Replacing the broken bearings in my pm1440gs headstock

richl

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There are 5 shafts in the headstock of a pm1440gs gearhead lathe. I have the misfortune of having one that is eating its bearings. On shaft B as labeled on page #39 in the manual, I isolated all the shafts so you could turn each of the shafts independently. Using a stethoscope I was able to turn each shaft and listen for clunking. On removing the plates covering shaft B from the left side as you look at the lathe headstock on your left. I got a nice pile of metal shavings, and that specific shaft does not spin freely as the others do...
PM says just use a slap hammer and pull the bearings out that way.... I am confused, I see a m6x1.0 thread in the end of the shaft. Is the intent I thread a screw into the shaft and use the shaft to pull the bearing out? I see no other way to remove the bearing.

Any help greatly appreciated

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On the chuck side of headstock I would guess those are covers with a Oring groove. The picture of the inside of headstock looks like the bearings bottom out to a flange on housing so they must go outward. I would probably use a brass punch for removal. Looking at pic again looks like outboard bearing would come out first using shaft to drive out. Then chuck side. Outboard pic of bearing and shaft its looks like a center in shaft not threads? If it is threads yes a slide hammer can be very helpful. Good luck
 
I took my PM1236 apart tonight. It’s not the same gearbox but the shaft in your third pic looks very similar to mine. I pulled the belt pulley off and used a punch to push the shaft out from the chuck side toward the left. The bearing in pic three stayed on the shaft, naturally, and the bearing beside the chuck stayed in place in the housing. Probably not much help for you but that’s what I worked on this evening. Is your problem on the belt side or the chuck side of the shaft? If I’m reading you correctly it’s pic three.
 
I have a 1440 GS, since about January of this year. Minimal hours running it. When did you get yours and how many hours do you think you have had it?

I previously pulled the top cover off and everything looked clean.
 
I got mine 1st week in August 2017. Hours of use, probably around 20-30 hours. It looks bad because I coated it with wd40 this past winter to keep her from rusting
If you are hearing clunking in the gear head the bearings in the pulley shaft or the shaft just above it are just cheap chinese bearings. I've had noise and vibrations issues with the machine since I got her.

That "best in the industry, 3 year warranty " you should read it sometime :rolleyes:
 
I took my PM1236 apart tonight. It’s not the same gearbox but the shaft in your third pic looks very similar to mine. I pulled the belt pulley off and used a punch to push the shaft out from the chuck side toward the left. The bearing in pic three stayed on the shaft, naturally, and the bearing beside the chuck stayed in place in the housing. Probably not much help for you but that’s what I worked on this evening. Is your problem on the belt side or the chuck side of the shaft? If I’m reading you correctly it’s pic three.

Thanks for taking the time to stop by and post. To answer your questions, I cant say for sure right now but it might just be the belt side. I plan on replacing both bearings. The belt side had a nice pile of metal shavings when I pulled the cover/flange off to expose the bearing. As Cadillac pointed, both bearings slide in from the outside of the case. There is almost no room to remove them from the inside, there are gears obstructing access on each side.

I'll make a harbor freight run this morning and pick up a slap hammer. I'm being extra cautious with this, not my typical dive in and get dirty approach.
 
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Looking at picture #3, all the black dust, u guessed it, that was from my bearing grinding itself up. I used to look in when I pulled the cover, it always looked dirty, I figured it was from the pulley belts. Now I know. Hopefully this gets this machine running much better...
 
the black dust may have been from the brake linings (lower left picture 3)
 
Possibly some, agree I had overlooked it. The shaving were metal though.

Ok, keeping my positive attitude
Plan A does not seem to be working. Taking some points from z2v. I am working on plate on the chuck side. I threaded in a m6x1.0 socket cap screw, nut and washer.
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I modified a mount for the bearing puller hammer
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It is not moving, I scrapped around the cover remo
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ving any material, paint, bonds, gasket sealer... whatever.
Anyone want to guess on how this cover comes out? Thread, pressed in, magic. She is in tight.
 
What Does the parts breakdown show that threaded part as a cover? I would imagine so because it looks the same od as the bearing from the inside pic. Cannot be shaft their would be no room for bearing.
With a slide hammer you will want to thread the end of hammer to the threaded cover. Any loss of motion is bad. Soak the cover with some pb blaster or your preference. Maybe a shot of co2 or air duster to try and freeze cap to shrink? Good luck
 
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