Author Topic: 1:28 9" Dahlgren (Read 4003 times)

The Jeff · « **on:** May 15, 2011, 05:04:27 PM »

I've kind of lost steam on my 1" bore mountain howitzer project, so this afternoon I decided to make something a bit smaller.

I've always liked the 9" Dahlgren because my great great grandfather manned one of the hot shot guns on the CSS Virginia. In a letter he writes "I was stationed at No. 4 hot shot gun, "Starboard Side" my station was No. 17 broad side battery."

I haven't quite figured out what that means, as I thought the #4 gun was on the port side, and 9" Dahlgrens only had a crew of 16. Perhaps he was the powder boy?

Anyway, here's the .32 caliber 9" Dahlgren I started this afternoon. It's roughly 1:28 scale. I still need to smooth up the outside a bit and drill the vent/elevation screw/breeching jaws. Also make and attach the trunnions. Maybe I'll make a shooting platform with a section of the sloping armor from the Virginia.

keith44 · « **Reply #1 on:** May 15, 2011, 05:12:34 PM »

nice, off to a great start

The Jeff · « **Reply #2 on:** May 17, 2011, 04:49:23 PM »

Today I managed to drill 3 holes and tap 1 all without breaking anything. I even managed to get them mostly square to each other! Considering my luck with small drill bits, it's probably a new personal record.

The vent is .039, the elevation screw hole was drilled 3/32 and tapped to #4-40, and the breeching jaw hole is 1/8th. I'll probably have to enlarge the vent, but .039 was the biggest "small" bit I could find. I'll have to see how it works.

I also shaped up the cascabel and made some trunnions. They're only .375" in diameter at the rimbase and I'm not too sure how to put them on. Right now I'm leaning towards grinding out a pocket with a dremel, soldering them in, and patching any gaps with bondo or something.

rampa room artillery · « **Reply #3 on:** May 17, 2011, 05:13:11 PM »

well, i know it is not standard pratice, but it would work, silver solder them on. I have a front gun sight that we have taked a hammer to and belt it over the silver solder never broke. and as small as that gun is I think it would work just fine. never do it to any bigger guns. but it can be done to that little guy,
it looks good. done mess it up now.

rick bryan

GGaskill · « **Reply #4 on:** May 17, 2011, 06:20:53 PM »

Most real silver solders are quite strong although they take a lot of heat to make a good joint. Is that a stainless or mild steel barrel?

The Jeff · « **Reply #5 on:** May 18, 2011, 01:28:46 AM »

Ah, I forgot to mention it's 1018.

seacoastartillery · « **Reply #6 on:** May 18, 2011, 08:18:50 AM »

Jeff, That's a great looking Dahlgren you are making. I had lots of fun making a .182 cal., BB shooting, nano cannon, a 10" Rodman about two years ago. The description of how I attached the trunnions is below. You wouldn't have to drill that deep, .030" would probably be enough. Silver solder is very, very strong. A coathanger wire can be used if you don't have drill rod handy.

Good luck!

Tracy & Mike

With the .080" deep pockets to be drilled, dimple first with a regular drill and finish with a flat bottom drill on both sides. Place a tiny dab of Brownell's silver solder paste in the bottom of each pocket and put the tiny two diameter, trunnion/rimbase piece in each pocket and hold them in place with a piece of bent, 1/8",drill rod, V-spring. Heat the whole thing to a dull cherry red and let cool. We can't pull them out!

The Jeff · « **Reply #7 on:** May 18, 2011, 04:14:22 PM »

Today I spent about 3 hours with a dremel whittling out the trunnion pockets. My hands are still vibrating and I've got a huge headache, but the trunnions fit! For the most part. One is about .04" ahead of the other, but there's not much I can do about it now.

Anyway, the pockets are .105" deep at the back, and .065" at the front. I figure I had about .25" of wall thickness before I broke through into the bore. The picture below shows the first one I did. The other isn't quite as rough.

Thanks for the soldering advice, Tracy & Mike. Brownell's silver solder paste looks a bit pricey, but if it's as easy to use as you make it sound I'm sure I can come up with more projects to use it in.

I'll have to order a batch of it tomorrow. I'm halfway tempted to try soldering them with a soft solder temporarily just so I can start on the carriage.

Quote from: rampa room artillery on May 17, 2011, 05:13:11 PM

done mess it up now.

In all of my projects I go from one step to the next in constant fear of royally messing something up.

kappullen · « **Reply #8 on:** May 19, 2011, 06:21:01 AM »

Jeff,
Borax, from the grocery store works as a cheap brazing, silver soldering, flux.
Try it on some practice parts, and have a go.
Kap

dominick · « **Reply #9 on:** May 21, 2011, 11:11:03 AM »

Jeff, That a good looking barrel you're making. You gave me the incentive to finish mine.

I had a Dahlgren barrel [3/8" bore] that was laying around here for a while that I decided to finish today. Here is how I attached the trunnions. I made a fixture from 4 pieces of angle iron and plate as shown. Clamp the barrel and trunnions in place after spacing. For a tapered barrel, I make a muzzle ring that is the same diameter as the breech. This will keep the barrel straight and level in the fixture when clamped. I leave the trunnions extra long for clamping. This is not a problem if you want trunnions with rimbases. Use round stock that is the diameter of the rimbase and measure and cut the smaller diameter as a wide groove in the extra length trunnion stock. I then fit and tig weld the trunnions to the barrel and saw the trunnions to length.

Pieces set in fixture.

Welded assembly.

Cutting trunnions to length.

Finished barrel.

Finished cannon.

keith44 · « **Reply #10 on:** May 21, 2011, 11:37:57 AM »

nice one dominick, what cal is the one pictured.

dominick · « **Reply #11 on:** May 21, 2011, 11:57:43 AM »

keith44, It's 3/8" bore which I call 36 caliber. It will shoot the 3/8" Daisey slingshot ammo or a .360" diameter lead ball. Thanks for the compliment.

The Jeff · « **Reply #12 on:** May 22, 2011, 05:11:24 PM »

Today I decided to clean out a few drawers in the workshop and lo and behold I came across some silver solder ribbon from an old bandsaw blade repair kit. So this evening I cleaned up the pieces with rubbing alcohol, dabbed on some flux, and gave it a try. The first few attempts I didn't get it hot enough, but on the last one I waited until everything was orange. That seemed to do the trick, as I can't push the trunnions over by hand. But I'm not going to try beating them out with a hammer either.

dominick, your jig and leaving the trunnions extra long really looks slick. Now I'm having one of those "why didn't I think of that" moments.

Microboomer · « **Reply #13 on:** May 23, 2011, 06:27:23 AM »

Great Project, Jeff!
I'm particularly interested in seeing how well the .039 vent works for you. I'm planning on testing out small vent sizes on a micro mortar. I'm thinking about trying step drilling so that it's easy to get powder into the vent, but the opening into the chamber will be small to prevent loss of energy from the main charge.

What kind of finish and carriage are you planning?
andy

The Jeff · « **Reply #14 on:** May 23, 2011, 04:55:18 PM »

Quote from: Microboomer on May 23, 2011, 06:27:23 AM

Great Project, Jeff!
I'm particularly interested in seeing how well the .039 vent works for you. I'm planning on testing out small vent sizes on a micro mortar. I'm thinking about trying step drilling so that it's easy to get powder into the vent, but the opening into the chamber will be small to prevent loss of energy from the main charge.

What kind of finish and carriage are you planning?
andy

Yeah, I'm thinking about making a small "cup" at the top of the vent to hold a bit of powder. Hopefully the flash from that will make it through the vent and set off the main charge.

I'm going with a Marsilly carriage. I'm not sure what color they were painted, or if they were painted at all. From the period pictures I've found, they seem to either have a dark stain, or painted black. Perhaps I'll have to read the "Ordinance Instructions for the United States Navy."

Note the field expedient AA wheel

dominick · « **Reply #15 on:** May 24, 2011, 03:13:41 AM »

It's looking real good Jeff. I vote for dark stain. Doesn't hide the wood grain.

The Jeff · « **Reply #16 on:** June 05, 2011, 04:26:05 PM »

I've either been too busy to work on my projects, or it's been so humid and hot that I didn't want to. But this afternoon I finished up the carriage and made a quick elevation screw so I could test fire. I'll make a better looking screw later. I still need to make trunnion caps and some other various bits of hardware. And a shooting platform.

I tried firing it this afternoon, but had no luck. First I tried lighting a pile of powder on top of the vent. That didn't work. Next I tried blasting the touch hole with a pen torch. No luck. Finally I tried Mike and Tracy's broom straw fuses. I didn't have any 4F so I crushed up some 3F. I didn't have any spray adhesive either, so I tried quick drying lacquer. No dice with this set up. I think the vent scraped all the powder off the broom straw when I pushed it in. I'll try nichrome wire and a battery at some point.

Latest progress:

Cat Whisperer · « **Reply #17 on:** June 05, 2011, 04:29:34 PM »

Quote from: The Jeff on June 05, 2011, 04:26:05 PM

...

Calendar Picture!

dominick · « **Reply #18 on:** June 06, 2011, 02:39:58 AM »

I wonder if the breech thickness makes the vent passage too long for its diameter. The carriage is looking very good Jeff.

The Jeff · « **Reply #19 on:** June 08, 2011, 02:58:04 PM »

Click to play movie

It works! I ordered some nichrome wire to try electrical ignition, but it hasn't come yet. So this afternoon I decided I'd try shooting it as if it was spiked. I cut a 1/4" strip of newspaper about a foot long, sprayed some quick drying lacquer on it and sprinkled some 3F on that. The charge was 30 grains with no wad or projectile. I'd imagine the recoil would be pretty fierce with a projectile, but for just powder in the barrel I didn't think it'd be too bad.

I also set it to a high elevation so the barrel wouldn't jump out of the carriage. I've made the trunnion caps, but I'd like to paint the carriage first as they'll be semi-permanent.

The Jeff · « **Reply #20 on:** June 17, 2011, 05:35:20 PM »

I decided to paint the carriage, mainly because I think it would be more historical. I couldn't find anything definitive saying what color the Virginia's carriages were painted, so I went with black. The paint also hides my rough woodworking.

The trunnion caps were made from an annealed rake tine. The rear part is nailed to the carriage, while the front part is just held in with a pin. That way the trunnion caps can swivel to the sides and I can take the barrel out. I don't have the patience to try and make a hook and wedge setup for something this size.

I also started on the scale casemate shooting platform. So far I've got the decking, 16"x16" (0.57") beams and the 4" (0.14") pine cladding. Next up will be 4" of oak running vertically and two layers of 2" (14 gauge sheet metal) iron.

RocklockI · « **Reply #21 on:** June 17, 2011, 09:51:59 PM »

Well that is just plain cool

no ...right much cool !

Gary

Microboomer · « **Reply #22 on:** June 18, 2011, 05:20:28 AM »

This is a great project - can't wait to see how it ends up!
andy

keith44 · « **Reply #23 on:** June 18, 2011, 07:22:13 AM »

Hey Jeff, I've been following this build, and really enjoied seeing it fired.

Quote from: The Jeff on June 08, 2011, 02:58:04 PM

It works! I ordered some nichrome wire to try electrical ignition, but it hasn't come yet. So this afternoon I decided I'd try shooting it as if it was spiked.

How are you planning to arrange the electric / electronic ignition?? Just curious. On one of my "proof of concept" barrels I tried using model rocket ignitors. It works, kinda, but I abandoned the idea.

The Jeff · « **Reply #24 on:** June 18, 2011, 10:48:06 AM »

Quote from: keith44 on June 18, 2011, 07:22:13 AM

How are you planning to arrange the electric / electronic ignition?? Just curious. On one of my "proof of concept" barrels I tried using model rocket ignitors. It works, kinda, but I abandoned the idea.

First I just bent a piece about an inch long in half and put it down the vent. That didn't work because the nichrome wire was touching itself or the vent and just took the path of least resistance. Next I tried insulating the wire with tape, but that made it too thick to go down the vent. Basically the whole idea was a flop.

My next step will be to drill out the vent about three quarters to a larger diameter so the flash can get through to the main charge but I'll still have less pressure loss thanks to the constricted vent. If that still doesn't work, I'll drill it all the way through for a fuse. And if THAT doesn't work, I'm heaving the whole thing into the nearest river.

Thanks all for the comments!

Zulu · « **Reply #25 on:** June 18, 2011, 11:14:26 AM »

Quote from: The Jeff on June 18, 2011, 10:48:06 AM

Quote from: keith44 on June 18, 2011, 07:22:13 AM
How are you planning to arrange the electric / electronic ignition?? Just curious. On one of my "proof of concept" barrels I tried using model rocket ignitors. It works, kinda, but I abandoned the idea.

First I just bent a piece about an inch long in half and put it down the vent. That didn't work because the nichrome wire was touching itself or the vent and just took the path of least resistance. Next I tried insulating the wire with tape, but that made it too thick to go down the vent. Basically the whole idea was a flop.

My next step will be to drill out the vent about three quarters to a larger diameter so the flash can get through to the main charge but I'll still have less pressure loss thanks to the constricted vent. If that still doesn't work, I'll drill it all the way through for a fuse. And if THAT doesn't work, I'm heaving the whole thing into the nearest river.

Thanks all for the comments!

You could throw it in my pool.

Zulu

keith44 · « **Reply #26 on:** June 18, 2011, 12:09:50 PM »

Quote from: Zulu on June 18, 2011, 11:14:26 AM

Quote from: The Jeff on June 18, 2011, 10:48:06 AM
Quote from: keith44 on June 18, 2011, 07:22:13 AM
How are you planning to arrange the electric / electronic ignition?? Just curious. On one of my "proof of concept" barrels I tried using model rocket ignitors. It works, kinda, but I abandoned the idea.

First I just bent a piece about an inch long in half and put it down the vent. That didn't work because the nichrome wire was touching itself or the vent and just took the path of least resistance. Next I tried insulating the wire with tape, but that made it too thick to go down the vent. Basically the whole idea was a flop.

My next step will be to drill out the vent about three quarters to a larger diameter so the flash can get through to the main charge but I'll still have less pressure loss thanks to the constricted vent. If that still doesn't work, I'll drill it all the way through for a fuse. And if THAT doesn't work, I'm heaving the whole thing into the nearest river.

Thanks all for the comments!

You could throw it in my pool.
Zulu

or my pond

dominick · « **Reply #27 on:** June 18, 2011, 12:54:10 PM »

Quote from: The Jeff on June 18, 2011, 10:48:06 AM

My next step will be to drill out the vent about three quarters to a larger diameter so the flash can get through to the main charge but I'll still have less pressure loss thanks to the constricted vent.

That's a good idea. Also, I like the diorama. It's lookin good Jeff!

Double D · « **Reply #28 on:** June 18, 2011, 01:38:25 PM »

Can you trickle FFFFg down the vent for fuse??

dan610324 · « **Reply #29 on:** June 18, 2011, 02:36:43 PM »

bend the ni-cr wire to the shape you want
then paint it , its not much insulation but it could be enough