This is something I have wanted to do for a long time. Now it’s a relatively simple process.
I saw a lot of ideas on youtube and thanks to Brian Brooks I came up with a similar but different idea.
I used my Nova 3000 lathe and accessories as a solid base for the jig.
The jig is in 2 parts. Part 1 is a router support & part 2 holds the work piece & moves an a X and Y axis.
At the left hand end I used my large bowl jaw set to hold the back of the router.
The front of the router is supported by a lathe steady bolted to the lathe bed.
It has a plywood piece screwed to it to attach the router.
The lathe centre was critical as an axis for the whole jig.
Part 2, the component that holds the chuck
This is also aligned to the lathe turning centre.
A M30 threaded rod was cut to length. This forms the basis for the thread and is the right size and thread for the chuck.
I tapped 3 1/4” threads in one of the nuts and turned up some handles to rotate the chuck into the router bit.
The router bit is an Enco 3/4” 60 degree included angle high speed steel double angle cutter. The same used by Brian Brooks.
for the back and forth axis I used 1/4” threaded rod fitted to an old umbrella winding handle (pays not to throw some things out).
The tool rest and a clamp helps support the front of the jig.
Note the m30 nut fitted into the jig. That controls the sideways axis and mimics the thread on the work piece.
The locking bar off the tailstock was fitted to a piece of angled steel as a back support.
And here is the result
Pretty neat even if I say so myself.
I am yet to do an internal thread but I don’t see there will be an issue.
Now for screw top lidded boxes. Even nuts and bolts, who knows.
Thanks for looking
Here is Brian Brooks’ jig