Replaced Bearings - Still Running Hot

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candy1land

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Sep 25, 2009
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UGH! I replaced the bearings in my lathe - ordered them from Delta directly. When I went to put the bearing in nearest the tailstock it was extremely tough to get it into the opening. Also it doesn't seem like the hole is cut perfectly for them so they don't seat in perfectly flush. I didn't notice if the prior bearing set had that problem or not. But the end result is that things are still running hot off the rod nearest this set of bearings. I know it's supposed to be a snug fit for these bearings but I had to beat them in with a dead blow hammer pretty hard. They still look fine and in tact with no visible damage but I have to believe that this is why they cause heat - the fit is just too tight. Any thoughts - I don't know what else to do to help this heat issue go away. I'm calling Delta today too.


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KenV

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How hot is your "hot"????

Your hand is not a good measure for bearings.

Bearings can be running just fine at 150 degrees F. Your hand will not like that temperature.
 

PatrickR

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That stinks. Yes, the first question they will ask is, how hot?
Try to get a temp, a non contact thermometer is about $20 from HF.
A little late but its best to press them in with a big clamp. Striking them would be a last option but might be okay if you only made contact with the race. Using a socket or pipe. Also it can help to put them in the refrigerator overnight and heat the housing before installing.
FWIW, my example of the hand test comes from an old-school auto mechanics trick for checking wheel bearings.
These may have a much higher operating temp.
 

randyrls

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When seating bearings, do not press (pound) on the bearing itself. Only press on the outer ring of the bearing. A socket that just fits into the bearing recess makes a good bearing seating tool. Make sure the bearing recess is squeaky clean with no debris, dried oil, or crud.

Hope this helps.
 

Woodchipper

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Patrick, does that mean when you touch the bearing and scream, "$%&^*, that is hot!" you have a problem?
I pressed a couple of bearings in my lifetime. A socket that is the size of the outer ring and a big C-clamp tightened very slowly.
 

PatrickR

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Patrick, does that mean when you touch the bearing and scream, "$%&^*, that is hot!" you have a problem?
I pressed a couple of bearings in my lifetime. A socket that is the size of the outer ring and a big C-clamp tightened very slowly.



Exactly! Scream it out and you need to fix it NOW, only mutter it and you're good for a few more miles.
 

candy1land

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Long Beach
Well crap! The videos I saw they used a dead blow hammer to pound them in. I used a scrap piece of wood over it because I didn't want to hit the bearings directly. They did not go in easy that's for sure. I'll try to get a thermometer soon. Hot to me is - I don't want to leave my hand on it for more than a second. The motor runs hot too which is my bigger concern - not the bearings - they are cheap to replace.


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MRDucks2

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I am no expert in lathes but happen to be one in rotating equipment. First, you have likely damaged the new bearings. They may last only a short while or a year or two but they will fail prematurely. Realize that any bearing that fits that tight will fail prematurely if it is seeing to much heat.

Question, is your lathe set up for 120 or 240 volts.


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frank123

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Put the old bearing back in and see if the fit is the same with it when it is mounted.

Use you micrometer to see if the bearing dimensions are exactly the same on the old and new bearing.

When I'm pressing a bearing in I like to use a little anti seize compound (don't know if it makes any difference from without it since I always use it).
 

candy1land

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I am no expert in lathes but happen to be one in rotating equipment. First, you have likely damaged the new bearings. They may last only a short while or a year or two but they will fail prematurely. Realize that any bearing that fits that tight will fail prematurely if it is seeing to much heat.

Question, is your lathe set up for 120 or 240 volts.


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120 volts. If I damaged the new bearings it's because the hole they are supposed to fit in is way too tight then. Nothing was going to get them in and seated without great force. So if that hole was cut incorrectly how in the world would I deal with fixing that? It's off by a lot.


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candy1land

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Put the old bearing back in and see if the fit is the same with it when it is mounted.

Use you micrometer to see if the bearing dimensions are exactly the same on the old and new bearing.

When I'm pressing a bearing in I like to use a little anti seize compound (don't know if it makes any difference from without it since I always use it).



I may do that - I am going to call Delta first. I'm afraid I will have to damage the bearings to get them back out because I had to use so much force to get them in - in the first place. But good idea. If I can get them out I will try it.

I damaged the old one's trying to pry them out of the holes.


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MRDucks2

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Any bearing can have a variation in actual size vs intended size and a little variation can be bad for large bearings. It can kill a small bearing. If there were any areas of discolor or rust in some part of the fit from your old bearing, it indicates the fit is not round, either.

However, you mentioned that is did not seem to fit correct. Cocking a bearing slightly can both make it hard to install and seem crooked when it is in. It should take no more force to install the new one than it took to remove the old one. If it is seeming tighter, I would check alignment and if needed sand and high spots or the entire bore before going further.

Trouble is, you would now have to get your new bearing back out.


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candy1land

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How hot is your "hot"????

Your hand is not a good measure for bearings.

Bearings can be running just fine at 150 degrees F. Your hand will not like that temperature.



Just to follow up after talking to a lathe mechanic - he said it's WAY not normal for the spindle rod to heat up hot enough to heat up my hand wheel and that if it's running that hot I will undoubtedly ruin my motor at some point because it's not designed to work quite that hard.

He blames the bearings not being seated properly as well. And my old bearings were probably just old and not turning easily enough so they caused way too much friction.




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