What's new
What's new

CNC Barrel Work Questions

skeeks

Aluminum
Joined
Sep 8, 2016
I'm looking into purchasing a CNC Lathe to increase production for precision rifle barrel work. I am new to CNC machining and am figuring it out as I go. I am not a machinist, nor do I know much of anything about CNC lathes. I do currently build rifles on a manual lathe.

I am looking at a couple different machines with a Doosan Lynx 220 being the front runner. I'd like live tooling and a tool presetter for future projects. Looking to spend around 15~25k$. What machine would you guys suggest?

Work holding - I'd like to use collets, but I am not sure how this can best be done. I have a couple ideas for traditional methods - 1 being barrel extension and your typical 4 jaw/spider setup. If possible I'd really like to go with collets. Whats the best way to do this? All barrels get dialed into .0000-.0002".

Programming - What do you guys thing (in layman's terms if possible) is the best route to go for cutting different tennons and chambers?
My first through was using CAD/CAM (don't know g-code yet... teaching myself currently) to draw up different tennons and run different programs for different tennons.
My second thought is having someone write me a macro program. I am still very much clueless on macros, but, again, I'm learning as I go. What do you think is the best option here? I taught myself to use Fusion 360 and already have pretty much every tennon that I would need drawn with tool paths as well. I would like to machine the tennon and then the chamber within about 20 thou of finish diameter to save wear on finish reamers.

Work Offsets - What do you think the easiest quickest most repeatable way to deal with work offsets?

Thanks for your time!
 
Collets can get expensive, a six jaw is a good option without having to buy all the collets to cover all sizes. If you're dialling in anyway a collet chuck is probably wasted. Tool paths for tenons and chambering are relatively simple and should be easy with the lathes conversational programming, it certainly is with Siemens. CAD/CAM, G-code or macros should not be needed. As for offsets, dead simple too; just put the barrel in the chuck, skim the face of it and set the Z offset without moving the tool.
 
Last edited:
I've been using a HAAS TL-1 since 2009 and have chambered over 7,000 barrels on it. I've been using the conversational program exclusively. Chambering barrels is simple work. For a one off it takes me maybe 10-15 minutes to build the program. When doing barrels in quantity it's takes less than 20 minutes a chamber. I use a tool post on mine. All I do on that machine is chamber work.

Dave
 
I hand write all my programs. I do a lot of cut/paste with proven programs to modify the tenon length, chamber prebore dimensions and reamer parameters. The problem I have run into now is my machine memory is full and I am constantly deleting programs I don't think I'll use again. I still have them backed up on my computer, but it is always a warm fuzzy to have a proven program in the machine.

I haven't completely decided yet, but I think what I am probably going to do now is have specific programs for common actions that do the tenon, threads and counterbore. Then have separate programs specific to the reamer that will drill, prebore, chamfer the chamber end and ream the chamber. This will save a lot of memory space in the machine. I can still put together one-offs quickly on the computer and load into the machine.

I won't get into work holding. That's one you've got to figure out based on your machine. If you are looking at an honest turning center, chances are that the spindle bore is going to be too long to grab the dead end with a spider. When you get into the capabilities of a turning center, you want things balanced. I cap my RPMs at 4500 for barrel work but I have run it up to 6k and it is still vibration free with my flush system attached.
 
I've been using a HAAS TL-1 since 2009 and have chambered over 7,000 barrels on it. I've been using the conversational program exclusively. Chambering barrels is simple work. For a one off it takes me maybe 10-15 minutes to build the program. When doing barrels in quantity it's takes less than 20 minutes a chamber. I use a tool post on mine. All I do on that machine is chamber work.

Dave

Thanks a ton Dave. I have considered 1-2 TL1's and having a shop similar to Stuteville, but after some consideration and some R&D projects I have in mind, I would really like live tooling. I'm not too concerned with purchasing living tooling just yet, but I am excited for some projects in mind.
 
I hand write all my programs. I do a lot of cut/paste with proven programs to modify the tenon length, chamber prebore dimensions and reamer parameters. The problem I have run into now is my machine memory is full and I am constantly deleting programs I don't think I'll use again. I still have them backed up on my computer, but it is always a warm fuzzy to have a proven program in the machine.

I haven't completely decided yet, but I think what I am probably going to do now is have specific programs for common actions that do the tenon, threads and counterbore. Then have separate programs specific to the reamer that will drill, prebore, chamfer the chamber end and ream the chamber. This will save a lot of memory space in the machine. I can still put together one-offs quickly on the computer and load into the machine.

I won't get into work holding. That's one you've got to figure out based on your machine. If you are looking at an honest turning center, chances are that the spindle bore is going to be too long to grab the dead end with a spider. When you get into the capabilities of a turning center, you want things balanced. I cap my RPMs at 4500 for barrel work but I have run it up to 6k and it is still vibration free with my flush system attached.

One of my ideas for programming was to just use a thumb drive and have all my programs saved to it so I could just pull programs from the drive based on which tennon I was doing. The more and more I think about it, a macro program sounds like the way to. One program, simple to change parameters, don't have to chase down programs. Biggest con is cost of having someone write one since I have no idea how to.

As for work holding, I think I've got that figured out after a quick conversation with Robert Gradous. I will likely go with a collet system holding the barrel, then make tapered inserts to hold the muzzle end. For my setup, it will be super rigid and be able to indicate axially and radially to get it running concentric.

If that doesn't work, I'll go to a barrel extension, spider and 4 jaw independent.

Appreciate the feedback.
 
One more thing to consider, are you doing this out of a garage or a commercial space with 3 phase power? It can get real expensive, real quick to power an honest 15-20hp 3 phase machine when you are staring with single phase power.
 
One more thing to consider, are you doing this out of a garage or a commercial space with 3 phase power? It can get real expensive, real quick to power an honest 15-20hp 3 phase machine when you are staring with single phase power.

Undecided on that. I was about to buy a house that had a shop with 3 phase, but that got put on hold for a little bit. I quoted out 30 hp rotary cnc grade converter. Currently use a 7.5 hp rotary for my manual machine. It works great. Zero problems there.
 
Undecided on that. I was about to buy a house that had a shop with 3 phase, but that got put on hold for a little bit. I quoted out 30 hp rotary cnc grade converter. Currently use a 7.5 hp rotary for my manual machine. It works great. Zero problems there.

Just make sure you know what you’re getting into before you purchase the machine. I was in over $10k just with my utility to upgrade from a 200a to 400a service (3ph wasn’t remotely realistic). That was just before the meter. I also did and paid for all the work including the panel swap and inside piping/wiring. I can’t remember off the top of my head, but I feel my 40hp RPC was somewhere around $3-$5k. I bet I was into it close to $20k our of pocket just to power the machine and I did all the labor.

Not saying don’t do it, just saying make sure you know exactly what you are getting into before you purchase a machine and hire a mover/rigger.
 
Work holding. Different strokes for different folks. I started in the point blank BR world. I agonized over everything. Fast forward 35 years. There are certain basic things we have to do and then the rest gets lost in the noise. I have spiders on both ends of my spindle. 25" is about the shortest barrel I can do. I have to have vibration mitigation mid way in the spindle. Sounds crazy but I've had barrels sing to me when running a reamer in without it. I use bushings with o-rings on the OD to center the bushing and o-rings on the ID to just lightly touch the barrel to stop vibration. Bushing are made in one setup so everything is concentric. I have inserts with matching tenon threads on the ID for muzzle work. When you have a run of 125 barrels it makes quick work setting up and dialing in a barrel. I have different style bushing to hold short barrels. All have o-rings on the OD. Some are solid Delrin to fit barrel tapers others have snug fitting o-rings on the ID. 99.9% of the barrels I've done the last 10 years are Bartlein and concentricity is great. On any barrel that isn't I put a new center in and true up a short portion on the muzzle. A couple of thousandths run out on the muzzle gets lost in the noise when chambering.
 
Work holding. Different strokes for different folks. I started in the point blank BR world. I agonized over everything. Fast forward 35 years. There are certain basic things we have to do and then the rest gets lost in the noise. I have spiders on both ends of my spindle. 25" is about the shortest barrel I can do. I have to have vibration mitigation mid way in the spindle. Sounds crazy but I've had barrels sing to me when running a reamer in without it. I use bushings with o-rings on the OD to center the bushing and o-rings on the ID to just lightly touch the barrel to stop vibration. Bushing are made in one setup so everything is concentric. I have inserts with matching tenon threads on the ID for muzzle work. When you have a run of 125 barrels it makes quick work setting up and dialing in a barrel. I have different style bushing to hold short barrels. All have o-rings on the OD. Some are solid Delrin to fit barrel tapers others have snug fitting o-rings on the ID. 99.9% of the barrels I've done the last 10 years are Bartlein and concentricity is great. On any barrel that isn't I put a new center in and true up a short portion on the muzzle. A couple of thousandths run out on the muzzle gets lost in the noise when chambering.

Awesome info, thanks!
 
Undecided on that. I was about to buy a house that had a shop with 3 phase, but that got put on hold for a little bit. I quoted out 30 hp rotary cnc grade converter. Currently use a 7.5 hp rotary for my manual machine. It works great. Zero problems there.

A 30HP converter is going to draw about 100 amps... With in-rush on a motor your looking at 120 amps or BETTER... If you are not familiar with the electrical codes I HIGHLY recommend you consult someone who is before moving forward on a residential property. You would be amazed how easy it would be to overload a residential service starting up a 30HP motor.
 
A 30HP converter is going to draw about 100 amps... With in-rush on a motor your looking at 120 amps or BETTER... If you are not familiar with the electrical codes I HIGHLY recommend you consult someone who is before moving forward on a residential property. You would be amazed how easy it would be to overload a residential service starting up a 30HP motor.

Thank you! I certainly will. I have no problem wiring that thing up, but how all that actually works, amps, watts, volts, etc. blows my mind lol. I do not like electricity.
 
Thank you! I certainly will. I have no problem wiring that thing up, but how all that actually works, amps, watts, volts, etc. blows my mind lol. I do not like electricity.

Electrical is where I come from. AND I am looking at exactly the same issue as I get ready to power my new shop this spring. My house sits 450' away from the shop, adding a little more complexity to my situation.

All of the loads in the shop need to be considered in planing. If you are going to drive a 30HP load you need to think about what else will be running when that load starts up... Lighting, the 5HP compressor, heating... In a one man shop out of your home It is unlikely that you would be running more than one machine at a time, but what would happen if you DID fire up a welder while the milling center was running a program and the compressor cycled on? And how does all of that effect the overall loading on the house when an AC unit fires up???
 








 
Back
Top