spindle temp

Those following RCM closely know I've been rebuilding my CNC mill.
I had startup early this evening with all new seals and bearings in
the spindle and drive head. I ran it at 2250 RPM for about 30 minutes. the outside of the quill was about 150 degrees (I could hold my hand on it several seconds before feeling it might burn). Normal? How hot is it safe to go? I can run 4000 but thought I shouldn't go there till it has several run hours.
it is nice to not have a machine that slings oil, and now there is virtually 0 defection in the spindle (vs. 0.006 before). Plus I found a coupling in the Z drive that was loose causing problems in Z dimension.
I still need to rebuild the one shot auto lube system and chase down one last air leak.
Those that REALLY have a long memory know I rebuilt the table and added a power ballscrew to the knee last year. I think this old girl is good for another 30 years now.
Karl
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On Mon, 29 Jul 2013 20:02:46 -0500, Karl Townsend

You may..may wish to back off the preload nut a smidgen. When doing bearings..ALWAYS start off slow for 30-45 minutes. Like...200 or less RPM, then go up to 400, then 800 and then 1200 and then 2400. etc etc
Seriously. I rebuild precision spindles regularly and most often the client wants to put the machine right back to work and is moderatly pissed that he cant. So Ill hang around off the clock checking on it for a couple hours and then put it back to work. Shrug About 1 out of 10 may need the bearings backed off a fraction of a turn. In 3 yrs...they may be loose and need tightening..or they may run the next 20 yrs dead nuts.
150F seems a bit warm for 2250, even with new bearings..so you may have the bearings a smidgeon too tight. Or they arent being oil dripped (if thats how they are lubed, properly.
Just a suggestion. Take it as you wish.
Gunner
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My bridgeport interact runs at 110-120 degrees at that RPM
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Karl Townsend wrote:

A break-in procedure I found says 500 rpm for 15 min, then 1000 and up in 1000 rpm steps of 15 min each. I see indications that 130-150F is the normal operating temp range. The break-in procedure is intended to distribute the initial factory grease and let regular lube in so there aren't grease globs for the bearing balls to slam into when running at high speed. It's reported that at each rpm step temps will spike to the top of the range initially then drop back to a lower stable temp. It sounds like you've bypassed most of the break in procedure, but it still wouldn't hurt to go through it while ensuring your spindle lube pump is replacing the factory grease with regular spindle lube.
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Karl Townsend wrote:

Take a look at:
http://spindle.info/answers/what-happens-during-spindle-break-in-grease-lube/how-to/131/
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On 7/29/2013 9:02 PM, Karl Townsend wrote:

When we replace Barden super-precision bearing in high speed quills and shaper shafts we follow a break in protocol in addition to smacking the shaft back and forth with a rawhide mallet. I can't explain how hard to hit it, how often or why, it's a feel thing...just the way I was taught. I've been very lucky for a few decades and never had a shaft run warm for long.
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The idea is to distribute the grease in a very thin film. The procedure involves starting out at some fairly low rpm and letting it run till temperature equilibruim is reached...the first time you pass through each step, you will see a temperature spike and then teh temp will drop slightly and stabilize, if so, you;re safe to move on up to the next step...but if it continues to rise, or if you have any doubts whatsoever, then best to shut it down and let it completely cool and start all over again.
When the grease is properly distributed, the spike dissapears altogether.
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Karl Townsend wrote:

Is this a spindle that has provisions for oiling? If so, it probably was meant for oil lube, not grease. You may need to put some oil in and let it run for a while, and slowly wash out the assembly grease.
If it is a sealed grease spindle, you may have used the wrong grade of grease. if it is heating to 150 F at 2250, you will probably have severe overheating at 4000. This much heating will definitely show up in growth of the spindle, probably a few thousandths, at least.
Jon
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Jon Elson wrote:

It sounds like it was factory applied grease, probably a small amount intended to provide initial lube. I expect the machine has a spindle lube pump unit, so the break in procedure should work the grease out to a thin film as the normal lube comes in to replace it. Jumping the gun and running it up to half speed probably didn't do it any good, but once it's fully cooled, the proper break in procedure along with enduring the lube pump has moved enough regular lube in should help settle things down to normal operating temps which are usually pretty warm anyway.
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Its just a greased spiindle, like on a car. I used ordinary car axle grease. Did i screw up? What should i have bought?
Got A LOT of work to do on the farm. I'll run it at 500 RPM and work my way up when i got time to sit and watch it.
Karl
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Probably, yes.

Kluber nbu15 is the usual, fill no more than 1/3 of the space between each ball. Generally I'll completely fill one space, note how much it takes, and then I'll suck 2/3 of it back out before finally applying the proper amount to the rest of the spaces.
Another way I've heard is to use mobiltemp shc-32, mix it with acetone, dip the bearings in it and then let the acetone dry out, I've never done it this way so can't really comment further except to note that I see no reason why one couldn't dispense with the acetone and simply apply with a syringe the same as above.
> Got A LOT of work to do on the farm. I'll run it at 500 RPM and work

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volley in

PT, I've recently upgraded controllers in my old BOSS series I machine. Next on my list is a spindle rebuild/upgrade.
I know how to do clean work, but I've never rebuilt anything as precise as a spindle must be. Two questions:
1) Am I better off just 'biting the bullet' and letting a spindle house re-do it, and 2) Can I get that spindle to reliably do 6Krpm with the right bearings and lubricants?
LS
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"Lloyd E. Sponenburgh" <lloydspinsidemindspring.com> wrote in message

I've got a feeling you'll be just fine, Lloyd.
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in

Heh! Thanks; but I was hoping you'd been through it and might have some recommendations. <G>
Lloyd
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"Lloyd E. Sponenburgh" <lloydspinsidemindspring.com> fired this volley in

The series 1 spindles are shot-oiled, which probably matters for this discussion.
Lloyd
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"Lloyd E. Sponenburgh" <lloydspinsidemindspring.com> fired this volley in

Um... revising that... they are "prelubricated bearings", as-supplied, and listed as 'permanently' lubed. But Vactra #2 flies around in that zone all the time, so I figure they probably end up getting washed.
Lloyd
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"Lloyd E. Sponenburgh" <lloydspinsidemindspring.com> wrote in message

Pretty sure you can upgrade those by reducing the spacer lengths and adding more bearings to the stack (quad instead of duplex set)....something to look into, perhaps...
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"Lloyd E. Sponenburgh" <lloydspinsidemindspring.com> wrote in message

I recall there being a toilet seat up there, then again once you've seen a few dozen knee mills they kinda all start looking about the same.
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"Lloyd E. Sponenburgh" <lloydspinsidemindspring.com> wrote in message

I think that oil only luricates the quill/housing sliding interface on those and that the bearings are "lifetime lubed" but I could be mistaken.
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"Lloyd E. Sponenburgh" <lloydspinsidemindspring.com> wrote in message

Not on that particular machine.

Figure out what bearings it takes, source them from ebay, and always keep a spare set on hand.
Use premium grease and don't overfill. Don't hammer on them, but especially don't hammer on the outer race when fitting onto a shaft, or on the inner race when fitting into a bore.
Why exactly do you thinkl that they need be replaced?
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