understanding chambering reamers...

[brian923]

i just have a couple questions about reamers.

1. can finish reamers be used to cut new chambers in Barrel blanks? im guessing they can, but the will dull faster.

2. piloted chamber reamers... are these made so that they can be used with different size pilots for mutiple cartridges? i.e. cut a chamber for a .221 fireball, and then change the pilot to cut a .300 whisper,300 fireball) with the same reamer?

these are gesses, so please dont make to much fun. thanks guys, brian

 

[Eddie Harren]

Brian, one can certainly use a finish reamer to cut an entire chamber. Many smiths use a rougher but just as many don't.
As to live pilot reamers, the removable pilots are used to match the pilot to the bore size as closely as possible. I wouldn't think that any of the 30 cal. pilots, that I have, will even fit on a 224 reamer. If, by some outside chance, you could get a pilot made to fit on the 221 reamer, that would fit a larger bore, you would still have to open the neck dia. as well as throat the chamber. Doesn't seem to be practical to me.

 

[mikecr]

I'm not a machinist, but have designed several reamer sets that have worked well.

The machinist who finished my latest barrels simply drilled a rough chamber. Then with my finish reamer only, he took very little metal in making the final cut. Same with my seater die.
My rough reamer was not used.

My reamer sets have bore pilots for the machinist to choose from for best fit.

 

[Cheechako]

brian

Pilots,bushings) come in different IDs appropriate to the caliber. You'll find that there are 3 or 4 different IDs. Generally, a 22 cal bushing will not fit a 30 cal reamer, for example. Ask your reamer maker what ID he uses for the different calibers. He could grind just about anything that your heart desires but don't expect to take a 22 bushing and use it on a 30 caliber reamer.

And, to get the optimum value from bushings you will need SEVERAL different ODs for a given caliber. Usually in .0002" increments. There is a big investment required for bushings unless you simply get the nominal diameter for each caliber. Then you have, in effect, the same as a solid pilot.

Ray

 

[Rustystud]

Brian:

You have brought up several very good questions. There is both an industry standard and there are independent reamer specs for both the pilot ID,s) and the drive shaft OD,.437). Generally there are 4 or 5 pilot bearing surface OD,s) they are ientified as 0-4. I would suggest you contact Dave Kiff at PT&G or Dave Manson at Manson Precision. Both of these reamer makers are very good about taking time with their customers. According to Dave Kiff I have one of the most extensive selections of reamer pilots in the country. I have approximately 25 pilotes in .0002 increments for each caliber from .17 thru .50. Some calibers such as .22, 6mm, 6.5, 7mm, and .30 I have pilots in .0001 increments. There have been several post lately, primarily on BRC web site saying better chambers can be cut with unpiloted reamers. Those folks who entitled to their opinion,however; I would not agree with them. Neither does Dave Kiff who is the best known reamer maker in the country.

Many folks pre drill and bore their chambers. Others use a roughing reamer. Then others use a highspeed/highpresure flush system and ream with a finishing reamer and a floating reamer holder. With the propper feed and speed along with an extreme presure coolant/lubricant wear on a reamer is minimal. I usually can get several hundered chambers with each reamer sharpening.

Rustystud

 

[tripcrow]

“I usually can get several hundered chambers with each reamer sharpening.”

Rusty, is that normal or is that because of the way you flush and lube during cutting? How long do reamers normally go between sharpenings? How much is taken off when a reamer gets sharpened?

Thanks,
Bill

 

[Rustystud]

Trip:

Reamers have changes in design due to a number of factors.

In the old days reamers were made with 1/2 flutes in other words two cutting surfaces. Today with better materials and cachining we see multi fluted reamers with straight, spiral or helical flutes. Today we see most non comercial reamers made from M-4 or M42 tool steel. Commercial reamers are made of carbide.

The old school of chamber reaming consist of a center to center set up wit a drive dog on one end and the other set up in a steady rest. The set ups were not designed for high speed cutting for a number of reasons. The first being the steady rest contacts were not designed to run stock at high speeds. The second being the set up is not very rigid. Barrels can become very dangerous when turning at high speed. They need to be in a rigid holding situation.

One can set up through a headstock and an out board spider very rigidly.

With the old system one would lubricate with a high sulfer, high animal fat soluable lubricant. Most times the cutting speeds were low,under 50 RPMs) to reduce heat and keep everything from moving away from the original set-up.

Today many smiths set up in the headstock and run higher speeds with flush coolants. The flush coolants are continously flooding and washing away the heat and chips. The coolant that I use is an extreame preasure semi sytnthetic coolant. It nevers gets warmer than the room temperature. I ream many chambers at speeds in excess of 125 RPMS. Today reamers are designed to turn higher speeds and cut more effeciently. When cutting with a lathe speed means heat. Flush coolant keeps the heat down as well as pushing the chips away.

Rustystud