spindle temp

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

My bridgeport interact runs at 110-120 degrees at that RPM

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.

Take a look at:

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.

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.

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

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.

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

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.

"PrecisionmachinisT" fired this volley in news:6qSdnXwTNtCUZ2rMnZ2dnUVZ snipped-for-privacy@scnresearch.com:

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

4000 RPM on a sealed greased spindle? Are you sure? Most of the Ser II Bridgeports and such have a much lower max spindle speed. The higher-speed spindles mostly have oil-lubed bearings. Anyway, 4000 RPM on a sealed greased bearing is going to require some sort of special grease for sure. There are things like Royal spindle bearing greases that are designed to run cool(er) in high speed low-clearance bearings.

Jon

The Precise S-65 spindle I recently acquired is grease lubed and sealed and rated to 45,000 RPM. The documentation for it is very insistent that the proper warm-up procedure be followed every time the spindle is started from cold.

And, I'll bet they don't use ordinary axle grease from the auto parts store in there, either!

So, what IS the start-up procedure? I have a 54K Precise spindle, and no manual or frequency converter. I will eventually build a converter to drive it.

Jon

FYI, I got that by emailing them, and they responded in about an hour and a half.

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

Thanks! If yours has brushes, it is even older than mine. Mine has a 2-phase induction motor, and although it has a scroll housing for a fan, there is no fan, you have to supply an external cooling blower. I didn't get the frequency converter with it, and will have to build something myself.

Jon

"PrecisionmachinisT" fired this volley in news:q6KdnfvfAcZP0mXMnZ2dnUVZ snipped-for-privacy@scnresearch.com:

Heh! Thanks; but I was hoping you'd been through it and might have some recommendations.

Lloyd

"Lloyd E. Sponenburgh" fired this volley in news:XnsA20E555E04BE4lloydspmindspringcom@216.168.3.70:

The series 1 spindles are shot-oiled, which probably matters for this discussion.

Lloyd