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

[Scott Harris]

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

It's chatter. What effect will it have? Probably nothing measurable on target. I'd still ask for a new action.

 

[Canadian bushman]

Thread mills leave that finish if they are fed quickly. Its the minor bits of pushoff between the cutting teeth. Slow it down or get a hobb with more teeth.

Mills leave waves lathes make records.

That was a 3fl hobb with 1 active tooth at 6200rpm and 42IPM.

No machine, no tool, no process is perfect. It comes down to how its controlled. Push anything hard enough and things will get weird.

 

[DaveTooley]

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

Mine don't

 

[boltfluter]

Mine don't

Neither do mine. Thread milling can cut some beautiful threads if the set-up is correct. Tucker 65 has it dialed in. Very nicely done.

Paul

 

[Canadian bushman]

Heres another one.

718 Inconel 170ksi yeild
1600rpm 8ipm 4fl 7 active teeth
3/8-24

Same machine, same process, same doofus on the control. Just a little more cautious because matl cost.

 

[Dusty Stevens]

View attachment 1042106 Heres another one.

718 Inconel 170ksi yeild
1600rpm 8ipm 4fl 7 active teeth
3/8-24

Same machine, same process, same doofus on the control. Just a little more cautious because matl cost.

That looks like a tap ran those threads

 

[carlsbad]

I don't think you want to try a tap on 170 ksi inconel.

 

[Canadian bushman]

That looks like a tap ran those threads

Does it?

I used an advent thread hobb.

If you look real close there is an intersecting hole down there, and the thread runs across the intersection.

Youll also notice there is no lead in at the bottom of the thread like a tap would leave.

 

[Dusty Stevens]

Does it?

I used an advent thread hobb.

If you look real close there is an intersecting hole down there, and the thread runs across the intersection.

Youll also notice there is no lead in at the bottom of the thread like a tap would leave.

I was just looking at how the metal was folded kinda at the top of the thread and all the tool marks are going with the threads. Always hard to identify what tool did what.

Ive done a bit of inconel machining. i used a fette thread roller to put external threads on a weld stud for inside ductwork that had corrosive and abrasive dust. But i made millions of them. Had a machine that ran them 24/7 for years on end.

 

[Canadian bushman]

I was just looking at how the metal was folded kinda at the top of the thread and all the tool marks are going with the threads. Always hard to identify what tool did what.

Ive done a bit of inconel machining. i used a fette thread roller to put external threads on a weld stud for inside ductwork that had corrosive and abrasive dust. But i made millions of them. Had a machine that ran them 24/7 for years on end.

How did that thread roller hold up?

Never seen anyone roll thread inconel before.

 

[Dusty Stevens]

It rolled about 5000 then had to swap the rollers around and it got about 5000 more. This was 1/4-20 threads. They had a kind of brown clearish coating on them. Once that wore off you better start planning a replacement. Couldnt get fette to tell me what the coating was but it was some tuff stuff.

 

[Canadian bushman]

It rolled about 5000 then had to swap the rollers around and it got about 5000 more. This was 1/4-20 threads. They had a kind of brown clearish coating on them. Once that wore off you better start planning a replacement. Couldnt get fette to tell me what the coating was but it was some tuff stuff.

Thats a good bit of threading from one tool.

 

[Dusty Stevens]

Thats a good bit of threading from one tool.

It was in a davenport. Seemed like i was changing wheels and loading rod in that thing all day long. Big money maker.

 

[Canadian bushman]

It was in a davenport. Seemed like i was changing wheels and loading rod in that thing all day long. Big money maker.

Those big, quick running jobs get very tedious, but they pay.