9" Dahlgren in .75 cal

[armorer77]

Hi , I made this from a set of prints for a .375 bore , doubled all dimensions and everything worked except the proportions look wrong . Is it just me ? Comments wanted . Armorer77





Thanks guys .

[Cat Whisperer]

I want one!   

[Double D]

I want one!   

Don't you "got one"?

[Cat Whisperer]

I want one!   

Don't you "got one"?

Not a Dahlgren.

[Double D]

If you are using the drawing I think you are using, here is the numbers you should have used.

Lengths         
oal   5 1/2"    5.5x2=11"
Muzzle swell 1/8 .125x2=.25"
first taper   2 9/32"*   2.28125x2=4.5625""
second taper   1  3/16"   1.1875x2=2.375" have got
cylinder    15/16"   0.9375x2=1.875"
cascabel     9/16"    0.5625x2=1.125"

*Keep in mind the first taper is 1/8 shorter in the drawing than the length given, 1/8" inch doubled to 1/4  to allow for muzzle swell.


diameters
Muzzle swell   19/32"   0.59375x2=   1.1875"         
MS at 1st taper    1/2"   0.5x2=1""
1st at 2nd taper    3/4"   0.75x2=1.5
2nd at cylinder   1  3/32"   1.09375x2=   2.1875""
cyl at cascable   1  3/32"   1.09375x2=   2.1875

Is that what you got?

Dan's right, fractions suck. 

[armorer77]

This is indeed the print I got from you . The only number I changed is the breech Diameter . I increased that from 2.187" to 2.25" . Other than that , all numbers check .

[Double D]

If you increased some svelte piece of female eye candy's waist by almost 3% she would look positively fat.  With a gun that small it makes a big difference.

I know why you made the cylinder 2.25.  What you need to do is  multiply all measurement by 2.057

Here are the number you should have used.

Lengths            
oal       11.314
muzzle swell 0.257
first taper    4.693
second taper 2.443
cylinder     1.928
cascabel     1.157
            
            
diameters            
muzzle swell        1.2213
start of 1st taper        1.0285
1st to 2nd taper        1.5428
2nd to cylinder       2.2498
cyl to cascable       2.2498


Try these numbers and send the barrel to me and I well you if they are right.  I am retired and won't be able to afford to send the barrel back, honest. 

[seacoastartillery]

     Armorer77, that's one good looking  IX Inch Dahlgren.  Mike and I looked it over very carefully and are pleased that you got the first and second tapers and their intersection correct.  We don't see any areas that demand changes or are out-of-proportion.  We posted three pics of one we found in Hartford, Conn. at Trinity College.  The gun and carriage are VERY well cared for and are almost perfect examples of naval artillery.  We are posting these pics so you can see the 'nuances of form' that never show up on a drawing, but we think are necessary for a cannon's looks.  Our constructive suggestion is that you look at the gently flared muzzle swell and the large outside radius that connects the true spherical radius of the breech to the end of the cascabel.  We judge that the cascabel and the connecting radius leave only about  50%  of the breech surface for the spherical radius which gives the breech end that "lollypop look".  We would be proud to own one of your Dahlgrens!  You did a fine job.

Mike and Tracy

[GGaskill]

Comparing the model barrel to the middle pic above, it seems like the transition from the cylinder is taking place too far forward, about the center of the trunnions, instead of a whole trunnion diameter behind the trunnions.

[Cannoneer]

Ed; I like its looks, and you might say that I'm kind of a Dahlgren aficionado.

PS: I'm still working on the specs, and I'm making progress, I'll get there soon!

[armorer77]

Thanks for the comments and the compliments . I will be starting the sales model in a couple of days .

[Double D]

Your model has a fat waist.  Your double measurement for the cylinder should be 2.1875, but you made it 2.25 for the one caliber wall thickness safety rule.. At this  size that .0625 is a huge difference. 

Use the new numbers. When you upscale you have upscale all of the them.   Your multiple for all measurements is 2.057.  If you multiply all measurements by that number all your proportions will be correct.  Try it one time, to humor me, I think you will be pleased.

Nuances, you say M&T.  I think I spot one.  The second taper isn't a taper, it's an ogee, isn't it?

[dan610324]

I think they both taper,
but between the both of them you got a hughe radius so its difficult to say where one ends and the other starts

[armorer77]

Don't worry , the next one will be scaled up in all dimensions . Armorer77

[RocklockI]

Your first blending is along the trunions . On Mikes picture the blend is foward of the trunion .  That gives it a nose heavy look .

Does it have a rear end bias ?

Call it a southern dalgren .......

We have a monster shell gun at the Nature and Historical Museum in Denver . I've been coming there since I can remember ........

[seacoastartillery]

Nuances, you say M&T.  I think I spot one.  The second taper isn't a taper, it's an ogee, isn't it?

     No, but at least you spelled it right!     Ogee is not a term you hear on the street these days, but back in the day, say a day in 1830 or one in 1853, you might, if you were among ordnance people.  There are first reinforces and second reinforces and the same with tapers always starting from the breech and going toward the muzzle end of the tube.  An Ogee is a different animal and a minor one in the total scheme of a tube's architecture.  Best described by a drawing, here is one from the  WASHINGTON NAVY YARD WASHINGTON DC 20374-5060.




And for those of you who are scratching your heads, it's the Muzzle End where you find the vast majority of these.  A taper is a taper is a taper unless it's a Chase!  But that's a topic for another day.

Mike and Tracy

[Double D]

An ogee is two arcs that curve in opposite directions whose ends are parallel.  

The shoulder on a 577/450 case is a ogee. Roy Weatherby used an ogee shoulder on his cartridges.  It is more common use in mouldings-woodworking  and architecture.

http://en.wikipedia.org/wiki/Ogee



This sure looks like an ogee to me.  Tracy do you guys have some original drawings of this gun, to check and see if it calls radii?



Gary I think the trunnions look like they are in the wrong place because he used a different scale for the chamber dimension than the rest of the barrel. That would make the cylinder length longer and shorten the section that may be a taper or ogee. The center line of the trunnions should 7.135" from the muzzle.

Here is the drawing Ed is working with

[armorer77]

I did miss on my trunnion placement . But this review will insure the next model is better . Armorer77

[little seacoast]

I know you were asking for criticisms of the design but I think it's a fine barrel as is and certainly wouldn't scorn one that happened to fall into my greedy grasp.

[seacoastartillery]

     First of all Mike and I agree with Little Seacoast and his most recent comment, it is a fine barrel and we want one too.  Now, to  satisfy the Montana Moderator's insatiable curiosity and to assist a fellow builder, we will post a drawing we purchased near Harper's Ferry, WV that is from one of our country's best archives, the name of which, I don't recall.

So, once again:

Nuances, you say M&T.  I think I spot one.  The second taper isn't a taper, it's an ogee, isn't it?

    No, it's a taper.  When counting tapers on a tube or reinforces, always go from breech to muzzle.  The second taper is a taper.  NOW, if the Montana metal mangler is talking about the general shape of the tube's top dead center as it goes from the muzzle to the cylinder, then you could loosely define it as an ogee. Yes, I could agree with that.

    

An ogee is two arcs that curve in opposite directions whose ends are parallel.  

The shoulder on a 577/450 case is a ogee. Roy Weatherby used an ogee shoulder on his cartridges.  It is more common use in mouldings-woodworking  and architecture.


Tracy do you guys have some original drawings of this gun, to check and see if it calls radii?




Here is the drawing Ed is working with

     Yes we do Double D, and it differs in some details from the one you fellows have.  See it below.  To help a fellow builder and the best metal mangler in Montana, maybe second best, that guy who lives 40 miles northeast is a pretty good one too, we have provided this drawing.  Note the differences in the muzzle flair and the breech radius, our two areas of concern.



AND, the Swede is correct, it is a large radius between the two tapers, it's about 18 inches according to our calculations, which, for a 1:14 scale gun would be about 1.3", fairly large on a 9" long gun.  Thanks, Dan, good observation.

Keep going Ed, you're doing a great job!

Tracy and Mike

[Double D]

Looks to me from the drawing you posted that it is indeed a flat taper with a radius transition at each end.  The drawing doesn't appear to show an ogee.

[dominick]

Ed,  The diagram in reply #16 shows the muzzle flare being very short and I don't think this is how the original barrel is.  I think the bottom diagram in reply #19 is the correct muzzle flare.
  I noticed with the few I built that the muzzle flare makes a difference in overall appearance.  Very nice job on it.   Dom

[dan610324]

what is the lined area ??
is it the casting that will be turned away ??

[seacoastartillery]

what is the lined area ??
is it the casting that will be turned away ??

     Dan, you are right, but it is more of a suggestion to the foundry, and, according to our reading on casting cannon for the Navy, follow-through depended a lot on how vigorous the Navy ordnance inspectors were in performing in-process inspections, as the tube went from one process to the other.  In short, the inspector had to be there to inspect the large wooden pattern when it was completed and then make darn sure that that particular pattern was actually the one which created the voids in the cope and the drag.  On the large seacoast guns, 3,000 to 4,000 pounds could be slated to be removed in lathe-turning operations, not something the foundry wanted to do, because of increased time and material costs.

Mike and Tracy

[dan610324]

its interesting to see that the chamber shape is similar to shapes that was used on swedish regimental cannons 200 - 250 years earlier .
they were light weight and something in between a cannon and a howie .
but still classified as a cannon

that model is very very thin in the muzzle area , I was thinking on the pressure curve when I was looking on how the wall thickness proportions is .
cant find it now , but Im sure I saved it somewhere in my computer .

Im sure that the pressure have fallen to maybe 20% of the max peak before the ball leaves the 1:1 ratio area

[Double D]

Ed,  The diagram in reply #16 shows the muzzle flare being very short and I don't think this is how the original barrel is.  I think the bottom diagram in reply #19 is the correct muzzle flare.
  I noticed with the few I built that the muzzle flare makes a difference in overall appearance.  Very nice job on it.   Dom

Dom,
The drawing Ed is working from is a William Green 1978  1/2"  scale drawing. Green took his dimensions from the 9 inch Dahlgren in downtown Vicksburg overlooking the Mississippi River..

[dominick]

Douglas,  Here's a link to a photo of that gun.  

   

I used to set the compound at 10 degrees when cutting the flare.  The diagram looks like it's about 30 degrees.  

[Double D]

Looks like the grainy picture in the Green plans except at a different angle.   

Green's finished barrel is 5 1/2 inch long.  Green's flare starts 1/8" from the muzzle at the 1/2 inch starting diameter of the first taper, flaring out to 19/32" at the muzzle.

That translates in Ed's upscale at 2.057x to:  flare starts .257" from the muzzle at the 1.028 inch starting diameter of the first taper, flaring out to 1.221" at the muzzle.

 

[Double D]

I just hijacked this picture from Little Seacoast thread on the SBR Dahlgren.



Look more  like the flare Ed is making.

[armorer77]

I plan to try a couple of variations , but I can't start cutting until Tuesday . Armorer77