Machining marks on chamber shoulder

[lazyeiger]

I always seem to get circular machining mrks on the chamber shoulder when cutting a chamber. The straight section of the chamber are perfect and smooth with no marks. Is there a way to avoid or correct this. I am using PTG reamers with floating reamer holder 95 rpm and feeding by hand with the tailstock.

Thanks

Jon

 

[Preacher]

Have you looked closely at the leading edge of your reamer ???

 

[lazyeiger]

Have you looked closely at the leading edge of your reamer ???

It has happend with 2 different chambers using 2 different reamers so I came to the conclusion that it is my technique not the reamers?

Jon

 

[WayneShaw]

That's where you'll get most chip-weld on a reamer.

 

[Preacher]

It has happend with 2 different chambers using 2 different reamers so I came to the conclusion that it is my technique not the reamers?
-----------------------------------------------------------
OK then... how far are you running the reamer in until you pull it and clean it ?
I usually check the leading edges really close towards the end with a 10X eye loupe, and only cut about .010 per pass for the last few cuts...
The reamer is trapped in the chamber when your that close, and I doubt technique
will ever change the way it cuts, as long as it's not buggered up...

 

[kendog]

I always seem to get circular machining mrks on the chamber shoulder when cutting a chamber. The straight section of the chamber are perfect and smooth with no marks. Is there a way to avoid or correct this. I am using PTG reamers with floating reamer holder 95 rpm and feeding by hand with the tailstock.

Thanks

Jon

Most tails stocks are too "low geared" for proper feed rate. Find a way to connect your tail stock to the carriage and feed the reamer with the longitudinal feed via the hand wheel.
"Lower the speed, up the feed" is the general rule.

 

[boltfluter]

lazyeiger,

I had the same problem. Finish the last .005 to .010 by hand(machine off) and your problem will be solved. Works great for me. 8)

Regards, Paul.

www.boltfluting.com

 

[X Ring Accuracy]

Are you using a flush system?

 

[kendog]

Some burnishing type marks are quite normal and polish right out when you are done reaming. Is this what you are seeing? Or, are they deep enough to feel when a probe or scribe tip is run over them?

 

[Hal]

Jon

You might try shutting the lathe off before extracting the reamer.

Hal

 

[sailhertoo]

Jon

You might try shutting the lathe off before extracting the reamer.

Hal

Plus 1. Also I cut mine at 190 rpm per Dave Kiffs recomendation. Your only cutting at 95 rpm?

 

[TRECustom]

I haven't done many chambers, but I've had the same problem with Clymer, Manson, and P.T.& G reamers. Good walls, necks, and throats, but light concentric ringing on the shoulder. I look at them with a Hawkeye borescope, and it seems to magnify any imperfection. They have no effect on extraction, don't mark the case shoulder, and some of the rifles shoot sub 1/4 moa, so I quit worrying about them.

Tom