Gearing Question

Cappybye · Jan 24, 2019

I'm new to this forum. I have a South Bend 13.5 inch (I think) lathe which I bought from a guy who didn't know too much about it. I changed the motor to a 2hp 1725rpm Leeson single phase.

The lathe is great except that the carriage speed is too fast. The settings are all set to the slowest, yet this is still way to fast to get a smooth finish. If I set up for threading, the machine cuts right around double the speed of what the tag says. I thought maybe the 1725rpm was too fast, but the old 3-phase I pulled out was 1730, so that's not the problem.

I have a friend who told me there's another setting on these old lathes where you can drop everything to a lower gear, but I haven't been able to find it.

Can anyone shed some light?

iwananew10K · Jan 24, 2019

likley has the wrong stud gear in place. there is normally 2 stud gears - one for the coarser threads/feeds(48T) and one for the finer ones(24T) and the coarser one simply doubles that of the finer one....whichever one is not in use goes to the "storage position" on the outside of the lead gear.

take a pic of your end gears with the door open, bet it's just a matter of swapping the 24T in place of the 48T

SLK001 · Jan 24, 2019

Or it is possible that you have the carriage selector in the threading position instead of the power feed position. How are you engaging the feed? Are you engaging the half-nuts, or are you using the clutch?

johnoder · Jan 24, 2019

Might find great info in here

https://redirect.viglink.com/?forma...ampkahler.com/files/How_to_R...he_SB_1of2.pdf

https://redirect.viglink.com/?forma...ampkahler.com/files/How_to_R...he_SB_2of2.pdf

iwananew10K · Jan 24, 2019

yes, read the links graciously provided by Mr.Oder- pay particular attention to pg.74 for the explanation of stud positioning.

Don't have to watch this video but the opening shot is a good illustration as I believe applies to your machine-
https://m.youtube.com/watch?v=NVSFsSDwBtQ

packardbill · Jan 24, 2019

Hi Cappy, looks like you have a 14.5" incher there. The motor "bell" on your machine was only used on the 14.5" and 16" lathes. The tailstock base looks like a 14.5" base. Your lathe, being a later model double tumbler, will have "14.5 in.south bend" cast into the face of the bed at the tailstock end. On the gearbox plate you should be able to make out the catalog number (cl 183) followed by a letter (b for 5ft bed,C for 6ft bed etc.). Like others above, I think you need to swap your stud gears. Good luck. PB

Cappybye · Jan 25, 2019

SLK001 said:
Or it is possible that you have the carriage selector in the threading position instead of the power feed position. How are you engaging the feed? Are you engaging the half-nuts, or are you using the clutch?

Forgive my ignorance with the terminology. I just lift the handle in the carriage to engage it. I've tried everything possible on the carriage, it can change direction but not speed. The present position of the studs it the slowest I've managed, any other combination only makes it go faster. The threading appears to be double the spacing it should be.

I'm offshore now, but will try and get a friend to drop in to my place and take a picture of the end gears.

Thanks for all you help!

Christian James · Jan 25, 2019

Which handle are you lifting?

steve-l · Jan 25, 2019

Please, please find yourself the very old and very common book written by South Bend "How to run a Lathe" and read it. Then, when you are up to speed and still have questions, come back here. At least then, we will be speaking the same language.

Cappybye · Jan 25, 2019

steve-l said:
Please, please find yourself the very old and very common book written by South Bend "How to run a Lathe" and read it. Then, when you are up to speed and still have questions, come back here. At least then, we will be speaking the same language.

I just want to use my lathe, terminology is not important, nor is English my first language. The perfect choice of words isn't going to slow down the lathe.

In the pictures it seems the double gears are obvious, I just need to compare with what I actually have. We've looked at this and couldn't figure it out, so I'm thinking maybe some parts have been removed by a previous owner.

Thank to everyone who helped.

Cappybye · Jan 25, 2019

I have the small gear on the outside there, it just isn't clear what I need to do with it. I know I need to gear it DOWN, so the smaller gear needs to go on the drive side, with the larger one on the driven side. Not quite the same as what I see in the manual on page 74 (thanks Johnoder)

I'm not home right now, wife took the pic for me, so I can't see it firsthand. I guess that small one is stored on the outside and I need to swap it with one somewhere.

kitno455 · Jan 25, 2019

yes, remove the upper most gear that is partially obscured by the upper cover, and replace it with the small gear currently stored on the end of the gearbox input shaft. You will have to swing the banjo upwards to make contact with the smaller gear.

allan

iwananew10K · Jan 25, 2019

yes, look very closely at that opening picture of the video.

you want your gearing to be exactly like that...and the wrench he is turning is the banjo holding bolt...loosen it a bit and you can swing the arm up and down, as noted by Allan.

Ps- your wife did a fine job.

Cappybye · Jan 25, 2019

Thanks guys for all your help. Much appreciated

steve-l · Jan 25, 2019

Cappybye said:
I just want to use my lathe, terminology is not important, nor is English my first language. The perfect choice of words isn't going to slow down the lathe.

In the pictures it seems the double gears are obvious, I just need to compare with what I actually have. We've looked at this and couldn't figure it out, so I'm thinking maybe some parts have been removed by a previous owner.

Thank to everyone who helped.

Terminology is very important. You asked this forum for help, yes? You did that because you don't know, yes? We want to help, yet your limited lathe vocabulary impedes our ability to communicate with you. This little pamphlet used to be shipped with every SB lathe to help people just like you. By reading that little book you help us help you. It will also help you use your lathe correctly.

iwananew10K · Jan 25, 2019

i would argue that Cappy came on with a clear title,clear question, and clear pics when requested...very well presented which made it easy.

Perfect forum etiquette.

SLK001 · Jan 25, 2019

Cappybye said:
Forgive my ignorance with the terminology. I just lift the handle in the carriage to engage it.

This is your problem. You are engaging the half-nuts for feeding and they will feed at the "threading" rate. On your carriage, you should have three controls 1) the half-nuts, 2) the selector switch, and 3) the power feed clutch (or knob).

Move the SELECTOR SWITCH to any other position (right now it is in THREADING mode). The other two modes are POWER FEED and POWER CROSS FEED. When the power feeds are selected, you ENGAGE them by either tightening the knob, or pulling up the lever (depends on what kind you have - can't tell from that wonderfully detailed picture you posted).

This should fix your problem.

steve-l · Jan 25, 2019

iwananew10K said:
i would argue that Cappy came on with a clear title,clear question, and clear pics when requested...very well presented which made it easy.

Perfect forum etiquette.

No he didn't. He pissed me off. He clearly did not know how the controls on the lathe worked, what they did or what they're called. He made no effort to use Google to even learn the names of the controls. I could have called him lazy and inconsiderate, but I didn't. I politely asked him to read the little handbook SB wrote 80 years ago. It would have answered all his questions, most of which he doesn't even yet know enough to ask. Queries like this are rude and inconsiderate without first doing your homework. It's called due diligence.

Cappybye · Jan 25, 2019

SLK001 said:
This is your problem. You are engaging the half-nuts for feeding and they will feed at the "threading" rate. On your carriage, you should have three controls 1) the half-nuts, 2) the selector switch, and 3) the power feed clutch (or knob).

Move the SELECTOR SWITCH to any other position (right now it is in THREADING mode). The other two modes are POWER FEED and POWER CROSS FEED. When the power feeds are selected, you ENGAGE them by either tightening the knob, or pulling up the lever (depends on what kind you have - can't tell from that wonderfully detailed picture you posted).

This should fix your problem.

Yes that seemed like a no-brainer at first, and it's the very first thing I thought, but no. I've tried all 3 settings and nothing alters the carriage speed, except the handle at the bottom, it spins around but never tightens up, and you can apply pressure to it, but it sort of jams things up and doesn't feel right when I push on it. Before I broke something here I am asking those who might know.

This picture should show it better, I uploaded low-res because most forums have a very low attachment limit. The gear swap really seems like the culprit, especially since it's so close to double the speed on the chart.

Over the past year or more I've been searching on the internet for instructions and manuals, I must have downloaded half a dozen, useless. There are lots of models and unless you know where to look,it isn't so easy to find specifics. Yes, you guys did make it easy, and many thanks for that.

View attachment 247911 View attachment 247911

johnoder · Jan 25, 2019

Thumbnail shows what must be done.

Has nothing whatever to do with changing carriage speeds - which is all controlled by quick change threading and feeding gear box on left end

Cappybye said:
Yes that seemed like a no-brainer at first, and it's the very first thing I thought, but no. I've tried all 3 settings and nothing alters the carriage speed, except the handle at the bottom, it spins around but never tightens up, and you can apply pressure to it, but it sort of jams things up and doesn't feel right when I push on it. Before I broke something here I am asking those who might know.

This picture should show it better, I uploaded low-res because most forums have a very low attachment limit. The gear swap really seems like the culprit, especially since it's so close to double the speed on the chart.

Over the past year or more I've been searching on the internet for instructions and manuals, I must have downloaded half a dozen, useless. There are lots of models and unless you know where to look,it isn't so easy to find specifics. Yes, you guys did make it easy, and many thanks for that.

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