mortar ignition method?

[eod20]

i am drawing up plans - modified from plans found here) for a beer can mortar    going with 4140 steel for the barrel and was thinking of using a musket cap and nipple with a remote laynard striker for ignition?    also thinking of extending the barrel to 1.75x or 2x the can length     any down side ?     thoughts?     ohh yes    i am going to mount it on a steel sled base

[Cat Whisperer]

4140 is good, although 1018 or 1024 will also do well and may be easier to machine.

Steel sled is OK too.  Only watch out not to do a replica of our 60mm or 81mm mortar as they are in the style (Stokes circa 1914) of newer than the pre-1899 designs and could cause some interruption of your lifestyle should the feds catch wind of it.

Love to see some sketches.

[eod20]

i will try to get some drawings posted for you      the sled i want to do is a scaled down copy of on from an old civil war pic i have     i think it is a seacoast mount  but it is pictured in a land battle being set up or tore down   i think it is a 10 or 13' mounted on it     not the dictator steel mount  but the one with the adjustable height screw thru the forward support      do you see an issue with threading a musket nipple into the barrel and using musket caps?

[eod20]

this is the sled design i want to copy    slightly widder and longer as i want to have the tube look "thicker" as the civil war era tubes appear   approx. 2" walls when done

[Double D]

If you are looking for that sqaut fat Civil War Mortar profile don't make the bore 1.75 to 2 X longer than the can.  The general rule of thumb for these mortars was to have the bore length 2X times the bore diameter.  A can is 2.6 inches in diameter, so 2x would be a 5.2 inch bore.  A can is 4.835 long. To accomodate a 2x bore, the bore will have to be 9.7 inches long, plus chamber length plus 1x thickness at back of chamber.

For safety purposes you want the entire projectile inside the bore. With the 2X bore you get that.

With the 2X projectile bore you also get protection of a bore longer than projectile, but you loose the profile.  I'm not so sure you gain anything, you might even loose a bit given the reduced charges of the mortar with the longer barrel.   

Just to be clear when I say bore here, I mean projectile bore and that doesn't include chamber.

[GGaskill]

Making a siege style mortar with a steel mount (in the style of the cast iron mounts of the 1841 patterns) in beer can bore will give you an extremely heavy piece which you will quickly tire of moving.  My freelance "Coehorn" in beer can caliber has "gained weight" (as I have gotten older) to the point of being difficult to move.  If the mount were steel too (barrel is made from 6" dia round), I couldn't budge it.

Aluminum cheeks would be plenty strong enough and one third the weight.

[eod20]

aluminum is a great idea     do you think it would be strong enough for the sled      and i know where i can get my hands on a 9' dia piece if you think it would be strong enough for a barrel ?

so what you are saying the bore should be approx. 5.2 inch deep just slightly longer than a can is long and 2.6 inch in dia    7.2 inch is 1.5 times the can length what would be gained or lost with a bore of that length?    or should i just stick to the can length plus a "bit"  say 5.25 inch?

[Double D]

George is not saying Aluminum barrel, George is saying Aluminum carriage. Stick with a steel barrel

A 2X bore would 5.2 inches.  A can is just a shade longer than 4.8 inches long.  So a bore 5.2, 5.25 inches would be fine. 

Actual bore size should include a bit of windage.  To find bore size with windage divide the projectile diameter by 39 and multiply that number by 40.  2.6/39 = 0.0667 x 40 = 2.667.  Windage gives you room for fouling and and an od size projectile as well as letting a little pressure blow by.

[eod20]

THANKS FOR ALL THE HELP    i will stick with the steel for the barrel and go with the measurements you suggest  and put it into a nice thick piece of steel     i am going for the short squat siege mortar look    weight should not be a problem    i live on a farm in s central pa     i will just pull it out of the barn with a shackel lug on the front  hahaha    what is your opnion of using mucket caps and a nipple for ignition?  do you see any problems with the length of the flash channel?

[GGaskill]

The problem with using percussion caps is you can't clean the vent easily or frequently unless you can remove the nipple.  Aluminum cheeks would be plenty strong since they would be more than an inch thick. 

An aluminum barrel, on the other hand, is not a good idea.  Aluminum never reaches a plateau in fatigue stress and will eventually burst.

[Blaster]

Here's a picture of my 2-inch Coehorn mortar that is fired with a slap hammer and a musket cap.  Works every time for me and when cleaning it, I always remove the nipple.  That projectile is a piece 2-inch electrical conduit filled with concrete.  With the elevaton at about 45 degrees, it only takes about 60 grains of cannon grade BP to launch it about 100 yards down range. 

[Blaster]

Here's my beer/soda can mortar that has an aluminum base.  Sorry, no mty BP powder can to display with this one.

[eod20]

thank you blaster    your 2in is just what i want to build    just with a thicker barrel profile to look like a 10 inch seacoast     when i get it all going i am sure i will be asking you ALOT of questions

[Blaster]

thank you blaster    your 2in is just what i want to build    just with a thicker barrel profile to look like a 10 inch seacoast     when i get it all going i am sure i will be asking you ALOT of questions

I'll be happy to attempt to answer your questions however there are a lot of true experts out here that'll make me look like a big old dummy.
Please do keep in mind that I did NOT build any of my cannon/mortars.  I just collect and shoot em and always enjoy them. 
Blaster (Bob in So. CO)

[Tropico]

Please do keep in mind that I did NOT build any of my cannon/mortars.  I just collect and shoot em and always enjoy them. 

Thats me. I am with ya there Blaster ., Damn grateful too. Cannon and Mortar is alotta fun !