How much bearing grease for this bandsaw motor?

[Jonathan Jung]

With electric motor bearings I'm aware that too much grease can get in the windings. But how do I know when I have enough? The tube going to the grease nipple is quite long, at least 6". I put two pumps in to start. Am I to expect to pump until fresh grease comes out?

[Jerry Bruette]

You couold do that but that would probably be too much grease. Is the saw a used one that you've bought? If so you could take the piping apart and blow out the old grease and pump fresh grease into it then reassemble the piping. That way you'll have fresh, new grease up to the end bell. Then a couple pumps of grease will take care of your bearing.

Some motors have a plug under the bearing to let the excess, dirty, grease out while greasing. If there is no way for the excess grease to get out of the bearing you'll over load the bearing and cause heat buildup and can shorten the life of the bearing.

The problem with motor bearings is that people think you have to grease them frequently. That's not so. Being a millwright for over 30 years our take is to usually not grease motor bearings at all. If the bearings are sealed it's harder to get grease into the bearing unless the proper seal was removed when the bearng was installed. And you already know what happens with over greasing. Trashing a whole motor to extend the life of a bearing is foolish.

[Kevin Jenness]

With electric motor bearings I'm aware that too much grease can get in the windings. But how do I know when I have enough? The tube going to the grease nipple is quite long, at least 6". I put two pumps in to start. Am I to expect to pump until fresh grease comes out?

I'm curious about the blade speed on this machine. I have not seen a direct drive bandsaw before and usually a saw this big will run at lower rpms than the motor to get a wheel rim speed around 3000 ft/second for cutting wood.. Do you have a low rpm motor?

[John Lanciani]

I'm curious about the blade speed on this machine. I have not seen a direct drive bandsaw before and usually a saw this big will run at lower rpms than the motor to get a wheel rim speed around 3000 ft/second for cutting wood.. Do you have a low rpm motor?

Saws that size tend to run 5,000 - 6,000 fpm for wood.

[Kevin Jenness]

Saws that size tend to run 5,000 - 6,000 fpm for wood.

Looking at the Northfield site they still offer 27" and 32" saws with direct drive motors ranging from about 4500 to 7500 ft/min. I recall being around a Northfield 36 once and thinking that it was running at what seemed like a high speed- apparently I was not wrong. Interesting that blade speed varies so widely among different classes of saw. Bandmills seem to run in the 5-6000 range. http://www.northfieldwoodworking.com/bandsaws/27and32.htm

[mike calabrese]

On regreasable bearings such as your's with the grease tube arrangement there should be an avenue for the greaseto escape from the actual bearing when you are adding via the grease fitting.This is important because the idea is to exchange the used grease , push it out with fresh grease thereby supporting the beraing. Regreased bearings are typically by this process initially over greased. However in operation the rolling of the bearing balls in the races will expell or pump the excess grease from the bearing. This is typically how it works.
If you have a thermal gun to measure the bearing temperature you will see a relatively higher temp in the bearing as it works to expells the new graese. This is a result of the over grease condition and is expected . As the bearing expells the excess grease the rolloing temperature will come down and all is normal in the world of re-greaseable beraings . Typically this takes several hours of operation. My guess it the bearings in your motor are elll suited to this condition. Pump in the grease one shot at a time taking a couple seconds between to allow the added pressure to work through the system. Stop when you see relatively clean grease exiting from the bearing.
Wipe away the expelled grease and make sawdust.
calabrese55

[Lee Schierer]

With electric motor bearings I'm aware that too much grease can get in the windings. But how do I know when I have enough? The tube going to the grease nipple is quite long, at least 6". I put two pumps in to start. Am I to expect to pump until fresh grease comes out?

I would suggest replacing the bearings while you have things taken apart. You mentioned in one of your other posts that the bearings sounded rough. Rough bearings are likely to fail.

[mike stenson]

I would suggest replacing the bearings while you have things taken apart. You mentioned in one of your other posts that the bearings sounded rough. Rough bearings are likely to fail.

Yea, I've never seen anything other than a (very) temporary improvement by repacking notch bearings. I'd replace, and probably with sealed given the locations.

[Bill Dufour]

About 30% fill is what is recommended and what a sealed bearing comes with. So 70% air.
Bill D.

[Jonathan Jung]

855 rpm motor

I think I'll take it apart as some of you suggest, the old grease seems very dry. But first I'll make sure there's a tire solution that doesn't cost an arm and a leg.