Group buy-group pour, bronze 24 PDR Coehorn golf ball mortar

[Double D]

[303smle]

Douglas was kind enough to send me his bronze golf ball mortar.  He started me on the slippery slope to a Martini Henry addiction.  Now he is enabling another addiction

All I had to do was find a suitable olive green paint for the base and paint the ironwork black.

Here is is in all its glory.



Now all I have to do is take it to the Back Creek, WV Artillery Proving Ground to make a video with smoke and noise.

Thanks again, Douglas

[Double D]

Last year we were just getting ready to leave the RV park and go over to 303SMLE-  Bob's house to visit with him and his lovely wife Becky, when my wife collapsed and passed away.

Bob and Becky took me into their home and cared for me for a week.  And I was in need of care, I can assure you. I was extremely grateful for their kindness, especially being 2000 miles away from home and suddenly alone.

Bob had asked me prior to build him a golf ball mortar.  I intended on building him  a one of these Coehorn out of steel as soon as I got home.  When the Bronze mortar group buy got going, I knew that was what I was going to build for Bob.

I think Bob likes it and Becky said "it's cute!"

Bob and Becky thank you again for coming to my rescue in my darkest hour.  Your kindness to me can never be repaid. 

[RocklockI]

Douglas , I am thrilled to hear from SMLE did you send some Fox balls with it ?
 
About a week ago I got the word that the last wax I gave the caster was ....another BUST !
 
Here is the situation on these mortars, it doesnt look likely that I can get these done as hoped . Mike and I have pondered this thing every which way and around agian ,about ,who knows how many times
 
I am torn between trying yet another caster with my one last wax or going back to one or the others hoping they have followed up on my instructions by contacting the wax makers ...on how to do it ? Ive talked with the makers and it is compleatly doable IF the casters will follow two very simple instructions .
 
more later
Gary

[RocklockI]

Well , I called the foundry today and had to ask about the goings on with the last wax .
Short story is they blew it and all waxes are gone .

This project is on hold . 13 waxes four differant foundries and none are capable most don't even listen to instructions .
I may make a mold someday .

Gary

[keith44]

I am sorry to hear this Gary.  You have worked so hard on this project and to have this happen every time. 

Thank you for the effort.

[Double D]

Gary,

Cast them solid and machine the bores.

There are any number of company that do cnc moulds  for casting.

[GGaskill]

Casting bronze in steel moulds is a horse of a whole different color than casting plastic, zinc or aluminum.  The temperatures are way higher.  That being said, a steel mould would probably last as long as the demand.  You could probably even use a core for the bore than would eliminate most of the machining.  A problem would be how long would it take to solidify before you could pour again?  Keeping the bronze melted costs money.

The cavity is pretty simple.  I bet you could do it with manual machines if you were willing to cheat on the trunnion diameter.  Or scale the barrel to a standard size for the trunnion (like whatever you can get in ball nose end mills.)  Or maybe even bore the trunnion on the lathe and insert plugs.

Maybe even use a wet chill like a Rodman.

[Cannon Cocker]

I can think of 3 different guys who make steel molds for projectiles.  The ones for minie ball style are almost identical to the mortar shape.  Even though you could cast in the bore with a core or mandrel, I like DDs idea of casting solid, then boring.  The reason foundries switched to this method in the 19th century was because they realized that the porosity and impurities collect in the center of the casting and are then removed by boring resulting in a barrel less likely to have voids and imperfections.

[Rock6.3]

What kind of bronze is needed for this project?  (I googled and found nearly a dozen different types of bronze)

[GGaskill]

... nearly a dozen different types of bronze)

There are many more alloys than that, especially with today's definition of bronze as any copper alloy in which zinc is not the major alloying element.  Mine are cast from silicon bronze but Everdur would be a good alloy, too.  And there are others that would work.

[Victor3]

Well , I called the foundry today and had to ask about the goings on with the last wax .
Short story is they blew it and all waxes are gone .

This project is on hold . 13 waxes four differant foundries and none are capable most don't even listen to instructions .
I may make a mold someday .

Gary

 Darn.
 
 Gary, I know you're big on lost wax but have you considered making a pattern and just have them sand cast? You've perfected the machining operations already; you could do one in wood if you had a mind to...

[Victor3]

Casting bronze in steel moulds is a horse of a whole different color...

 I think maybe Gary's talking about a mould for the waxes(?)

[Double D]

Casting bronze in steel moulds is a horse of a whole different color...

 I think maybe Gary's talking about a mould for the waxes(?)

Yes, I think he is thinking that also.

[RocklockI]

Yes I was thinking of a reinforced silicon mold to cast Victory brown wax which is all these people know about . Everdur is the bronze they use and it is a good one ,I'd rather
have 90-10 but the foundries are stuck on everdur as well as their methods .
 
But with a mold there will be parting lines ,chasing ect. The whole key to these being a reasonable price was to have the bore cast in . Sure I could cast them solid and then bore ,that would take 'several hours' and double the price ......
 
I've got a wedding to pay for in early August as my daughter Cheryl is gettin hitched . SO not much is going to get ordered right away but I'll give it some thought .
 
Thank yous guys for all the encouragment and kind words . This is just about the time last year DD got this thing going
 
Gary

[guardsgunner]

If decide to continue, I would take couple in the rough. Boring if easy enough.
 
Bob

[Double D]

Gary,

Take a look at the poll we used to open this discussion.

as cast unfinished-rough casting     12 (24%)
as cast finished bore     21 (42%)
fully finished     17 (34%)

Total Members Voted: 50

Pay attention to what the audience wants. 
   
Get  a casting made-.  Figure the price for the rough casting. 

Take the casting and get the bore machined.  Figure a price for a a finished bore.

Fully finish a mortar and figure the price for that.

Make sure when you  figure the prices,  that when you sub-contract you get a quote to do say 10 pieces at a time, not just one piece.

When you have all three prices post them.   Let the fellows know what the prices are and let them decide if they want to spend the money.  You might be surprised.

For those of you who are new or newer to this board, this is a group buy project that we finalged  Gary into ram-rodding.  Gary dabbles in lost wax bronze casting so it was only logical we get him to run this..   Once Gary gets the wax issue worked out then he will tell us and set up the group buy for us.

 

[Cannoneer]

Gary,
This info may be contained somewhere in this thread, but I'm just going to be lazy and ask a couple questions.
Did you ever try the foundry that cast your VOC barrel (the one with all the intricate details) on this project (because they did a fine job on that one-off barrel)?
One of the  foundries that you used did a fairly good job on the Coehorn model that Douglas gifted to another member, in fact IIRC the only problem was some excess metal in the powder chamber, so did you ever give them a second chance, or did you just move on to a new one?

 

[RocklockI]

Yes the origanal casters got a chance and they did produce a very rough casting . He didnt want to do a second one  .
 
The DD mortar was cast localy and it was first ,I was thrilled they got six waxes in two batches of three . They couldnt reproduce the first results .....!!!
 
Coleco in Cody got one ,they couldnt reproduce the first results of the test mortar .
 
I've got quotes for batch runs that's not an issue ,1 hasnt amounted to a batch yet  .   

[Cannoneer]

Gary,
Would all these foundries that you've already tried be considered top of the line, or are they more like commercial mass production foundries that basically produce home decor type castings?
To be more precise, would a top flight artist take his projects there to have his work cast, or would they go to more specialized (and expensive) foundries where the artisan's possessed higher skill levels?
If the answers to the questions above are yes, is the reason you're not taking the project to these better foundries, because the cost would be prohibitve?