I'm working on a lathe I picked up a few months ago and the inboard spindle bearing (chuck end) runs HOT. IR thermometer show 130F after 10 min at 1200 rpm at the spindle nose and you can not hold your fingers in the bore.Day 1 I did multiple oil changes until the oil ran clear which did yield small silver flakes and lots of filth. I had to use compressed air to get the dirt plug out so the oil could drain freely. The outboard bearing doesn't get as hot but the oil was just as bad and the inner oil seal is shot, as in self draining. I'd like to replace the bearings and seals sometime soon.
Jet has discontinued 2 of the 4 oil seals. Motion Industries has all of the seals available and I ASSUME I should use single lip seals. Currently the spindle is stiff-ish even with the bearing pre-load loose, once again I'm ASSUMING the seals are no longer flexible and dragging. Is this normal? I can't seem to locate any bearings that are more accurate than trailer wheel bearings. With all of it's faults the spindle runs very true (just a slight blip on my 1/2 thou indicator) and I'd like to stay there. Any suggestions on precision replacements?
I rebuilt the apron which had been crashed at some point in time. It was also flat worn out due to the casting sand and CI dust lapping compound it was filled with. I did have to buy a new drive pinion shaft as mine was slightly bent but, the bronze gear was new and looked good. I bought a 1340 apron for $50 from a guy in Atlanta who converts Birmingham lathes to CNC, selling take off parts cheap. The Apron internals (with the exception of one counershaft and the input shaft) are identical so was able to use all new gears and shafts. My casting was cracked at the hand wheel pinion shaft from a crash and needed to be repaired. I cut it off and bolted on a much larger bronze replacement. You can see the oil pushed thru the crack and cutting it off revealed how deep the crack went. I made a cover for the feed rod worm and gear out of a 2 liter bottle, which was sealed with permatex. Adding a fill tube and a 1/8"npt drain plug will allow the worm to run in an oil bath. Since it isn't sealed at the feed rod the oil level will be self regulating.
While I had it apart I balanced the hand wheel. Turning an aluminum handle saved about 90 grams. I drilled a series of holes most of the way thru the wheel on the near and far sides. The far side I filled with lead while the near side was plugged with a small piece of foam. Using rollers and a drill to remove small amounts of lead I was able to get a decent static balance. I filled everything with epoxy (encapsulating the lead) and sanded it smooth.
I have a 2 horse three phase inverter duty motor standing by and will be implementing Mark's amazing VFD controls, soon. I really want to get the spindle up to speed before I get into re powering the lathe and could really use some bearing advise. Thanks, Wes
Jet has discontinued 2 of the 4 oil seals. Motion Industries has all of the seals available and I ASSUME I should use single lip seals. Currently the spindle is stiff-ish even with the bearing pre-load loose, once again I'm ASSUMING the seals are no longer flexible and dragging. Is this normal? I can't seem to locate any bearings that are more accurate than trailer wheel bearings. With all of it's faults the spindle runs very true (just a slight blip on my 1/2 thou indicator) and I'd like to stay there. Any suggestions on precision replacements?
I rebuilt the apron which had been crashed at some point in time. It was also flat worn out due to the casting sand and CI dust lapping compound it was filled with. I did have to buy a new drive pinion shaft as mine was slightly bent but, the bronze gear was new and looked good. I bought a 1340 apron for $50 from a guy in Atlanta who converts Birmingham lathes to CNC, selling take off parts cheap. The Apron internals (with the exception of one counershaft and the input shaft) are identical so was able to use all new gears and shafts. My casting was cracked at the hand wheel pinion shaft from a crash and needed to be repaired. I cut it off and bolted on a much larger bronze replacement. You can see the oil pushed thru the crack and cutting it off revealed how deep the crack went. I made a cover for the feed rod worm and gear out of a 2 liter bottle, which was sealed with permatex. Adding a fill tube and a 1/8"npt drain plug will allow the worm to run in an oil bath. Since it isn't sealed at the feed rod the oil level will be self regulating.
While I had it apart I balanced the hand wheel. Turning an aluminum handle saved about 90 grams. I drilled a series of holes most of the way thru the wheel on the near and far sides. The far side I filled with lead while the near side was plugged with a small piece of foam. Using rollers and a drill to remove small amounts of lead I was able to get a decent static balance. I filled everything with epoxy (encapsulating the lead) and sanded it smooth.
I have a 2 horse three phase inverter duty motor standing by and will be implementing Mark's amazing VFD controls, soon. I really want to get the spindle up to speed before I get into re powering the lathe and could really use some bearing advise. Thanks, Wes