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gas tube replacement options? for short gas sys gun?


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ok, tried t odo a 13" gun but could never get to run birdshot with the ports not ridiculously massive....so ive turned down barrel in lathe and have the tromix shorty gas piston replacement, but im still confused as how to deal with the gas tube problem.... some folks seem to beat the ridges out? others make new tubes? im sure its simple buuuuuut

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You can easily waste a ton of time on it and still end up with something that will not work well or look good. Just get the Tromix tube and focus your time and efforts on more important aspects of the build.

Edited by evlblkwpnz
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If you must do it yourself, try using a sucession of ball bearings and knocking them thru with a BFH and punch. Anneal the part before starting and between each size of bearing. This will keep it from cracking as you stretch the metal. Always knock the bearing thru cold. Temper after reaching the desired size.

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I think that would run a good chance of growing the thing lengthwise, or buckling the end as you push the bearing through. Also keeping the bearing or mandril, or whatever centered would be the big difficulty. Typically the weakest spot will deform, and all the force will go that way. IMO, just buy the tromix one.

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Has some dang machine marks though. I gotta read up on how to work with the slop

Back your cross slide out a few turns and then go back into the workpiece. Do the same with your compound slide. If you run either back out at all then you have to do it again. Just pay attention to where you are before you back out in terms of the dial (can't remember what it is called, one more cup of coffee please, lol). You may be able to adjust the gibs to make it a little tighter (I have no clue exactly what you are working with and I am under the assumption it is a well worn lathe). I hope this helps.

Edited by evlblkwpnz
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  • 3 weeks later...

Slop like the backlash in the dials? If so take evil's advice, the machine I use at school has about 50 thousands before actual tool movement happens. Just pay attention to what number you were at on the previous cut

I bought a new lathe last year and it had slop from day one. I adjusted the gibs a little to reduce transverse movement, but no matter how I am doing it, if I run away from the piece or headstock at all I go out further and then back into it. +1, the dials are your friend.
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gotcha... and prob using dull crappy taiwan(what.gif ) bits isnt helping.... more like scraping off the metal vs cutting it!  anyways, im gonna confuse things more by suggesting that the barrel stub can be used to turn into the gas tube!   seriously folks, mic it! (mayeb this is already common knowledge?!?!?!)

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I've been messing with my tailstock(that's what she said) for a couple of weeks now(3 days a week, couple of hours each) and finally have it down under a thousandth from one end of my 29 inch blank to the other. I pray to God that someone in another class doesn't start tapering their barrel before I do and throw it out for me. Our machines are well maintained but are still about 50 years old with hard student/learning curve usage. Carbide is my friend.

 

As for using barrel scrap, never occurred to me, I don't have measuring stuff handy, or any stubs to play with(that's what she said) but I'll take your word for it, not a bad thought. And your scrapping comment reminded me of a video someone was telling me about the other day where they watched a guy octagon a barrel on his lathe. He had a custom ground bit, the machine was off and the barrel was locked in place, and he just traversed his bit across the length of the barrel until he'd created a flat, indexed 90 or 180 degrees and did it again. I'd forgotten about it, I want to see it, I'm gonna go look for it now.

Edited by Goose
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