Thread depth w/ wires - what measurement do you aim for on a muzzle thread?

[LVLAaron]

Threading a muzzle - and I do not have the device that will live on the barrel. What measurement do you aim for?

Theoretical machinist gives me "over wire" dimensions of "0.6328 / 0.6288"

Aim for the middle? Loose end of it?

 

[55fairlane]

I am a tool maker....if you dont have the mating part always shoot for the low side....but I try to never thread anything thing without the mating part in hand....who knows what thread spec the other manufacturers used.
You can always contact the maker and ask them for a thread spec.
If the thread is a little tight...thread the ???? On until it stops and give a gentle love tap with a lead hammer...it will loosen up.....

Need help? Get stuck shoot me a pm....

 

[55fairlane]

And do your self a favor turn the major o.d. .003 to .005 under....use a sharp tool, always pick up the same number on your chasing dial (if thead is critical) that will help eliminate gear train/lead screw discrepancy

 

[Dusty Stevens]

Man i hate wires

 

[55fairlane]

If your lathe has some moderate backlash in the screw, (or a deap thread) always go 2 turns out & in on your cross slide

 

[55fairlane]

Do you know the trick of taping your wires together to help be your "third hand"

 

[Dusty Stevens]

Do you know the trick of taping your wires together to help be your "third hand"

Shars sells thread mics pretty cheap. They come with a bunch of anvils

 

[LVLAaron]

Shars sells thread mics pretty cheap. They come with a bunch of anvils

I've seen those and wanted to get them but they're so inexpensive I didn't have faith.

 

[Dusty Stevens]

I've seen those and wanted to get them but they're so inexpensive I didn't have faith.

Theyre so cheap get a 0-1” and a 1-2”.

 

[LVLAaron]

I am a tool maker....if you dont have the mating part always shoot for the low side....but I try to never thread anything thing without the mating part in hand....who knows what thread spec the other manufacturers used.
You can always contact the maker and ask them for a thread spec.
If the thread is a little tight...thread the ???? On until it stops and give a gentle love tap with a lead hammer...it will loosen up.....

Need help? Get stuck shoot me a pm....

It's a barrel that will probably have more than one thing on it... and who knows what that part may be. I measured some other custom barrels I have had made in the past and they were all 1-2 thou over minimum, so I did the same thing.

 

[LVLAaron]

Theyre so cheap get a 0-1” and a 1-2”.

Will do. Nothing worse than dropping tiny wires into a chip pan full of swarf.

 

[tobnpr]

Bought Pee Dee wires along with the proverbial fishtail gauge when I bought my first lathe.
Used them once and then bought thread mikes.

What measurement do you aim for?

I often don't have the device- but I definitely want to know what it is, especially for a can- so I can look up the print from the manufacturer. Brakes are pretty nondescript and usually Class 2, but suppressor mounts can require more specific machining and are usually Class 3.

If I'm cutting "universal" threads, e.g. customer says "maybe a brake, maybe a can" etc., I shoot for a major diameter and PD where class 2 and 3 overlap and a "typical" tenon length.

 

[clowdis]

Thread the muzzle to about 95% depth and then finish with a die. You can find 5/8-24 and 1/2-28 dies at about any machine shop supply store or on line.

 

[Tucker65]

On a 5/8-24 thread my chart for pitch diameter using .024 wires shows these for tolerances.

3A - .6340 / .6310
2A - .6328 / .6288
1A - .6328 / .6268

I like to have the part in hand when fitting threads to make sure things are going to fit correctly. If I didn't I would shoot for the low end of the 3A tolerance that way you'd still be in specs for a suppressor mfg's tolerance and you'd be right in the middle of the range for a 2A fit.

 

[DaveTooley]

It's a barrel that will probably have more than one thing on it... and who knows what that part may be. I measured some other custom barrels I have had made in the past and they were all 1-2 thou over minimum, so I did the same thing.

View attachment 1336238

I don't see much of a flat on top. I always turn the major diameter 5-7 thou under. On barrel tenons 10 thou doesn't hurt anything. With experience you can tell by the width of the flat when to start checking the fit.

 

[LVLAaron]

I don't see much of a flat on top. I always turn the major diameter 5-7 thou under. On barrel tenons 10 thou doesn't hurt anything. With experience you can tell by the width of the flat when to start checking the fit.

I licked it with a file after the photo and polished with some high grit paper.

I ended up copying the diameter of a barrel I got from masterpiece arms - it's had probably 10 different devices on it.. It measured a thou over the low end of a 2A spec.

 

[dnellans]

I've got 8 or so different muzzle devices (primarily 2 manufacturers) who claim to hold their devices to 3A spec and I can thread to one randomly and 2 others won't go on and 2 are sloppy usually.

I have marked which one is the tightest of them all that I've seen and will use that one as my test guage if I'm threading for something where I know that a single device won't be on it most of the time.

 

[LVLAaron]

I've got 8 or so different muzzle devices (primarily 2 manufacturers) who claim to hold their devices to 3A spec and I can thread to one randomly and 2 others won't go on and 2 are sloppy usually.

I have marked which one is the tightest of them all that I've seen and will use that one as my test guage if I'm threading for something where I know that a single device won't be on it most of the time.

I did the same thing for the first few I threaded. I have a 300 blackout VG6 muzzle brake that's pretty snug. Might be because of the coating on it, but it's been my go gauge.

 

[Bamban]

I do from 14 to 20 donated Shilen barrels a year for the TX Jrs. Though the barrel extensions (BE) and flash hiders (FH) are all sourced from the same place, hardly any two time and thread in the same. FH are worst. Tenons are threaded to their own BE and FH. We could easily get away without the FH, as not required by rules, but I use them for crown protection. No 1/2x28 for the AR15 barrels, all are A2 5/8x24.

I do not use crush washers and wrench to torque down the FH to TDC, just hand spun with Locktite. They are timed to TDC specific to each barrel. Almost all needed to be faced off to get them to time.

 

[butchlambert]

I'm with Dave on barrel tenons, but on the muzzle I get close and finish with a die.