Chambering----reamer advance increments

[Lucky Shooter]

In other threads there have been comments on chip loading and
cutting a smooth throat.

How much do you advance the reamer in each step ?

How much advance when you get to the throat ?

Old timey math tells me that with a Krieger barrel----.003" land height
and a 1.5 degree throat angle on the reamer-----the throat will be approx .115" long.
Hope I didn't screw this up.

What is a good/best procedure for reaming a good throat ?

All replies appreciated.

A. Weldy

 

[Nightraider]

Drill and a boring bar, remove all but about .010" of material. 55rpm feed as fast as the reamer will eat, which you can feel and hear. My first pass on a 6.5cm chamber is 1.2" deep with the reamer. All swarf is practically dust.

 

[Danny1788]

Use a flush system, drill and bore short of the shoulder. With my red neck setup I still take light passes of .050” but I let the fluid clear most the swarf.

 

[Stan Taylor]

Here is a picture of the chambering lathe I use a 300 win mag for example takes me around 15 minutes or so to plunge a chamber take a measurement about .200 short of finish take an set dial indicator proceed fairly slow that last .200 thousands using a flushing system on the reamer I don't pre bore at all finish reamer all the way backing reamer up for flushing going by feel.

 

[GenePoole]

Flush is the way to go. I use flood coolant and could probably cut the bulk in one pass, but I'm still a little scared to try. I will take about 0.250 a pass (2 full turns on the tailstock wheel) and pull back a bit to let the coolant flush out everything. Reamer always comes out clean as a whistle. My system uses a carbonator pump, modified with a smaller spring to lower the pressure to something that doesn't flood the whole shop.

 

[Lucky Shooter]

Flushing sounds wonderful----how about us guys
who only flush in the bathroom ?

Any words of wisdom ?

A. Weldy

 

[GenePoole]

Flushing sounds wonderful----how about us guys
who only flush in the bathroom ?

Any words of wisdom ?

A. Weldy

Before I had the carbonator pump, I used a cheap Lowes submersible fountain pump. Just dropped it into a 5-gallon bucket of coolant mix and ready to go. Chip pan just drains back into the bucket. Not as much flow as the carbonator pump, but easy cheap way to get started. The most expensive part was the Deublin rotary union. About $50 used from ebay. When not using for through-flush on barrels, the same setup works great for general purpose coolant needs.

 

[DaveTooley]

I know this isn't the answer you're looking for but "It all depends"
For the most part I use caliber specific core drills to rough in chambers. Body only. I stop about .040" short. I use a low pressure flush system with oil. Mainly for lubrication but I do get some chip evacuation. I run most reamers at 250-350 RPM's. I feed pretty aggressively until I feel the leade and then the neck start to cut. Then I slow the feed down. Because there is room between the shoulder and the neck for chips I usually push forward until I feel the shoulder make contact. I can feel the chips being rearranged as the shoulders comes together. Then clean, take a measurement and make the final pass.

Back to your question. Rough out as much material as you can. I still rough with a drill bit on occasion. About .020" under shoulder diameter. Stop about .050" short. Bore a short section, maybe .500" to shoulder diameter. This aligns things and also applies support on the body. This can prevent chatter from just the shoulder touching before the pilot enters the bore. Even then you may get some chatter. If no one has told you the age old trick is to wrap the reamer in wax paper then head back in. Might take several passes but has always worked for me. If I'm dipping and spinning I would go maybe .050" once the neck starts cutting. .025" or less on the last pass. I used a pipette to lay down oil in the barrel. If cutting the entire chamber with the reamer then probably .050"-.100".

 

[tobnpr]

using a flushing system on the reamer I don't pre bore at all finish reamer all the way backing reamer up for flushing going by feel.

Stan,

I'm assuming you make a truing cut on the muzzle end, then into the Jacobs collet chuck (my SB is set up exactly the same way)? How are you getting the flush lubricant into the muzzle through the spindle?

 

[Stan Taylor]

Stan,

I'm assuming you make a truing cut on the muzzle end, then into the Jacobs collet chuck (my SB is set up exactly the same way)? How are you getting the flush lubricant into the muzzle through the spindle?

There is a seal at the very end I would have to take apart to explain 100 percent yes the muzzle is square.I will take a pic of the end of machine tomorrow.

 

[Lucky Shooter]

Dave Tooley----thank you for your answer.

Will be back later.

A. Weldy

 

[Walt Krafft]

New barrels, I drill and tap 1/8 npt and screw in a rotary coupling. Cut the thread off when I cut to length and crown. Old Barrels, I make an adapter for the rotary coupling that slides over the muzzle and is secured with an o-ring and set screw. Once you chamber with through coolant you will never do it without it. I use Castrol Syntilo 9974. It is a clear odorless synthetic that is a delight to use compared to the old stinky sulfurized oil.

 

[Lucky Shooter]

Dave, finally made it back.

I learned to chamber through the headstock from the good folks on BRC and use
a floating pusher like Mike Bryant posted on BRC. This seems to work OK and when the
reamer is put back in the chamber, there's a good fit with no wiggle

I do pretty much as you described except I use the tightest fitting bushing all
the way and taper bore. I know I don't have to taper bore but am more comfortable
with it.

I don't understand the why----or why not----for using a smaller bushing and have
seen posts where some remove it completely at the end.

I'd appreciate hearing about how to polish throats.

I certainly appreciate the tremendous amount of knowledge on this forum.

A. Weldy