Lathe speed

[DickE]

What is your preferred lathe speed for reaming a chamber(without flush system)?

 

[Nvclay]

When I prebore leaving .030/ side, I use 60 rpm

 

[WayneShaw]

Without a flush, I use dark sulfur cutting oil, and turn around 75 getting started then turn it up to 100 or a little more. You have to pull it out frequently when you are getting close, to clear swarf from the reamer and clear the barrel. I blast the barrel with carb cleaner then blow it all out. Then more oil and repeat. Takes time. But look at your reamer, the flutes in the throat aren't very deep, you need to keep these clear and not build up.

 

[wkdickinson]

Without a flush, I use dark sulfur cutting oil, and turn around 75 getting started then turn it up to 100 or a little more. You have to pull it out frequently when you are getting close, to clear swarf from the reamer and clear the barrel. I blast the barrel with carb cleaner then blow it all out. Then more oil and repeat. Takes time. But look at your reamer, the flutes in the throat aren't very deep, you need to keep these clear and not build up.

I've only chambered one barrel, which was in 308 Win, so I am far from an expert, LOL. The barrel was a take-off Obermeyer that I had on a 308 match rifle, that I shorten by 6" and recontoured. I bought a brand new Manson reamer with the correct size live pilot (Obermeyers are tight). I did not pre-bore the chamber.

I have an old (mid-40's) SB 9" lathe, so I did it between centers, with the steady rest and no flush. I got a lot of good advise from some very generous people on this forum. I ran my lathe using the back gears at about 80 rpm. I didn't have a "floating" reamer holder, so I made a wrench that held the reamer on it's round part, with the handle riding on the compound and used a dead center in the tailstock. I used Viper's Venom (generously donated to me by Viper - great guy!) and only took a 0.020" cut before pulling the reamer back, blowing it off and also blowing out the hole with compressed air. Then I relubed the reamer (I dipped it in the Venom) and made another 0.020" cut. It took awhile, but I never got any chatter and the finished chamber was beautiful.

Very intimidating concept, but in practice it wasn't that hard.

 

[jackieschmidt]

None. I use a 3/8 end wrench and ream by hand.

but then, all the reamer does is establish the final dimensions and finish.

 

[JMA]

None. I use a 3/8 end wrench and ream by hand.

but then, all the reamer does is establish the final dimensions and finish.

Jackie
I assume by "reaming by hand" you mean without the spindle turning?
I found that interesting when I first saw that in the Chambering Prebore Methods thread.
Thank you for all the information and pictures in that thread they were very informative.
John

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[gunsandgunsmithing]

I like to run at about 115rpm

 

[Will Henry]

90 for most stuff. 240 for throaters. I often use Jackie's technique for the last couple of cuts for chambering but always use power for throaters. WH

 

[jackieschmidt]

Jackie
I assume by "reaming by hand" you mean without the spindle turning?
I found that interesting when I first saw that in the Chambering Prebore Methods thread.
Thank you for all the information and pictures in that thread they were very informative.
John

​

As a machinist, I believe that the worst way you can establish a round and truly straight hole in anything is with a reamer.

That is why keep as much of the reamer out of the equation as possible.

Hence, I decide what and where I want to true a barrel up, rough drill and taper bore the chamber so that runs true with my two determined points, and then use the reamer to establish the final size and finish.

By hand reaming that minimum amount, I am in control of anything that can go wrong. I don’t have to worry about heat, chips building up, or any of the myriad of things that can go wrong with a reamer.

I have been thinking about making a video on chambering barrels in a long headstock lathe. I just have to find the time, as it would be fairly lengthy.

 

[hpshooter]

I have been thinking about making a video on chambering barrels in a long headstock lathe. I just have to find the time, as it would be fairly lengthy.

Looking forward to the possibility of this happening. Have read some of your techniques in Butch's compilation of chambering techniques. (that is where I THINK I have seen them). I did an AR barrel in my gear-head Hendey by using a light push fit ring turned to a tight slip fit in the spindle with success. Ring was turned to final diameter on the barrel between centers.

 

[Hal]

Jackie

That would be great if you could share your knowledge from a machinist point of view.

Hal