Lathe spindle nose thread

I am trying to positively identify the spindle nose thread form for my Murad Antarctica lathe.

It's 1 3/8'' diameter x 10 tpi.

I have tried Measuring the angle with both 55° and 60° thread cutting tools but without grinding the tip of the tool off it's difficult to judge the angle accurately.

I first thought it to be 55° whitworth form however this does not seem to be a standard size. Can anyone advise?

I would almost guarantee that being a UK based manufacturer, it would be 55 degrees.

At the sort of sizes you are talking about, almost anything goes, they would use whatever size and thread combination that would get the job done, no thought about interchangeability with other makes at all.

But to put your mind at rest, Boxford threaded items, at 55 degrees angle, fitted perfectly well on my Atlas (US built) lathe spindle at the same size and pitch, but cut at 60 degrees.

John

Mine too but I did give the thread on the backplate a light skim to make sure the chuck is located on the register and not the thread.

Russell.

Cut an internal thread using a lump of Delrin or Aluminium and see how well it fits

Using the 55 and the 60 tools

Only takes about 5 mins with a soft material

Had a quick look at one on lathes.co.uk and it just screams "atlas lathe!"

Edited By Ady1 on 27/03/2012 11:04:33

How about filing a bit of aluminium sheet to 55 and holding it against the thread. Although the wrong thread may fit it will be stressing the tips of the thread and may not ragiter correctly.

Hi

several points

1. Hold a strip of card or shim at the side of your screw cutting tool this will make the tool wider with a flatish end, and allow you to see which fits best, without grinding the end off the toolbit.
2. Buy some thread pitch gauges you will always use them. need 55Deg for BSW BSF ME etc, 60 deg for UNC-UNF. plus Metic and BA
3. By standard size I assume you are comparing with fasners nuts and bolts. When it comes to non fasners designers use TPI and Dia to suit the application. It becomes standard tothat product and sonetimes it gets documented in a national standard other times it doesnt.

Steve Larner

Thanks to you all for the responses.

After further careful measuring under a magnifying glass and a strong light it does seem to be a 55° thread form.

I shall be machining a test thread on a piece of aluminium before I machine the face plate I have obtained for the lathe.