Interchangeable Barrels

[cutter]

[[attachment=9458:Barrel-id=56.JPG]

 

[attachment=9459:Barrel plate-id=57.JPG]

 

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[attachment=9461:Gage block-id=59.JPG]

 

[attachment=9462:Clamp & screw-id=60.JPG]

 

[attachment=9463:Clamp screw slot-id=62.JPG]

 

[attachment=9466:Clamp in slot-id=61.JPG]

 

[attachment=9465:Final-id=63.JPG]

Was the goal to have 10 barrels that could be put in any barrel plate hole without regard to the extractor notch?

Clutch

[cutter]

No, they will not fit in ANY barrel plate.
I prefer machining to hard dimensions, not a scribed line.

I like your barrell mounting solution very much. I also would rather machine to a \"dimension or size\" verses a scribe line.

If I may ask, what size are the SHCP\'s used to secure the barrell wedges.

[cutter]

I used 4-40 X 5/8 lg

Good Luck

Jerry

Thanks!

Cutter,

I am to the point of maching my Rear Barrel Plate and mounting the Barrels. I like your approach to fixing the barrel very much.

Have you fired the gun using this approach? Did the 4-40 screws prove adequate to keep the barrels tight? Is the .376 barrel tendon sufficent size? I considered increasing the screw size to a 6-40 but the space is really tight?

Thanks

nitewatchman

[cutter]

nitewatchman,

I have fired about 250 rounds and no problems with the tightness.
With a good seat at the shoulder, I doubt if they would ever loosen.
I had already cut threads on my barrels when I decided to make the change.
You can see the witness marks of the thread in the pictures.
If I were to do it again, I might bore and turn to .390, the tap drill size for the 7/16-20.
Very little difference.

Cutter

cutter,

Thanks for the response. I was thinking along the same lines. I had thought about .400\" for thr tendon since it is such a nice round number. Will likely start tonight, I have most details programed.

nitewatchman

Great idea. I may well use this on my D&E build. I just need to cut the tapers on the barrels and I\'m ready to start assembling the barrels together.

Nightwatchman, Is there a possibility that you might share your barrel plate program? I am very new to cnc and I would like to try and compare a few things to see if I am taking the right paths or not. I purchased a used Robotool cnc vertical mill a while back and still have not fired it up yet, but I am close. G-codes woulkd be enough in a file. Thanks in advance. Bruski

No problem, they are broken down into 5 or 6 separate programs and written in absolute G-Code. How can I get them to you?

nitewatchman

Thanks a million. I sent you a pm with my email address if you could send them to me in an email attachment file that would be great. Thanks again. Bruski

Just remember that they are only worth what you paid for them.  They worked for me so far but your mileage may vary.

nitewatchman

Thanks, I don\'t plan to actually use your files to machine with, just to check and compare a few things because cad and cam is like learning a new language for me. I will check my emails. Have a Happy New Year!

Did the code help?

HI nitewatchman, I am still drawing with Bobcad and I will have to admit that there are a lot of miracles that will have to happen when I am finished. I studied your G codes and have gained a lot especially from your mill rim reliefs file. The Robotool controller is capable of entering G codes right on the machine. So maybe if my drawings don\'t work out very well I will try to enter just the G codes from one of your files on a piece of wood or wax to see what happens. Did you zero the tool on the top surface of your material on center? Thanks, bruski

Yes, X and Y Zero is on the part center and generally Z zero on the top surface.


I machine all of the \"round parts\" Barrel Plate, Recoil Plate, Carrier Block, Front Plate, etc. on 3/8\" Shoulder Bolts of varing length. When the part is in the lathe, I will drill, bore and ream the center hole to 3/8\" so that it is dead true to the OD and turned features. Then for the milling operation I attach a plate to the mill table and face it plate. In the center I again drill, bore and ream a 3/8\" hole about 3/8\" deep and then drill and tap a 5/16-18 hole in the bottom, this becomes X and Y Zero for all future operations. Directly above this hole on the fixture I will drill and ream a 3/16\" hole at X=0.0, Y=0.625. this becomes the index pin for all parts.


To setup a part to be milled, the 3/8\" hole in the fixture is indicated and zeros set. The blank is then bolted into place with the 3/8\" shoulder bolt. Next I drill and ream a 3/16\" index hole through the part on thin pieces and 3/8\" deep on thick parts. For the thick parts I turn the part over reclamp and put the index hole in the second side after locating the first hole with a 3/16\" dowel pin to the fixture.


This approach keeps all the features on the pieces \"timed\" to each other and allows the part to be removed or put back on the fixture easily and without having to worry about rotation.


This approach works for me.



nitewatchman

 

[attachment=9467:IMG_20101111_214534 (Small)-id=351.jpg]

 

[attachment=9468:IMG_20101111_215942 (Small)-id=352.jpg]

 

HI nitewatchman, I am still drawing with Bobcad and I will have to admit that there are a lot of miracles that will have to happen when I am finished. I studied your G codes and have gained a lot especially from your mill rim reliefs file. The Robotool controller is capable of entering G codes right on the machine. So maybe if my drawings don\'t work out very well I will try to enter just the G codes from one of your files on a piece of wood or wax to see what happens. Did you zero the tool on the top surface of your material on center? Thanks, bruski

 

HI, Thanks for taking the time to explain how you setup your pieces for milling. I could understand everything you mentioned perfectly and will probably setup mine exactly as you did yours. bruski

[maccrazy2]

Cutter. Do you have any specs on the barrel plate, barrel cuts and wedges? Anything you would do differently if doing this setup now?

I definitely like the idea of this setup much more than the plans design.