CNC or Chatter 12 O'clock or does it matter?

[avidflyer]

Was having a beer with a friend, looking at a new action. He (knowing how anal we shooters can be) pointed out the chatter in the insert. I had noticed it, but always thought that's how high speed CNC work came out. I don't have a ton of experience with CNC work, but the couple barrels I have had done via CNC always have that weird what I thought was CNC markings on the threads. They always seems to have nice crisp high spots and threads but just that chatter look to them.

SO what do the masses think....Is it chatter or my self described CNC markings?

I noticed upon further review that the bolt doesn't close in a (hate to say) perfect 12 O'clock position. More like 11:50 11:55 it canted from straight up and down. Just a little off but noticeable.

 

[sdean]

If that is a Panda then don't pay any mind to all the comments you will read. Call Kelblys and they will know best period..

 

[Dusty Stevens]

I think that is from thread milling. Never seems to be an issue

 

[Cloudrepair]

I think that is from thread milling. Never seems to be an issue

I think Dusty may be right maybe something about insert geometry or single point tool geometry and thread milling.
I'm interested to hear what kelbly says if you call and get an answer.

 

[Dusty Stevens]

I think Dusty may be right maybe something about insert geometry or single point tool geometry and thread milling.
I'm interested to hear what kelbly says if you call and get an answer.

I do know theyve been like that for a long time and it matters none- theyre top shelf.

 

[Cloudrepair]

I do know theyve been like that for a long time and it matters none- theyre top shelf.

I didn't mean to imply anything negative.
I do a lot of thread milling and know it can/will produce high quality threads.

 

[tac284]

Looks like it was thread milled.... at first it seems odd to be done that way when its an insert, but then i wondered if they place the insert in the action body then thread mill them after picking up center line on the bolt raceway. Vertical in a cnc mill...

 

[AndyA]

that makes sense. They probably bore the insert after installation on center and square then thread mill.

 

[Dusty Stevens]

No the inserts are completed off the action then screwed in complete. Its a very nice process. Yall should take a tour if youre ever in north ohio

 

[tac284]

No the inserts are completed off the action then screwed in complete. Its a very nice process. Yall should take a tour if youre ever in north ohio

Well that discredit’s my theory.... that would be nice to have a tour of there facility.

 

[Toolbreaker]

Being thread-milled, I'd guess the finish shown is probably from very minute runout at the cutter. Just depending on inserted, carbide single-form, ect., plus the tool holder. Judging by how the light is reflecting across the threads in the first pic, it doesn't look to amount to much of anything.

 

[Tucker65]

This is what my thread milled threads look like using a Vardex thread milling cutter with a single insert.

 

[Dusty Stevens]

Being thread-milled, I'd guess the finish shown is probably from very minute runout at the cutter. Just depending on inserted, carbide single-form, ect., plus the tool holder. Judging by how the light is reflecting across the threads in the first pic, it doesn't look to amount to much of anything.

You cant even feel it screwing a barrel into it. Just the right light i guess. Once theres grease in there you dont even see it

 

[avidflyer]

You cant even feel it screwing a barrel into it. Just the right light i guess. Once theres grease in there you dont even see it

So lets say it is a thread mill, why do CNC tenons have the same look?

 

[Dusty Stevens]

So lets say it is a thread mill, why do CNC tenons have the same look?

Maybe theyre thread milled on a cnc and you just dont know which one they used? Ive never seen a cnc lathe cut like that but its all in the operator/programmer and tool quality i guess

 

[avidflyer]

Maybe theyre thread milled on a cnc and you just dont know which one they used? Ive never seen a cnc lathe cut like that but its all in the operator/programmer and tool quality i guess

not a great pic but here is what I’m talking about

 

[Dusty Stevens]

That looks like a 3phase machine running on a static converter or too slow on carbide or bad tooling. Is that a pre-fit?

 

[Someoldguy]

There was a fella on here a couple of weeks ago cutting stuff like that on his lathe, but he got upset and took his toys to some other sandbox, I think.

 

[Dusty Stevens]

It happens on some steels. Not a problem at all.

 

[carlsbad]

That is simple, single point chatter. It happens to all of us sooner or later. Once it starts it is hard to stop. As you feed in, the cut is bigger and the tendency to chatter gets worse. It won't hurt anything. I would tighten and loosen the barrel several times to make sure any high spots are flattened out. Use good anti seize.

Harder material is more likely to chatter. I'd rather have good material with slight chatter than soft material with beautiful threads.

Thread mills make perfect threads and can even be very well timed. The only imperfection, besides the cost, is there may be a very slight raised area where the mill stopped. It can be misinterpreted as where the tap stopped in tapped threads, but it won't be deep. It also won't be a problem.

I assume it is CNC. CNC is used for most custom actions. It stands for Computer Numerical Controls. It isn't magic. Then it would be MLC (Magic Lathe Controls). A CNC job is only as good as the tooling and the program. Often you will see perfect CNC work since if you're making a million of them, you take the time to get it set up perfect. It might even be engineered to be easier to machine. For actions made in small lots that likely will not happen.

--Jerry