1" Bore IX Dahlgren

[The Jeff]

I wasn't going to make a new post about this project until I had a little more work done, but I decided to do it anyway. I don't want any of you to go into cannon withdrawals while they're restoring the forum posts. 


So my plan is to make a 1" bore IX Dahlgren. I don't have access to a milling machine and making a strong trunnion connection has always been a concern. I wouldn't mind welding them on if I were making a Brooke rifle or something that had flared rimbases, but the IX Dahlgren has a sharp corner. So I've been thinking for a while about the easiest way for me to do it. Eventually I decided I'll make a built up gun of sorts. A seamless piece of tubing will form the bore, and 3 hoops will be shrunk onto it. The middle hoop will be drilled through sideways and the trunnions shrunk into it. Then the bore will be reamed out to size and a breech plug shrunk and welded. With that figured out, I made a drawing.



I decided to start with the middle section and drilled a 1-7/32" hole through the center of the piece. Then I turned it sideways in the 4 jaw chuck and drilled and bored a 1.160" hole all the way through. This hole is for the trunnions.



Next I started on the curve in the area of the trunnion. Better get that done now while I can get to it or I'd be getting well acquainted with a file later on.



Next I made the trunnion piece. It is 1.168" in diameter. The surface looks a bit different, but it everywhere seems to measure within half a thousandth or so in my calipers.



And lastly I used a reamer to smooth up the hole I bored to 1.165.



Looking around on the internet I figured out steel expands at .0000064" per degree F per inch. So .0000064" x 1.165" x 405º = .003". So I need to get the temperature difference between the hoop and trunnion to at least 405º F. I'm planning to put the hoop in my oven for an hour or two as hot as it will go, then blast it with an oxyacetylene torch until it's good and red. I might do that tomorrow if I work up the nerve.

[seacoastartillery]

     Jeff, that looks like a very novel and also effective way to construct this type of naval artillery.  Mike and I will be following this build very closely.  Go for it!

Tracy

[GGaskill]

You shouldn't need to go all the way to red to be hot enough.  600° should be plenty, especially if you cool the trunnion piece.  600° is about dark blue on the color temperature scale.  But the work has to be clean before heating for the colors to appear properly.

[Phils69]

I have worked with press fits a lot in the past. I worked in a hot steel forge die shop before and some of the forge presses the only thing holding the dies in the top holders was a heat shrink fit. Some of those dies were 18" in diameter by 16" thick so its imperative that the proper fit is achieved for sure. Just remember that the interference amount changes on the size of the part. A .001" interference on a .25" dia part is more than enough but that same .001" on a 10" dia part is not. The .003" should be more than enough on what you are doing, good job there. Believe it or not I have seen people trying for .01" on something that size and after pounding with a sledge they wonder why it didn't work. Another trick of the trade is have a short length on the end of the "pin" that will be pressed in just slightly smaller than the bore so that this section falls in but holds the pin dia parallel to the bore, we call in a lead in. It would not be good in this application though as that area is not flat going in on the side of a dia.
  Heat the part up the female part  in your oven and let it bake a while, at the same time throw the pin in your freezer for like 30 minutes. Line them up the best you can together and drop the pin in. Have something to tap with as those sizes change fast once the parts come together. Another cooling process for pins that works really well is liquid nitrogen, like -330 degrees, but hard to come by that at home. Good luck!

[247machine]

anxious to see this build progress and im curious about your thoughts on the expanding reamers, I have some I picked up in an auction but as yet hav'nt taken the time to learn how to set them up properly.

[MKlein]

Looks like a cool project Jeff
 
Look at this Dahlgren being admired by some old guy
 

 
http://www.gboreloaded.com/forums/blackpowder-mortar-and-cannon-sponsored-by-seacoast-artillery/micro-dahlgren-2/
 

[de_lok]

Looks like a cool project Jeff
 
Look at this Dahlgren being admired by some old guy
 

 
http://www.gboreloaded.com/forums/blackpowder-mortar-and-cannon-sponsored-by-seacoast-artillery/micro-dahlgren-2/

Ha Ha ! ! ! !

[seacoastartillery]

HEY  HEY    That's enough of that!   MKlein  remember that Maxwell Air Force Base is not too hard to find.

             Iuka guy,  I know EXACTLY where you live.  HA  HA  !!!!   

Mike

[MKlein]

Looks like a cool project Jeff

 
Ha Ha ! ! ! ! This is what It should have said. Paste and cut must have messed up.
 
Look at this Dahlgren being admired by a meticulously crafty young guy. Mike "The Machinist Superstar of the Seacoast Boys"


 
Sure is a nice looking carriage. I think it is a marsilly type.
 
http://www.gboreloaded.com/forums/blackpowder-mortar-and-cannon-sponsored-by-seacoast-artillery/micro-dahlgren-2/

 
Montgomery only gets about 40 hours of my time. The rest is spent at Wetumpka which means "Rumbling Waters" from the Indians that lived there.

[de_lok]

Looks like a cool project Jeff

 
Ha Ha ! ! ! ! This is what It should have said. Paste and cut must have messed up.
 
Look at this Dahlgren being admired by a meticulously crafty young guy. Mike "The Machinist Superstar of the Seacoast Boys"


 
Sure is a nice looking carriage. I think it is a marsilly type.
 
http://www.gboreloaded.com/forums/blackpowder-mortar-and-cannon-sponsored-by-seacoast-artillery/micro-dahlgren-2/

 
Montgomery only gets about 40 hours of my time. The rest is spent at Wetumpka which means "Rumbling Waters" from the Indians that lived there.

MKlein,
To late for tale kissin, ha ha, you've already stepped in the poop..................lmao..........

Mike,
Yea, you got my number, but it may be harder than you think for MKlein! There is more than one base for Maxwell AFB! You could be runnin' in circles trying to catch him! ha ha.............. (The main base and Gunter annex)

Dewayne

[The Jeff]

All I'm going to say is that old guy has impeccable taste in cannons!


247machine, I set the reamer close by using my calipers to measure across two opposite corners of the cutters. Then I'd twist the nut 1/4 of a turn and tighten the other until it started cutting. I've read these are definitely for hand use only, don't use them while the lathe is going. I have little experience with them, so we'll see how it goes.


Thanks for all the advice on shrink fitting, I'm going to do it tomorrow after I weld on a temporary stop so the trunnion *should* just drop through and stop centered. I don't want melted fingers and stuck parts trying to get it right by eye.

[GGaskill]

Which kind of adjustable reamer are you talking about?  This kind:



or this kind:



The first is only useful in through holes and the second has only a few thousandths of adjustment.

[Eddie2002]

Look around for some dry ice to shrink the pin. You might need to check out industrial vendors but if you can score 5 lbs it will really help. Nice build I love Dahlgrens.

[Indygunworks]

Meijer sells dry ice around here.

[The Jeff]

Well this week got off to a fine start. Sunday afternoon the trunnion got stuck, that evening the Broncos forgot how to play football, and Monday through Wednesday I was sick with a stomach bug. But, I got the trunnion fixed, so all's well that ends well.


I let the hoop sit in my oven at 450º for an hour, put it in an old ammo can full of fiberglass insulation, and took it 10 minutes away to work to heat with the oxyacetylene torch. I had quite a bit of trouble getting the trunnion lined up because the edge of the hole is curved in two directions. By that point the hoop had cooled down and it got stuck. #$%^@#$ Now what to do?! Luckily I remembered about my 25 ton "press" and managed to press the edge of the trunnion through over halfway.



Then it was back into the lathe to drill the bore.



I spent about 45 minutes trying to get it back into the 4 jaw chuck so I could turn the trunnion, but never did manage to get it just right. So I made a collet I guess you would call it and used a piece of plastic sheet to wedge the hoop on. Then I attacked with an angle grinder like a wood lathe. I'll clean it up and get the edges square with files later.



Next I made a new trunnion. When the point bottoms out the rimbase should end up in the right position relative to the breech diameter.



Then it was back into the oven at 450º for an hour, another trip to work, and this time I blasted it until it was orange around the hole. I spun the trunnion with my fingers for 13 seconds before it grabbed. I'm not playing around any more haha.

[Frank46]

Pretty neat idea using the wood splitter as your 25 ton press. That's one I haven't thought of. Frank

[The Jeff]

Arms are killing me, but I reamed out 13 5/8" of metal from 1.219 to 1.252. 247machine, I now have ample experience with expanding reamers. The best clothing to wear is shorts and a tee shirt   


At least on my reamer, turning the nut 1/2 a turn increased the hole diameter by around 4 thousandths. That's about as much as my arms want to turn. 2 thousandths was noticeably easier. Lots of oil helps as well. As far as things to look out for, I found that towards the end of the hole the flutes on the reamer will get cocked a little and it gouge the metal a bit. Reaming from both ends made the finish a lot better.

[The Jeff]

I had a near disaster this week but managed to fix it, so the cannon hasn't quite made it into the scrap pile yet! First I started with the the trunnion band. I reamed everything out so the tube is only .001" bigger than the hoop. I stuck a shaft collar on the tubing so the hoop will end up in the right place. Heated to 550º for an hour and it slipped right on. The same with the breech hoop.



With that done I machined the hemispherical bottom. This time I only advanced in 5 thousandths per cut so there was way less filing. The steps by the trunnions were 10 thousandths and required quite a bit more work to smooth out.



Embolden by my success with the two previous hoops I thought the muzzle one should be a piece of cake, but no such luck. I actually started one of these Dahlgrens 6 months ago but crushed the tubing when I tried to press a stuck breech plug in. So this time I made a plug that would just slip down the bore to hopefully prevent that from happening this time.



I found some interference fit calculators on the internet and figured it should take 8-10 tons to move the hoop, so I took it over to a friend's shop and used his 12 ton press.



Next I'll turn the rest of the outside profile, ream the bore to 1.026" and make the breech plug.


On a sort of side tangent, I've been going through the Ordnance Manual and drawing the projectiles in CAD. I love it when this stuff all fits together. For example, IX Shell should have a diameter of 8.85" and a wall thickness of 1.6". That leaves a hollow sphere with a diameter of 5.65" to fill with gunpowder. The ordnance manual says to use a charge of 3 pounds. A sphere with a diameter of 5.65" has a volume of 94.4 cubic inches. Black powder weighs roughly 235 grains per cubic inch, so that's 22,184 grains or 3.17 pounds. How about that!