Author Topic: Yorktown Mortar Drawing ? (Read 5451 times)

accuratemike · « **on:** March 11, 2006, 04:36:08 PM »

Anybody have a sketch of a "Yorktown" mortar ? I have a chunk of steel that is 3 1/2"dia x 5 1/2"long. Holding up a caliper to my monitor (scientific), the Cannon-Mania 1" Yorktown would scale up 75% (golf ball sized) and still fit my chunk. I like that Rev. War stuff (to boot). I haven't been able to find many other sources of info though. Just looking for the basics.
I thought I could be making smoke sooner (I think I have found metal for the golf-howitzer project) if I started with a mortar. I could use practice with trunions, and the Yorktown's are in pockets like a cannon's would be, as well. Thanks, MIKE

GGaskill · « **Reply #1 on:** March 11, 2006, 07:44:35 PM »

You have a link to this image?

accuratemike · « **Reply #2 on:** March 12, 2006, 03:02:54 AM »

That should work, MIKE

accuratemike · « **Reply #3 on:** March 12, 2006, 07:36:44 AM »

I made this with the caliper & counting pixels in PhotoShop:

Little crude, but it is a start. Any comments ?

Thanks, MIKE

Cat Whisperer · « **Reply #4 on:** March 12, 2006, 11:21:01 AM »

Good drawing (but move the trunion diameter dimension OFF the object :eek: ).

With the trunions where they are, attention should be paid to how they're attached - how deep the sockets are, etc.

Thanks for posting it!

GGaskill · « **Reply #5 on:** March 12, 2006, 11:59:41 AM »

That looks a lot like this French 10" mortar from Round Shot and Rammers. The linked image is a whole page so be sure to expand it to full size when looking at it.

Click the image for a large version.

accuratemike · « **Reply #6 on:** March 12, 2006, 12:50:56 PM »

Thanks alot ! You guys are too good to me.
CW, I'm a pen and ink draftsman from before the day of this CAD stuff. I have had to teach myself AutoCAD and am still nowhere near proficient. Part of the problem with this one was getting it to print out on my 8 1/2x11 printer at 1:1 scale. The dimension on the object never should have happened. Mr Truskowski would have waited till I inked it in, and then made me redraw it. (It's fixed, wonders of technology.) Good eye. I think I could pocket the trunions about .225" deep, and still be 1/2" thick there. Bore could/should be shallower maybe. I will probably TIG them in.
GG, thanks alot for the pictures. Exactly what I was after. I have a better feeling how they were chambered. The "Escutcheons" around the trunions would be beyond me though. We'll call it "stand off" scale. On the C-M model, the touch hole was nearer to the trunion center line, I like this chambering more. I have a better feeling for the detail around the muzzle as well. Thanks again.
I greatly appreciate your input., MIKE

Cat Whisperer · « **Reply #7 on:** March 12, 2006, 02:40:10 PM »

Accuratemike -

I could tell from the whole layout you'd had GOOD drafting experience. I taught AC for 13 years at the local community college. I still remember having the 2 disk (5-1/4") set of AC version 1.2 ! Didn't know what a mouse WAS!

You might consider making the powder chamber as a truncated cone (rounded edges of course).

Drilling the touch-hole into the curved surface can snap bits too. If drilled first, there is no problem, otherwise it can be moved up a little.

GGaskill · « **Reply #8 on:** March 12, 2006, 07:09:47 PM »

If you start the hole with a center drill, you shouldn't have any problem drilling the touch hole, as long as the barrel is clamped so it won't move while drilling.

Cat Whisperer · « **Reply #9 on:** March 13, 2006, 12:45:54 AM »

Quote from: GGaskill

If you start the hole with a center drill, you shouldn't have any problem drilling the touch hole, as long as the barrel is clamped so it won't move while drilling.

The problem is not with the curve on the drill entering the hole (although that is problematic if done on the sloping curved area) but on the drill entering the powder chamber, and having to cut only on one side - I've snapped small drills off there, as have others, because it tends to force the bit to the open side and if the feed is not greatly reduced it will snap the bit off - inside the hole.

It may not be a problem with brass/bronze but it certainly is with steel/iron.

Then you're stuck with a bit in the fuse hole. I was lucky, it was large enough underneith the tip of the bit so I could take a punch and simply drive the broken piece through.

accuratemike · « **Reply #10 on:** March 13, 2006, 05:26:58 AM »

I drafted in Jr High, High, Comm. Coll. & U. Del. At U.Del. I learned the momentarily usefull HP CAD of some sort. I have never had a job drafting though. I stll love it, my 10yr old is the future draftsman.
I did the hidden lines as an afterthought. I had not seen the great drawings yet. I'll re-do the whole thing now and post something soon. I have seen the truncated cone theme in other works, I'll surely try to incorporate it.
Here at the machine shop we make removing broken taps, drills and bolts a way of life (dealerships and garages don't know when to give up). I'll be really careful though. Thanks again, MIKE

Cat Whisperer · « **Reply #11 on:** March 13, 2006, 07:12:46 AM »

Sounds like you've got a good grip on it!

We anxiously await pictures of smoke and flame!