10EE Square dial threading gearbox rebuild

bll230 · Aug 4, 2017

Thanks Cal...

What you don't want to see bouncing around in the bottom of your gearbox as you are taking it apart:

It turns out that a previous owner had tried to disassemble the gearbox and didn't remove the double setscrew on the bottom of the casting.

The cone shaft end was a bit mangled from his hammering, but thankfully nothing that couldn't be recovered from.

The gearbox uses three different bearings. An 88505 on the input shaft right behind the feed pulley, one SKF type everywhere else, EXCEPT, one location which uses a smaller id.

I guess the previous guy didn't notice there was one different bearing and didn't bother reordering when he put it together. This is the bearing that was used in this location. I guess he just wanted a place holder.

daryl bane · Aug 4, 2017

I hate to see this type of stupid s**t. Now you have to wonder...what else did he get into.

bll230 · Aug 5, 2017

I had a chance to read Gernoff's thread on the gearbox, thanks Glug. I did it differently than he did. I was convinced that Monarch designed in disassembly without having to drill holes in anything. The fact that the cast iron bearing caps on the right had the hole in the middle and the ones on the left didn't told me there had to be a plan.

All the shafts except the clutch shaft came out easily, tap from the right to knock out the left bearing and cap, then once the left cap is out, tap from left to right to remove the right bearing. The clutch shaft puzzled me though. You need to tap from right to left to push out the intermediate shaft that is to the left of clutch shaft, but you can't tap to the left because the large freewheeling gear on the left of the clutch shaft can't move left.

After a couple of hours of puzzling over it it hit me. The freewheeling gears have a bronze bushing in them. When you tap the clutch shaft to the left the shaft is pushing on the bronze bushing, not the actual gear, and the bushing is then pushing on the left bearing. Tapping the clutch shaft from right to left pushes the bushing out of the gear, and then the bearing pushes the intermediate shaft out the left. Once the left bearing and cap of the intermediate gear pair is out the intermediate gear pair can be removed, and then the clutch shaft can be tapped out to the right.

The bushing is then pressed back into the freewheeling gear. Done. All shafts out. All it took was a piece of aluminum rod to tap through the bearing cap holes, and a hammer!

I will replace the Fafnir bearings with the New Departure bearing like Gernoff had. My Fafnirs are C1 bearings, which may have contributed to the shafts spinning. All the bearings in the apron were New Departure, so I am going to go on the assumption that the ND bearings were the bearings the gearbox was designed for.

rimcanyon · Jun 15, 2021

bll230 said:
I had a chance to read Gernoff's thread on the gearbox, thanks Glug. I did it differently than he did. I was convinced that Monarch designed in disassembly without having to drill holes in anything. The fact that the cast iron bearing caps on the right had the hole in the middle and the ones on the left didn't told me there had to be a plan.

All the shafts except the clutch shaft came out easily, tap from the right to knock out the left bearing and cap, then once the left cap is out, tap from left to right to remove the right bearing. The clutch shaft puzzled me though. You need to tap from right to left to push out the intermediate shaft that is to the left of clutch shaft, but you can't tap to the left because the large freewheeling gear on the left of the clutch shaft can't move left.

After a couple of hours of puzzling over it it hit me. The freewheeling gears have a bronze bushing in them. When you tap the clutch shaft to the left the shaft is pushing on the bronze bushing, not the actual gear, and the bushing is then pushing on the left bearing. Tapping the clutch shaft from right to left pushes the bushing out of the gear, and then the bearing pushes the intermediate shaft out the left. Once the left bearing and cap of the intermediate gear pair is out the intermediate gear pair can be removed, and then the clutch shaft can be tapped out to the right.

The bushing is then pressed back into the freewheeling gear. Done. All shafts out. All it took was a piece of aluminum rod to tap through the bearing cap holes, and a hammer!

I will replace the Fafnir bearings with the New Departure bearing like Gernoff had. My Fafnirs are C1 bearings, which may have contributed to the shafts spinning. All the bearings in the apron were New Departure, so I am going to go on the assumption that the ND bearings were the bearings the gearbox was designed for.

Old thread, but gearbox rebuild threads are few and far between. I just disassembled the threading gearbox that is going into my 49 mfg. lathe. A few pictures below. Everything that bll230 said was spot on. I should have read it before I did the disassembly (ha!). But it came apart exactly like he said, even down to the inner bushing on the freewheeling shaft getting separated from the gear when tapping the shaft to the left. One thing not mentioned is that there is a double setscrew in the bottom of the gearbox that locks the coneshaft end cap in place.

The reason I am rebuilding the gearbox is that it was full of congealed oil. I suspect the gearbox came from a machine that sat outside for a while and water got into the gearbox. Now the search for bearings is on. The (11) Fafnir 204K C1 bearings are proving hard to find. C1 is a clearance spec, and specifies minimum clearance. I checked with several on-line bearing retailers; none had any 204K’s with C1 clearance. I may just reuse the bearings I removed, all of them are smooth, but they also feel looser than I would expect a C1 bearing to be; not surprising for a 53 year old gearbox.

Included a couple of pics of the gearbox case in the parts cleaner, just because. I was very happy to find that it fits. The cleaner is a 30L ultrasonic from fleabay, the solution is oil eater, 1 gal to 4 gal water. Does a great job on grease as well as oil.

AlfaGTA · Jun 19, 2021

Don't think there is any advantage here in running C1 bearings.
Nothing high precision here...just linear shafts running parallel carrying gears....which likely have greater run out than any class of clearances on the bearings.
I would have no issue calling out "standard" clearance (CN) for this application....Its not like its a spindle.
Monarch likely used C1's because that is what they were buying from the bearing makers...Bulk orders having all the same clearance specs....
If you are worried about the shaft to bearing clearances, a drop of RC 640 (loctite) will put your mind at ease....
Cheers Ross

rimcanyon · Jun 20, 2021

AlfaGTA said:
Don't think there is any advantage here in running C1 bearings.
Nothing high precision here...just linear shafts running parallel carrying gears....which likely have greater run out than any class of clearances on the bearings.
I would have no issue calling out "standard" clearance (CN) for this application....Its not like its a spindle.
Monarch likely used C1's because that is what they were buying from the bearing makers...Bulk orders having all the same clearance specs....
If you are worried about the shaft to bearing clearances, a drop of RC 640 (loctite) will put your mind at ease....
Cheers Ross

I ended up buying whatever Monarch provides as replacements. Monarch's price on the 204K's is only $15, can't do a lot better than that elsewhere. Haven't received them yet, but I expect they will not be C1.

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