Author Topic: What Alloy? (Read 620 times)

RvanM · « **on:** April 07, 2005, 06:06:37 PM »

I was thinking about making a golf ball mortar. Would 1010 or 1018 hot rolled be safe? If I was to make it out of DOM does it have to be cold drawn? I'm sure the answer is already on the forum, just having a hard time finding it.

GGaskill · « **Reply #1 on:** April 07, 2005, 06:24:58 PM »

Depends on the dimensions. 1018 CRS or 1020 HRS would both be satisfactory in sufficient quantity. The 2" 1144 has to be bored to at least 1.70" diameter for golf balls leaving a wall thickness of only .15" in the upper part of the tube. As long as you only fire golf balls, 1018/1020 would probably be OK but can you guarantee that no one will ever fire heavier shot than golf balls? You want to build guns with some safety factor to allow for their use when out of your control.

RvanM · « **Reply #2 on:** April 07, 2005, 06:33:52 PM »

I was thinking about 4" 1020 bored at 1.75" I would like to keep the wall thickness above 1" for safety and the occasional blank load :-)

GGaskill · « **Reply #3 on:** April 07, 2005, 06:49:42 PM »

I would consider that well over the minimum for safety assuming some degree of intelligence is exercised in loading. (-:

Cat Whisperer · « **Reply #4 on:** April 08, 2005, 12:53:00 AM »

Agree. 1" wall thickness is plenty.

Double D · « **Reply #5 on:** April 08, 2005, 01:48:31 AM »

If you make a mortar that you will have a breechplug with apowder chamber in it. The breech plug with say a 1/2 hole no more than 3/4in inch deep powder chamber is you cannon. The bore is 1/2 inch so you need 1 caliber or 1/2 ich all around the breech. The bore holding the golf ball is an expansion chamber. There will be pressure the but not as much as in the 1/2 inch bore and you can get away withthe thinner walls.

Rvan you can still get inthe mortar contest. Check the post at the top of the board.

RvanM · « **Reply #6 on:** April 08, 2005, 03:05:02 AM »

In mortars with a powder chamber are you loading with loose powder? If so, is there any trick to it? The whole powder chamber thing has me confused.

Cat Whisperer · « **Reply #7 on:** April 08, 2005, 06:58:34 AM »

The idea of the powder chamber (by Coehorn) was to provide lots of metal around the powder (at the early part of the burn where the pressure spike is) and thinner metal around the rest of the tube (where the extra strength isn't needed).

Some folks wrap up the powder in aluminum foil - and insert it into the powder chamber; pierce it with the spike and insert the fuse.

I use a drop tube for one of my mortars with a funnel at the top to pour in a measured amount of powder directly into the powder chamber.