Posted on 07/31/2013 2:49:55 PM PDT by jstaff
I might be out of place, but I know there are some very knowledgeable folks on here, and I'm hoping someone can help with a project. I need to make a plug that screws into the reciever of an M1 carbine, to keep everything neat and clean while the barrel is off, but I don't have the design specs for the threads. I could just measure the old barrel but there's no way to tell if it was made in the high end or low end of machining tolerence. I can see it's an Acme thread and 10 tpi, but I want the precise major and minor thread diameters. Any help will be appreciated.
wine cork?
I gotta ask, why do you need a plug for the receiver while the barrel is off?
Are you sure you need a machined metal plug for so simple a task? Seems to me as a temporary plug for sanitation I’d find a plastic plug like for hydraulic tubing and force-fit the threads. You really don’t want to mess up the receiver threads (assuming you intend to re-barrel at some point).
TC
Get an appropriate diameter wooden dowel.
wood dowel , wine cork , wadded up paper towel... it all works ... This isn’t anything delicate after all , it’s meant to be hauled through mud , rinsed and shot after all ...
I sold my M1 Carb (a Rock-Ola) 2 years ago ... I’d just grease up any spare parts and bag them if it’s long term storage you’re looking at...
A rubber cork, even a wood plug carved from any soft wood will do.
However, Nancy Pelosi wanted you to know that she is saddened by your choice of such a violent hobby.
;-)
LOL!!! Starting a gun thread on FR is always good flame bait. /s
Can I ask a dumb question? If you are really concerned about it, why wouldn’t you just coat the threads with cosmoline and shove a wooden plug or a rag in there? Why does it have to be a threaded plug?
I suggest that you contact a parts distributor and see if you can just find a spare barrel that you can adapt for your purpose of, uh, "receiver plug". Might save you some time and trouble in the machine shop.
Or you could just use a cork...
Since no one else did, I’ll bite:
From here
http://forums.thecmp.org/showthread.php?t=47494
“29° Acme variant with 10 tpi pitch and .971”-0.005” major diameter, and .913”-0.005” minor diameter. 0.052”-0.003” width at the midpoint height. Inside corner radius is 0.01” and the outside corner break is 0.005” maximum. “
(unverified)
Personally, I’d thread some Maple so you could at least lock it in w/o dealing with cork debris. In that respect the exact specs for the threads are irrelevant, as you want a loose fit, lest you deposit cellulose on the threads to interfere with the next time you thread the barrel. In line with others, I see no reason for metal.
Thanks everyone for all the suggestions. I don’t absolutely have to have a threaded plug, but I already own a lathe, tooling and a piece of Delrin that I have no plans for, so I thought I would make a plug. It gives me a project, protects my rifle and will look cool as he77. Win, win, win.
That data looks like it was for a garand vs a carbine friend ..... On the link ya provided.
Really. Who wants to talk about guns on Freerepublic? I bet this thread won’t have any more than 324 million replies before the nights over.
Well, exactly. Who’s going to bump this thread by posting to it, anyway?
“Who’s going to bump this thread by posting to it, anyway?”
Not me, that’s for sure.
I used to have one before the unfortunate boating....ah, never mind...
Put a thread on the plug that is only a couple of turns or so, since it is not load-bearing or taking any stress. That way, the tolerance issue goes away.
You’re right, I just wanted to work on my machining skills, since I’ve never really cut Acme threads before, except just playing around. I planned to thread it far enough to push against the bolt. That way, pressure from the bolt would hold in in place, keep it from turning out. I didn’t want to introduce any foreign material (wood fiber, paper fiber, extraneous grease) so I chose the plastic rod. Way over-engineered I guess, but there’s a fridge with beer just a few feet fron the lathe, so Ima gonna gophrit.
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