A_Pmech
Stainless
- Joined
- Dec 27, 2004
- Location
- Central IL, USA
Gentlemen,
I'm working on my Do-All saw rebuild this weekend and I've hit a snag. I'm looking for advice on how to re-fit a bronze bearing.
The bearing in question is pressed into the output shaft of the transmission, which carries the band wheel and blade tension load. The bearing stabilizes the output shaft, so that it will not rack the main output bearing. It does this by accepting a portion of the input shaft, which rotates in the opposite direction. Below is a photo of everything laid out:
The existing bearing is bell-mouthed and rather worn. At the widest point the bore is around .025" larger than the shaft. I'm going to clean up and re-polish the input shaft, remove the existing bronze and press in a new one, then bore to fit.
My question is: What clearance should I leave between the bearing and the shaft? The bushing is not directly lubricated, nor bathed in oil. It's sole means of lubrication is via a passageway drilled though the input shaft gear and down the center of said shaft. Oil picked up by the reduction gear "falls though" the input gear into the concentric passage and then into the bushing. Not much lubrication at all, I'd suspect!
The speed differential is probably around 800 RPM, lubricant is 80W gear oil. Bearing bore is 5/8"
I'm thinking a bore .005" to .007" over the journal would be in the neighborhood. I don't want anything too tight or it might seize up with the temperature rise bound to occur with light lubrication.
Any thoughts on this?
I'm working on my Do-All saw rebuild this weekend and I've hit a snag. I'm looking for advice on how to re-fit a bronze bearing.
The bearing in question is pressed into the output shaft of the transmission, which carries the band wheel and blade tension load. The bearing stabilizes the output shaft, so that it will not rack the main output bearing. It does this by accepting a portion of the input shaft, which rotates in the opposite direction. Below is a photo of everything laid out:
The existing bearing is bell-mouthed and rather worn. At the widest point the bore is around .025" larger than the shaft. I'm going to clean up and re-polish the input shaft, remove the existing bronze and press in a new one, then bore to fit.
My question is: What clearance should I leave between the bearing and the shaft? The bushing is not directly lubricated, nor bathed in oil. It's sole means of lubrication is via a passageway drilled though the input shaft gear and down the center of said shaft. Oil picked up by the reduction gear "falls though" the input gear into the concentric passage and then into the bushing. Not much lubrication at all, I'd suspect!
The speed differential is probably around 800 RPM, lubricant is 80W gear oil. Bearing bore is 5/8"
I'm thinking a bore .005" to .007" over the journal would be in the neighborhood. I don't want anything too tight or it might seize up with the temperature rise bound to occur with light lubrication.
Any thoughts on this?