how fast is too fast when chambering

A

AMMASHOOTA

Gary Gruber
i am about to cut a 9.3 X 62 barrel and have noticed on a test run that as i get about 75% toward the end of the chamber i do not have enough torque on my small lathe to cut the remainder of the chamber at 80-100 RPM. i am only cutting about 0.025 before flushing and cleaning.

how fast can i cut without work hardening the barrel?
 
I'd be surprised if you 'could' work harden a piece of 416R while chambering. 416 in it's hardest state isn't hard (by any standard).

About your question, you say you don't have enough torque to do the job at 80-100, but then ask how fast. Are you saying you want to increase the spindle speed? I should think that would reduce the torque, unless you're using some sort of variable speed drive.

Given that you're saying the machine is short on power for this job, I'll just assume it's not a great big machine that would, maybe, handle the higher rpms without chatter. That's the thing you're really looking to avoid. Not so much hardening of the steel.
 
4Mesh said:
I'd be surprised if you 'could' work harden a piece of 416R while chambering. 416 in it's hardest state isn't hard (by any standard).

About your question, you say you don't have enough torque to do the job at 80-100, but then ask how fast. Are you saying you want to increase the spindle speed? I should think that would reduce the torque, unless you're using some sort of variable speed drive.

Given that you're saying the machine is short on power for this job, I'll just assume it's not a great big machine that would, maybe, handle the higher rpms without chatter. That's the thing you're really looking to avoid. Not so much hardening of the steel.
Click to expand...

the reason i mentioned work hardening is because i have done this to a barrel before. several years ago when i was expermenting with lubricants, i managed to select the wrong one and buggered up a barrel and reamer pretty badly because of it. i realize now that it was due to the lubricant. i did manage to finish the chamber, but had to turn the spindle speed up quite a bit to get past the part i (believe) was hardened.
 
4Mesh said:
About your question, you say you don't have enough torque to do the job at 80-100, but then ask how fast. Are you saying you want to increase the spindle speed? I should think that would reduce the torque, unless you're using some sort of variable speed drive.

Given that you're saying the machine is short on power for this job, I'll just assume it's not a great big machine that would, maybe, handle the higher rpms without chatter. That's the thing you're really looking to avoid. Not so much hardening of the steel.
Click to expand...


4mesh is correct. Reducing RPM, if you are doing it with a gear change or belt change, will increase torque (lugging power). For example, without serious calculations, if you are running at 100 RPM then reduce to 50 RPM you will double the torque. If you are reducing RPM by changing the motor speed you will petty much cut the torque in half.
 
I have never understood the 'need' to chamber at higher rpm. I usually chamber about 45 rpm... that's the slowest my lathe will go... I am in no rush... and the finish is fine...
 
Dennis Sorensen said:
I have never understood the 'need' to chamber at higher rpm. I usually chamber about 45 rpm... that's the slowest my lathe will go... I am in no rush... and the finish is fine...
Click to expand...
Dennis, I think some of this high-speed chamber reaming is in search of a speed on some of these ChiCom lathes will not chatter as bad. As you already know, with a variable speed spindle control, you can tune in and tune out some chatter.
 
My question about using a flush system was from my own experience with it, in that when doing a fairly long chamber (along the lines of a 257ACK), the reamer would get real tight towards the end. I used the water soluble oil "mix" as recommended by Tannel, but still had the problem. I could shut off the flush, and go back with dark sulfur cutting oil and the reamer cut fine. Used the same RPM's, changed nothing but the lubricant.

I gave up on the flush system several years ago.
 
Wayne Shaw said:
My question about using a flush system was from my own experience with it, in that when doing a fairly long chamber (along the lines of a 257ACK), the reamer would get real tight towards the end. I used the water soluble oil "mix" as recommended by Tannel, but still had the problem. I could shut off the flush, and go back with dark sulfur cutting oil and the reamer cut fine. Used the same RPM's, changed nothing but the lubricant.

I gave up on the flush system several years ago.
Click to expand...
Wayne, we have used water soluables for years, Cemcool, Cemcut, etc., and none stand up to a good quality sulfuized oil especially on extra low Carbon and carbon free materials.
 
I chamber at 425-475 rpm (which equates to about 55-60 SFM with a .480 OD cartridge-a real good starting point with barrel grade Stainless Steel) with HSS tooling using a 50/50 mix of Marvel oil and Castol Moly D tapping fluid.

No chatters, no rings, no drama. Just perty little holes for bulletz to go into. Feed rate is at .0001"/per tick on the dial and I wiz it along at a pretty good pace.

Good luck.

C

http:
//www.cuttingtoolexpress.com/html/speeds_and_feeds_-_reaming.html

http://www.custompartnet.com/calculator/drilling-speed-and-feed
 
Last edited by a moderator:
NesikaChad said:
I chamber at 425-475 rpm (which equates to about 55-60 SFM with a .480 OD cartridge-a real good starting point with barrel grade Stainless Steel) with HSS tooling using a 50/50 mix of Marvel oil and Castol Moly D tapping fluid.

No chatters, no rings, no drama. Just perty little holes for bulletz to go into. Feed rate is at .0001"/per tick on the dial and I wiz it along at a pretty good pace.

Good luck.

C

http:
//www.cuttingtoolexpress.com/html/speeds_and_feeds_-_reaming.html

http://www.custompartnet.com/calculator/drilling-speed-and-feed
Click to expand...

You are not talking apples to apples. First, a chamber reamer for a 30/06 has about 50 times the cutting tool to workpiece contact area as a 1" straight flute reamer. Second, you are using CNC which has spindle bearings that cost more than a half-dozen ChiCom home-style engine lathes. Third, you can accurately feed-rapid retract-rapid back-feed again with a CNC peck cycle that is not available to the average 12" engine lathe operator.
 
Wells, it sure worked good on the little bamboo lathe that Nesika had when I first started with them. Crazy I know. I said the same thing. No, the early days at Nesika (for me anyway) was a benchtop no name Harbor Freight lathe that Lisa bought for Glen when he first started making actions. The zillion dollar NASA stuff came later.

Work holding and tool holding are the first things to look at. . .

Not trying to be a smert alic, just saying. Get a junk barrel and start playing with different ways to hold onto the thing and different ways to hold onto the tool. Might just be surprised.

DSC_0113.jpg
 
Last edited by a moderator:
JerrySharrett said:
Dennis, I think some of this high-speed chamber reaming is in search of a speed on some of these ChiCom lathes will not chatter as bad. As you already know, with a variable speed spindle control, you can tune in and tune out some chatter.
Click to expand...

you nailed it, however i rarely have had chatter problems with my little lathe and have turned out some nice shooters. this is the longest chamber i have cut. any advice on which hi-sulfur oil?
 
AMMASHOOTA said:
you nailed it, however i rarely have had chatter problems with my little lathe and have turned out some nice shooters. this is the longest chamber i have cut. any advice on which hi-sulfur oil?
Click to expand...

I would guess the hi sulphur oils available today are about the same. In times past I could go to any of the local petroleum distributors, Texaco, Shell, Exxon, etc., and buy a jug or a barrel of it. In todays Eco-freak society I'd say buy what you can get.

In the 1980's we, at Kodak, ran some cutting fluid tests as to best finish, horsepower consumption, users skin reactions, etc and Sun Oil's Sun-E-Cut came out on top.
 
You must log in or register to reply here.
Back
Top