CNC Setup??

jackie schmidt

jackie schmidt

New member
In another thread, we were discussing setting up a barrel in a CNC machine to do the operations, i.e., truing , chambering, facing, etc.

I am yet to see an article explaining how they Machine trues the lands and grooves in a specific spot to within .0002 so that all other subsequent operations run dead true with that spot.

Anybody have an article or a link?
 
there is an ar builder for dcm/cmp type shooting, in fla that uses a machine center,
but they are not in the br accuracy game, not even close.
 
jackie schmidt said:
Is there a video on TouTube showing the complete procedure?
Click to expand...

I don't think so.

I've thought about getting a GoPro camera and doing a time-lapse video from inside the machine showing my process start to finish. I'm a little hesitant to do so because part of what I do is unique to myself. I spent a lot of time developing it and building the tooling and I think it would be showing my hand to the competition. I guess the chuck end is nothing special, I could do that and omit my secret sauce at the other end.
 
R Stiner said:
Jackie

I'm not sure if this is what your looking for! take a look at these two videos might give you some ideas or answers.

https://www.youtube.com/watch?v=RKvEf8MwnoE

https://www.youtube.com/watch?v=s4xEo5GcXHk


Russ
Click to expand...

The first one was right on. Of course, to accomplish this, you have to have the True Bore Aignment Chuck, which is a really nice piece. I have thought about getting one.

How does one accomplish this type alignment without this particular style of Chuck in a CNC machine.?
 
CNC only controls the tool path. Positioning the work piece is another effort.

We have taken workpieces with integrate bores like a rifle chamber and used solid carbide boring tools to successfully machine comple bores as small as, say, a 22 K Hornet chamber.


.


.
 
indicate chamber.JPGindicate muzzle.JPG
I use gage pins on the muzzle these days.
For shorter barrels I have bushing that go inside the spindle. That can drive you nuts thinking about the best way to do that. I'll just say there are times when theory says to do it one way but in practice it doesn't help. So simple is better.
 
Last edited:
Yrs ago

10 15 yrs ago i had taken a barrel to county work shop to chamber it in a few seconds it was done all but chamber by cnc bill brawand
 
I watch a guy

in Huston who has several big turning centers who does all sorts of parts, midsize through monster and he trues everything the same way we all do. He has probes and all but mostly he is 4 jawing it.

Pete
 
I have a way of holding the muzzle bore concentric to a plug that fits tightly in my spindle bore. This centers the muzzle and also is the coolant connection. The muzzle is attached to this plug and the barrel is put in the spindle from the back side. I then close my collet chuck on the shank. The throat is nearly always within a thousandth or two at this point. I then adjust the chuck like a set-tru to get the throat dialed in. I start with a “Grizzly” rod then verify with a long reach Interapid DTi. Once that is dialed in, I lock down the chuck adjustment screws, set my Z zero and run the program.

When the program is finished, I remove the barrel and have a way of holding the freshly machined chamber end in a plug that fits snug in the spindle bore. I attach the barrel to it, stick it in the spindle from the rear, close the chuck on a tapered collet adapter, dial in the muzzle, set my Z and run the muzzle program.
 

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Phew!

Rubicon Prec. said:
I have a way of holding the muzzle bore concentric to a plug that fits tightly in my spindle bore. This centers the muzzle and also is the coolant connection. The muzzle is attached to this plug and the barrel is put in the spindle from the back side. I then close my collet chuck on the shank. The throat is nearly always within a thousandth or two at this point. I then adjust the chuck like a set-tru to get the throat dialed in. I start with a “Grizzly” rod then verify with a long reach Interapid DTi. Once that is dialed in, I lock down the chuck adjustment screws, set my Z zero and run the program.

When the program is finished, I remove the barrel and have a way of holding the freshly machined chamber end in a plug that fits snug in the spindle bore. I attach the barrel to it, stick it in the spindle from the rear, close the chuck on a tapered collet adapter, dial in the muzzle, set my Z and run the muzzle program.
Click to expand...

What have you saved? Other than being able to do the workon the machine you have?

Pete
 
Jackie

Man clled for 25 cal blts later he called said first grp 110 chambered with cresent wernch invice friend put on threads bill brawand
 
Pete Wass said:
What have you saved? Other than being able to do the workon the machine you have?

Pete
Click to expand...

Time. I’ve saved a ton of time. And I’ve added amazing surface finishes, incredible repeatability and features such as blunt start/Higbee threads that are unrealistic on a manual.
 
Pete Wass said:
What have you saved? Other than being able to do the workon the machine you have?

Pete
Click to expand...

Pete,

Manual or CNC, setting up a barrel for chambering is pretty much the same and is done manually. I am not aware of any way to throw a barrel in a CNC lathe and have it dial in both ends of the barrel...the man running the machine has to do that.

Where the CNC machine is gonna shine is once the barrel is properly set-up, the subsequent operations of machining the barrel tenon and crown is going to happen ALOT faster than it would on a manual machine. It might take me an hour to machine and thread a barrel tenon, where Rubicon or Dave Tooley can do it in 5 minutes (a guess) on their CNC lathes. And since these guys chamber rifles for a living, CNC makes total sense as time equals money. I can guaran-damn-tee you that Dave Tooley couldn't chamber 50 barrels during a normal work week using a manual lathe like he can using his CNC lathe.

Rubicon's talk of plugs to capture the muzzle and chamber are his work arounds for dealing with a headstock spindle that is longer than the barrel. Anybody who has chambered on a lathe with a long headstock spindle (Tooley, Jackie, me) has come up with something similar.


Dave Tooley and Rubicon,

Now I'm curious...what are your run times for machining a barrel tenon?

Justin
 
Zebra13 said:
Pete,

Manual or CNC, setting up a barrel for chambering is pretty much the same and is done manually. I am not aware of any way to throw a barrel in a CNC lathe and have it dial in both ends of the barrel...the man running the machine has to do that.

Where the CNC machine is gonna shine is once the barrel is properly set-up, the subsequent operations of machining the barrel tenon and crown is going to happen ALOT faster than it would on a manual machine. It might take me an hour to machine and thread a barrel tenon, where Rubicon or Dave Tooley can do it in 5 minutes (a guess) on their CNC lathes. And since these guys chamber rifles for a living, CNC makes total sense as time equals money. I can guaran-damn-tee you that Dave Tooley couldn't chamber 50 barrels during a normal work week using a manual lathe like he can using his CNC lathe.

Rubicon's talk of plugs to capture the muzzle and chamber are his work arounds for dealing with a headstock spindle that is longer than the barrel. Anybody who has chambered on a lathe with a long headstock spindle (Tooley, Jackie, me) has come up with something similar.


Dave Tooley and Rubicon,

Now I'm curious...what are your run times for machining a barrel tenon?

Justin
Click to expand...

CNC or not...good machine work starts with a good setup, before the tool meets the metal.
 
Zebra13 said:
Pete,

Manual or CNC, setting up a barrel for chambering is pretty much the same and is done manually. I am not aware of any way to throw a barrel in a CNC lathe and have it dial in both ends of the barrel...the man running the machine has to do that.

Where the CNC machine is gonna shine is once the barrel is properly set-up, the subsequent operations of machining the barrel tenon and crown is going to happen ALOT faster than it would on a manual machine. It might take me an hour to machine and thread a barrel tenon, where Rubicon or Dave Tooley can do it in 5 minutes (a guess) on their CNC lathes. And since these guys chamber rifles for a living, CNC makes total sense as time equals money. I can guaran-damn-tee you that Dave Tooley couldn't chamber 50 barrels during a normal work week using a manual lathe like he can using his CNC lathe.

Rubicon's talk of plugs to capture the muzzle and chamber are his work arounds for dealing with a headstock spindle that is longer than the barrel. Anybody who has chambered on a lathe with a long headstock spindle (Tooley, Jackie, me) has come up with something similar.


Dave Tooley and Rubicon,

Now I'm curious...what are your run times for machining a barrel tenon?

Justin
Click to expand...

I'm running an Aloris tool post on my Haas so I have to work a bit harder. Machine cycle time for most chambers, turn (maybe twice), chamfer ( maybe twice), thread relief groove(maybe), thread, rough chamber about 5 minutes. Thread muzzle less than 2 minutes run time.
We all have our own bag of tricks to deal with physical limitations of our equipment. We make it work.
 
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