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1937 south bend lathe threading dial question

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  • 1937 south bend lathe threading dial question

    hi guys, i just picked up my first lathe and after some searching with serial numbers on the net and came up with 1937 south bend 9''. it does not have a threading dial and was told i needed one for threading. i see where i can buy one on ebay but am not sure whats involved in installing. is this a difficult process? i am new so can't add a pic of the machine as of yet. any info would be great pete

  • #2
    Threading dials are not required for threading but for those pitches where they do work they may be helpful. The Grizzly lathe I bought new had no option for a thread dial so I made one. Later I adapted a dial from a similar lathe. I've used it about 10% of the time as I've grown accustomed to leaving the half-nuts engaged and reversing the carriage to the beginning of the cut.

    When I made one I researched the subject at this forum and also at practical machinist and found excellent examples that can easily be reproduced.

    There is a thread here that is a good introduction to thread dials, what they can do, and how they work or don't.
    Last edited by dp; 10-20-2014, 12:14 PM.


    • #3
      What dp said is correct about not needing one if you do not dis-engage the nut during threading.
      Pulling the tool bit out and reversing the lathe is really good practice for a beginner.
      It is especially important for odd threads or metric for example on many lathes.
      You didn't mention if you had a quick change gear box (QC) or loose change gears ?
      Since your feed screw is 8 threads per inch , any multiple of that does not require you to need a thread dial.
      For example , if your gears give a 3 to 1 reduction (total) , That times 8 equals a 24 thread pitch regardless of engagement.
      So the easy threads you can do are 8,16,24,32,40,48
      Everything else requires a dial or using dp's method

      hope this helps
      Congratulations on having a fun machine



      • #4
        thanks dp & rich . so much to learn. just picked this thing up a week ago after a month of run around from the seller. i've only used a lathe a few times to make bosses so just simple drilling and then chucking up a tap in the tail stock and letting it slide on the bed for tapping so im very very green and hope to pick up some very much need knowledge from all the members here. i've just completed a full clean up,lube,paint job and am very proud to own. wasn't used in the past 18 years as the owner passed away . i only payed $275 and has some tooling but am missing some too i think,dog plate etc but gonna go back and look around to see if i can locate. i'd like to post pics but don't have clearance from the mods yet. maybe it won't be too long ???? no quick change but i do have a stack of change gears leeding to more questions. i think normal would be 13 but i have way more then that pete


        • #5
          Hi Pete
          You can post pictures, but they have to be hosted at another site, see:


          • #6
            thanks for the heads up richr . seems pretty complicated for me to upload pics. im on another forum as im a welder so anyone wanting to see what i started is welcome and i will be uploading pics of my new paint job pete


            • #7
              Not sure if its original, but if so, looks like youve got a floor pedestal mounted countershaft. Cool.

              Your lathe probably didnt originally have a threading dial originally, but theyre not difficult to add. Depending on your abilities, you could likely even make your own.
              "I am, and ever will be, a white-socks, pocket-protector, nerdy engineer -- born under the second law of thermodynamics, steeped in the steam tables, in love with free-body diagrams, transformed by Laplace, and propelled by compressible flow."


              • #8
                As mentioned, if you keep the half nuts engaged and run the lathe in reverse to return to your starting point, you can get by without a threading dial. Or, if the tpi is a multiple of the leadscrew pitch (proably 8 tpi, thus 8, 16, 24, 32, 40 are not a problem, you can freely disengage and re-engage the halfnuts as you wish.

                When I first got my lathe I got by for a few years without a threading dial. Except for threading up to a shoulder, when one typically wants to disengage the half nuts to keep from crashing the toolbit, it's not a big deal. I eventually got a threading dial, and it's more convenient and a bit faster.

                I think there have been articles in Home Shop Machininst about making your own, or try
                Try to make a living, not a killing. -- Utah Phillips
                Don't believe everything you know. -- Bumper sticker
                Everybody is ignorant, only on different subjects. -- Will Rogers
                There are lots of people who mistake their imagination for their memory. - Josh Billings
                Law of Logical Argument - Anything is possible if you don't know what you are talking about.
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                • #9
                  The reversal technique works fine.

                  It does nearly double the wear on leadscrew and halfnuts.

                  A threading dial is easily made, and works fine.

                  Keep eye on ball.
                  Hashim Khan


                  • #10
                    As has been mentioned already, you don't NEED one. And if you WANT one there are lots of examples and plans floating about for these things. If you decide to just buy one, this is one of any number of sources (no connection to me...)for one that may fit your machine:


                    Welcome to the forum!


                    • #11
                      Here's a great video that shows the thread being cut with the half-nuts locked. The tool is backed out and the machine is reversed to the beginning. That way the next cut always starts in the right place. The thread dial allows opening the half-nuts and using the carriage traverse to relocate to the beginning of the cut while ensuring the start of cut is correctly positioned.



                      • #12
                        Threading up to a shoulder really sucks with the locked half-nuts method, on a lathe like the SB9 that doesn't have a brake.

                        My SB9 didn't have a dial either; I attached one from another brand lathe, I think an Atlas. It was only about $20 on ebay; the South Bend dials go for way too much money, unless you just really have to have original parts.


                        • #13
                          My solution for threading to a shoulder so far has been to not do that . It really is a problem but doesn't come up much.


                          • #14
                            My method of threading to a shoulder on my old Drummond lathe is to stop the lathe and cut the last turn or so by manually turning the chuck. It is a clumsy process and requires me to disengage the back gear otherwise turning the chuck is too hard with the drag of the motor etc.


                            • #15
                              Look at the picture in this thread:

                              If you look on the right hand side of the carriage you'll see a post sticking out just above the lead screw. That's where the threading dial attaches. The post is held into the carriage with a set screw; the thread dial slides on the post and is held with another set screw. I couldn't see in your picture if yours has the hole and set screw or not.

                              If you need a better picture, let me know.

                              Edit - Look at the FIRST picture. I forgot that Doozer had added some pictures later.
                              Last edited by browne92; 10-22-2014, 10:34 AM.
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