10L under drive motor pulley

xplodee · Jun 29, 2015

Hi All-

My 10L didn't come with a motor or motor pulley. Is this something I can machine on my own from scratch or should I be on the lookout to buy one? Are there any off the shelf pulley's that have the correct outer geometry which I can then modify? I don't even know the base dimensions to work off of :/

hitandmiss · Jun 29, 2015

It is my understanding that the headstock with iron bearings have a lower max speed than the newer ones with bronze bearings.
The bronze bearing headstocks have 2 pipe plugs on the top of each spindle bearing, and the iron bearing units have none.

My iron headstock motor pulley is 3.4" and 2.12" OD, I seldom use the larger step.
Max speed is a little over 1300 RPM.

Bill

thomasutley · Jun 30, 2015

xplodee said:
Hi All-

My 10L didn't come with a motor or motor pulley. Is this something I can machine on my own from scratch or should I be on the lookout to buy one? Are there any off the shelf pulley's that have the correct outer geometry which I can then modify? I don't even know the base dimensions to work off of :/

Just went through that with my 16" which has a four groove sheave/pulley system between the motor and countershaft.

If similar to mine, you'll find the aftermarket pulleys, regardless of the number of belts, have the grooves spaced wider than SBL did. I had decided to make a new motor pulley when PM member nt1953 stepped in and helped me repair my original part by brazing it and then re-boring it to fit my new motor.

If you do need to make a new pulley from scratch, all the geometry you need to reproduce it is on the countershaft pulley. Just make a smaller version with the same groove angles, depth, and spacing. The SBL Parts List document has the motor pulley ODs I believe.

Ted likely has pulleys, but the ones he'll have are likely to be taper key designs which may or may not fit a modern motor shaft and keyseat design. Also, depending on your motor shaft size, an original SBL pulley may need to be bored out and then re-broached same as mine. Not difficult to do, just need access to a generous friend with the right tools to do the job.

Good luck!

xplodee · Jun 30, 2015

Thanks Bill and Thomas.

Can anyone else with a 10L confirm the pulley OD's of 3.4 and 2.12"? If so ill just machine and broach a new from 4" aluminum stock.

Skilly56 · Jul 1, 2015

Re the headstocks with the segmented cast iron bearings - my understanding from Denis Turk was that these were the best bearings South Bend ever made (although they didn't realise it at the time), and will run a higher speed with safety than the bronze items do. Can anyone confirm this?

Skilly

garyphansen · Jul 1, 2015

I could be wrong, but I believe the only advantage that the bronze bearings offered over cast iron was that they were replaceable if damage occurred. However, with that said, no damage can happen if they are kept properly oiled. They will both last one or two days short of forever (give or take a day) if kept oiled and the wicks are working correctly.

thomasutley · Jul 1, 2015

garyphansen said:
I could be wrong, but I believe the only advantage that the bronze bearings offered over cast iron was that they were replaceable if damage occurred. However, with that said, no damage can happen if they are kept properly oiled. They will both last one or two days short of forever (give or take a day) if kept oiled and the wicks are working correctly.

Agreed. However, the penalty for poor lubrication is a new headstock if you're not set up for a complicated line boring job on the existing one. The folks who owned my 1943 previously were keeping the cups full of oil, but the wicks turned to rubber sometime around 1950 and the spindle along with its cast iron journals were wallowed out several thousandths beyond spec.

The later model headstock I got from Ted has bronze bearings and almost no wear on the spindle. It's a thing of beauty. My only regret is that SBL never offered a Camloc option for my machine. That would have been a nice upgrade, and fabricating my own is still far above my current skill level.

SBLatheman · Jul 1, 2015

thomasutley said:
My only regret is that SBL never offered a Camloc option for my machine. That would have been a nice upgrade, and fabricating my own is still far above my current skill level.

Tom,
Never say never

The cam-loc spindle was offered on later models.
I know where to find one, but it is "salty" $$ :scratchchin:

Ted

thomasutley · Jul 1, 2015

SBLatheman said:
Tom,
Never say never
The cam-loc spindle was offered on later models.
I know where to find one, but it is "salty" $$
Ted

Haha. I guess there was just no Camloc option for my old cast iron bearing model spindle then? I'll post photos later on my resto thread and stop hijacking this one, but the Cushman and Union 10" threaded spindle chucks that came with my lathe have been worked pretty hard. They're usable, but it wouldn't hurt my feelings one bit to trade up to a Camloc while my headstock is still torn down for paint.

bradjacob · Jul 2, 2015

Tom - I JUST got done machining a new pulley for my 13". I'll post the video here for you (and anyone else) who wants to make their own. Pretty simple part to make.

thomasutley · Jul 2, 2015

bradjacob said:
Tom - I JUST got done machining a new pulley for my 13". I'll post the video here for you (and anyone else) who wants to make their own. Pretty simple part to make.

Heh. Was that the source of the squeaks in your videos? I know it drove you nuts, but it really wasn't that bad on our end watching.

StrayAlien · Jul 2, 2015

refer to this thread:

http://www.practicalmachinist.com/v...ulley-sheave-50hz-10l-running-1415rpm-301234/

there is an attachment that shows the motor pulley dimensions for both 50hz and 60hz.

btw, Ted probably may have some pulleys about ...

Greg.

xplodee · Jul 9, 2015

Ok, well now I realized something. As we all know the SB motor pulley is designed for a V-belt but the countershaft is not.

Would it be advantageous for me to make the motor pulley flat so that I can use a serpentine belt instead? It would also save material since the diameter of the pulley wouldn't need to be nearly so large.

Any thoughts on this?

kitno455 · Jul 9, 2015

I made a poly-v belt pulley for mine.

allan

iwananew10K · Jul 9, 2015

I would say stay original because a serp would be hard to move step to step.

Edit- just saw Allan's reply... Is that with a vfd and you just stay on one step??

kitno455 · Jul 9, 2015

I use a VFD, so I don't switch it often. But the belt moves easy enough from step to step. In fact, I'd say its easier than the V belt when moving from the big step to the small on the motor pulley, since there is no significant groove to lift it out of.

allan

Dobermann · Jul 10, 2015

There is no advantage to making a V-groove pulley for the countershaft drive. South Bend knew what they were doing and there is plenty of diameter and belt "wrap" so that the belt will most likely slip in the smaller pulley on the motor first. And as mentioned above, if you want to change pulley step, if you have a V-groove pulley on the driven end of the countershaft, you'd either have to run the belt quite loose or slide the motor each time you want to make a change. With no groove in the pulley the belt slides over quite easily.

I changed over to a serpentine belt on my 9 Jr mostly because I had the belt and I needed to make a motor pulley and it's a lot easier to make a flat pulley than a V-goove pulley but I see no performance advantage to the flat belt.

kitno455 · Jul 10, 2015

Dobermann said:
There is no advantage to making a V-groove pulley for the countershaft drive.

we are discussing the motor pulley...

allan

iwananew10K · Jul 10, 2015

since Allan did it sucessfully go for it, it would be very easy to make and if it didn't work easy to switch.

This thread did prompt a thought going back to the other thread on quieting the lathe, one of my SBs had significant run out on the countershaft pulley,enough to cause a vibration...maybe check yours while its apart.

xplodee · Jul 11, 2015

Dobermann said:
I changed over to a serpentine belt on my 9 Jr mostly because I had the belt and I needed to make a motor pulley and it's a lot easier to make a flat pulley than a V-goove pulley but I see no performance advantage to the flat belt.

As was mentioned, my question is specific to changing the motor pulley to a flat style and using a serpentine belt. I too will be using a VFD with mine. Did you see any negatives to making the motor pulley flat? I would prefer this route since it will be so simple to machine that part.

10L under drive motor pulley

Hot Rolled

Titanium

Hot Rolled

Hot Rolled

Aluminum

Titanium

Hot Rolled

Titanium

Hot Rolled

Titanium

Hot Rolled

Cast Iron

Hot Rolled

Titanium

Diamond

Titanium

Hot Rolled

Titanium

Diamond

Hot Rolled

Similar threads