing through my head, so to speak.
Here is another. I have been considering a twin head on my mill too. I make some aluminum parts that are 5" long. With a setup like this, I could mill twice as many. Just something else that has been flowing through my head.

[philbur]

The speed rating on spindle bearings in the X2 type spindle may vary but it appears to be in the region of 12,000 rpm. So the spindle bearings do not appear to be a weak link when seeking speed improvement above the stock 2,000 to 2,500 rpm.

The OP says nothing about efficiency or noise reduction, but is concerned about overheating at 4,300 rpm.

Phil

Originally Posted by LeeWay In any effort to increase speed on an X2 head, the spindle bearings speed ratings are the weak link. The OEM motor is probably running max as well. In the case of the OP, I don't think he was looking to increase speed as much as efficiency and noise reduction. Not chewing up gears anymore is another benefit.