Machining question

[M-61]

Is the machining of interrupted threads a difficult or overly complicated task?

 

[DShortt]

If you don't understand basic threading operations then yes.

What is your skill level or are you 'asking for a friend'?

 

[Walt Krafft]

Depending on the rigidity of your lathe, it could be best to cut the interuption after the thread.

 

[M-61]

If you don't understand basic threading operations then yes.

What is your skill level or are you 'asking for a friend'?

Absolutely not asking for a friend.
I have an idea which involves interrupted threads. Before I proceeded I wanted to know if this machining operation was unusual or difficult for a machinist.

 

[paperpuncher]

I’ve never done it but just spitballing. I think I would cut the male and female parts normally Assemble the two parts and time them to fit your needs Mark both parts so that you can index them in the milling machine I would use a rotary chuck and mill the appropriate relief to achieve your objectives IIRC there may be a section in the machinery’s handbook that covers it but not 100% on that

 

[dave@aDave]

It may be more complicated that what it seems at first thought:

Question regarding interrupted threads

Does anyone know how to time and cut an interrupted thread (ACME or buttress) with manual lathes or mills? I would like to start collecting the fixtures and tooling for cutting interrupted threads for a few gun-related projects. I would like to make bolts/receivers with interrupted threads for...

www.practicalmachinist.com

There is a strength problem:

Interrupted screw - Wikipedia

en.wikipedia.org

Which was addressed by the stepped thread:

Welin breech block - Wikipedia

en.wikipedia.org

There may be more than one (1) thread.
I believe a buttress thread is commonly used.
Buttress threads are located in the 30th edition of Machinery's Handbook on page 1997.

 

[Old Navy]

Absolutely not asking for a friend.
I have an idea which involves interrupted threads. Before I proceeded I wanted to know if this machining operation was unusual or difficult for a machinist.

You thinking of building a really big riflw?

 

[jackieschmidt]

It is easy.

you have a lock on your carriage. Tighten it to where you have some resistance to the carriage Movement. This will keep the half nut loaded against the lead screw so it can’t jump forward.

You will have to judge how tight, kinda like Goldilocks. Not too tight, not too loose, but just right.

I assume you are talking about something like this

Is the machining of interrupted threads a difficult or overly complicated task?

 

[ckaberna]

Is the machining of interrupted threads a difficult or overly complicated task?

Why?

 

[dave@aDave]

Stepped threads or more than one thread would add some tension to the job

 

[M-61]

It is easy.

you have a lock on your carriage. Tighten it to where you have some resistance to the carriage Movement. This will keep the half nut loaded against the lead screw so it can’t jump forward.

You will have to judge how tight, kinda like Goldilocks. Not too tight, not too loose, but just right.

I assume you are talking about something like thisView attachment 1511237

Yes, but a bit smaller.
I want covert a press I have to accept “Lee’s
Breech loading dies as they call them .
You got it right and that pic is some breech.
My real purpose was trying to find out if it’s something a machinist would have problems doing, meaning ratting up a lot of time or just a pain in the ass. There’s a load of machinists were I live. Mostly subcontractors for the Electric Boat Company . Known them for decades. They like to swap work rather than money with me. I didn’t want them to short themself as they tend to do.
I had/ have no idea how hard this is.

 

[M-61]

Why?

Didn’t know I had to have reason to ask a question but I don’t know you at all. I don’t take orders from anyone but I’ll try to be nice.
I know some machinists.
We’ve swapped work over the years.
Most the time it’s a swap.
I wanted ‘nicely ’ to ask if this jobs tricky.
Because if it is I wanted to be sure to pay the right amount. I don’t want him to short himself.
Satisfied?
You’ll never get that from me again

 

[WSnyder]

I’d do like suggested above. Run the threads and machine away the threads you don’t want in a rotary on the mill.

 

[ckaberna]

Didn’t know I had to have reason to ask a question but I don’t know you at all. I don’t take orders from anyone but I’ll try to be nice.
I know some machinists.
We’ve swapped work over the years.
Most the time it’s a swap.
I wanted ‘nicely ’ to ask if this jobs tricky.
Because if it is I wanted to be sure to pay the right amount. I don’t want him to short himself.
Satisfied?
You’ll never get that from me again

Sorry my question rubbed you the wrong way. Won’t ever hear from me again.

 

[BobT]

It's more difficult than a continuous thread and depending on available equipment may involve a pretty complex setup. If a CNC mill with thread milling capabilities is available then it's not a big deal.

 

[wvlongshot]

Looks like lee sells that bushing to convert a press over to the breech lock. If you have press that has reducer bushing in top just switch it out. If not bore and thread press for said bushing, not bad at all. Think it is 1 1/4 x 12 thread.