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[4]

K&T vertical mill, spindle runs hot

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amesgang

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#1
After running my mill about 30 minutes making some very light cuts on aluminum I noticed the spindle bearing area was very hot (160), the main body of the mill was 79 degrees. Any idea what would cause this, oil levels are normal.
 

Bill W.

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#2
Bearings going bad or pre-load out of adjustment...???
 

Bob Korves

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#4
Or perhaps petrified grease in the bearings after decades without being serviced...
 

Bob Korves

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#5
Regardless, it probably is time for a tear down and inspection.
 

amesgang

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#6
After running my mill about 30 minutes making some very light cuts on aluminum I noticed the spindle bearing area was very hot (160), the main body of the mill was 79 degrees. Any idea what would cause this, oil levels are normal.
Where can I get information on how to tear it down?
 

Bob Korves

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Where can I get information on how to tear it down?
First thing is to study a parts breakdown of the vertical head. Do you have one? You also might post the model of your K&T so someone familiar with it can step in to help...
 

markba633csi

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#8
I was thinking petrified grease also
 
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#9
Does it have grease fittings?? Any leaks by the spindle ?? Any hole with a plug an endoscope will fit in. There like $20. For a cell phone or tablet you can look without dismantling to a point. If it's grease you'll see it.
 

projectnut

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#11
160 F is a typical operating temperature for rolling element bearings, it is 60 Deg. higher then human body temps. SKF gives some guidance here.
http://evolution.skf.com/us/whats-normalthe-role-of-temperature-in-bearing-applications-3/
While it may be wise to inspect the bearings to be sure they are properly lubricated I do agree that bearings of that era do run HOT to the touch. Here's a warning note from the operators manual concerning the heat generated by the motor bearings in my Sanford MG surface grinder:

1526837906641.png
 

Bob Korves

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#12
160 F is a typical operating temperature for rolling element bearings, it is 60 Deg. higher then human body temps. SKF gives some guidance here.
http://evolution.skf.com/us/whats-normalthe-role-of-temperature-in-bearing-applications-3/
Agreed that 160 F. is a normal temperature for bearing elements. However, the OP was not likely measuring the actual bearing elements' temperature, he was likely measuring the hefty cast iron housing they are mounted in, which will be at a much lower temperature than the bearings themselves are. Carbon steels typically start to lose their hardness above about 400 F., alloy steels somewhat higher depending on the alloy, so by the time the housing gets to 160 F., the bearings themselves may already be ruined. It is certainly worth a look if the OP was not measuring the temp. of the bearings themselves. The mill was also only doing light work for 30 minutes, which usually should not show that much bearing heat, though I must admit to not knowing specifically about K&T vertical mill operating instructions and limitations, and do not even know the exact model, the OP never told us...
 

Janderso

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#13
Or perhaps petrified grease in the bearings after decades without being serviced...
Watching H&W machine’s video on spindle bearing replacement/packing, the tech., Used a very small amount of grease. He said, too much grease will cause overheating.
Just my 2 cents.
I have run my Bridgeport enough to verify it runs very cool at the spindle.
Something is going on with your mill. Imho
 

P. Waller

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#14
Agreed that 160 F. is a normal temperature for bearing elements. However, the OP was not likely measuring the actual bearing elements' temperature, he was likely measuring the hefty cast iron housing they are mounted in, which will be at a much lower temperature than the bearings themselves are. Carbon steels typically start to lose their hardness above about 400 F., alloy steels somewhat higher depending on the alloy, so by the time the housing gets to 160 F., the bearings themselves may already be ruined. It is certainly worth a look if the OP was not measuring the temp. of the bearings themselves. The mill was also only doing light work for 30 minutes, which usually should not show that much bearing heat, though I must admit to not knowing specifically about K&T vertical mill operating instructions and limitations, and do not even know the exact model, the OP never told us...
Any temperature above 169.3216 Deg. F is out of spec, this is why most machines are supplied with spindle bearing temperature monitoring equipment.
Your machines do not have this feature? Shame shame, you probably use them up to 170.0000 Deg. F. A prolonged period of more then 171.0032 Deg. F will result in catastrophic failure.
 

amesgang

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#15
I changed the oil, backed off the pre load on the bearings, was set very tight. retested, still gets hot on high speed (1000 rpm), does not heat up on low speed. K&T 2H vertical mill.
 

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