Author Topic: forging breech plug (Read 9955 times)

David R. Pennington · « **on:** July 19, 2015, 04:18:24 AM »

Here is my second attempt at forging a breech plug blank. The first try failed, sheared off at juncture of round to square. It was from old wrought wagon or plow part, evidently pretty low grade stuff. This one from wagon tire folded and forge welded and refined some. I drew out the tang and shaped some today. It is cooling in the ashes of the forge. A lot of file work to do and threading. The barrel is breeched for 9/16"- 12. I found an old adjustable die this size.

bowkill · « **Reply #1 on:** July 19, 2015, 05:22:12 AM »

very cool, say hard to do..

Acer Saccharum · « **Reply #2 on:** July 19, 2015, 05:36:17 AM »

I'm impressed!

ddoyle · « **Reply #3 on:** July 19, 2015, 05:37:26 AM »

Nice work, thanks for sharing.

James Wilson Everett · « **Reply #4 on:** July 19, 2015, 03:37:20 PM »

Super job, very well done. Please show us the work as you finish the breech plug. Thanks a lot for the posting.

Jay Close · « **Reply #5 on:** July 19, 2015, 05:12:10 PM »

That's the ticket!!!!

IKE · « **Reply #6 on:** July 19, 2015, 05:22:37 PM »

NICE!

David R. Pennington · « **Reply #7 on:** July 19, 2015, 10:46:58 PM »

Here is plug with tang drawn out some. Pulled it out of the cold forge this morning.

Mark Elliott · « **Reply #8 on:** July 20, 2015, 03:37:02 AM »

Excellent job! When are you coming over to teach me?

David R. Pennington · « **Reply #9 on:** July 20, 2015, 04:24:48 AM »

Not really as hard as it looks. Once I got the stock welded up thick enough from the wagon tire I began to draw out the round end over the anvil edge. Dressed up the round shape on a 3/4" bottom fuller. Hardy hole was the right size so I knocked it down in the hole to square up the shoulders. Next part is easier with a helper and a sharp hot cut. Cut about a third of the way down on the underside of the square part. With this cut aligned on anvil edge it is opened up and shaped. Just have to remember to work the iron real hot.
Well Mark I have a standing invitation to work in the museum shop every week end but am lucky if I can get there once a month. Would like to play in your shop some time. Between work and family obligations I get very little time for this "hobby".

Mark Elliott · « **Reply #10 on:** July 20, 2015, 05:00:26 AM »

David,

What was the size of the stock you made up before starting on the breech plug? I have wagon tire that I have welded up. That can be very hot work!

David R. Pennington · « **Reply #11 on:** July 20, 2015, 02:10:01 PM »

I had a piece of tire that was about 2" x 1/2" and about 30" long. I just folded over about 4" on itself and welded. This gave me a piece of stock about 4" x 2" x 7/8" with a nice piece of parent stock for a handle. I parted it off after forming the round.

Jay Close · « **Reply #12 on:** July 20, 2015, 03:43:06 PM »

One thing I've noticed on old breech plugs is that the bolster area is nowhere nearly as massive as we tend to make them in modern times. I've even see some with no metal below the threaded section so there is only one shoulder fit up to the back of the barrel.......not that I'm advocating this, but just observing a period practice. In the past, this may have meant the plug could be made from a smaller (cheaper) bit of iron, and forged quicker and fit up faster.

David R. Pennington · « **Reply #13 on:** July 20, 2015, 05:02:55 PM »

Jay that description immediately gave me a picture of a sheared off plug when trying to extract it. That might also explain a lot of originals with shortened barrels.

jerrywh · « **Reply #14 on:** July 20, 2015, 06:30:14 PM »

Dave.
I have a large piece of wrought iron I will give you if you remind me before the next Oregon gunmakers fair.

Mark Elliott · « **Reply #15 on:** July 20, 2015, 09:58:01 PM »

Thanks David for the instructions. Let us know how things progress with the breeching.

David R. Pennington · « **Reply #16 on:** November 17, 2015, 05:45:37 AM »

Here is another forged breech plug, successfully threaded, spotted and fitted to barrel. Forged from wrought iron wagon tire. I ruined a couple forged blanks before I got this one fitted. I am learning what others have said about threading wrought iron. It does grow in diameter as threads are formed. The barrel is breeched 9/16-12 and I found an antique adjustable die stock that would cut this size. I filed the plug to 9/16" diameter with a gauge. I was afraid to start with an undersized blank as I wanted a tight thread. As I learned, the threads are partially cut, partially displaced, or swaged. I started the die at the back end of plug, opposite of how you start a modern die. You can do that with an adjustable stock and it is nearly impossible then to start crooked.
As the threads were forming I noticed the peaks of the threads starting to chip a little. I realized that the diameter was growing and I was running out of room in the grooves of the die. I carefully filed the diameter back a little and continued.

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I hacksawed to rough shape. Now to file to barrel contour and shape tang.

rich pierce · « **Reply #17 on:** November 17, 2015, 04:34:35 PM »

Would love to work the bellows while you do this!

JCurtiss · « **Reply #18 on:** November 17, 2015, 04:47:54 PM »

This is a fascinating subject. Thank you for sharing!

Question please: What causes the outside diameter to grow during the threading operation?

JCurtiss · « **Reply #19 on:** November 17, 2015, 05:13:31 PM »

Quote from: JCurtiss on November 17, 2015, 04:47:54 PM

This is a fascinating subject. Thank you for sharing!

Question please: What causes the outside diameter to grow during the threading operation?

Perhaps the threading operation releases compressive stresses in the part alowing it to expand slightly?

okieboy · « **Reply #20 on:** November 17, 2015, 05:16:44 PM »

Thanks for sharing all of this with us, it is very good.
Here's a thought. Your thread O.D. grew due to metal displacement as you worked. You were running the die counterclockwise to get alignment. Even though you can do that with split dies, the die teeth were probably still ground to cut clockwise. Meaning that one face of the teeth was ground to cut, and the other face not so much, as well as there may be some relief (for cutting clearance) ground into the die threads. So, it might be that the dies ran clockwise would not grow the thread. You would only know by dong a test cut.
Thanks again, great stuff.

JCurtiss · « **Reply #21 on:** November 17, 2015, 05:29:55 PM »

Quote from: okieboy on November 17, 2015, 05:16:44 PM

Thanks for sharing all of this with us, it is very good.
Here's a thought. Your thread O.D. grew due to metal displacement as you worked. You were running the die counterclockwise to get alignment. Even though you can do that with split dies, the die teeth were probably still ground to cut clockwise. Meaning that one face of the teeth was ground to cut, and the other face not so much, as well as there may be some relief (for cutting clearance) ground into the die threads. So, it might be that the dies ran clockwise would not grow the thread. You would only know by dong a test cut.
Thanks again, great stuff.

Ah, yes. Displaced metal makes perfect sense!

David R. Pennington · « **Reply #22 on:** November 18, 2015, 12:18:39 AM »

Look at James Wilson Everett's posts on making wrought iron screws. He starts with undersized blanks via trial and error because the diameter increases. What appears to happen is that some of the metal does displace or swage instead of cutting. I got very little cuttings and they were very fine almost like grit. Also I noticed the end of the plug became concave as the last threads were formed.

David R. Pennington · « **Reply #23 on:** November 18, 2015, 12:29:20 AM »

Rich, we can always use a hand on the bellows. I had two twelve year old boys double teaming on it for me one Friday a couple weeks ago. They were cousins and came through the shop with their school class. After the museum tours were over they talked their folks into bringing them back by and they visited till closing time.
That bellows does a great job as long as you can keep the mice out. I kept the fire and maintained welding heat for the master smith one day while he welded up a bunch of Damascus. When I lay down that night I could still hear the bellows valves clacking.

James Wilson Everett · « **Reply #24 on:** November 18, 2015, 03:21:51 PM »

David,

Really great work here, thanks for posting your progress. It is so wonderful to see craftsmen like yourself using the old techniques and materials. I believe that your excellent work should be in the tutorial section. Your observations are completely correct that when using a split die the thread crest O.D. grows outwards about the same dimension as the thread valley grows inwards. The roughness that you observed is a common occurrence, it often smooths out as the thread is completed. If you look at the tutorial "making 18th c wood screws" you can see that the roughness, or split crest as I call it, is nearly gone when the thread is finished. The small relief sections on the split dies are not cutting edges and are not biased to act differently if the tool is rotated either CW or CCW. These relief sections are just there to provide a place for the tiny bit of fine metal dust to go.

Here is a topic showing the way I made the breech plug without forging.

http://americanlongrifles.org/forum/index.php?topic=33217.msg318587#msg318587

However, I feel certain that the forging, as you have done, is both better and more historically correct than my method.

Again, great work!

Jim

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Author Topic: forging breech plug (Read 9955 times)

ddoyle

IKE

JCurtiss

JCurtiss

JCurtiss