[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

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

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]

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

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.

[Adamj12b]

The noise is not what is really bothering me. It is not very loud at all. Mostly just resient noise inside the cabinet. The heat of the spindel seems very exissive though. When I installed the kit I removed all of the gears inside the spindle, except for the ones directly on the spindle shaft. No matter how hard I tried I could not get the spindle out to remove the gears. I only snugged the spanner nut down to the top of the spindle, and the spindle turns very freely, but I will check this out when I get home tonight.

Also, I do plan on running a flood coolant setup in the very near future, but dont want to realy on having the coolant running when ever I use the mill. I will be making parts out of all kinds of material, some of which you would not want to drench in coolant.

One more thing, If somebody could tell me how to remove the spindle, that would be great. I tried hitting it with a mallet but it wouldnt even budge. -Adam

[LeeWay]

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

No reading between the lines where you are concerned is it, Phil.
I did make an assumption about Adam's reason for going with a belt drive based on what he posted.
I would like to know where you located the bearing specs for the X2 bearings though. That is the first time I have seen anyone say they rated anywhere near that high. As I mentioned, I was looking at some bearings in the 7000 RPM range. It would be kinda crazy to use those if the others are rated @ 12,000. If you could enlighten some of us, that would be great. Several guys on here and elsewhere are concerned about the belt drive kits increasing the heat on the bearings because of the speed increase.

Adam, LMS has a dvd that explains how to remove the spindle bearings. It is $25 plus shipping though. It explains how to make the pullers and spacers and the steps involved in removing the bearings. These would pretty much be one shot tools though. It is all pretty simple if you are familiar with how bearings are pulled and pressed in.
It could be that the bearings were too tight from the factory. I asked in some of my ranting earlier if it got warm with the original gears or did you notice?

[philbur]

You can get the bearing number from the user manual then look it up in any bearing catologue. I came up with 6206-2Z. which has a 12,000 rpm limit. I didn't check the load conditions for this limit.

A quick read here might also help:

Sorry if I seemed a bit precise previously but I felt that the OP was being lead away from what was the real issue.

Phil

No reading between the lines where you are concerned is it, Phil.
I did make an assumption about Adam's reason for going with a belt drive based on what he posted.
I would like to know where you located the bearing specs for the X2 bearings though. That is the first time I have seen anyone say they rated anywhere near that high. As I mentioned, I was looking at some bearings in the 7000 RPM range. It would be kinda crazy to use those if the others are rated @ 12,000. If you could enlighten some of us, that would be great. Several guys on here and elsewhere are concerned about the belt drive kits increasing the heat on the bearings because of the speed increase.

[LeeWay]

Phil, you did cause me to research these a little closer. I did find a couple links @ VBX bearings.

http://www.vxb.com/Merchant2/merchan...Category_Code=

This is for the lower bearing on an R8 spindle. Says it's rated @ 6,500.

http://www.vxb.com/Merchant2/merchan...Category_Code=

This one is for the upper bearing on all models. Says it's rated @ 10,000.

Those are both higher ratings than I have seen before. Sooo.......given the new info, I do retract the earlier statement about the weak link thingy.
I also apologize if I strayed from providing any useful help.
Adam, I meant to tell you to PM me if you need this DVD. I am done with it. I won't sell it to you, but you would have to pay shipping.

[philbur]

This bearing is larger than that required by the X2 so the speed limit is lower. The speed limit is due to the seal type and lube, it is not an inherent limit in the bearing design. With difference seals and lube it can go to much higher rpm - upto 15,000 rpm. It's not a design limit it's a low cost option for a spindle that does not need to go higher than 6,500.

Phil

Phil, you did cause me to research these a little closer. I did find a couple links @ VBX bearings.

http://www.vxb.com/Merchant2/merchan...Category_Code=

This is for the lower bearing on an R8 spindle. Says it's rated @ 6,500.

[LeeWay]

Not sure I am understanding here. These are the size replacement bearings that LMS ships. They are of course sealed as would any direct replacement bearing be for these spindles. Are you saying that to get 12,000 rpm, you have to use unsealed bearings and seal the head and fill with gear oil?

[philbur]

I can't see that LMS gives the actual bearing number, so it's not clear where you came up with the following reference:

http://www.vxb.com/Merchant2/merchan...Category_Code=

However assuming the reference is correct you could use a none rubbing shielded bearing, for example 6007.2ZR, with additional protection with a labyrinth seal or flinger ring etc if necessary. Max permisssible speed 11,000 rpm.

However the minimill spindle bearing number according to the user manual is 80206, which is equivalent to 6206-2Z, which according to my bearing manual has a none rubbing seal also good for 11,000 rpm max.

So It seems to me that the current minimill spindle has a bearing rated at 11,000 rpm. Whether you can get even close to this depends on a large number of other factors though, 4300 rpm should be no problem if it is set up correctly.

Phil

Not sure I am understanding here. These are the size replacement bearings that LMS ships. They are of course sealed as would any direct replacement bearing be for these spindles. Are you saying that to get 12,000 rpm, you have to use unsealed bearings and seal the head and fill with gear oil?

[LeeWay]

They do give the bearing numbers at LMS.
http://www.littlemachineshop.com/pro...219&category=6

http://www.littlemachineshop.com/pro...220&category=6

Though by looking at these numbers in other catalogs, you do get higher speed ratings than these spindles actually turn on a mill without the belt drive. Higher than what I had initially thought. I am not sure just where I got lower number ratings. Clearly the spindle bearings should be able to handle 4300 easily. Mine handles 3740 without even getting warm.
I have had my bearings out before though to replace a busted gear. I made sure I put only a light preload back on the bearings.

I think this is good news though. Good to know the bearings should be rated 6000 RPM with little trouble. This will allow me to try some different pulley sizes. I would be able to increase some cutting speeds with carbide tooling turning faster.