Tailstock thread help

[molyknow]

Hey all!

First off, happy holidays. The other day when using my lathe my tailstock seemed to stop working. Upon dissection I have found the acme thread on the quill to be stripped. I found the following thread on practical machinist.

https://www.practicalmachinist.com/vb/south-bend-lathes/tailstock-quill-nut-stripped-201513/

One user mentions boring out the stripped threads and replacing it with a threaded bronze bushing. I think i will end up going down this path but wanted to get others opinions on it.
Also just as an aside if anyone would be willing to make said bushing I would be happy to get you a technical drawing, but basically I need a bronze bushing with an OD of .8750 with a through hole that has been drilled and tapped to ACME 1/2 -10 LH.
Unfortunately as Holbrook lathe are a little more niche replacement parts are hard to come by.
Thanks in advance,

alex

 

[John Conroy]

When I needed acme nuts for my mill I bought them from Roton. They list a acme LH 10 bronze nut with OD .875 for $21 USD. They shipped my stuff to Alberta with no hassle. Great to deal with.

https://www.roton.com/family/acme-left-screws-and-nuts-7159284/

 

[molyknow]

oh amazing! I’m gonna order one ASAP! Thank you!!!

 

[YYCHM]

Why an OD of .8750?

 

[PeterT]

Dumb question before you order but is it a reverse thread? My 14x40 is likely different mechanism but I think most lathes are screw handle clockwise = quill extends towards headstock.

 

[John Conroy]

Yes it should be left hand thread. Turning the handle clockwise pushes the quill out. The nut in the picture is left hand. You can also buy acme lead screw from them but I was able to get my lead screw at the Bolt Supply House locally to save the shipping charge. It was 1.25" left hand thread acme.

 

[YYCHM]

Dumb question before you order but is it a reverse thread? My 14x40 is likely different mechanism but I think most lathes are screw handle clockwise = quill extends towards headstock.

My (9" Utilathe) turns clockwise to extend towards the headstock. The quill bore thread is Acme 1/2"-10 LH.

 

[Tom Kitta]

Bolt supply house has acme thread? Wow, did not know that! Good to know. I am going to replace worn out acme screws. My choice was Macmaster Carr but saving on shipping is good. Now I can add Roton to the list!

 

[John Conroy]

They had to order it Tom but it took less than a week and was around $80 for a 3 foot piece of 1.25" left hand thread acme shaft. They couldnt supply the bronze nuts so I got them from Roton.

 

[John Conroy]

I documented the machining of the nuts and shaft here.

https://canadianhobbymetalworkers.c...10-x-50-mill-brought-back-to-life.1053/page-2

 

[RobinHood]

Calgary Fasteners can also order in ACME rod and brass nuts.

https://www.calfast.com/16681_0-rod-acme-12-10-x-36-plain.html?search_query=Acme+rod&results=15

This one is probably a RH one. Better quality and LH ones should be available.

 

[molyknow]

Hey all just wanted to update and close this thread out. Hopefully it can help someone in the future. I ordered the nut from roton as john recommended, bored out the old one, pressed the new one in and drilled and tapped some holes for 8-32 screws. I have reinstalled it and everything is working lovely.

Thanks everyone for your help!

 

[John Conroy]

Nice work Alex. Better than new probably.

 

[molyknow]

Nice work Alex. Better than new probably.

Thanks! Honestly this has been the first part that I have made where tolerances actually mattered, but I took my time, set everything up and indicated everything I could think of and it came out great... now I’m itching for more

 

[RobinHood]

Good job.

 

[Hruul]

That is awesome. Congrats.