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HUGE Thread on Preventing Chatter

INTJ

There isn't one, unless this one becomes that. There are lots of threads all over the Internet about how to stop chatter when it starts. Chatter is basically vibration/harmonics, and we fix it by doing something different: speed up, slow down, tighter busing, wax paper, etc.

The consensus seems to be chatter is just part of chambering life and we just need to deal with it. However, what about setting things up as much as possible to prevent it from happening?

So what approaches do you use to prevent chatter?
 
Dusty Stevens said:
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
Click to expand...

Before this thread turns into monkeys throwing poop at each other, would you call "5R runout", "Chatter"?

I see runout and chatter as two different problems.
 
I'm just a dummy who likes shiny things but here's how I see and understand it:

Chatter - Creates a poor surface finish. You can usually hear (or feel) it. If it's a low tone... speed it up. If it's high pitch... slow it down.
Runout - Round tool creates not round hole. Caused by deflection, machine, or poor setup.


I have a carbide reamer that can really easily sing like a choir... but makes a beautiful and perfectly round chamber... just to complicate the conversation.

Go on. I look forward to this being 72 pages long when I wake up.
 
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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.
 
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Chatter is when a tool is not cutting smoothly and evenly. It is 'skipping' as it cuts. Caused by tool or work deflection, not proper feeds and speeds, not a ridgid set-up, or maybe the tool is "too sharp". After sharpening a dovetail form tool, we'd run a fine India stone across that fresh edge to dull it just a little. Otherwise, the first few pieces would show chatter. Run-out simply means not concentric.
 
shortgrass said:
Chatter is when a tool is not cutting smoothly and evenly. It is 'skipping' as it cuts. Caused by tool or work deflection, not proper feeds and speeds, not a ridgid set-up, or maybe the tool is "too sharp". After sharpening a dovetail form tool, we'd run a fine India stone across that fresh edge to dull it just a little. Otherwise, the first few pieces would show chatter. Run-out simply means not concentric.
Click to expand...

All my instances of chatter have happened with brand new JGS reamers. @Alex Wheeler says they are sometimes too sharp.
 
LVLAaron said:
What exactly did you have? Runout, or what a machinist would call chatter? (what is a 5r barrel?)
Click to expand...

It was more tool deflection in the 5R throat initially. The second time it was real chatter that left ridges on the shoulder and made a screaming sound.
 
JGS reamers tend to be "too sharp". When I get a new JGS reamer, the first time I use it I don't drill/pre-bore. I can tell right away if it's going to chatter. If it is, I stop and run my fine ceramic stone lightly across the cutting edges that cut the shoulder. When I start cutting again, I increase the feed rate. 99.9% of the time, that'll cure it. I haven't noticed that condition with Manson or Clymer reamers. Could be tool geometry (clearance and rake).
 
shortgrass said:
JGS reamers tend to be "too sharp". When I get a new JGS reamer, the first time I use it I don't drill/pre-bore. I can tell right away if it's going to chatter. If it is, I stop and run my fine ceramic stone lightly across the cutting edges that cut the shoulder. When I start cutting again, I increase the feed rate. 99.9% of the time, that'll cure it. I haven't noticed that condition with Manson or Clymer reamers. Could be tool geometry (clearance and rake).
Click to expand...

What grit? Do you have a link to your stone?
 
INTJ said:
It was more tool deflection in the 5R throat initially. The second time it was real chatter that left ridges on the shoulder and made a screaming sound.
Click to expand...
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.
 
Imma post the picture again. No clue why it did it. No clue how to stop it- not a machinist. I put the blue mark on there to see if it was moving- it wasn’t. I’m an idiot with a lathe in a converted 3rd car garage. Not a professional. Cleaned up with wax paper. This was a Manson. Oddly enough, I did another one with a JGS and it was glass smooth. Both with floating reamer holder- which may have been part of my problem. Who knows? I just keep making chips and turning 33” blanks into SBRs.

D6D63475-E991-495B-B88E-549332E73F11.jpeg
 
This video shows a parting tool in the beginning stages of chatter. I normally am able to feed the tool much harder, but I was filming with 1 hand and my wrist got bound up after the initial cut started and again 5 seconds later. You can hear the chatter just barely starting because the tool is rubbing and being pushed out of the cut. I normally feed hard enough that it pulls a solid spiral curl with zero chatter. This is a "feeds and speeds" issue in the video.

It's not really the same as reamer chatter though. I've only encountered "true" chatter twice in about 500 barrels. Once when I tried to start a reamer without the pilot engaged and again on a long .338L where I kept preboring ahead and never let the neck cut until the vary end.

Somebody once told me that if you count the number of chatter marks, it will always be 1 less than a dividend of the number of reamer flutes. I don't know if that's true or not, but I do believe that when you use wax paper, only 1 flute cuts through effectively turning the reamer into a single point tool.

 
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