View Full Version : Change gear knick knacks

12-17-2003, 05:17 PM
When you say to purchase a used lathe with change gears, to make sure you have all the change gears, that is a great tip. However, I would also add to that, that the seller should also have all the Bushings, washers, nuts, T-bolts, etc. You need those things just as much.
Well my lathe does not have all that stuff, lol. The way im going to tackle it is just set it up for a .0021 fine feed, maybe a .0031 fine feed, and leave it at that.
I guess I could use my chinese lathe to make all the bushings.
For anyone that has a southbend lathe, do you have pictures of where each bushing and washer goes for the gear setup? Thank you for the Gear Chart Evan, it shows me that I need another 4 or 5 change gears.
Hmm, looking at the thread chart, I see one bushing needs to hold 2 gears and be keyed, hmm, actually 2 bushings.
Also, The Stud Gear, that is the gear that mounts to the reversing assembly right?
Thank you all for all the wonderful help you've been giving me as of late.

12-17-2003, 05:35 PM

There are several bushings needed and a couple of tee bolts. One of the change gears is a double gear as shown in fig 1, 3 and 4 on the chart. It is 72 teeth and 18 teeth. Another double gear is 54,18 as in fig 4. The bushings should be easy to make from mild steel. You don't even need tee bolts, you could get by with regular bolts and some fender washers. Re: stud gear, yes.

The keyed gears are the screw gears and go on the lead screw or the stud gear. The rest are idler gears.

I almost never use the lead screw for feeding unless doing long cuts. I cut mostly by handwheel and save the lead screw for threading.

12-17-2003, 05:40 PM
hmmm, Never thought about it that way.
Well in that case, I have a bunch of leadscrew gears, and only 2 idler gears.
I imagine those double gears are rather expensive on the used market..
Thanks for simplifying things Evan.

John Foster
12-17-2003, 06:36 PM
Bill, when I had a change gear SB I hooked a DC drive to the right end of the lead screw, to use for turning. The variable speed on the DC really worked great for cutting. If you got a little chatter just change the feed faster or slower to get rid of the chatter. John

12-17-2003, 07:05 PM
Good idea John!, Man too bad I sold most of my Electric r/c airplane stuff, I had some nice brushless DC motors. Still though, I'd like to get my lathe as original as possible, but I do like that idea, may give it a try at some point.
I was just in the garage cleaning up the gears I do have. Every one of them has a key slot, so I only have stud and screw gears, no idle gears at all...
Lets see, need 16t stud gear, 18t/54t double gear, and 18t/72t double gear so I can get that fine feed.

[This message has been edited by BillH (edited 12-17-2003).]

12-17-2003, 07:09 PM
BillH: Check out this link. It has parts diagrams including the change gears for the B & C.


12-17-2003, 07:17 PM
Thanks Nheng, just what I needed, I see the parts I need now.
You know, rebuilding Southbend lathes is strangely becoming very addicting!

John Stevenson
12-17-2003, 07:40 PM
Just to muddy the waters up a bit here's the metric charts for the SB lathe.
These are actually from the UK Boxford book which is a copy of the SB

Does anyone know the DP of the SB gears. I may do a few whilst carrying on testing my hobber - not promising, depends on hobs.

John S.

12-17-2003, 07:54 PM

I'll take a picture of some of the gears and bushings so you have an idea of what you need. The bushings aren't critical at all and could easily be brass, easy to turn. The ID of the bushings is non critical as it is bolted to the quadrant arm. The OD should be fairly close to the ID of the idlers but even that doesn't have to be perfect.

12-17-2003, 07:55 PM
Good to see that site back on line. It was off for quite a while. I have all the parts manual as well.

12-17-2003, 08:00 PM

DP is 18

12-17-2003, 08:11 PM
It seams to me that it will be hard to find that one double gear, that came with model C's only, the 54t/18t. I wonder why model B's didnt need it?
I plan on making those bushings from brass Evan, if I cant find them. I never turned brass before, just steel and aluminum, should be fun.

John Stevenson
12-17-2003, 08:26 PM
From what I can see of the various charts that went with the various models they all used an 8tpi leadscrew so if you stick to one chart and not mix and match you should be OK.

Evan thanks for that info, unfortunately I don't have an 18 DP hob and the S/H gear folk in the UK aren't listing one.
I have a 10, 12, 20 and 32 at present plus 2 Mod, 14 and 16 DPon their way.

John S.

Paul Alciatore
12-17-2003, 09:35 PM

The SB9 gears are on E-Bay all the time. A nice looking complete(?) set was there a few days ago and the bid was only up to about $35. Many individual ones also. My lathe was short several gears when I bought it but I have managed to buy all I need and also three compounds (3:1, 4:1, and 6:1) since then. Virtually all of them were in good to very good condition.

Having them made in quantity of one each will cost $35 to $100 per gear. E-Bay is a much better bet unless you make them yourself.

As for spacers, washers, nuts, etc.; I have a nut, a 3/8" spacer, and a washer (1/16"?) for the lead screw and each compound seems to have a different ID so I have three different hubs for them (bolt, T-bushing, washer, and nut). As far as I know, that's all you need for the C model. I'm not sure about the As and Bs.

Paul A.

12-17-2003, 09:46 PM
At first, I was confused to how many bushings there were, because I was wondering how to stack an 18t with a 72t, until Evan told me that was a single double gear.

12-17-2003, 10:49 PM
With most lathes, double gears are usually two gears mounted on a common sleeve. I've never been this close to a S/B C, but doubt it would be different.
eBay, or the advertisers in HSM are your best source of change gears. New are available, but you won't want to pay taht price.

12-17-2003, 11:42 PM
Bill: JC is right. If memory serves the SB Change gears are ALL single gears, coupled by a keyed bushing. They look like a single gear but if you press firmly or use a drift on the center hole, the bushing will probably slip out and you have two gears in hand.

I've seen the gears, half nuts etc on EBAY. I'd suggest you find out what SB charges for any parts, and the part numbers (per the link you were given) and haunt EBay till you find them about half price or less.
AndCongrats on the machine!

12-18-2003, 12:29 AM
The SB compound gears are double gears, two gears on the same bushing. The gears are permanently pinned together.

Al Messer
12-19-2003, 06:27 PM
Now I know why I like my M/W Logan the best!