Gunsmithing Chamber Reamer Tight

[cuutter]

Hello, I have only chambered about a dozen barrels and ran into a situation I haven't run into before. On a SS and a CM barrel the reamer got tight and was hard to pull out. They were 2 different calibers with new reamers. It felt like the chips weren't moving out of the way while reaming and getting between the reamer and the barrel. I have been using the dark heavy cutting oil. Anyone have any ideas on what I might be doing wrong?

Thanks
Wayne

 

[wnroscoe]

Re: Chamber Reamer Tight

Normally I use Krieger barrels and haven't had this problem with them but, some of the other barrel blanks seemed to actually work harden as I chambered. One Lilja and one rock that I chambered was this way. I used a piece of 320 grit paper and polished the chamber a little and the reamers started cutting again. This continued until the chamber was complete.

When I started using a chamber flush system this problem went away.

 

[GunjunkieM24]

Re: Chamber Reamer Tight

How much are you cutting before you pull out and flush / re-apply cutting oil?

As William said, the flush sytem is the way to go but I chambered many barrels with Rapid Tap or Tap Majic before I started using the flushing system. I have had my reamer get tight before but I usually found that I took too much of a cut and let it get "dry". As you get deeper into the chamber, you will need to take less and less of a cut as you can only get so much cutting oil on the work. This gets worse on larger "magnum" type chambers.

The second possible issue is that your pilot is "too big" for the given chamber you are running. You may be getting a tight pilot....Just a guess as you did not post what type of reamer you are using. Sometimes when you use a reamer pilot that is really close tolerance, add some chips and a little temp change from the cutting process, things tighten up and will give resistance.

my 02 cents worth.....

Hope it all works out for you,

 

[DAVETOOLEY]

Re: Chamber Reamer Tight

Here's something else that I've observed with several of my reamers. It seems there is an issue with the freebore section of the reamer. It's as if it is an interference fit, not cutting freely but plowing. I feel it when I pull the reamer out and I feel it when I put the reamer back in barrel, it doesn't cleanly bottom out in the chamber.

 

[tmxring]

Re: Chamber Reamer Tight

Also try using a de-magnetizer on the barrel before you start machining it. The barrel can magnetize when machined. TM

 

[Jkob]

Re: Chamber Reamer Tight

Or...you may have bought on the cheap and gotten a couple bad reamers. I can't imagine having a stainless barrel work harden. You should also try reaming less deeply for each cut.

 

[300sniper]

Re: Chamber Reamer Tight

How are you holding the chamber end in the lathe and how tight? You aren't holding it so tight that the bore is distorting, are you?

 

[cuutter]

Re: Chamber Reamer Tight

Thanks guys. I do remove and clean every 0.050". I run the lathe at 90 rpm. Sometimes I will go up to 120 rpm. I feed the reamer appox. 0.005"-0.008" per second. Do you think thats too slow or too fast? I use the Bald Eagle Floating Holder. The reamer is a PTG. The customer bought the reamer. It is the solid pilot type. I buy the PTG reamers with the removable pilot. This has happened with them also. The SS barrel was a Rock and the CM barrel was a factory take off.
Thanks again for the input.
Wayne

 

[LRI]

Re: Chamber Reamer Tight

I'm guessing your getting some compaction of chips in the gullets on your tool.

Try a shallower depth of cut and ensure you evacuate the chips with air from the tool and the hole before reinserting the reamer.

Pressurized cutting oil to the tool (as Mr. Roscoe stated) will for all purposes eliminate the problem.

I chamber my barrels between 400-475 rpm. Based on speed/feed charts this is right around 50SFM which pretty much is the starting point for any barrel grade steel getting reamed to a final ID of .480" (basically anything with a 30-06 case head diameter). (SS or CHROMO) It does however require good work holding and good support of the tool. A tap wrench and tail stock probably won't work very well. This is likely about 3-4 times higher RPM than what anyone else uses. If anyone was to work harden a barrel I'd probably be the guy to do it. So long as your tool is sharp, a good cutting fluid is used, and your not going bezerk on the feed rate your fine. A barrel isn't going to work harden on you. There are some barrels that do have spots in them harder than others. I've proven this by taking a barrel or two and cutting them up to make test coupons to inspect in a hardness tester. This is likely what a guy "runs into." A cut barrel is typically a smidge harder than a button barrel. The single point tool that makes the twisties cuts better when the steel is harder. (especially SS) A button barrel has to be a little softer otherwise the stick with the little M&M looking buttons will break inside the thing when making the "wrinkles".

Make sure your reamer pilot isn't sticking. That can cause headaches too. Most the time these days I don't even use the pilot. (which sucks as I spent almost $1000 with PTG buying every size reamer pilot they make from 17 to 338) If stuff is on center and you DIDN'T cram a drill up the ass of the barrel to rough out the chamber you really don't need it. The key is single pointing a tapered bore that's undersize before reaming.

I often find myself agreeing with Mr. 300 Sniper as he's a pretty sharp guy. In this case though I'm afraid I have to sort of counter his question. I hold my barrels in a Dunham Hydraulic 16C collet chuck. I apply over 200lbs of drawbar pressure. I've never taken the time to compute exactly what the mechanical leverage is at the collet taper to see how much I'm clamping the barrel cylinder but I can tell you it's significant. That being said I would be very impressed if anyone (short of using a 3' pipe as a cheater bar) could duplicate the pressure I'm using with a conventional 3/4 jaw scroll chuck. Just saying it'd be pretty difficult to collapse or distort the ID of the barrel with the amount of steel between it and OD of the cylinder.

Good luck.

C

 

[bohem]

Re: Chamber Reamer Tight

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: cuutter</div><div class="ubbcode-body">Thanks guys. <span style="font-weight: bold">I do remove and clean every 0.050".</span> I run the lathe at 90 rpm. Sometimes I will go up to 120 rpm. I feed the reamer appox. <span style="font-weight: bold">0.005"-0.008" per second</span>. Do you think thats too slow or too fast? I use the Bald Eagle Floating Holder. The reamer is a PTG. The customer bought the reamer. It is the solid pilot type. I buy the PTG reamers with the removable pilot. This has happened with them also. The SS barrel was a Rock and the CM barrel was a factory take off.
Thanks again for the input.
Wayne
</div></div>

Initially when you're not cutting much material along the reamer length this is probably acceptable, however as you get near the end of the chambering process this is going to be too much IMO. I clean the chamber out with air/oil about every 0.010" for the last 0.050" of the reaming process and that 0.010" will take about 10s to cut.

I've run into chip jam issues previously and I slowed down my feedrate at the end as I realized that this was causing it. I don't have the high pressure oil feed to work with so I clear the chips a lot.

 

[GasLight]

Re: Chamber Reamer Tight

are you guys pre-drilling and then boring the chamber first? Or is this running the reamer into a virgin bore?

Thanks

DD

 

[bohem]

Re: Chamber Reamer Tight

I precut the chamber some. Precutting it too far will make it so that you can't get the pilot into the bore when the reamer starts cutting. I don't get a good feeling about cutting a chamber without both ends of the reamer supported (ie in the reamer holder and pilot running in the bore) so I only pre-cut part way.

 

[wnroscoe]

Re: Chamber Reamer Tight

If you pre drill at least touch off with a small carbide boring bar and make the hole concentric prior to chambering.

I use a finish reamer from start to finish. I may start using a carbide roughing reamer first though.

 

[LRI]

Re: Chamber Reamer Tight

I don't get a good feeling about cutting a chamber without both ends of the reamer supported. . .

All depends on how you hold the tool.

 

[Hateca]

Re: Chamber Reamer Tight

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: cuutter</div><div class="ubbcode-body">Thanks guys. It is the solid pilot type. Wayne
</div></div>

I would bet this is your problem right there. More common then you think. I will not ever chamber a custom barrel without a reamer with a removable pilot so I can fit it to the barrel bore. To tight or too loose and you're asking for trouble. I also don't use rented reamers or reamers supplied buy customers unless they have the removable pilot.

 

[bohem]

Re: Chamber Reamer Tight

Chad- I agree with you there, but I don't have the stiffness in my setup like that to take advantage of.

 

[tmxring]

Re: Chamber Reamer Tight

Also a really thick cutting oil won't let the chips release really well. I use "Rapid Tap" for cutting fluid. TM

 

[300sniper]

Re: Chamber Reamer Tight

since the op said he used two different reamers, this probably isn't the problem but i did have a reamer that was acting like being described though.

i cut two chambers with it on two barrels from the same manufacture and received at the same time. the other machine work on the barrel was difficult too so i was blaming the sticky reamer on the barrel steel. the chambers turned out excellent in the end but they were a pain in the ass to cut.

i used that same reamer some time later on a different manufacturer's barrel and it had the same issue. the rest of the machine work went smooth though. i started looking closer at the reamer. to my non-tool maker's eye, it appeared that the relief angle was not steep enough on the back side. it looked like the non cutting edge of each flute was touching at nearly the same time as the cutting edge. i sent it back for inspection/repair. i got it back with no charge or explanation on what was wrong but i could tell it had been reground. the next chamber i cut with it worked out perfect.

 

[bohem]

Re: Chamber Reamer Tight

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: 300sniper</div><div class="ubbcode-body">since the op said he used two different reamers, this probably isn't the problem but i did have a reamer that was acting like being described though.

i cut two chambers with it on two barrels from the same manufacture and received at the same time. the other machine work on the barrel was difficult too so i was blaming the sticky reamer on the barrel steel. the chambers burned out excellent in the end but they were a pain in the ass to cut.

i used that same reamer some time later on a different manufacturer's barrel and it had the same issue. the rest of the machine work went smooth though. i started looking closer at the reamer. to my non-tool maker's eye, it appeared that the relief angle was not steep enough on the back side. it looked like the non cutting edge of each flute was touching at nearly the same time as the cutting edge. i sent it back for inspection/repair. i got it back with no charge or explanation on what was wrong but i could tell it had been reground. the next chamber i cut with it worked out perfect. </div></div>

I didn't think about it, but I've seen that once before as well on a choke reamer.