Gunsmithing Chambering a rifle - Reamer would bind???

[mram10]

A friend and I were chambering a 338 edge in a 30" Brux barrel a couple days ago. The first inch was fine, but after that, it would go about .010-.050 and start to bind.

Here are the facts:
1. Reamer has been used before and sent back to factory twice, both times saying nothing was wrong with it
2. Good reamer oil was used and a lot was used
3. Barrel in a 4 jaw and reamer had a pilot. Reamer was pushed in by, not locked in to the machine.
4. Took off pilot to see if any change and didn't help
5. Don't remember speed of lathe.

Any ideas??

 

[bohem]

Re: Chambering a rifle - Reamer would bind???

Chip jam is my first thought, second would be the cutter relief angle. Since it's been back twice to the reamer maker, the second option is not likely the culprit.

If you're not flushing the chamber during the cutting process with a high pressure oil system then chip jam is my first suspicion when you're getting 0.030" deep on a chamber that's got a lot of material to remove.

 

[300sniper]

Re: Chambering a rifle - Reamer would bind???

i had one reamer that was tough to pull out after a peck. the first two barrels chambered with it were barrels i hadn't worked with before and were made at the same time so i was blaming it on them. then i did a barrel months later from a different manufacture and had the same issue. all of the chambers turned out nice but it felt like the reamer was not cutting as good as it should and took quite a bit of force to pull it back out.

to my untrained eye, it appeared that the relief was not cut steep enough on the back of each flute. the rear of the flute appeared to be touching the chamber walls at nearly the same time as the cutting edge. i sent it back with an explanation of the issues. it was quickly returned to me without an explanation of the problem but i could tell it had been reground. it works great now and i wasn't charged for anything so i am assuming my hunch was correct.

if you are having the same problem with this reamer on more than one barrel and your chambering technique has been proven with other reamers, i'd send it back to the manufacture for inspection/repair.

edit: i missed (or ignored) that you had already sent the reamer back twice. i guess it could be what the others are saying about chip jam. maybe it is something inherit of the cartridge you are reaming for,

 

[cuutter]

Re: Chambering a rifle - Reamer would bind???

+1 on Chip Jam. I just did a .338 Edge over the weekend and ended up only cutting 0.010" at a time do to the reamer getting hard to pull out. My reamer is by PTG. I ream at 90 rpm and have great luck intill I try and feed it to much at a time.

Good luck on the build
Wayne

 

[300sniper]

Re: Chambering a rifle - Reamer would bind???

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: cuutter</div><div class="ubbcode-body">+1 on Chip Jam. I just did a .338 Edge over the weekend and ended up only cutting 0.010" at a time do to the reamer getting hard to pull out. My reamer is by PTG. I ream at 90 rpm and have great luck intill I try and feed it to much at a time.

Good luck on the build
Wayne </div></div>

.010" pecks? how long did that take?

 

[mram10]

Re: Chambering a rifle - Reamer would bind???

This was also a PTG. We blew out the chamber each time with air to get the junk out before starting again. It seemed that if we let the reamer spin in the chamber a little longer after cutting it would free it up a little.

 

[crumpmd]

Re: Chambering a rifle - Reamer would bind???

I chambered a rifle this past weekend. 6.5mm not .338 but the machining is the same. I don't have a flushing system.
I bought two reamers from PTG, a rougher and the finisher. I feed the rougher a quarter inch and pull it out, blow out the barrel and relube the cutter and make another pass. When I am within a tenth I replace with the finish reamer and make passes at .001 til I am close and then .0005 until it just closes on the go gauge. I blow it off and relube each time. Ir you are getting chip jam you may need to rough out the chamber first. Of course you may have done that already and if so OK.
I would for sure run more rpm. I chamber at 600 for the rougher and 270 for the finsher.

 

[LRI]

Re: Chambering a rifle - Reamer would bind???

Turn a center on your lathe and leave it in the chuck.

Put a live center/dead center in your tail stock.

Stick the reamer between the two centers. Now mount an indicator off your carriage, bed, whatever.

Lay the stylus on a single flute and zero. Somewhere reasonably close to the middle of the tool on the case body.

Now rotate slowly and note the TIR (total indicated runout) of the tool.

If there's any (assuming your setup is good) then the tool is junk. It's not a reamer at this point, it's a sharp jump rope.

Chances are its not the tool although stranger things have happened.


FWIW I chamber at 400-475 rpm and I plunge typically about .300-400" per pass to the final depth. Chip evacuation isn't an issue with .01-.100" depths of cuts. Especially on a big 338 as the chip gullets are huge.

If your experiencing some funky loading its because the tool isn't on center. Recheck your setup.

 

[joemagee]

Re: Chambering a rifle - Reamer would bind???

It may also help to pre bore the chamber a bit, get rid of some of the material so the reamer has less to cut. I also run coolant through the bore from muzzle and out the chamber, helps flush chips out..

 

[colchester]

Re: Chambering a rifle - Reamer would bind???

I was also going to suggest that you prebore the barrel before running the reamer in. I did a chamber this way for the first time last weekend, I was very please with the results, and the chamber cut easily and quickly since most of the matl. is removed via drill and boring bar

 

[Glen Seekins]

Re: Chambering a rifle - Reamer would bind???

I dont pre bore as i like the pilot to start and stay in the rifling. If proper speeds/feeds are used with lube the reamer will last a long time. Just a different way to skin the same cat.

The reamer is long, and it has a long tapering body. When yo start cutting, as the reamer goes in further there is more surface area engaged in the barrel. This taper sticks because you aren't cutting the barrel steel like it wants to be, instead the tool is rubbing and creating friction. Some of the tool is cutting and some of the tool is being pressed into the very tight chamber. In theory, if you had a perfect chamber your reamer if stuffed back into the chamber without cutting should be a zero fit tolerance and it will stick.

What do your chips look like? If they look like dust then your rubbing. Also watch your heat. If the reamer gets hot its growing..You can also work harden the barrel and it will take a bit to get threw it if you do.

 

[mram10]

Re: Chambering a rifle - Reamer would bind???

The chips when it was binding were small. It seemed to bind less if we let it spin with no inward pressure. Bent reamer?

 

[Glen Seekins]

Re: Chambering a rifle - Reamer would bind???

I still say you are rubbing, not cutting. You may have work hardened the barrel a bit. With most reamer I chamber around 350rpm and feed it to where it likes to cut slightly changing RPM if needed. I know you dont want to ruin the tool, but if you baby it too much that can cause problems too.

A bent reamer would still cut unless it too is rubbing or dull..

 

[mram10]

Re: Chambering a rifle - Reamer would bind???

I see. Thanks again for the input. I will change up the rpm next time to stay around 350.

More clarity:
We apply pressure to the reamer with a rounded bolt head, while letting the pilot be the only guide for the reamer. Good or bad?

 

[border_reiver]

Re: Chambering a rifle - Reamer would bind???

If they are lapped barrels, you will end up with a flare or bellmouth at the chamber end.. choose pilots wisely, always go smaller than tighter fit. check to make sure your tailstock is aligned, if that's kosher, bump your pilot diameters down another .0002..never just remove the pilot. If you're binding and your barrel/tool is aligned it is probably at the pilot causing your headache.