Use of a 50 degree faced tool?

[twooldvolvos]

My village has a not-for-profit tool store where all inventory is donated and the proceeds go to support our senior citizens. Since I have started learning to use a lathe, I have enjoyed looking at the machining tools that come into the store with some regularity. A few weeks ago I picked up this HSS tool for a buck: I know that thread cutting tools typically have a 60 degree face but what would be the use of this 50 degree face?

 

[mmcmdl]

General turning as the angle isn't important and you could grind it to a threading tool very easily if wanted . I have to turn mandrals with plastic extruded between steel shoulders . I use such a tool but still , the angle is not important . Just more of a clearance thing .

 

[Illinoyance]

You can re-grind it to any shape that pleases you.

 

[Jim F]

Sure it is not 55 for Whitworth ?

 

[Tozguy]

How did you measure the angle?

As is it could be used to cut 60 deg threads using the compound feeding at 30 deg.

 

[twooldvolvos]

Sure it is not 55 for Whitworth ?

Yep. Measured it more than once.

 

[twooldvolvos]

How did you measure the angle?

As is it could be used to cut 60 deg threads using the compound feeding at 30 deg.

I used a machinist's protractor. It makes sense that it is a little less than 60 because it was sloppy in a 60 deg gauge. BTW, I tried turning with it and it was next to impossible to get a smooth finish with a point that sharp.

 

[mmcmdl]

Stone a radius on the tip . In my case , I'm only turning clearance on a mandral .010 below metal surfaces . Finish is not an issue as the plastic is just a support , and a sharp tip reduces chatter on the piece . The " work " is performed on the metal journals where the chuck jaws are located . A part is fitted over this mandral and cnc slitting saws cut the log into various sizes as needed by the customer . Neat idea they came up with also .