HUGE Thread on Preventing Chatter

[shortgrass]

What grit? Do you have a link to your stone?

No link. Probably had that stone for 25-30yrs. Most likely got it from J&L or MSC, maybe Enco. It's just your simple 3 corner, fine, white ceramic stone, about 6"L.

 

[Dusty Stevens]

What grit? Do you have a link to your stone?

 

[INTJ]

Boom. Two different problems. The first… pre-bore the lands. Run a borescope up the barrel and align your cutter. Pull 8 thou out up to the top of the neck.

That is Gordy's method to bore out the lands in a 5R.

 

[Carl S]

If everything is running true and inline.feeds and speeds correct,lathe and set up is rigid not normally an issue.reamers can be to sharp and uneven once one flute digs in chatter and ridges occur.i think prebore and remove as much material as possible..less work for the reamer to do.use plenty of cutting oil.

 

[std7mag]

Never heard of the wax paper method.

While not gunsmithing, we usually have chatter issues at work when using a 1.25" ID groover with 0.125" wide carbide insert.
We have changed feeds & speeds quite a bit.
And a quick pass with a fine diamond file on a new insert helps.

One thing i've started doing is checking the print for the part & shortening the length the groover sticks out of the holder till i only have 0.125" clearance from the part to the back of the furthest groove.

High production setting with CNCs running coolant, not oil.

 

[boltfluter]

Should be an interesting thread. Any insert, reamer, or cutter can definitely be to sharp at first. I have one particular insert that I use for fluting that cuts beautifully at the start of the flute, but chatters at the end of the flute. Once the initial sharp edge dulls a little it works great at both ends. Every speed and feed has been tried to eliminate this phenomenon. Only the slight dulling of the edge fixes this. Fun times, not!! Lol.
Paul

 

[Carl S]

Slightly off the chatter issue.if one fitts a new horizontal band saw blade for cutting steel its to sharp-run it in,cut a few discs of a 50mm mild steel bar.just to take that sharp edge of.it will last twice as long.just like a reamer to sharp in some cases.

 

[Alex Wheeler]

All my instances of chatter have happened with brand new JGS reamers. @Alex Wheeler says they are sometimes too sharp.

I have only had actual chatter in a chamber once, it turned out to be the reamer. I could not fix it so i set it on the shelf .250 short on headspace and ordered a JGS reamer. When it came in, everything went back to normal. Some reamers are ground too aggresive in my opinion. Not JGS though. I will normally cut the whole chamber with a new reamer to knock the edge down. Not because of chatter but because they want to cut fat when super sharp. I hate floating reamer holders, i suspect thats the root of the problems. The 5r thing is not chatter and is dealt with in different ways.

 

[WSnyder]

All my instances of chatter have happened with brand new JGS reamers. @Alex Wheeler says they are sometimes too sharp.

I always cut a test chamber with a new reamer just for that reason. Over the years I have seen several reference running an old real copper penny down the flute to clean up the edge on a new reamer. I've never done that so can't comment.

I step bore and start a chamber with a center and switch to a pusher pretty deep into the chamber.

 

[skeeljc]

Maybe we should add preferred reamer holder to this discussion?

 

[WSnyder]

Maybe we should add preferred reamer holder to this discussion?

Homemade "Bryant" pusher. I have a cool holder made by Bill Myers that works fine but I seem to prefer the simple pusher made from a Sinclair neck turning case holder. Bill's contraption is kind of a hybrid between a pusher and a floater. I'll take a picture later and post it. He was selling them commercially at one time through Brownells I think. He made me one and sent it to me quite some time ago before he passed. That guy was full of cool ideas and made lots of great stuff.

 

[X Count]

It would be really cool if guys could post what they do to keep from getting chatter.

Today I had chatter. Cartridge is a 6mm SAUM IMP with a .220 throat. I stopped with about .300" remaining as usually to take a peek with the Hawkeye borescope. I had a little chatter in the throat, as we can get with a long skinny throat. By using the @DaveTooley wax paper approach--actually, thin waxy coffee filter paper, I cleaned up the chatter. I then cut some more without he paper and it sang--ridges on the shoulder and all.

Well now I was .030" from final headspace. So I wax papered up again and cut .020". It worked. The only chatter left was a little at the front of the shoulder. I made the final pass with wax paper. I didn't use the flush, though I did fill up the barrel and then shut it off. It cleaned everything up and I hit my headspace.

So I patted myself on the back for fixing that. My bosses background is troubleshooting issues with high end coaches, and he thought that getting reamer chatter with 4 of the 14 reamers I have used over the last few months was a red flag. He wondered if we could do something different to stop chatter before it started.

I haven't seen THAT kind of discussion before. I only see how to fix it once it starts.

A 6mm SAUM imp with a .220 throat. The pilot is small and a long way from that large diameter body. Reamer itself is probably flexing.

How many issues have you had with something like a standard .308 where the pilot is relatively large compared to the case body and the reamer is fairly short and rigid?

 

[INTJ]

A 6mm SAUM imp with a .220 throat. The pilot is small and a long way from that large diameter body. Reamer itself is probably flexing.

How many issues have you had with something like a standard .308 where the pilot is relatively large compared to the case body and the reamer is fairly short and rigid?

Since the weird looking cuts on rifling aren't considered chatter but reamer deflection, I guess I have only had chatter with the 6 SAUM IMP and one other that I can't remember. That's out of 50 chambers cut so far. I have had the reamer deflection issue on the 6 SAUM IMP, 6 Dasher with a .250 throat, a 300 Norma, and a 375 CheyTac.

The 300 Norma didn't even cut a full chamber. We happened to have two 300 Norma reamers and when I swapped reamers it fixed it. I never did get it fixed on the CheyTac.

Interestingly, I sent the Norma and CheyTac reamers back to JGS, and they just got back to me. They said that both reamers were so worn that they needed to be resharpened.

Is it possible to dull a reamer with one use on a new barrel, with a flush, and chambering at the 200-300 RPM range that JGS recommends?

 

[Dusty Stevens]

Since the weird looking cuts on rifling aren't considered chatter but reamer deflection, I guess I have only had chatter with the 6 SAUM IMP and one other that I can't remember. That's out of 50 chambers cut so far. I have had the reamer deflection issue on the 6 SAUM IMP, 6 Dasher with a .250 throat, a 300 Norma, and a 375 CheyTac.

The 300 Norma didn't even cut a full chamber. We happened to have two 300 Norma reamers and when I swapped reamers it fixed it. I never did get it fixed on the CheyTac.

Interestingly, I sent the Norma and CheyTac reamers back to JGS, and they just got back to me. They said that both reamers were so worn that they needed to be resharpened.

Is it possible to dull a reamer with one use on a new barrel, with a flush, and chambering at the 200-300 RPM range that JGS recommends?

Ive seen a lothar barrel smoke a reamer in half a chamber

 

[INTJ]

Ive seen a lothar barrel smoke a reamer in half a chamber

These were benchmark stainless barrels, 416
I think. I wouldn't be surprised having issues with LW-050.

 

[jackieschmidt]

If you even slightly detect chatter, stop and change something. If it gets too far you wont recover if the case has pretty straight walls

It might even be too late then.
reamers have a terrible habit of following what ever is there.

 

[INTJ]

So is the only way to prevent the non-straight cut rifling to bore out the lands in the throat?

 

[LVLAaron]

So is the only way to prevent the non-straight cut rifling to bore out the lands in the throat?

A 5 flute reamer would the best... The deflection happens because of uneven pressure on the reamer. If you had a 4R or 6R barrel, the "problem" wouldn't exist.

It takes 5 extra minutes to bore the lands out... but you can never bore the leade/ramp part of the lands...

 

[INTJ]

A 5 flute reamer would the best... The deflection happens because of uneven pressure on the reamer. If you had a 4R or 6R barrel, the "problem" wouldn't exist.

It takes 5 extra minutes to bore the lands out... but you can never bore the leade/ramp part of the lands...

I also see some interesting shaped rifling in six groove barrels. It's almost trapezoid shaped. I guess that occurs mainly in button barrels. That makes uneven rifling ends as well.

 

[Dusty Stevens]

It might even be too late then.
reamers have a terrible habit of following what ever is there.

I have found if i still have quite a way to ream, sometimes i can give er a strong feed then back it off quick itll cut and get rid of the chatter