Chambering----lubing, pushing, cleaning

[Lucky Shooter]

Increments of push ?

I'm totally manual-----including no power flush.

I've been following the practice of drilling and pre-boring----and know others save time by not
doing all this----but----this works and I have confidence in the results. Not to say I won't someday
get away from this.

I start with .050" reamer advance per step and at some arbitrary point reduce the increment to .025"
per step. When the headspace reading gets less than .025" above the target reading, I try to hit the
target reading with one last pass.

The reamer and hole get cleaned between passes. I spend probably too much time on this clean-up
but there are no chips left in the hole or on the reamer-----guaranteed.

In spite of all this, I still get scratches on the body of the chamber. This scratching occurs with more
than one reamer.

I've been using these chambers as-is with no attempt to polish them out. They indicate to run true to the bore and there is no wobble when the reamer is put back in the chamber.

Would appreciate hearing other methods----power flush is not an option.

A. Weldy

 

[Dusty Stevens]

Sometimes you have to go less- the reamer tells me how much i can feed

 

[PWS]

Depends on the chamber. A .458WinMag chamber is so close to the bore size, it doesn't produce much swarf per unit of advance. 300WSM? Lots of chips as you go forward.

 

[ridgeway]

High PSI flush system is in order. Those chips need pushed out.

 

[Walt Krafft]

Through barrel coolant does not need to be high pressure. The reamer needs to be made or modified so coolant can get past the pilot. A normal coolant pump will then work without making a mess. The reamer will tell you how far to go before removal. Once the pilot clears the bore the coolant flow will wash all the chips from the chamber and reamer. The size of the reamer makes a big difference. 9mm Luger can be done in one pass. 338 Norma Mag takes a lot of bites.

 

[Stan Taylor]

Well if you are at the mercy of doing it the way you're doing and have no way of putting in a flush system ,there's probably nothing wrong with how much you are feeding at a time, but as far as those scratches they're going to be evident in most situations ,that's why I'll buy this belt paper in rolls and tear off a piece and wrap around my split Dowell rod and I'll make a pass to the shoulder and come back out real slow an I'm going to run a patch behind that and back out no scratches.

 

[Danny1788]

I do the same as Stan, but I use a plastic bic pen body with a slit in the middle. Wrap my “oiled” 320grit Emory clothe around the pen and spin the barrel at 360RPM. Normally I call that good. I have done it with 600grit to a mirror polish shine but I feel the 320grit cross hatch pattern grips the brass better. Real life testing proved it didn’t really make a difference, just my test others may have had different experiences with polished chambers.

 

[ridgeway]

I flush mobilmet 766 mixed with ATF. The coolant pump didn't cut it...high PSI makes it work. No mess with my setup. Chambers come out smooth and bright....

 

[Lucky Shooter]

Thanks for all the information. Could it be that I was just obsessing over my work not being very pretty ?

I don't do many barrels per year and most range from the 221 FB up to PPC size.

You guys have given me some things to think about.

A. Weldy

 

[Danny1788]

I use a flush system @ 40psi with a 1hp water pump, not high psi. Using ridged dark sulfur cutting fluid and ATF. Can you explain or show the scratches your experiencing? Maybe that would help?

I get small color rings in my finish, I think it’s from the cutting oil I use. It clearly shows each cut and when I back the reamer out to flush chips out. I have heard a term before called “glaze” I’m assuming this is it, because once I run the Emory clothe in the chamber it’s gone and my chambers are not over sized, maybe this is what you are seeing too?

 

[Walt Krafft]

I use Scotchbrite with a pistol cleaning rod and 22 cal nylon brush to polish chambers.

 

[Gappmast]

I use Scotchbrite with a pistol cleaning rod and 22 cal nylon brush to polish chambers.

That make two of us works great

 

[gme]

what do your chips look like? If you feed the reamer too slow the chips will be very small and be carried between the tool and the chamber wall leaving small grooves

 

[butchlambert]

Gary is right. After a chip got caught between the reamer flute and chamber wall, I no longer move my reamer back until the spindle stops. I also do as Stan does it with 320 and a crosshatch. I do not want a polished chamber.

 

[Lucky Shooter]

Sorry to bail out on this thread-----tempororarily medically indisposed-----whatever that means.

gme---you possibly have the answer to the scratches. I push the eeamer with a floating pusher
and hold the reamer with a T-handle between my thumb and forefinger. I normally feed at a rate
that doesn't make it difficult to hang on to the T-handle.

Will need to watch more closely on the next barrel.

A. Weldy

 

[tobnpr]

The reamer and hole get cleaned between passes. I spend probably too much time on this clean-up
but there are no chips left in the hole or on the reamer-----guaranteed.

Well, ya can't get deep scratches unless there's a chip involved.
Before using a flush system, I never had issues. Dark cutting oil is important far as I'm concerned. I know others use synthetic coolants, but this process isn't about reducing tool wear with coolant. It's about lubricity.

Chamber blown-out with compressed air between passes. Reamer blown off, then sprayed with brake cleaner to get every speck off it.
Be sure to spindle has come to a complete stop before withdrawing the reamer. Be sure not to contaminate your "dip" container also- I used a separate one for chambering. Sprayed the brush with brake cleaner and blew it off before dipping it into the oil to brush on the reamer. No point putting a brush into an oil bottle full of chips and then brushing it on...

Assuming these are minor scratches that come out when abrading the chamber walls (I do as those above- either scotchbrite or emery cloth wrapped around a split dowel- you don't want polished chamber walls as this increases bolt thrust) there's no harm, no foul.

 

[Lucky Shooter]

Dorked up another one-----have been, carefully, backing the reamer out with the spindle turning.

If I were to leave the reamer in the chamber----should I hold the T-hanldle while the spindle winds down---or--should
I release the handle and let the reamer turn with the spindle ?

I was fat, dumb and happy before using a borescope. This is now in the category----if its worth fooling with, its worth doing right.

A. Weldy

 

[msalm]

If you are drilling and pre-boring your chamber you should be able to feed a lot more than.050”, that’s not much for chips. I leave .010-.015” undersized to within .100” of the shoulder and feed to just shy of the shoulder cutting on smaller chambers, probably two to three pushes in long chambers. That last .100” will be a .050, a ,030, and the final to final depth....I try and leave .015-.020” for the final pass. Works for me I guess. This is without a flush system, just a dark sulphur cutting oil with a little MolyD and ATF added.

 

[Will Henry]

I rough with a drill about .015 to .020 under the chamber diameter at the shoulder. I drill to a depth which allows about 1/2 of the pilot to engage at the start. Usually about an inch and an eighth. For cartridges like the 6BR, there will be only one roughing cut. First cut with the reamer will be about a half inch deep. I use Rigid NuClear oil. Pull the reamer, blow out the chips and oil, blow off the reamer. Squirt fresh oil in the chamber and oil the reamer. Next cut will be about 1/4 inch at which time the neck portion will be starting to cut. Repeat the blowing and re-oiling. Once the neck is cutting, cut depth is held to around .200 or so. Once the shoulder starts cutting, feed depth is reduced to around .075" and I like to leave about .025" for the final cut. Before making the final cut, I clean the reamer by stoning the face of each flute with a triangular ceramic stone. Check each eadge with a fingernail. If you feel any catches, stone them off; working on the face only. Unless you are adept at stoning a reamer, you'll want to stay away from the circumference of the reamer.
When cutting chambers for short cartridges with little body taper (like the 6BR), one has to be more careful early on since the reamer won't remove much of a flaw with later cuts. A cartridge like the 6.5x55, with much more taper, is a little better in this regard since it cuts more on the body with each cut.
Anyway, for the final cut, the chamber is cleaned well, some more oil squirted in, and the last .025 is cut. The reamer is fed in much more slowly and not allowed to grab at all.
The finished chamber is blown out and wiped. Polishing is done with Scotch Brite. If the scotch Brite is in the chamber for more than ten seconds, to eliminate any tool marks, the chamber is flawed.
I pull out with the lathe running. Never re-insert the reamer without cleaning the chamber and reamer. WH

 

[DaveTooley]

Everyone should check the face of their flutes for micro chip weld. I've had that happen on several reamers. Probably more that I didn't pick up on. It will be scattered along the length of the body. It's so fine it takes magnification or young eyes to see it. It will ring a chamber. It won't affect performance, just cosmetics but it violates rule #1 DON'T DO ANYTHING TO MAKE THE PHONE RING.