Thread size?

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That's why I said for suppressors. Single point on the lathe is the way to go for large threads. Just remember you can't disengage the half nut while cutting metric threads with an imperial lead screw. When there's no room for a run off gutter I cut the threads in reverse to prevent crashing the tool.

 
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bigHUN said:
I am not recognizing for which FX shroud is in the picture, but the 2019-20 MK2 shroud muzzle end cap (prior the CF barrel tuner) was M27, and the thread was conical. I never removed the action end cap from the shroud.
Another hint... use hotmelt rubber glue (for archery arrows), melts low temp - with a cigarette lighter, but the connection is really strong.
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M27 by what pitch? 1.5?
 
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jking said:
M27 by what pitch? 1.5?
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M27x1.5, but the male thread is not cylindrical but conical. Smaller OD start with 26 dia (you see that on a black part) and the thread tip ends at 27mm. Just look into the shroud end and you will see why ????
I source it to a machine shop last year, I didn't wanted to alter the original part but make a new with an internal air stripper.
This how I learned.

20200629_134458.jpg

20200629_134309.jpg
 
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jking said:
So Heavy you were talking about the M20X1.0 being for the inlet side of the Impact moderator? I was asking about the thread size and pitch on the cone that screws into the action side of Crowns sliding shroud. No wonder there was some confusion lol. I appreciate the video, I like that idea of working back toward the tail stock.
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Yeah, I quoted the guy that said "The FX stuff that isn't 1/2UNFx20 is usually M18 threaded." So I replied it's M20x1 for moderators. Then another guy confused me when he replied to someone "there is no such thread as M20."
I answer too quickly sometimes. I apologize for the confusion.
 
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heavy-impact said:
Yeah, I quoted the guy that said "The FX stuff that isn't 1/2UNFx20 is usually M18 threaded." So I replied it's M20x1 for moderators. Then another guy confused me when he replied to someone "there is no such thread as M20."
I answer too quickly sometimes. I apologize for the confusion.
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No apologies needed I should have done a quick check to begin with.
 
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bigHUN said:
M27x1.5, but the male thread is not cylindrical but conical. Smaller OD start with 26 dia (you see that on a black part) and the thread tip ends at 27mm. Just look into the shroud end and you will see why ????
I source it to a machine shop last year, I didn't wanted to alter the original part but make a new with an internal air stripper.
This how I learned.

View attachment 312679
View attachment 312680
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Thanks for the clarification and photos bighun. Is it conical due to the limited depth (as in length) the threads were cut into the shroud? I know there is only about a 1/4" of them, lengthwise. Got both of my shrouds currently installed and the way I have them set up don't want to pull one off just yet or I would to figure out (guess) what you're referring to.
Also noticed that the tips of the threads on the 26mm section look flat on your original as they do on my cone piece compared to the one you had made.
Couldn't you just machine it to 27mm all the way and knock the top off the first two or three with a file while it's still in a lathe if has to be conical?
 
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jking said:
... the tips of the threads on the 26mm section look flat on your original as they do on my cone piece compared to the one you had made.
Couldn't you just machine it to 27mm all the way and knock the top off the first two or three with a file while it's still in a lathe if has to be conical?
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Yes, that little flat on the thread tip makes the OD smaller, that is why I called it "conical".
I would cut the thread on 27mm OD and when done just recut let say 1 or 2 degree from the start. Now that taper I am speculating but need to calculate.
I don't have my own machines, but have friends with machine shops... but hours driving away. So if I need something I need to do a good homework first.
 
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jking said:
Anyone know what the thread pitch is on these FX shroud cones? I don't have a threads gauge for the metric sizes but will soon order one. I'm pretty certain it's the same on the muzzle end.
jk
View attachment 310898
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Sure wish this tapered end would’ve went on all the different shroud lengths for the impact. It would’ve given the valve knob more outwards adjustment like it does on the 700 shrouds
 
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