Blunt start and END threads

[SMT]

How would you do the end? I get the start part.

The only thing I can think of is run the exact same thread cycle a second time but play with the end point to get it to cut out the end thread and blunt it.

Yay? Nay?

Go be a greater at Walmart?

 

[pgmrmike]

Have to start in thread relief and feed out. I dont know of a way to do it without trial and error. Adjust start point for timing and end point to get full thread

 

[DDoug]

Doo you mean a "Higbee thread detail" ?

 

[litlerob1]

As Doug asked...I'm sure that's what he means though.

I use a Grooving tool and a Threading cycle. But no way around it, it takes some try and do.

R

 

[Vancbiker]

I get the blunt start or "higbee" need. What's the point of a blunt end other than to drive up the cost of the part? Something screw on from both directions??

 

[pgmrmike]

I get the blunt start or "higbee" need. What's the point of a blunt end other than to drive up the cost of the part? Something screw on from both directions??

A company I worked for is an oil tool OEM. They assemble, run, disassemble, clean then reasseble some tools repeatedly. The engineers didnt typically call out the angle going from thread OD to thread relief. The manual guys would cut it square, then thread. The problem was that it left a thin feathered weak thread at the end that was easily bent over. When they torqued or unscrewed the bent thread would ruin the threads on the way out. It wasnt unusual to literally friction weld them together unintentionally. So the "solution" was to required higbee at the finish also. It took a while but I finally convinced them to allow me to just lead in at 45 degrees and omit the higbee ( I was the programmer ) This eliminated the weak feathered thread.

( actually I did this for quite a while before it was approved and nobody ever even noticed.. )

 

[Vancbiker]

I guess I can see that. I did some training on API threads with higbee start for drilling tools for a customer. The female thread was always relieved back from the face far enough that an imperfect thread near the relief on the male never touched anything therefore no need for any special treatment of the end of the thread.

 

[pgmrmike]

I guess I can see that. I did some training on API threads with higbee start for drilling tools for a customer. The female thread was always relieved back from the face far enough that an imperfect thread near the relief on the male never touched anything therefore no need for any special treatment of the end of the thread.

Yes sir. In my instance I am talking about Acme and Stub Acme. ( the tools themselves were assembled using stub acme and acme but the connections to drill stem was API ) I did work for one shop that would higbee some API pins but not boxes. I do remember some Baker API threads ( dont remember which ) had a large "thread relief" they called a "bore back". I guess everyone has their own idea of what should be done.

 

[litlerob1]

And if a person is in production, using live Tools is an easy way, especially if you have Y.

R

 

[SMT]

Doo you mean a "Higbee thread detail" ?

Yes. I think Higbee is a generic term. All the prints I've ever seen call it out as a blunt start.

A company I worked for is an oil tool OEM. They assemble, run, disassemble, clean then reasseble some tools repeatedly. The engineers didnt typically call out the angle going from thread OD to thread relief. The manual guys would cut it square, then thread. The problem was that it left a thin feathered weak thread at the end that was easily bent over. When they torqued or unscrewed the bent thread would ruin the threads on the way out. It wasnt unusual to literally friction weld them together unintentionally. So the "solution" was to required higbee at the finish also. It took a while but I finally convinced them to allow me to just lead in at 45 degrees and omit the higbee ( I was the programmer ) This eliminated the weak feathered thread.

( actually I did this for quite a while before it was approved and nobody ever even noticed.. )

I suspect this is the exact reason this part has the end of the thread called out as Blunt.

And if a person is in production, using live Tools is an easy way, especially if you have Y.

R

Unfortunately no access to the end of the thread with a cutter in the axial direction. I guess I could do it with a radial tool but it might look a little weird, with the radius of the tool still showing on the thread. I could ball mill profile it I guess but I feel like that would be getting a little crazy.

I think I am down to calculating the angle the thread exits at and try to blunt it from there using a groove tool. I really hate trial and error. I mean, we're machinists not guess-chinitsts

 

[litlerob1]

Unfortunately no access to the end of the thread with a cutter in the axial direction. I guess I could do it with a radial tool but it might look a little weird, with the radius of the tool still showing on the thread. I could ball mill profile it I guess but I feel like that would be getting a little crazy.

Use a key seat cutter, Parallel to the Spindle.. Or Perpendicular to the Spindle, just ramp off with a flat Endmill a tiny bit greater than the width of the Pitch. It's already a gay requirement, might as well help them out with it. A tiny Concave on an vanishing Thread (incomplete Thread) isn't going to show up much. Use C and Y simultaneously, and it's barely even perceptible.

R

R