Barrel Fitting Fixture

[quickdtoo]

Ever since I dd my first barrel fitting I've been trying to think of a more precise but economical method of maintaining a true cut on the underlug. A few days ago, I got an idea to use a chainsaw sharpening tool to keep the a file in alignment in both axes, the next issue was finding a file with the right diameter. I already had the sharpening tool, so I went to the local tool store hoping to find a chain saw file that was .375", but no such thing exists, but I found a tapered round file that had a 4" straight section of .372" that should work well enough since the amount of "slop" in the mechanism, while slight, will probably create a cut that is slight larger than the file diameter, but in any event, should be much more precise than doing it by hand. I removed the adjustable nylon piece and replaced it with a piece of 1/8" aluminum angle and epoxied it so to hold the file in perfect alignment with the pivot. I used the square end and top of the underlug to make sure the file was square to the barrel, as soon as the epoxy cures, I have a barrel to test it on and see if it works as good as it seems to appear at this point. I thought it very lucky that the spread of the bottom of the fixture was just .009" wider than the width of the underlug!! A piece of .009" feeler gauge blade used as a shim and a C-clamp used to clamp the fixture in position on the underlug worked well.

Tim







 

[smokinjoe5150]

Damn, Tim, I wish I had one of those last week. I spent about an hour with a .370 rod and 320 paper dialing in a 28" B/C barrel.

Good looking fixture!

Joe

[backstrap]

quick what kinda opoxy do u use for this is this what u guys do that buy barrels else where and not from the h&r program i would like to buy a barrel for my frame and see if i can get it to fit if i had the stuff to get it set up for the  notch to be cut out i have a machine shop that i think could do the rest for me

[quickdtoo]

Thanks Joe, if it works as good as it looks, I'll be happy! 

Backstrap, please see the barrel fitting info in the FAQs and Help sticky. Buying used barrels is routine here, many fit with no problems, specially if you have multiple frames to try them on, that's one of the advantages of having more than one frame, but a lot of barrels still need to be fitted, some are loose and need to be shimmed, some are too tight and some metal needs to be removed to allow complete lock up with no gap tween barrel and standing breech. Many only need the latch shelf honed a bit to allow good latch engagement which is checked after the barrel fits the frame good and appears to lock up.

Ideally changing the underlug pivot depth would be done on some sort of milling machine by a smith, but not many of us have that option. You can see what H&R uses in the factory tour video in the FAQs.

Tim

[handirifle]

Necessity IS the mother of invention.  Nice going.

[skifastchad]

hoping to find a chain saw file that was .375", but no such thing exists

If you can find Nicholson files, they make a 3/8"x8" straight (not tapered) chain saw file.  (For BIG chainsaws)

[quickdtoo]

The 3/8 they refer to is the pitch, largest diameter is 5/16". I've done exhaustive internet searches and had MCK tool  go thru all of their catalogs, to the best of my and their knowledge, there is no 3/8" diameter chainsaw file.

Tim

http://www.cooperhandtools.com/brands/nicholson_files/index.cfm

[myarmor]

Looks good Tim, I like it.
I might have to swipe the plans and make myself one of those


-Aaron

[skifastchad]

The 3/8 they refer to is the pitch, largest diameter is 5/16". I've done exhaustive internet searches and had MCK tool  go thru all of their catalogs, to the best of my and their knowledge, there is no 3/8" diameter chainsaw file.

Sorry its not on their website, but it does exist.
I have one.  "Nicholson #186" is stamped near the handle.  It measures a consistant .374 in my dial caliper and the working length is just over 8".  I don't know what kind of chainsaw it is for, but it does have the smooth end for clamping in a fixture.

[quickdtoo]

Maybe they don't make it any more, the old 2-man Molls had larger teeth on the huge commerical chain saws of the 40s and 50s. If you can find a source for the 186, I'd order one in a heart beat!!

Tim

[smokinjoe5150]

Tim, J & L industrial supply has a Nicholson 10" X 3/8" round for about 5 bucks, available in Bastard, 2nd cut or smooth.

# 24764J

http://catalogs.shoplocal.com/jlindustrial/index.aspx?storeid=1038424&circularid=7228&jlpass=1646&loggedin=false&itemcount=0&jsessionid=hch3yjiaktjzrlaubiwsfevmcqfcyiv0&pagenumber=1668

[MSP Ret]

Thanks smokinjoe5150, I may just get a couple of those for myself for Christmas!!! What are the 2nd cut and smooth like? I take it they are progressively smoother than a bastard file?....<><....

[smokinjoe5150]

Yep, they're progressively finer.

[quickdtoo]

Joe,

That's probably what I have already, it's tapered,  probably has part of it straight just like the one I got,  but thanks. That's all I've found in the better part of about 4 hours searching, plus an hour at the tool store!

This file seems to work pretty good, I cut a barrel pivot today with it, after I was done and satisfied with the fit, I measured with my digital caliper from the bottom of the pivot on each side to the latch shelf notch and got 2.425" and 2.426" which I thought was about as close as I could ask for considering my non-technical method!!

Tim

[deerjackie]

www.grainger.com has .375 files item nu 1aka6.

[quickdtoo]

Good luck with that, I've order many ".375" files, they're ball park close, good enough for chain saws, but not .375", always undersized or too big. 

Tim

[rickt300]

I just sent Blaze a money order for his superlight 223 barrel and I hope it doesn't fit so I can fit it to my frame. (Grin).  I have access to a milling machine and a variety of good sharp 2,3 and 4 flute .375 mills.  With my luck I'll end up shimming but that will be ok too.