Cut, Crown, and Thread

[L1A1Rocker]

One of my on going projects is a Form 1 SBR in 300BLK. I made a custom break (or is that brake?) that will also be used as a QA/QD point for a silencer (another of my on going Form 1 projects). Anyhow, I wanted the brake to just tuck in the handgards. But that meant a custom length barrel. Sooo, I finally got off my duff and chopped off three inches from a 10.5 barrel I've had waiting for this project.







Next step is to parkerize the brake and the exposed metal on the barrel.

 

[Brad]

I hate to be "that guy" but no photos of the work in progress? I love that stuff. The set up, the tooling, all that.
You know, the guy stuff.

And how loud is that gonna be next to you at the bench without the silencer? Short barrel, large brake. Looks loud to me.

 

[minmax]

Great job!!!!

I wish I had been exposed to macining and metal work gowing up. I'd love to have the knowledge and tools to do cool stuff like that.
My mom did't want me to be a factory rat. Even though I have great mechanical aptitude.

 

[smokeywolf]

Nice work sir. What material used for your brake? Did you single point the internal thread on it? External thread on brake; am I seeing a double start?

If your fits are as good as your finishes you're obviously a "class A" machinist.

 

[L1A1Rocker]

I hate to be "that guy" but no photos of the work in progress? I love that stuff. The set up, the tooling, all that.
You know, the guy stuff.

And how loud is that gonna be next to you at the bench without the silencer? Short barrel, large brake. Looks loud to me.

Sorry, I really hadn't planned on posting this so I didn't take any "during" pictures. I normally do, and have a number of pics on making the brake.

Loud? I might be. The 300Blk takes well to a short barrel so it shouldn't be anything outrageous - like say, a 10in 556. . . I actually stole design aspects I liked from three different brakes. Mostly I was influenced by the Rolling Thunder brake by Benny Hill. It has been very successful in 3-gun competitions. In addition to the side ports, there is a top port, and a very small port on the right hand side. This is all designed to keep the muzzle on target during recoil. We shall see how it works . . .

 

[L1A1Rocker]

Great job!!!!

I wish I had been exposed to macining and metal work gowing up. I'd love to have the knowledge and tools to do cool stuff like that.
My mom did't want me to be a factory rat. Even though I have great mechanical aptitude.

Thanks. I'm just a hobbiest that tinkers though. The best thing to have is a good lathe operation manual. There are also some great videos on Youtube on running lathes.

 

[L1A1Rocker]

Nice work sir. What material used for your brake? Did you single point the internal thread on it? External thread on brake; am I seeing a double start?

If your fits are as good as your finishes you're obviously a "class A" machinist.

Thank you.

Yes - kinda. I start with the single point threading until it's almost complete. Then I cheat and finish it out with a tap. That way I get the accuracy of the lathe - but I don't have to worry with the final thread specs.

Yes, the external threads (for the silencer to screw on) are double start ACME stub threads (8:4 IIRC)

Thanks for the kind words but I'm not a real machinist. I'm just a hobbiest tinkering around in the shop.

Edit: Oops, missed one. The brake is 4140. I didn't bother with hardening it. I'm just going to parkerize it and when it starts to ware, I'll make another.

 

[L1A1Rocker]

There were a couple of questions on the brake. Here's my doodles for those interested.

 

[Ian]

I gotta get over there and see this myself. This evening, when it cools off to below 100F, I'm planning on loading up the steel goodies on my trailer to bring you, perhaps tomorrow AM?

Some of the work you've been doing with Titanium is very interesting as well.

 

[smokeywolf]

I start with the single point threading until it's almost complete. Then I cheat and finish it out with a tap.

You are a real machinist even if you don't recognize it.
On most larger threads, it is proper procedure to single point to within a few thousandths of finish pitch dia. then take it to finish with a tap or die. For obvious reasons this is more often the norm with external threads than internal. However, I often practice this procedure when the internal thread I'm cutting is 5/8" or larger.
Even with internal threads as small as 3/8" I will sometimes single point a short distance into the hole prior to running the tap in, to insure that my internal threads are concentric with the O.D. of the part.

 

[L1A1Rocker]

I gotta get over there and see this myself. This evening, when it cools off to below 100F, I'm planning on loading up the steel goodies on my trailer to bring you, perhaps tomorrow AM?

Some of the work you've been doing with Titanium is very interesting as well.

My schedule is completely clear this weekend.

 

[Brad]

Very nice work.

I am glad to hear that I'm not the only one who finishes external threads with a die. I got tired of making bullet sizers that were sometimes a bear to thread into my press. A 7/8 x 14 die cleared that right up.

 

[Ian]

What ever works. Chasing threads can sure even things up and get rid of microscopic burrs.