Lathe thread identification or advise
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  1. #1
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    Post Lathe thread identification or advise

    Hello all from St. Maarten Dutch West Indies. I am a beginner in the skill of metal machining and learning all I can. I have limited funds and would like to start from scratch by making my own lathe. To this end some time ago I bought a head and tail stock from Ebay. I have tried to find out what I have until I saw the website of Tony at lathes.co.uk and he identified and posted pictures I sent to him. He has said that I have the head and tailstock of a Sloan and Chase 4 1/2 lathe. Since then I have searched the web for information on this lathe. I have found old catalogs on archive.org. One specific bit of information I cannot find is the the type of threads that are on the spindle.
    I would like to find a chuck to fit or advise how to modify or adapt a more modern chuck to fit may be an adaptor. I will pay for adaptor if one can be made.

    Thank you for this forum.

  2. #2
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    Adapters (back-plates) can be made.

    Your lathe part/spindle/nose thread may or may not be a "standard" size. Many, perhaps most were not. You can use a micrometer (digital vernier will do nicely) to get a read on the OD of the threads, and a "thread pitch gauge" will allow you to determine the threads per inch. Or failing in this second, you can correlate the threads you see which may be less than an inch total to what it would be IF it were to continue for that inch. I.e. 4 threads in 1/2 inch correlates to 8 threads per inch. Looking at standard charts online you should be able to tell if something is close.

    If you find the threads ARE a standard size, you potentially could do this work - drilling a hole and threading a round backing plate using a standard tap - in a drill press. A lathe would be better.

    If you find the threads don't seem to match anything "standard" then you're forced into using the spindle from your head stock as a go-no go gauge and cutting the threads single point tool style in the traditional inside (female) nut threading practice which has been done on lathes for generations. Take a cut, try the spindle for fit, take another cut until it does.

    Were you to have a complete lathe I would say you could use your lathe and a face plate to make another backing plate - the only challenge is in the testing for fit - you have to unscrew both face plate and backing plate TOGETHER without changing the two plates positions relative to each other - turn it end for end and try the female thread you just cut on the spindle you just used to make the cut.

    Since you do not have this luxury you'll have to find another lathe and possibly an operator skilled in its use to do this using your spindle as a model. He will thank you for having the loose spindle as this makes the task easier. Likely he understands how this is done as it is not uncommon in trade education to do this as training exercise according to method of one paragraph up.

    It IS a challenge. But nothing is quite so satisfying as making something using your own hands, mind and developed skill. Sometimes you have to develop what you don't have of these three to make it happen.

    But there is the challenge AND the satisfaction.

    A good book online describing basic operations on the lathe and other machine tools is "Advanced Machine Work" by Robert H. Smith. Not necessarily so advanced, it describes by using good pictures and narrative most of what you need to know. http://www.opensourcemachinetools.or...chine-work.pdf

    Joe in NH

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    I have seen one or two Sloan and Chace lathes in over six decades of noticing lathes, which is another way of saying they are very uncommon, even in the USA. If you are very lucky, someone that owns one may see your question and provide an answer. But S&C made at least two sizes of lathe, so you need to get dimensions that fit your spindle. I suppose there is no useful printed information, so you really need to get the thread measurements taken from the headstock you have. That means measure the outer diameter of the threads and the shoulder behind the threads. Then measure the pitch, which will likely be in threads per inch. An assortment of American bolts can be used as cheap thread pitch gages. You need to define the thread form. Most American lathe spindles have a 60 degree vee thread of Sellers or Unified form. But Tony has a picture of a Sloan and Chace with square threads on the spindle nose. I don't know if all S&C lathes were made that way.

    The other question is what collets your headstock takes. I have an early Hardinge collet list that gives the dimensions of two different S&C collets. In later years, Hardinge began marking their collets with type designations. The two S&C collets are marked 5SC for the No. 5 lathe and 52SC for the No. 5-1/2 lathe.

    collet-list-p2.jpg

    Sloan & Chace Lathes

    history of screw threads

    There is no one standard thread for lathe spindles. Each maker decided what they liked and the result is many different threads. Currently available chucks and chuck adapters with threads are very limited, concentrating on sizes that date to the early 20th century and later and which were made in large numbers.

    You can get better answers if you provide pictures of your parts.

    Larry

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    Thank you so much for your response. The greenish looking lathe head stock on Tony's site with the square threads are the pictures I took and sent to him. I had started my search with him since he has so much information. I will just have to take in all the advise and decide on a plan of action.

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    Especially if you have limited funds and no access to a well furnished workshop, building a lathe from the parts you have will be definitely an educational experience, buy many times more expensive than acquiring a working lathe first.

    Paolo


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