View Full Version : Metal Lathes cutting a custom lathe spindle to Supernova body threading

Brad Whitham
04-27-2016, 11:42 AM
I have a great 60-70 year-old Walker Turner mechanical variable speed 36" x 12" inboard/outboard wood lathe that I love except for the fact that the old spindle has always had a bit of annoying run out, and though I rebuilt the head with new bearings a few years back, it didn't help the issue much.

Now that I'm not (quite) a poor as I used to be and going to be using the wood lathe more often, I've decided to collect a full set of Teknatool Supernova chuck bodies so I don't have to change the four jaws every time I have a different diameter work piece to work on. This has sparked an idea: I'm thinking of machining my own 1" spindle for the WT with the mating chuck threads single-point turned into the spindle itself, as opposed to using one of the Nova inserts that the company provides to adapt different brand lathes to their chuck bodies. I also have a South Bend 9C that should easily handle this spindle project once I'm past the learning curve working on practice mockups made from some scrap AL alloy stock I've got lying around.

My questions are:
1) What specific material do you think is best to turn the spindle from?
2) Has anyone here gone so far as to actually single-point Teknatool's proprietary chuck threading to eliminate the need for an adapter?
3) should I just scrap the custom thread idea and go with 1-1/4" by 8 TPI?

In a perfect world, I'd like to be able to spin on and off these chucks at will without any fuss. Thanks in advance for any help!

Bill George
04-27-2016, 7:29 PM
As a hobbyist who started with a SB Heavy 10 and did what was needed to make it accurate again and then graduated to other lathes I can say the turning and doing it accurately is one thing and I can do that well. Threading on a lathe takes lots of skill and practice. So you get your perfect project done except for the threading.... that's where the real test begins. Ok, there will be lots of people jumping in and say its a piece of cake, ok... but how many years did it take? I use my current lathe about 2 times a year, and its not for threading. External threading, buy a set of dies and make a holder for your tailstock or buy one. That's what I do.

Bruce Page
04-27-2016, 8:07 PM
As a retired machinist, chasing threads is not a big deal and produces a much better thread than a die. Just do some practicing if you are inexperienced or rusty. You can even practice on some wood dowel material, or thick wall plastic pipe, your lathe doesn't care.

As far as what material to use, almost any medium carbon steel like AISI 1029-1053, 1137-1151, and 1541-1552 would be a suitable material for a lathe spindle and can also be heat treated.

David Bassett
04-28-2016, 2:31 PM
Before you spend too much time on this, find out what threads are "native". IIRC- they are metric. The (few) metal lathes I've seen don't do threading, do imperial threads naturally, or do metric threads naturally. I'll assume you wouldn't consider this if you weren't set up to thread at all, but doing metric threads on an imperial lathe has always been either impossible or required fairly heroic measures. Good luck.

Richard Casey
05-02-2016, 9:44 AM
Brad, there are lots of ways to do this with various pitfalls. 1 inch is not much of a spindle, can you upgrade the bearings and pulley to 1 1/4 inch?, much stronger. If you have the skills, make it yourself, but a good machine shop should not cost that much. I built my own lathe, threaded the spindle in Metric to suit the Vicmark chucks without inserts I had at the time, sure simplified working. The other feature I added, seeing I started from scratch was to bore the morse taper hole so that I could leave the chuck on and open the jaws up to insert a 4 prong drive dog that stood proud of the jaws.
Hope this helps,

Dennis Ford
05-06-2016, 9:28 AM
I made my lathe and the spindle was not terribly difficult. I am not a machinist but have learned how to use a lathe. Your South Bend will cut imperial threads like 1-1/4 x 8tpi without much trouble, just watch U-tube videos and practice a few times. Drilling, boring and reaming the taper was more trouble than the threading for me.
I used steel made for hydraulic cylinder rods, forgot the ID number. 4140 steel would be great also.