Author Topic: Cat Whisperer--Some Mortar Questions..... (Read 761 times)

Smoothbore · « **on:** April 11, 2005, 10:27:24 AM »

Mr. CW:

In a recent post I mentioned I had obtained some bronze rounds, one of which is 3" dia. by 13" long. I would like to turn a portion of it into a golf ball mortar. Since your posts suggest that you are a mortar guru, I am addressing my questions to you, however, anyone else who can and would like to help me----please chime in!!

A: When bored for a golf ball, will the remaining wall thickness be sufficient?

Provided A is a yea, I'll continue....

B: What depth of the bore would you recommend?
C: What depth/diameter for the powder chamber?
D: I do not have the ability to mill the slot for a trunnion, so the best I can do is a partial rounding of the base with enough flat surface left to bolt it on. How many, and what size, bolt(s) would you recommend?

Any suggestions, tips, pearls of wisdom, etc. would be very much appreciated.

Irrespective of if you say go for it with all kinds of help, or say the stock isn't appropriate and to do something else with it, I am considering the purchase of a golf ball coehorn in steel---since I do not have the tools or equipment to work with it. This brings me to my last question: I have surfed all the suppliers on this forum's list, and the candidate I like the most is one offered by "Cannon Mike." Can you (or anyone else) give me any feedback on his offerings?

Thanks in advance for any forthcoming help.

Smoothbore

Cat Whisperer · « **Reply #1 on:** April 11, 2005, 12:48:24 PM »

Smoothbore -

Â“Since your posts suggest that you are a mortar guru, I am addressing my questions to you, however, anyone else who can and would like to help me----please chime in!!Â”

Thanks for the compliment, but my claim to fame is that IÂ’m still alive after a number of years of KNOWING IÂ’d never live to see 21. I tend to overbuild things now - partially based on fear.

There are two ways of designing - one by applying the engineering principles (IF you are a qualified metallurgist or mechanical engineer - which IÂ’m not); and the other is by looking to see what other folks have done successfully and has been proven by much experience (this we both can do). So other comments are most welcome, as there are a number of very knowledgeable folks attending.

A: bronze round 3" dia. by 13" long: When bored for a golf ball, will the remaining wall thickness be sufficient?

With a bore of about 1.750Â” that would leave about 1.25Â” divided by two for a wall thickness of 5/8Â”. My first of two feelings (bear in mind IÂ’ve only had one experience with an OLD bronze 1Â” bore signaling cannon - and it exploded firing blanks) is thatÂ’s a lot of metal. My other feeling is that if it were to be used with lead spheres the pressures would be much increased.

B: What depth of the bore would you recommend?

ThatÂ’s easy. As deep as you want. Keep a lot of metal around the powder chamber. Longer barrel gives more velocity, uses less powder.

C: What depth/diameter for the powder chamber?

I use a Â½ inch diameter by about 1Â” deep chamber (holds about 50 gr. of powder. Suggest slower powder than what I use for steel (FFg instead of FFFg).

D: I do not have the ability to mill the slot for a trunnion, so the best I can do is a partial rounding of the base with enough flat surface left to bolt it on. How many, and what size, bolt(s) would you recommend?

Size it proportionally - I assume a brass or bronze trunnion. Larger is better. I have heard some talk of bending the trunnion, but IÂ’ve not seen it myself. You may have enough length (13Â” tube is right-much long) to drill a hole at the very bottom of the round for the trunnion, and then to turn or shape the spherical radius (if desired). There isn't much lateral stress. I'd use two 1/4-20 socket headed cap screws placed as wide apart as I could to keep them away from the powder chamber.

FWIW you have received an opinion. Get some others. Make a decision based on confidence of several others' experience. It's your responsibility to know whether it's a cannon or a bomb of which you're lighting the fuse.

(That's my approach. I've done both, one is very much better.)

CU_Cannon · « **Reply #2 on:** April 11, 2005, 03:37:49 PM »

Have you thought of making a Mountain Howitzer out of that chunk of bronze? It is just the right size for a 1/3 scale barrel. If I were to do that I would make it 1 in bore with a steel liner.

What is the reason for not building a mortar from steel? The tools and equipment are the same as you would use for the bronze.

GGaskill · « **Reply #3 on:** April 11, 2005, 08:46:59 PM »

Bronze barrels are prettier.

Smoothbore · « **Reply #4 on:** April 12, 2005, 03:37:33 AM »

TEST,TEST,TEST.

Smoothbore · « **Reply #5 on:** April 12, 2005, 03:43:30 AM »

Gentlemen, thanks for your responses, and sorry for the Test message, but something isn't jiving. I have tried several times (after logging on via the instructions) to respond to your posts. I type a message and when I click preview my message disappears and I get a log on screen, and scrolling up to the top I am no longer shown loggen on.

I did the same procedure with the test message and it posted, and i can't figure why this time and not the others. Is there a max length to a post that I have been going over?? The replys were a dozen or so paragraphs, is this too long for a single reply??

GGaskill · « **Reply #6 on:** April 12, 2005, 06:28:33 AM »

It's probably taking you too long to type it. This board has a pretty short logon timeout. When it happens, just logon again, then click the back button to get back to your post and re-click the Preview or Submit buttons.

Smoothbore · « **Reply #7 on:** April 12, 2005, 09:07:29 AM »

I'm still at a loss to what's going on. I typed a shorter response and was still shown as logged on when I tried to submit it. Off to cyber space again. I logged back on and have been surfing forums checking my logged status from time to time. I have done this for longer than any of my responses attempted earlier today and am still shown as logged on, so now I will try to post this message. If it goes through this time I am still in need of an explanation--as it appears time out isn't the problem.

Still shown as logged on, so here goes with submit!!!!

Smoothbore · « **Reply #8 on:** April 12, 2005, 09:13:30 AM »

Well dudes, as can be seen, the above message posted......beats the heck out of me. Enough for today, I'll try again tomorrow to post my follow up to your responses.

later,
Smoothbore

GGaskill · « **Reply #9 on:** April 12, 2005, 09:51:38 AM »

Is your browser accepting cookies? I have 4 cookies from graybeard on mine so the forum is obviously using cookies.

Smoothbore · « **Reply #10 on:** April 13, 2005, 07:49:06 AM »

Well it's another day and I'll try again to respond to your responses.

CW: "Still alive after 21." You were more optimistic than me. I didn't figure to get past 18. Eons ago in the sixth grade, I had a class in ancient history, in which Roger Bacon and BP were discussed. They made the mistake (?) of listing the ingredients and the proportions. I was in the drug store the next Saturday. That was the beginning.....45 years later.....it continues. If my father, back in those days, only knew what he was authorizing me to purchase when he signed my order blanks---in today's vernacular he would have "freaked out."

I am also not an engineer (formal education in biological sciences), which is why I posed my questions on this forum---to get input from those with the knowledge, wisdom and EXPERIENCE, who have been there and done that.

I asked about the depth of the bore as from what little info I have come across on gb mortars, they have mentioned bores of one or two calibers, but they have all been of steel. In my way of thinking shorter bore with a given wall thickness=safer. Since this may not necesssarily be true, again that's why the thread was started--to hopefully hear from those who know the answers.

Also I thought of a way to get around the no milling ability and the trunnion slot. I have some 1" bronze round that can be used for it, so the thought is to drill thru the base of the mortar stock, cut it off just short of the hole's diameter, then turn the radius down the the diameter point. Sounds feasable, will give it a try.

CU Cannon: I didn't consider a MH (or other cannon) as to work this stock in my lathe (7 x 20) I will have to shorten it 1/4 to 1/3 which would throw off the proportion of length vs diameter without turning the diameter down quite a bit. It will be just too stubby for a cannon barrel. Besides I just wanted to make a mortar this time!!

As for working with steel, from what I have read it is quite a bit harder to work with than bronze, and the reference to tools was more about ME than the actual tools. I originally obtained this lathe to make rocket motor nozzles (graphite) and aluminum "cannisters" that hold small charges of BP to deploy the parachutes on our rockets. I have had to learn by trial and error, and a bit of reading material I have run across. In other words I am basically a duffer with a metal lathe. I am still on the hunt for a mentor to help me unleash the many things one in the know can do with a lathe, but so far no luck. I just keep plugging along.

GGaskill: Right on dude!! Not only is bronze quite pleasing to look at after being turned and polished it, almost immediately, begins to develop a patina even more pleasing eye candy.

Later, Dudes
Smoothbore