SB 9" Counter Shaft Help

Andrew R Stewart

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I have had my 9"C since winter and have found it far nicer then the "toy" Atlas I had before. It came with a single pulley motor and countershaft arrangement, offering only 6 speeds. As my nature is i have begun to see if I can expand this range. So i bought a dual step counter shaft pulley and shaft recently. I also sourced another 110V AC motor with a two step pulley. (I have plans to make a motor to counter shaft belt tension adjustment swing arm, but that's another story). My current question is in two parts.

First is part numbers and compatibility. The two step counter shaft pulley and shaft has #PT2542NL1 cast on it. I can't find it in the manuals I have, or on line. Any insights?

The second is the condition of the shaft. It is well worn and scored with a rib like surface. The shaft measures about .875" in the non work portions. Of course the portion between the driven pulley and the cone pulley area is worn more then the other bearing area. The wear is about .050" taken from the tops of the "ribs". (My current single step pulley and shaft are also worn to the amount that I can jiggle them easily, no measurement but a lot IMO).

This second aspect has me wondering if I can source a section of precision ground stock, ,875" in diameter, and replace the worn shaft. The pulley's tapered drift pin would have to be driven out and a matching tapered hole made in the replacement. Is this reasonable? Am I over thinking the wear and ribbed surface of the new to me shaft? I wonder about the counter shaft cast housing/bracket's bushing wear too. In my world of human powered stuff this wear would be a lot.

This is a long term project as my day job is very busy these days. In NYS the bicycle service business is considered an essential one and the shop I work for is very overwhelmed. Dreams, now if ever, are important to maintain connection to a normal future. Between riding and my frabrication/frame building projects I have little stress relief these days. Any help, history or insight is appreciated. Andy
 
A follow up. I pulled the original counter shaft and pulley (part # 1936N1) and measured across it's bushing wear portions. They are also deeply ribbed BTW. The pulley end diameter measures about .858/.857" and the free end about .874". The recently received two step pulley shaft (part # PT254NL1) has about .863/.857" at the pulley end and .872" at the free end.

Having run the lathe with the original counter single step pulley/shaft and now actually seeing it's condition I am less inclined to seek replacement and will just install the new to me two step one. The two step one will have slightly less slop at the pulley end, which I feel is the more important bushing WRT the set up and loading.

I am curious how people fix this wear, I have my thoughts not that I have the skill to do so:)

BTW the motor's mounting on a hinged element to allow belt tensioning when switching between the two step pulleys, motor and counter shaft, is going well. I've made the hinge and motor base plate. I still need to establish the mounting location of both the motor on the base plate and the hinge on the counter shaft WRT the Vee belt length and the flat belt's clearances. Then discover how the Vee belt's tensioning will be handled. Andy
 
Hi Andrew A bit of a late reply but my counter shaft was worn terribly as well. The bushings are not too bad but will need replacing one day.

I machined a new shaft, drilled and tapped new holes. Theres a tiny bit of play in one bush at one end but it all works fine still. I can get photos of the motor mount and adjustment if you are still going in that direction.
 
As is the way in these projects I am moving forward as I can. (Bike shop work has been crazy for 4 months but as we're running out of repair parts the work load might relax a tad soon:)). Currently I have done some paint removal and clean up on a bunch of parts including the countershaft assembly and am waiting for a rainy day to sand blast then primer the bits. I plan to go with the two step pulley and shaft with a fresh set of oil felts. My motor belt hinged mount is about done and waiting for the to be painted parts to be finished before it's final drive belt length is determined. But fiorst another project is nearing completion and is stealing what little freetime I have between the shop and riding (not to mention the wife). Andy
 
Danshell- A lot has gone past the bridge in the last 5 months. But my wish for a not so worn countershaft remains. I have had the same thoughts of just getting a section of ground shaft and replacing the old one (transferring my two step big pulley). But not yet having made a taper pin joint I am looking for tips to minimize my fumbleness. Do you have any tips or shots of your replacement?

Since the summer's post I have bought a second lathe to fix up. I'll start a different thread as this project has other specific questions. Andy
 
Hi,
Consider taking a look at Halligan142 on Youtube:

Greg replaces a countershaft on a SB13. The lathe is bigger than your 9inch, but Greg shows how he specs the tapered hole, makes the drill extension and inclines the pulley during drilling to accommodate the pulley size ( it's likely that you will also have this issue).

Cheers,
BTW, if you come across another SB 9 two step countershaft pulley, please let me know.
 
Hi Andrew I could take some pics but the shaft is in place. Halligans video that splinter has posted pretty much sums it up, it is a relatively easy little job.
I am pretty sure I simply transfer punched and drilled my taper pin hole in the press though, not while the pulley was on the shaft. My skill are no doubt a little primitive compared to Halligans but I go the job done and it all seems ot be working fine.
 
Here's a shot of the new (to me) horizontal drive after paint and clean up. The pulley's shaft is what is pretty rough surfaced/worn in the bearing area (but you can't see that...)

Note the hinged motor mount. I have a few motor pulleys of different diameters that I can run with so I needed a range of drive belt adjustment. Andy
 

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