Left hand thread nut for Pinnacle Bench Grinder

I have a Pinnacle 6" bench grinder, bought around the early 1980's and I've lost the left hand threaded end retainer nut. Does anyone know what the thread is? Looks coarse, measures 13mm - but I wonder if it might be imperial. The thread on the shaft is 18mm long (7/10th inch) and over than length I count 9 thread ridges. Any ideas?

Possibly 1/2" Whit which is 12 TPI roughly 2mm crest to crest.

John

Two wheels? If so, remove the other side and check that?

Measure again carefully. Likely to have been built for the American market where UNC 1/2 in has 13tpi.

If the thread diameter is 1/2 inch I would bet the thread is 1/2-20. I have never seen a coarse thread on a bench grinder. No experience with bench grinders made to metric standards.

Just a rain check.

(7/10th inch) and over than length I count 9 thread ridges

How many valleys? Wondering here whether first ridge counted was number zero.

Edited By not done it yet on 12/06/2017 06:32:44

Can you use a bolt of known pitch to check the pitch of your threads? Do you have a friend with thread pitch gauges?

Hi John,

You could be right there. I got a gauge which only goes down to 13 TPI - it's close but I think 12 would nail it.

Thanks for all the responses. Next Question - bearings are a bit dry. Should I attempt to pack with grease, straight 30 SAE oil, heavier oil (EP90) - or does it not really matter.