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Rings in Chamber

gremlin-garage

Aluminum
Joined
Dec 8, 2006
Location
Spring,TX
What causes these rings? Both chambers are just about dead nutz according to the SAAMI drawings that I have. I tried to polish them out with flitz but I can still feel ridges with the wood end of a cotton swab. I did one chamber and was not happy with it, so I cut it off and started over. I didn't like the second one either so I cut it off also and decided to mill them in half for inspection. PTG reamer, dark thread cutting oil, cleared chips about every.025"
th_chamber2_zps300aed35.jpg

th_chamber1_zpsb94162a8.jpg
 
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Gremlin,

Hold down your Ctrl button and hit the ++++++. About 8 times gives me the max on my puter. Closer pics would be better cause it loses definition when blown up.

Ben

On edit, Ctrl and zero button brings it back to original. It works quicker than ------
 
Gremlin,

Hold down your Ctrl button and hit the ++++++. About 8 times gives me the max on my puter. Closer pics would be better cause it loses definition when blown up.

Ben

On edit, Ctrl and zero button brings it back to original. It works quicker than ------

Neat tip I never knew that....:)

Charles
 
I have heard that high volume chambering machines flushed oil from the muzzle end of the barrel, like thru coolant in reverse, to fluch the chips out the back... have not seen one in person.
 
I have heard that high volume chambering machines flushed oil from the muzzle end of the barrel, like thru coolant in reverse, to fluch the chips out the back... have not seen one in person.
I have heard of these also....However, this does not answer the original question.
 
If these are ridges and not grooves.
Maybe not enough coolant, work hardening small lines when stopping and not withdrawing quick enough to clean. You can get weird spots on the outside if you stop feeding, why not the inside. Just a guess as the ridges aren't in the same place on the different chambers.

If they are grooves my guess would be chips causing it.

Ben
 
Are you flushing the chamber, the reamer or just one? What RPM are you turning the barrel when you're reaming?

Can you take a high res picture of your reamer flutes?
 
Ok, I blew it up and it looks like you are not getting the chips out of the way and dragging them. If the reamer is dull it might do that too.

Ben
 
I cut about .025", blow all the chips out of the chamber and off of the reamer, squirt some oil in the chamber and coat the reamer, and repeat. Rpm was 80, I tried some other speeds but it didn't seem to change much. The reamer was new and that was the first time that it had been used.

If I'm not getting the chips out, how often do I need to take the reamer out to clean it? I'm only cutting .025" at a time.
 
Poor pictures, but it looks like a very slow reamer feed rate. Put the object to be photographed on a solid area with the camera on a tripod. Shut off the flash and focus and shoot. If its a digital camera set it to auto and shut off the flash. Load the picture into Microsoft Paint and then save the image as a JPG type photo. Then load it as an attachment here. They have to be JPG or other compressed format.

You should be taking up to .050 inch each time if you are not using power oil and driving the reamer pretty hard. .005 to .010 inch per second at 100 RPM with a modern reamer or faster. I would drive no faster than 100 RPM if you are new to chambering or are using a floating reamer holder. Even with the poor pictures it does not look so bad. Did you burnish with 320 wet and dry paper on a dowel after?

You may be seeing more than there is. You have to fire a couple cases after you cut the chamber and see what is imprinting on the case. I would have lightly polished what I'm seeing with 320 wet & dry and kerosene and shot it. I think it would have been just fine. Chambers are not supposed to be mirror finishes.
 
Speerchucker,
yes the pics do look pretty poor. But I can asure you that they did not before I posted them. They were taken on a tripod, without a flash, long shutter time, remote shutter release, and a macro lens. They were very sharp and filled my 22" monitor with plenty of detail. They didn't look like something I would hang on my wall but they were plenty good for this investigation. That is up until I linked them here to the forum. I did it the same way that I have always posted pictures except these got tiny and look like crap now.

So your saying 5-10 thou per second at 100 rpm. I think i have been advancing the reamer a bit slow thinking I would get a better finish. I think I should be a able to get a very smooth finish without having to use sand paper afterwords. At the very least feel smooth but not necessarily look pretty.
 
You can slightly ease off the cutting pressure if you like but do not withdraw the reamer until the barrel has stopped rotating. If you even slightly withdraw the reamer while running you can trap some swarf and score the chamber. This assumes that you have already had a very hard look at your reamer.
Mike
 
Reamers, in general, want to be fed about twice the feed rate of a drill, at less than half the RPM. Don't ever turn a reamer backwards. I extract my reamer while the barrel is still rotating. I just pull off the feed and come straight out, or I ease up on the pressure and wait until the barrel stops turning as Mike suggests. My choice is dictated by how the reamer "feels" in the cut. Some reamers and some steels cut wonderfully and I don't worry about the reamer being hard to remove from the bore. Others... well, that's when I get the reamer out of engagement while the barrel is still rotating.

I do my chambering around 90RPM (or thereabouts) and when I clean out the chamber, I blow the chips from the muzzle towards the working area. I want the chips out of the "new" portion of the barrel, so I don't hang up the pilot on the reamer. Then I want the chips out of the area being reamed. I use brake cleaner or something similar to flush the chips towards the tailstock, followed by air.

OK, then as for lube: I like to use a lighter lube, with the idea that heavy sulphur cutting oil seems to retard chip removal from getting out the flutes of the reamer.

Before starting a chamber, I always examine the reamer closely, while wearing a opti-visor or a set of reading 2+ glasses. I'm looking for nicks, dull edges, problems with the pilot, etc. To start chambering, I'll use a twist drill about 0.070" under the diameter of the front shoulder, and then a boring bar set on the case taper to hog out most of the chamber area up to the shoulder - say within .040" diameter. On larger calibers (eg, .35 or larger) with .473 case heads, you might not need to do this, but I find it helps with smaller calibers - eg, 7mm or less with a .473 case head.

To clean off the reamer, I dunk it in naptha. Sometimes I use naptha to thin out cutting oil for lube, if I don't have light cutting oil available.
 
mf205i and wyop,

That's the kind of info I was looking for. thanks

I have been removing the reamer while the barrel is still turning. You said just ease up on the pressure and wait for the barrel to stop turning. I don't know how easy other reamers cut but this one requires zero effort. The tailstock hand wheel turns like there is nothing there so I'm not sure how to judge the pressure.

I didn't pre bore the chamber before reaming, thats probably a good thing to do. It should reduce the amount of chips during each progression of the reamer.
 
You have chip weld at the shoulder edge of the reamer or swarf build up due to lack of cutting edge relief and lack of cleaning during reaming process.
Nat Lambeth
 
That could be but my thinking is he is not feeding fast enough or long enough. When roughing, I normally take about .100-.125" per pass and at about 150rpm, faster is better. Remmeber, all dark cutting oil is not the same. Get some of the Rigid, it works. I had a problem with what I thought was "black" cutting oil, it ain't the same.
 








 
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