I was recently asked by a friend of how I cut the thread in my sanding disc(s) that I use on my lathe
The fact that he had to ask made me realise there may be squillions of people out there postulating a similar conundrum,... if only they had bothered to come visiting me in my workshop and looked at my lathe when I have the disc mounted… just don’t leave your wallet behind.
My spindle is a M33 x 3.5RH thread, but I do recommend you use your own spindle’s specs.
The first step was to centre an appropriate block (with a backing piece),
more so to protect my bit and the chuck rather than blowout… though lack thereof is a bonus, and drill a 1 3/16” hole through it on my lathe,
Then using the appropriate tap, not…
which has a hole/dimple in the end
to accept a live (or dead if you don’t mind friction) centre so it can be loaded up using the lathe. You can then tap using a spanner and slow turning/advancing the handwheel in sync with the spanner’s rhythm
Advance it as far as you can without cutting steel (chuck) and then finish off, off the lathe, on a vise
with a bit of elbow grease.
Now normally I would attach this type of mounting plate to the disc, drill and tap them both in one piece and not be concerned about the hole in the middle as you would never (or should never) use that part for actual sanding... From a previous post (on LJ):
end of copy.
I would then mount on a dedicated lathe attachment to round it off to ensure it is dead centre,
Don’t like working too close to the head stock.
Now before yazall rush out and spend your meager shekels, the tap and a dedicated forstner bit (also with a hole/dimple in its tail)
that I purchased off the Bell Tool Coy… who I’ve just been informed has been sold to Lee Valley. Currently the parts are not available on their site, but I have been informed that they will sell it and I have a query with Lee Valley about availability of Beall items.
This method is great for making jam chucks... and I don't mean tossing one of these, over the neigbours fence... sorry for the wrong picture... I'm not a sweet person!
And again, this is not a REVIEW!
If your first cut is too short... Take the second cut from the longer end... LBD