1st SB, is 16", have re-motoring question please

I've been lurking here for a while and trying to do my homework before I bother folks with beginner questions. I have ordered a used copy of, "How To Run A Lathe," and have some skimpy parts info so far.
Here's the story: neighboring friend and farmer bought a 16" x 10 foot-bed SB a few months ago at a farm auction. Then, more recently, together we saw another SB 16" x 8 foot at the same auction site...looked a little ragged, but passer-by acquaintence machinest thought it would clean up. Neighbor bought it for, "parts," as he put it, for $600. He doesn't have room for another one, so it's here in my little shop. It might just stay here. Model 117E, s/n puts it close to a 1941 model. It is cleaning up OK. One problem is the quick change gearbox, "arched," lever was broken off so I have that out and hope it can be brazed or welded. I've used little cheap hobby lathes some, but this is my first REAL lathe and I'm pretty happy to deal with something that seems built well. I have no illusion of it being laboratory quality for precision, but I think it can do all I need and I'm not in any hurry with projects. It does have a taper attachment.
What I have to deal with is that it is a 3-phase motor. I know I can buy a converter. I also think I might be able to find a single-phase 220V motor. What do any of you suggest as to how you would go about checking out this lathe's motor?? I don't even know if the motor in it works. I expect to just pull the motor out, but if I got a converter, maybe I don't have to. I also haven't worked on one of these so it will be a learning experience.
I guess I'm really asking what you might suggest in my approach to a new, old lathe, with unknown qualities and motor.
I do not have 3-phase available here.
Thoughts for me as a new participant here would be appreciated.
Dennis
Odessa/Ritzville, E. WA state

Well Dennis I'm in the same boat as I have been lurking after buying my first South Bend a war time 9A. But I have rebuilt a few other non metal working machines and have a thought or two on the motor.
How about walking the motor into a motor shop and asking them to fire it up and 'check it out' for you? If it runs smooth there are some advantages to using it. If you want to use a reverse switch, the three phase route is simple enough. If you choose to use a VFD instead of a phase converter you can have motor speed control.
3 phase motors are pretty rugged. If the shaft spins you got a good chance it will want to turn under power. Bearings may or may not have life left in them.
Of course a single phase motor may be easy enough to go with as well and they can be made to reverse.
Chris

Thanks, Chris. Good idea. I might as well throw some nice, soft material on the floor next to the lathe and prepare to spend some time on my back digging into that motor cavity. Looks like it's coming out. Good learning experience anyway.
I didn't understand all your abreviations, but get the idea. However, what is a, "VFD?" I guess there is some flavor of rheostat controlled power that gives variable speed, (and variable speed does, indeed, sound good).
Dennis

Thanks, Chris. Good idea. I might as well throw some nice, soft material on the floor next to the lathe and prepare to spend some time on my back digging into that motor cavity. Looks like it's coming out. Good learning experience anyway.
I didn't understand all your abreviations, but get the idea. However, what is a, "VFD?" I guess there is some flavor of rheostat controlled power that gives variable speed, (and variable speed does, indeed, sound good).
Dennis

VFD = variable frequency drive, a cool way to get variable speed out of an induction motor. I have no direct experience of these, but not for want of wishing.....Here's a wikipedia explanation: http://en.wikipedia.org/wiki/Variable-frequency_drive
Generally, a single phase motor will reverse, but not while rotating. Since the reversing switch only switches the polarity of the start winding relative to the run winding, and the start winding switches out while running, if you flip the switch while it's running, nothing at all will happen. It's still handy to have, but you can't use it to stop the machine.

You can actually "test" the motor out yourself in one of two ways.
First you can jury rig a phase converter with just a starting capacitor.
About 70 uF perh HP will work.
Just need an off on switch (DPDT) and a momentary contact switch.
connect the cap to one winding through the momentary contact switch, to one side of the 220 Volt main off on switch. Connect the main switch to another winding.
Push the montery swith, flip the on-off switch, release the momentary switch. The 3 phase should now be running.
Second you can use a poney motor, same rpm's please. Just connect both shafts, let the pony spin up the 3 phase, power up one of the windings, any one and power down the poney.
Jim B.

... what is a, "VFD?" I guess there is some flavor of rheostat controlled power that gives variable speed, (and variable speed does, indeed, sound good).

VFD is a gift from the Machinery Gods. I was skeptical until I installled one on my 14" lathe due to mechanical VS mechanism problems. Unbelievable . Smooth and controlled acceleration and deceleration, use the lathe's existing F/N/R switch, speed control at the turn of a knob, E-stop, jogging, plus bunches more features if you get into the advanced options. $300 for a 3 HP sensorless-vector unit.

Downsides -- it's a hassle to run multiple motors off a single VFD, gotta protect the unit from swarf, adds a thoroughly modern tint to antique machinery which is a turn-off for the purist restorer.

Regards.

Finegrain

AC motors are syncronized to the Line frequency. Increasing the frequency caused the motor to run faster. Decreasing the frequency causes them to run slower.
The Line voltage has little impact on the (unloaded) motor speed.
The VFD takes in power from the AC line (can be single or 3 phase) converts it to DC and then generates precise 3 phase at almost any frequency, Say from 0 to 400 or more HZ.
The little box has total control of the output so controlled speed ramp-ups and ramp-downs are easy.
Reversing is simple and can use an external switch. You can use the existing drum switch but it must be rewired. A 1 HP VFD can be had for $125 new.
As Finegrain states it is best to dedicate one VFD to one machine at a time.
You can look here for more INFO
http://web2.automationdirect.com/adc...alog/AC_Drives
Jim B.

You can make some simple checks on the motor before you pull it out.
1. take the three leads loose from the drum switch (be sure to tag them and note where they connect before removing)
2. take a ohm meter and measure the resistance between each, A to B, B to C and A to C. These reading should be very nearly the same, If there is much difference then your motor may have a problem. By much I mean one reading is twice the other leg's reading.
3. check each lead to ground. This should be infinite resitance.
If checks 2 and 3 are ok then odds are good that the motor will run.
The other check a motor shop can do is a "megger test" which tests the condition of the insulation on the windings.
If the two checks are OK then you can hook 3 phase power to it and it will likely run without and sparks and smoke.
There is lots of info available about VFDs on the Transformer, Phase Converter and VFD Forum on this site. You will be looking for a single phase input, 3 phase output, 230 volt VFD with the same horsepower, or larger, rating as you motor. These are nice little electronic devices. I have used TECO FM-50 (the lease expensive) and Hitachi L100s, Hitachi SJ200s, Reliance SP500s and one Toshiba G7. I have a LG and a Reliance GV3000 that I have yet to install. I like the Hitachi and Toshiba manuals best of the Asian imports and I like the Reliance manuals. I have also read an Altivar (Square D) manual and it is good but they are costly. For a lathe, I really like the Hitachi SJ200 which is a sensorless vector drive that gives you good torque at low speed. Note that VFDs have lots of capabilities and options that you may not need and the manuals can be overwhelming.
Bruce Norton
Kingsport, Tn

I appreciate all the wonderful information on motors and my, "new," SB. The VFD concept sounds terrific. I suspect this 16"x8-foot I have had a 1.5 hp motor, (or still does). I have crawled around the lathe base and so far can see no printed info on the motor. The motor does, however, look a LOT newer than the lathe. I'll get under there and wipe things down more and take a good light with me. Maybe I'll see something. I'll also do the motor test suggested by Bruce, however, Bruce I do not know what you mean by drum switch. I suppose you are suggesting I do all tests from the electrical junction box adjacent to the motor itself. I seem to recall there are wire-nutted connections that tie three wires together on at least two legs at that box.
There is also what looks to be a three-position switch, (in box), on the electrical pipe arm that sits above and behind the head stock. I would guess that has forward, off and reverse.
I'm guessing Bruce's test is checking winding resistance on three windings. Also a test to check that one or more windings is/are not shorted to case ground. Seems simple. Still not sure about, "drum switch."
This could turn out a lot better in dollars than I figured.
Dennis

There is also what looks to be a three-position switch, (in box), on the electrical pipe arm that sits above and behind the head stock. I would guess that has forward, off and reverse.

That corresponds to the "drum switch" mentioned earlier. Back in the day, these switches had a rounded front, hence the term drum switch.

Finegrain

An easier way to test that motor is to remove the belts, leaving the motor thankfully in place, wire up any two of the three leads, even 110 would work, wrap a piece of cord several times around the pulley, and yank the cord like starting a lawn mower, as soon as the cord is off the pulley, turn on the lathe switch and the motor should be running.
The photo in my avatar is an SB16 with the 1944 motor and a VFD.

Thanks, Tom. I'm checking that. I've been pulled five different ways this past weekend...none of them pointed me toward my lathe. Ha.
Sounds like you have exactly the lathe and set-up I need. I'd be interested in what VFD you are running. I've just begun to read about them and I'm totally confused as to how to approach them, except it sounds like that's just the ticket for me.
I've begun lurking around this site's VFD forum....too scared to ask anything yet, (grin).
Dennis
SB 16"x8-foot; tired but eager to live again...........

Add new comment

Images
More information
  • Files must be less than 2 MB.
  • Allowed file types: png gif jpg jpeg.
Documents
More information
  • Files must be less than 2 MB.
  • Allowed file types: zip rar.