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RE: [southbend10k] Quick Change Gear Box Install

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  • Neal Winblad
    I ve been doing the Model A conversion to my 9 Workshop lathe. Yes, you need to shorten the leadscrew at the headstock end. And, it requires a new threading
    Message 1 of 2 , Oct 31, 2005

      I’ve been doing the Model A conversion to my 9” Workshop lathe. Yes, you need to shorten the leadscrew at the headstock end. And, it requires a new threading of the end you just cut off. Here’s the dilemma: you have the leadscrew off the lathe and chucked up in order to shorten it, so you can’t cut threads. You could use a die and put the threads on, but I took the easy way out and bought one of the right size on eBay.


      You also will need a 20 tooth 18 pitch stud gear. And, if you didn’t get them with your QC gearbox purchase you also will need a 56 tooth and a 40 tooth change gear. The 56 tooth drives the leadscrew

       And the 40 tooth is stored next to the 56 on the leadscrew until you need to use it as the stud gear if you are cutting threads from 4 to 7 tpi.


      You also need to drill another hole in the ways for the third screw on the QC box. The old arrangement had two screws about two inches apart. You need to drill a new one about four inched toward the tailstock and then counterbore it to hold the third mounting screw.


      Also order some felt from McMaster Carr, cuz when you take apart the gearbox to clean it you will probably mess up the ones that are there (there are five or six felts on the various shafts and holes).


      I recommend taking the whole gearbox to an auto machine shop and have them dip it in degreaser for a few hours, then it’s not so messy to work with.


      I didn’t turn new shafts for the gears and there is some wear and looseness which causes a lot of noise, so I still have to take it all apart again and turn new shafts or put in new bronze bearings so there is no slop. That part will be a fair amount of work, so I am putting it off until winter when I can’t be working on the house outside (too many projects!).


      There is a guy on eBay that sell replications of the plate that lists all the threads and settings of the two levers if you need a new one. I just got my plate from him today and it looks great (like new…since it is).


      Good luck and let me know if you have more questions.






      -----Original Message-----
      From: southbend10k@yahoogroups.com [mailto:southbend10k@yahoogroups.com] On Behalf Of arnoldre298
      Monday, October 31, 2005 9:49 AM
      To: southbend10k@yahoogroups.com
      Subject: [southbend10k] Quick Change Gear Box Install


      Dear Group:

      I recently purchased a QC gear box to install on my manual South Bend
      lathe. Can anyone in the group give me quidance to how this is done?
      Does the leadscrew have to be altered in length? Is there any source
      which demonstrates this installation? Thanks for your help. Arnold

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