Sebastian Gold Seal 12"x48 School Lathe 2hp 1800 RPM motor install
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  1. #1
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    Default Sebastian Gold Seal 12"x48 School Lathe 2hp 1800 RPM motor install

    Okay my lathe spindle speed should be 500 rpm's and the new motor would be 1800 rpm's. Now I can get close, using components from Burdens Surplus. The components would be a motor drive double sheave 2.5" and a driven would be a double sheave 8.75". Now has anyone have the shaft diameter of the gear head drive for the correct bore for the pulley? AND has any tried to update to the 1800 rpm motors? I mean I don't know if there would be room to get the larger pulley on with interference from the adjacent spindle shaft nose? Any experience out there moving up to newer motors? The 1200 rpm single phase motors are prohibitively expensive "IF" you can even find one. Yes, the 2 hp is larger than probably necessary (not sure if it will be too long to fit in the Leg compartment), but I'm in love with larger 7/8" diameter shaft. These ol' lathes are just fine for most users and in my case I've got work with what I got. Any comments/advice is really appreciated thank you. bjr23

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    I don't think you will hurt anything upping the input RPM of the input shaft of your lathe by using a smaller OD sheave. As for boring out a sheave to fit your input shaft, use a taper lock bushing. Use a taper lock bushing with the appropriate size to fit your input shaft. I have re-bored taper lock bushing out to fit odd ball shaft sizes in my past, so don't let that stop you from using them. You will like them in the long run. If you need help figuring out the taper lock bushing sizes let us know, we'll help you. There's lots of surplus stuff on eBay to pick from, too. Ken

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    Posting photos will help folks have an idea of what your are trying to do. Good info here on posting them.

    Posting Pictures on the South Bend Forum

    have fun

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    I'm sure that changing the pulleys to allow use of a 1800 RPM motor will work as long as heavy cutting is not intended. Slowing down the output would require putting a smaller pulley on the motor, larger pulley on the driven shaft or combination of both. What will happen is belt wrap on the motor pulley will decrease while the larger pulley wrap will increase. Belt slippage will decrease transmitted torque.

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    Quote Originally Posted by Froneck View Post
    I'm sure that changing the pulleys to allow use of a 1800 RPM motor will work as long as heavy cutting is not intended. Slowing down the output would require putting a smaller pulley on the motor, larger pulley on the driven shaft or combination of both. What will happen is belt wrap on the motor pulley will decrease while the larger pulley wrap will increase. Belt slippage will decrease transmitted torque.
    Exactly, that's the reason for a double groove pulleys.

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    L&S was a firm believer in belt wrap and freely used idlers on flat belt drives

    ls-model-rt.jpg

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    Some scans from Catalog 33 in that area

    catalog-33_08.jpgcatalog-33_09.jpg

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    bjr, this is another surplus source also: Surplus Center Jim

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    Well I got out to the shop tonite with a tape measure; mirror and a lite. Guys, I think I'm just plain stuck with a 3 phase motor and probably have to use the VFD. There's a ~7" (the catalog shows a 2.25 drive pulley and a 6" driven pulley) on the input shaft and ~2.25" on the motor and I'm pretty sure it says 1200 RPM on the motor tag, so, that's it. There's no room between the input shaft with that ~7" pulley and the lathe spindle shaft. A bigger pully is just out of the question. I'll be fine as long as that almost 80 year old motor holds up. I tried shifting the gears and as near as I can tell I've go four gear choice on the one shifter and two on the other shifter. I didn't see any reference in the catalog on gear speeds. Does anyone have information on the spindle speed selection? There no tag for that. The only tag is for the threading quick change. bjr23
    Last edited by bjr23; 10-15-2020 at 11:19 PM. Reason: add catalog page for reference

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    Default adding a PDF isn't gonna happen, I tried.

    Well I tried to edit and add a PDF and that didn't happen, so maybe I can add here

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    Photo of the motor will help! Odd the RPM is listed as 1200 RPM, most motors do not provide the synchronous speed (speed with no load on the motor that is in sync with the 60Hz AC line) Usually the Listed speed the motor will deliver is when 2HP load is applied. However I have seen motors rated at sync. RPM but usually they are special duty in that they are actually larger than the listed HP. A VFD is your best method plus it will give you the option to adjust the speed. However it is the most expensive method. RPC can easily be made from another 3 phase motor that are quite cheap. A static converter is also an option and cheaper than the VFD.
    I have a 1200 RPM (sync speed) 70 year old motor on my Hendey lathe that runs like new!

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    Agree! Along with your excellent description, we need good pics.

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    Quote Originally Posted by jmm03 View Post
    bjr, this is another surplus source also: Surplus Center Jim
    Surplus Center is Burden's Surplus, iirc it was Burden's Surplus Center originally, now its just Surplus Center.

    If you have the original 1200 rpm motor, clean it up, slap a new set of bearings in and run with it.

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    Well this lathe is buried in a shop that's extremely cluttered with Grandkids belongings much to my aggravation. I've tried to post a PDF of the page of the catalog that show as built pulley size & RPM's for that lathe, but somehow I get crossed up and it won't post. On one try there was a pop up that said I could drag and drop, but, that didn't seem to work either. Now tomorrow, I'll remove the pulley/belt cover and maybe be able to get a clear view and picture of the motor tag. I've read other posters having difficulty posting picture on this site as well. Yes, I've got a 10 hp 3 ph. motor & the capacitors and various boxes/switches and electrical paraphernalia. I just need time and some patience to get out there and assemble it. I'll just have use a momentary push button type start circuit till i figure out a time to open type relay. I'll have get it running and then check voltages to balance the phases with the run capacitors. bjr

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    Spec Page from Catalog 33 - geared head down the page. Says the 12" pulley was 6"

    catalog-33_39.jpg

    And a crop of the 12" geared head stuff

    catalog-33_39cropa.jpg

    A bit up from this crop it says the 12" lathe input pulley turned 500. If the original motor ran at - say - 1150, the motor pulley would have been close to 2 5/8 OD.

    1150 / 500 = 2.3 to 1 ..... and 6 divided by 2.3 = 2.609



    Quote Originally Posted by bjr23 View Post
    Well this lathe is buried in a shop that's extremely cluttered with Grandkids belongings much to my aggravation. I've tried to post a PDF of the page of the catalog that show as built pulley size & RPM's for that lathe, but somehow I get crossed up and it won't post. On one try there was a pop up that said I could drag and drop, but, that didn't seem to work either. Now tomorrow, I'll remove the pulley/belt cover and maybe be able to get a clear view and picture of the motor tag. I've read other posters having difficulty posting picture on this site as well. Yes, I've got a 10 hp 3 ph. motor & the capacitors and various boxes/switches and electrical paraphernalia. I just need time and some patience to get out there and assemble it. I'll just have use a momentary push button type start circuit till i figure out a time to open type relay. I'll have get it running and then check voltages to balance the phases with the run capacitors. bjr

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    You have 2HP on the lathe and intend to use a 10HP motor as an RPC? Kind a bit of over kill but will work. Problem is starting 10HP. You would be better off getting something like a 2 or 3HP motor. If you do have a 6 pole motor (1200RPM) a 2HP motor will work, slower motors start easier. Furthermore if that 10HP is 2 pole (3600RPM) it will be even harder to start. If you intend only to operate the lathe off the RPC you would be better off finding a smaller motor. In addition I would not bother trying to connect Run or Balance capacitors. Use a capacitor to start the motor and let it run single phase. I have read quite a bit about adding Run and Balance capacitors and don't agree with most of it! Furthermore I had friends that attempted building an RPC and failed due to the Balance Capacitor. I have helped friends build RPCs using only one capacitor for start and all are working fine. In my shop I have quite a few 3 phase motors (15 from 2 to 10HP) and use only a Start Cap to get the RPC motor running! If you do want to use the other Capacitors you can add them later.

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    Those pages that were posted were the ones that I was trying to upload, thank you. Same information.
    This has been a multi-year project (it took two years just to pay the fellow that I bought the lathe and mill from). I keep backtracking on the same issue's (reading catalogs till I fall asleep). I like your thinking and experience. How do you take the start capacitor out of circuit? Momentary pushbutton? I've got a smaller 3phase hp motor somewhere in the weeds a fellow gave me. I'll see if it's been cold enough to freeze out the wasps and black widow spiders and dig and find it. I just got to get this lathe turning some how even "Dirty and quick" works for me. Then maybe later on I can "Refine My Work". Ain't tryin' to compete with Elon Musk here. The information you fella's have shared with me has helped keep me goin' in these dark days and all I can do is offer my "Thank You's". bjr

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    I use 2 contactors, and yes momentary push buttons. On smaller RPCcs a relay can be used. On contactor/relay (large enough to handle RPC motor and lathe motor) self locks like in a push button start. Start push button momentary NO contact will close the run contactor which will lock in, the same start push button also operates a second contactor/relay large enough to handle the start current provided by the Cap. but not self locking so when pressure is removed from the start button the contactor/relay will open. Naturally the Stop switch NC contact is wired to the locking circuit so when pushed the locked contactor/relay will de-energize. When operating I'm near the RPC motor, so I don't need anything to confirm the RPC motor is running. Push and hold the start switch long enough get the motor started. There is a very remote chance that without something to confirm the RPC motor is running that it will burn-up. I've never had that happen and not sure what will cause that. However if there is a thermal overload switch on the RPC motor it's possible it can stop the motor and when it cools causeing the RPC motor to burn-up. If temporary power is lost the locked contactor/relay will drop out. The control power I'm using is 120VAC and taken from light power so at the end of the day, tired and starving I leave the shop turning off the lights will also shut down the RPC and all power to the machinery. Next day turning on the lights will not start the RPC, I must again push the start button. Usually I do shut down the RPC but there have been a few times when I came in and found, the RPC running having forgotten to shut it down.

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    Is there a MT5 taper in the chuck end of the spindle? The reason I'm asking is to be able to fit a lever type draw tube collet assembly. Or is there just 5C internal on a threaded adapter? The catalog says MT2, that must be on the tailstock spindle. I can shove a 1" piece of pipe thru the spindle so if there's a taper it's got to be bigger than 1-3/8" on the small end of the taper? bjr

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    Quote Originally Posted by bjr23 View Post
    Is there a MT5 taper in the chuck end of the spindle? The reason I'm asking is to be able to fit a lever type draw tube collet assembly. Or is there just 5C internal on a threaded adapter? The catalog says MT2, that must be on the tailstock spindle. I can shove a 1" piece of pipe thru the spindle so if there's a taper it's got to be bigger than 1-3/8" on the small end of the taper? bjr
    Spec sheet says hole is 1 5/16. 1" pipe is very near to that. Seems doubtful on the MT5 - since it is 1.75 big end - and the spindle nose thread is but 2 1/8 - 8

    Also states collet capacity is 7/8"

    South Bend used 1.629 big end of taper, 1 3/8 thru hole and an adapter to suit the 5C

    Here is that data

    sb-spindle-dims.jpg

    Here hopefully is a little more readable scan of the specs

    20201018_184650.jpg


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