New problem to me. I started to chamber a 405 barrel today and about 1/4 of the way in the reamer started to chatter. I tried the filling the flutes with bees wax trick but used machining lube wax instead and increased the feed. Still chattered. I tried hand reaming, chatter again.

Since this is a new problem to me, I'm quickly running out of ideas. Or at least good ideas. Any suggestions?

If your reamer has the same number of flutes as your barrel has grooves you have a custom made chatter generator.

I am not a gunsmith so I will give them the first shot at an answer.

What did your search of this forum turn up? THis has been brought up a lot and there are many ways to skin this cat, most of which have been discussed.

I am sure you read in your search where I increase the turning speed, wrap the reamer in Saran Wrap, really increase the feed rate. Pray VERY hard. Very reliable method.

Most of the time chatter can be traced to the lead angle of the shoulder portion of the reamer. Too sharp of a cutting angle at the shoulder will cause chatter and is somewhat common. This can be corrected through the careful use of a diamond hone to reduce said angle. How are you holding or driving the reamer?

Believe it or not, sometimes brand-new reamers are TOO sharp! If you have this problem with a new reamer the first time it's used then frequently a super-light stoning to very slightly dull the flutes' cutting edges will cure the problem.

Also if the flutes are evenly spaced around the reamer's axis then A) you need a new reamer grinder guy 'cause B) it's guaranteed to chatter.
Good luck, Joe

Try this, I didn't believe it until I tried it. I was having problems with chatter on an occasional chamber and could not figure out what it was. I finally determined that I was running the lathe too slow. I speeded up the process and found sucess. The one way I know of to repair a chamber with chatter, is to drill out the offended neck and throat area only enough to take the chatter out from there. Next, you must taper bore the body portion of the chamber to the same taper as the reamer. I usually set the reamer up between centers and incicate in the angle on the body flute and transfer that to the chamber with a small boring bar.

Now, here is another black magic way to do it. Take a piece of typing paper and wrap it around the reamer, insert it in the chamber and feed it with a course feed. It works, believe me. You can do this before the taper bore method.

I put a piece of pipe over the tap handle holding the reamer, and rest the pipe on the ways.

If I hold the handle, that is a high compliance countering the cutting torque. The ways are low compliance and prevent the reamer from chattering.

I lift up on the pipe occasionally, to feel the torque, so I can tell how much I can advance the ram without too much torque.

Interesting post. I have heard of loading the flutes with chaulk like one would do with a file. I have heard of using pork fat. I have heard of wax paper. I have heard of typing paper. But Saran wrap is a new one to me.

Chatter is a relationship between the reamer geometry and the harmonics caused by the speed and feed. One thing for sure if you don't stop it when it starts it will only get worse.

You might send it back to the maker and aske him to re-check the geometry. Most shops are not in the reamer making business and don't have a comparison microscope or a precision cylindrical grinder. In my experience slight imperfections can be stoned out but most lack the knowledge and to do any more risk ruining the reamer.

Longshot

Wrapping the reamer with cloth to eliminate chatter has never failed for me. Supporting the reamer wrench (if you are using a wrench)on the toolpost has always helped to prevent it.
The cutting edges of the reamer are staggered to help control chatter and the margins limit the cut which also helps. One can stone the margins if he knows what he's doing but there is nothing to be done regarding stagger. Regards, Bill

The guy who taught me how to make guns showed me the Saran Wrap trick. I was working on a personal project in his shop and he was cutting a chamber that started to experience a little chatter. He called me over there to show me how to fix the problem.

A key is to do like you do with any lathe work chatter-STOP as soon as it starts. Increasing speed and feed are vital. Load the reamer up with oil, wrap with Saran Wrap, and really jam it in there. Plus lube-lots and lots of lube. Has worked for me when I experienced chatter.

I chambered some barrels with a fast speed a feed from the beginning. They seemed to cut pretty damn good. Never had a bit of chatter when cutting that way. Maybe it was luck, or maybe there is something to it. I sat down one night and calculated ideal “book” speeds and feeds for chambering but lost that paper several moves ago. I think chambering faster is fine, but all of the gunsmithing books I know of tell to do it as slow as possible.

Hopefully a real machinist who also ha chambered a fair number of barrels will chime in with his opinion. I am just a hack who knows how to make machines do some of the things I need them to do and would NEVER call myself a machinist, even in my drunkest moment.

But I do think holding your mouth just right comes into play every now and then. Maybe that is how the “WTF!?!” tricks like Saran Wrap came into being?

Does production count? We only made 120000 or so pistol barrels last year.

The biggest contributer to chatter is not enough margin on the reamer. A radially ground margin that prevents the reamer from grabbing is vital. 0.085mm margin is fine (about .003").

Getting the chips flushed out is vitally important for final finish. We use water soluble sythitic and lots of it flushing the reamer and chamber.

I have to agree with the speed feed group
I use to encounter the same issues in the past and those were the first issues I addressed the only other thing it may be that to much material is being removed

Rusty,
Thanks.
Posts based on experience, calculations, or data are rare on the internet.

quote:

Margin

The unrelieved part of the periphery of the land adjacent to the leading edge.

It is easier to find a diagram of a drill.

The only times I have experianced bad chatter it was traced back to the reamer. Sometimes they just don't get ground right but without a comparator you can't tell by looking. Also new reamers usually take a little time to settle down. I chamber as fast a 200 rpm while flushing coolant down the barrel. When there is chatter the resonance increases with rpm and there seems to be a point where it usually settles down. More often than not speeding up helps more than slowing down. A loose pilot can also be the culprit. But..the only times I have not been able to stop the chatter I was using brand x reamers instead of my usual.

I just chambered a 280 Ackley last night, and the last time I used the reamer I experienced A LOT of chattering... that was also my first chambering job I've done (7 years ago now I think). If I remember right I used paper towels and a lot of lube and feed to get rid of it last time. And my set-up was poor at best.

Step up to last night, I pre-bored the chamber and right off it chattered a little bit. I fed hard and fast at 175RPM and the chatter disappeared. It never came back and the reamer cut perfectly. I was about ready to borrow a friends reamer as I thought this one may just be crap, but it turns out it's just experience and knowing what in the hell to do! I'm no pro, but I have chambered 30+ barrels in the last 6 months and can say I haven't had any problems with reamers chattering if the set-up is correct. It seems to me the better dialed in the barrel is before chambering, the smoother it cuts and less problems you have. I've gone to dialing in the bore where the throat of the cartridge will be along with the muzzle, and then drilling and boring at least some of the chamber area away. Since doing that and using a bald eagle floating reamer holder (pusher really), my chambers are turning out great IMO.

quote:

Originally posted by matt salm:
I've gone to dialing in the bore where the throat of the cartridge will be along with the muzzle, and then drilling and boring at least some of the chamber area away. Since doing that and using a bald eagle floating reamer holder (pusher really), my chambers are turning out great IMO.

Don't spend too much time worrying about the alignment of muzzle end of the bore when setting up to chamber. Concentrate on dialing in the area where the throat will sit. If the throat is centered, then anything beyond the throat won't matter because there is nothing you can do about it.

Concentrate on the muzzle when you set up to cut the crown. BTW, I use the Bald Eagle floating reamer holder myself. It does work good!

Westpac,
The only reason I dial in the muzzle (bore) true is to minimize needing to index the barrel to 'point' up at 12:00. Otherwise I did play around with getting the bore itself to run true for the first 4" or so on the chamber end and let the muzzle go where ever. That seemed to turned out a great chamber also, but then I would index the barrel tenon so the 'curve' would point up at 12:00 and that was more dink'n around that I really wanted for no appreciable gains as far as accuracy. For long range rifles I still go with that method as I figure the chamber/throat is just as good, but I get extra elevation (however minimal) out of it.

One other question for you since you do use that bald eagle holder, if needing to use a throating reamer for a special chamber, do you use the holder or something else? Although it shot well enough, I used a throater on a 6BR and really didn't like the 'feel' as it is such a light 'whippy' cut. Almost feel as though supporting a throater with a live or dead center might offer a cleaner cut, although I haven't played with that yet.

quote:

Originally posted by matt salm:
Westpac,
The only reason I dial in the muzzle (bore) true is to minimize needing to index the barrel to 'point' up at 12:00. Otherwise I did play around with getting the bore itself to run true for the first 4" or so on the chamber end and let the muzzle go where ever. That seemed to turned out a great chamber also, but then I would index the barrel tenon so the 'curve' would point up at 12:00 and that was more dink'n around that I really wanted for no appreciable gains as far as accuracy. For long range rifles I still go with that method as I figure the chamber/throat is just as good, but I get extra elevation (however minimal) out of it.

One other question for you since you do use that bald eagle holder, if needing to use a throating reamer for a special chamber, do you use the holder or something else? Although it shot well enough, I used a throater on a 6BR and really didn't like the 'feel' as it is such a light 'whippy' cut. Almost feel as though supporting a throater with a live or dead center might offer a cleaner cut, although I haven't played with that yet.

I use a lathe dog to hold the throater and I use the ball end of the Bald Eagle adapted to keep it centered.