BA die rod sizes

[minime]

Hi,

I've been playing with toy steam for awhile and have now started to do some repairs on some of my engines. Has anyone got a list of the required finished material sizes for BA dies, eg, is 3BA 5/32" etc.

Thanks

Chris

 

[mklotz]

Attached is a chart from my archives that probably contains more than you ever wanted to know about BA threads.

View attachment THREADBA.TXT

 

[CrewCab]

Welcome to the forum Chris ............ is This of any help.

CC

 

[minime]

Thank you, to both of you, , that's exactly what I need. How close do those tolerance's need to be? I've only got a vernier caliper at the moment, do I need to get a micrometer to use if I'm using a hand cutting die rather than cutting the thread on the lathe (lack of knowledge, .

Cheers

Chris

 

[wareagle]

Chris, welcome to the forum. Take a moment and introduce yourself in the Welcome section. Not everyone reads all of these posts!

Are you chasing threads, or making new fasteners? Sizes, etc? Calipers are not a close tolerance measurement tool. If it has to be "on", then you will need a micrometer. Depending on how I angle, twist, alter pressure, etc., I can see differences approximately .005" with my digital calipers on the same item. Probably could get more with some persuasion! This is not to say you need to run out now and buy a new set of mics! You might be fine with what you have.

 

[minime]

Wareagle wrote

Are you chasing threads, or making new fasteners? Sizes, etc? Calipers are not a close tolerance measurement tool. If it has to be "on", then you will need a micrometer. Depending on how I angle, twist, alter pressure, etc., I can see differences approximately .005" with my digital calipers on the same item. Probably could get more with some persuasion! This is not to say you need to run out now and buy a new set of mics! You might be fine with what you have.

Again, thanks for your advice, I don't generally have fine tolerances to worry about, I'm only repairing/ making new parts for my and other peoples toy steam engines.

Eg, currently I'm making a small wide topped screw, out of brass, to blank off an existing BA3 threaded collar in a toy steam boiler (14psi type). The threading doesn't seem to be going well, even though I've changed the OD of the brass a few .0001 each time. I'm now wondering if its the cheap set of BA taps & dies I bought, lack of tolerance in my cutting or the threads of the die I'm using blocking up. I do use a cutting/threading compound, but the thread on the last two I tried to make, simply got chewed up each time.

I have a high quality 3BA die on order, but an wondering if it's me or the cheap die.

Cheers

Chris

 

[Maryak]

Change of Pace,

Help please

How do I place a video in a post? ??? ??? ???

Regards
Bob

 

[tel]

Wareagle wrote

Again, thanks for your advice, I don't generally have fine tolerances to worry about, I'm only repairing/ making new parts for my and other peoples toy steam engines.

Eg, currently I'm making a small wide topped screw, out of brass, to blank off an existing BA3 threaded collar in a toy steam boiler (14psi type). The threading doesn't seem to be going well, even though I've changed the OD of the brass a few .0001 each time. I'm now wondering if its the cheap set of BA taps & dies I bought, lack of tolerance in my cutting or the threads of the die I'm using blocking up. I do use a cutting/threading compound, but the thread on the last two I tried to make, simply got chewed up each time.

I have a high quality 3BA die on order, but an wondering if it's me or the cheap die.

Cheers

Chris

Try threading your brass dry, for a start, and it might help if you turn down a little bit of the end to the minor diameter (tapping drill size) to give your die a true start. 'arf turn forward, quarter turn back and you should have no problems.

 

[Bluechip]

Hi Chris

Possibly a silly question, but ..

Have you got the die adjusted in the diestock OK.

They'll cut very undersize on some dies/holders if not.

Dave