• June Project of the Month (Click "x" at right to dismiss)
[4]

K&T vertical mill, spindle runs hot

[3]
[10] Like what you see?
Click here to donate to this forum and upgrade your account!

amesgang

Swarf
Registered Member
Joined
Jan 23, 2014
Messages
10
Likes
1
2
#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.
 

Bob Korves

H-M Supporter - Sustaining Member
H-M Supporter - Sustaining Member
Joined
Jul 2, 2014
Messages
5,118
Likes
5,471
20
#4
Or perhaps petrified grease in the bearings after decades without being serviced...
 

Bob Korves

H-M Supporter - Sustaining Member
H-M Supporter - Sustaining Member
Joined
Jul 2, 2014
Messages
5,118
Likes
5,471
20
#5
Regardless, it probably is time for a tear down and inspection.
 

amesgang

Swarf
Registered Member
Joined
Jan 23, 2014
Messages
10
Likes
1
2
#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

H-M Supporter - Sustaining Member
H-M Supporter - Sustaining Member
Joined
Jul 2, 2014
Messages
5,118
Likes
5,471
20
#7
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...
 

Silverbullet

Active Member
Active Member
Joined
May 4, 2015
Messages
3,229
Likes
1,532
#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

Active Member
Active Member
Joined
Apr 14, 2014
Messages
364
Likes
240
15
#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

H-M Supporter - Sustaining Member
H-M Supporter - Sustaining Member
Joined
Jul 2, 2014
Messages
5,118
Likes
5,471
20
#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

H-M Supporter - Premium Member
H-M Supporter-Premium Member
Joined
Mar 26, 2018
Messages
418
Likes
165
15
#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

Active Member
Active Member
Joined
Mar 10, 2018
Messages
139
Likes
80
10
#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

Swarf
Registered Member
Joined
Jan 23, 2014
Messages
10
Likes
1
2
#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.
 

Attachments

[6]
[5] [7]
Top