Need 2-1/4-6 backplate for my 1947 14.5 South Bend
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  1. #1
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    Default Need 2-1/4-6 backplate for my 1947 14.5 South Bend

    I have a three jaw chuck that came with my South Bend 14.5" lathe. I also have a four jaw but the back plate was threaded for a different spindle. I am brand new to machining but still attempted to bore and rethread the backplate 2-1/4 and 6 tpi. The boring was the easy part but I failed miserably cutting the internal threads and ruined the piece.

    Now I am looking for a backplate. Is my best option to try again or does someone have an old back plate laying around? Best source for a semi finished back plate?

    My existing, ruined, back plate is about 6" in diameter and about 1-1/2" thick.

    Thanks in advance for your help.

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    Good on you for having "a go" at making a backplate, but as a newcomer to machining, you have chosen quite a difficult job to do as your first one! Try looking at You Tube to give yourself some idea on how to do an internal thread, but consider roughing the next one out and giving it to an experienced machinist to finish for you. I'm not sure if you will ever find a correct original backplate for your machine, but you might be lucky. Good luck.

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    How about bore it, sleeve it and try again?

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    I owned one of these lathes, model circa 1967. I made backing plates for several chucks and made a gauge that simulates as close as I could come the spindle thread so I could check as I went. I sold the lathe but it is only a short distance away. the new owner says I can borrow the gauge, so if you want to have an unthreaded plate sent here, I will thread it, no charge, just pay shipping. Macch17 is correct, this is no job for a beginner.

    Bill

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    Bill,
    I have recently begun working on my lathe after the holidays and just today saw your post. You still willing to thread a plate for me? In crossthread's post there is a link "Used Metal Lathes... that lists a semi finished 6" back plate,HK30 870-106. Will this work? Thanks in advance!

    Tom

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    Are you sure the internal thread is 2 1/4 X 6 and not 2 1/4 x 8? The only reason I ask is that I have seen a few references to the latter but not the former.In your situation , until you get the threading skill behind you, I would definitely get a semi finished backplate and not just a blank. If it already is threaded then it is much easier to turn it to fit your chuck. Make sure the spindle shoulder is clean and don't spin the plate onto it too hard. Just snug it up by hand. Machine it to an easy press fit into the chuck.

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    Man, how I wish it was 2 1/4X8. I found some South Bend literature on the internet that gave various dimensions for the different model lathes including spindle size. I have removed the chuck and confirmed with a thread gauge.

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    Post the literature that shows a 2-1/4 x 6 thread. I've never seen a SB with that. Maybe it was a custom....

    There are tons of backing plates on Ebay for under $75...if you can use the 2-1/4 x 8.

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    Quote Originally Posted by GregSY View Post
    Post the literature that shows a 2-1/4 x 6 thread. I've never seen a SB with that. Maybe it was a custom....

    There are tons of backing plates on Ebay for under $75...if you can use the 2-1/4 x 8.


    Catalog right on the forum makes no bones about it - 2 1/4 - 6 on the 14 1/2

    http://www.wswells.com/data/catalog/1948-cat-100-G.pdf

    See catalog page 15

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    Well you and John are certainly correct. I would have lost that bet. You might try on the SB forum and see if anyone has one, although most people don't leave a lot of back plates laying around but you never know. Did you hear back from 9100? Might be your best bet to consider his kind offer to thread it for you. After that it's not difficult to finish it off.

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    I seem to remember the old LeBlonde Regals liked to use 6 tpi for the spindle thread.

    -Doozer

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    Iusually just thread an appropriate size piece of round stock. in your case 3" or a little less. Then put into the right sized hole in a 1/2 or 3/4 plate .Weld it in and face the front back off to clean up.I can come up with those size pieces easier than a 6" diameter piece to do it all from. Usually have to get rid of first two threads to get it to hit the shoulder.


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