Help with ID of SB lathe

It's been quite a few years since I've posted on this forum but I'm back.
Anyway, today I helped my buddy bring home a SB lathe. Looks to be a 16" swing and the plates says 6' bed. Kind of weird, looks to only swing about 30" or so between centers. Guess that's the overall bed length. Useless specification.
I figured there would be a serial number/Cat No chart in the stickys but nothing there.
Bed SN is 13266HKX
Cat No CL81140
This uses a two speed Reliance Duty Master AC motor and has two sets of Allen Bradley push button switches mounted down by the tailstock. Each switch box has forward/reverse/stop.
Motor specs are as follows.
HP RPM Voltage Amperage
3 1745 230 8.8
1.5 860 230 7.6

So it looks to be wired as a 230VAC motor with no other options. There are two sets of forward reverse contactors on the headstock pedistal on the back.
He has a 5HP rotary phase converter that I gave him to use on his Bridgeport and Marvel roll in saw. When I powered the lathe up I could hear contactors pulling in but the motor would not energize. I know the previous owner and he told me that there was an issue in the contacter box as it was hit and would not work anymore.
There is very minor damage to one of the contactors. I'll probably have to change that one out.
I'd love to find a wiring schematic for this lathe. Does anyone have the same setup?

Thank you

Mr Bridgeport

serial # date estimate 1970ish South Bend Lathe Serial Numbers

catalog number explanation South Bend Lathe Co.

explination of the 3 letters after the serial# SBL Serial Number File


Its probably been wired by Danny the shop drunk you should at least check all bits of wiring to make sure it wont catch fire.

Thanks for the help with the numbers. So it's newer than I thought. It certainly had an easy life and spent the last 15 or 20 years tucked in a one man maintenance department. Very little wear on the bed or anything I can see except the morse taper is chewed up in the tailstock spindle.
I believe the two speed motor and double set of forward/reverse contactor's is factory issued. Nothing unprofessional about the wiring at all. That's why I was looking for a schematic. Is a two speed motor a rarity on a SB?
I've worked on industrial machine tools all my life, very little on SB lathes though.

Mr Bridgeport

Pics, or the machine does not exist.

With that motor hp range, I would guess a 16". The 6' bed is total length as you guess.

While I can't think of a reason for a 2 speed motor, not to work both speeds in either direction. . . The usual set up is high and low speed fwd, and just high speed reverse.

I have a two speed motor, but mine is GE, and I use drum switches.

With different switches, I would think one speed or more should work.

I'd recommend pulling cover off motor connection box. Document, and/or tag the wires, take pics. Disconnect the wires from motor. Now power up and verify if you have all 3 legs from your 3 phase source to motor with a multi meter, checking with each speed select switch. If so, most likely a short in motor. If not, check your 3 legs back to switches, and so on to figure out which leg dropped.

Should be 6 powered wires coming from switches to motor. 3 for high speed, 3 for low speed. In the switches, or switch box, 2 of the the 3 wires for each speed are swapped to go in reverse. Only 3 wires are powered at a time to motor though.

Everybody needs pictures! This is all I have at the moment, taken as we were unloading it. As you can see, there are two electrical boxes mounted to the headstock pedistal, they contain the contactors. I will try and get better pictures this afternoon.

Like I said, this thing is in amazing shape except for the tailstock spindle taper being badly scored. A light coating of rust that is cleaning right up leaving no pitting, it was only outside for about two weeks.

OK, posting pics is a lot different than before and I'm having issues. I'll figure that out latter.

Anyway, this lathe is in remarkable shape aside from the scored tailstock taper. Light coating of rust as it sat outside for several weeks, it was going to be scrapped so my buddy picked it up for the sum of $225.00.
Came with taper attachment, hand wheel 5C collet closer with 5C spindle adapter, some 5C collets, steady rest, 3 jaw chuck with reversable jaws and a crate of tooling. As noted, the bed shows very little wear. A darn good deal for the money.

Mr Bridgeport

Might want to check this thread for the TS spindle:
FS: Tailstock Spindles 13” & 14” & 16” N.O.S.

$225 is not a good deal. That's more like free, .

It pretty simple to clean up a tailstock MT with a the proper MT hand reamer. It doesn't have to be "perfect" you just can't have dings that raise metal up. The reamer will shear those off. I've cleaned up spun JT chuck sockets with a Foredom grinder and a 80 grit flap wheel.

Even if the wiring looks good it's a good idea to check it over well. It was bought used and is fairly old it's easier to replace a wire nut than it is to explain why something caught fire. I have seen stuff catch fire because a $20 contactor stuck closed.

However it's your call.

Yea, I've cleaned up MT before in a tailstock but this one is to far gone. The first inch or more is gone, nothing but heavy scoring. I'd have to ream in pretty deep to get most of the surface back. I sent a email to SBLatheman on info on a quill.
As far as the wiring, I'm a machine tool service tech by trade, that's why I was looking for a schematic but I can trace it as a last resort. Just trying to save time. Overall the wireing looks decent, nothing cloth covered in this.

Mr Bridgeport

Mr Bridgeport said:

Yea, I've cleaned up MT before in a tailstock but this one is to far gone. The first inch or more is gone, nothing but heavy scoring. I'd have to ream in pretty deep to get most of the surface back. I sent a email to SBLatheman on info on a quill.
As far as the wiring, I'm a machine tool service tech by trade, that's why I was looking for a schematic but I can trace it as a last resort. Just trying to save time. Overall the wireing looks decent, nothing cloth covered in this.

Mr Bridgeport

Click to expand...

For wiring, I doubt yours is original, so I think you will need to check from switches to motor. I could be wrong, I don't know every factory set up under the sun, but two switches without a factory lock out of one, while the other is powered is telling me something. I'm working blind though, as (sigh) , no pics.

Mine is considerably older, 1942, but even then, there was linkage set ups, so only one drum switch could power motor at a time. I don't know how many years they did it this way, but I have seen my set up on newer lathes as well. While not complete yet, note the handle cage on top of head stock here, pics 3 and 4:
South Bend No. 2-H Turret Lathe 16"x6' Restoration

While I don't have perfect pics of the linkage setup, you can see the two drum switches, with cast iron over it, in pic 2. It was linkage set up inside that, that only allows power to motor from one switch at a time. Also you can see the power lever up on top of headstock in pic 3:
South Bend No. 2-H Turret Lathe 16"x6' Restoration

That was the set up at least as far back as 1942. I would guess 1970's lathe to have equal or better safety. So if you don't have a lock out from one switch to the other, then I would think that set up is someone's own answer to do a 2 speed motor, with no schematic.

Another indicator is motor hp. 16's came with 1.5 or 2 hp motors from factory. But it is not uncommon for people to "upgrade" to a little more hp themselves . Like yours is 3 hp.

How do you add pics to a post with this new software?
Anyway I spent about an hour on it today. Found a few loose connections so I went through all of them on the contactor board. Still no joy.
There is 2 sets of contactors, each set has both a forward and reverse contactor.
Six wires from the motor, L1,L2 and L3 need to be energized for low speed, L11,L12 and L13 need to be energized for high speed. Looks like there is two complete separate windings in the motor.
There are 4 contactors in the panel in total, remember both low and high speed have forward and reverse.
This is where I get lost. When I push high speed forward one contactor energizes but only two legs (L11 and L13) go to the motor. The middle leg of the motor (L12)is on the low speed reverse contactor and that leg will only be energized when the low speed reverse contactor is pulled in.
At this point I would like to find a wiring diagram as it's getting confusing.

@texasgunsmith, mechanical interlocks haven't been used in decades. I started installing and servicing machine tools over 35 years ago and back than they were obsolete. Instead each contactor has a normally closed set of contacts that the power from the other contactors coil passes through to complete the circuit. As long as one contactors coil is energized it's impossible for the other contacter's coil to receive any power. To this day I have never seen any kind of failure using this setup. Even if it did fail all it would do is take out the main line fuses.

Mr Bridgeport

Mr Bridgeport said:

How do you add pics to a post with this new software?
Anyway I spent about an hour on it today. Found a few loose connections so I went through all of them on the contactor board. Still no joy.
There is 2 sets of contactors, each set has both a forward and reverse contactor.
Six wires from the motor, L1,L2 and L3 need to be energized for low speed, L11,L12 and L13 need to be energized for high speed. Looks like there is two complete separate windings in the motor.
There are 4 contactors in the panel in total, remember both low and high speed have forward and reverse.
This is where I get lost. When I push high speed forward one contactor energizes but only two legs (L11 and L13) go to the motor. The middle leg of the motor (L12)is on the low speed reverse contactor and that leg will only be energized when the low speed reverse contactor is pulled in.
At this point I would like to find a wiring diagram as it's getting confusing.

@texasgunsmith, mechanical interlocks haven't been used in decades. I started installing and servicing machine tools over 35 years ago and back than they were obsolete. Instead each contactor has a normally closed set of contacts that the power from the other contactors coil passes through to complete the circuit. As long as one contactors coil is energized it's impossible for the other contacter's coil to receive any power. To this day I have never seen any kind of failure using this setup. Even if it did fail all it would do is take out the main line fuses.

Mr Bridgeport

Click to expand...

On pics, some post from phone which many find easier, but I think it somehow cuts size of pics down, so the pics don't look great.
I post from pc. I want to say the website doesn't exactly like full size pics, though I have not checked in a while. I load pics to pc. I open the pics, and using a messenger app I cut the pics myself, so the byte size is smaller, but visually large.
From pc. you click reply to a thread. On new window, click "go advanced". Scroll down, click "manage attachments". A small window pops up, click "add files". Either click "browse" in drop down to seach your pc for pic, or click + symbol to add up to 5 pics. After pics selected, click "upload". Then click "insert line" at bottom of small window.

I understand mechanical lock outs are old. I mentioned them because in my minds eye I am picturing two individual switches on TS end as you described. It sounded to me like I could push buttons on both, simultaneous.

From your description, it sounds like switches are wired wrong. If its me, I need to confirm motor is good, both speeds. I'd totally disconnect motor from switch wiring. Where/how is machine plugged in ? Is there a breaker between how machine is plugged in and phase convertor ? Make or run 3 wires directly from motor to breaker, socket, or whatever you got. Use the breaker as your power switch to test motor, both speeds. Power L1, L2, and L3 first. Disconnect, then power L11, L12, and L13 next. Only power one speed at a time.

3 phase isn't all that complicated. Its 3 wires. Let's call the supply legs A,B, & C. Let's say A to L1, B to L2, and C to L3, We'll guess this is forward rotation.

We'll also say A,B, and C to orient the same to L11, L12, and L13, for also forward rotation.

You can ONLY power low speed, or high speed. NOT both at the same time. Same for reverse rotation. Either power low, or power high, Never both at the same time.

To change rotation for reverse, swap any two supply legs. In this case we'll say B to L1, A to L2, and C remains L3. Likewise for L11, L12, and L13.

However, whatever the switches are, only 3 wires can be powered at a time, and all three must be powered for the SAME speed, either L1, L2, and L3. . .OR L11, L12, and L13. Again, never both at the same time.

Now, 2 speeds and two rotations, right ? Three wires per could mean 12 total wires to motor. . . But noone wires that way. You should have 6 wires to motor. Three for high speed, three for low speed.

To accomplish two speed and two rotations, they will jumper inside the switches. So when forward is UN-powered, you can power reverse. The jumpers should do the wire swap thing,ie: B to L1 and A to L2. . .

Anyway, I'd check motor like I stated with breaker or whatever you got. The switches and jumpers you can check unpowered using the ohm portion of multi-meter. See what contacts are activating what, and get it to look like what I wrote above. During this draw or write out your own connection chart, but it is really as simple as abc to 123.

Ok, pictures and further post about the electrical problem will be covered under this post.

SB 2 speed motor wiring problem

Thank you

Mr Bridgeport