New project pulling a mold off a nice little mortar

[KABAR2]

Well about a year ago I bought a little mortar made from materials salvaged from the Royal George, the Royal George was a 100 gun ship of the line which sunk at anchor in 1782 the ship was undergoing repairs and the cannon were moved past center to heel the ship over another ship was unloading barrels of rum through the gun ports on the side the ship heeled to causing it to quickly take on water there were some 1200 people on board including women & children some 900 perrished . in 1840 the ship was salvaged and some of the bronze and wood was used to build cannon models which were engraved..... Over the years I have seen several cannon that were made but this is the only mortar I  have ever seen... I would think that both the cannon and mortars are more available in England.......

http://en.wikipedia.org/wiki/HMS_Royal_George_(1756)
 
The Peoject.... I like the lines of this little mortar but it is bored straight with no chamber so I have decided to pull a mold of it, the following photo's are the beginning of the project....

The lead ball next to it is 1" for scale.

I turned an aluminum stem to fit in the muzzel...


 



The fence below the touch hole was damaged so I have built it up
so I can reshape it on the model.


here it is set up for pouring the scilicone, to lock mold halves together
I use bolt heads in the clay.  Tomorrow I will add some photo's on making
the mold process.

[Shortwave5]

Thanks for sharing your project. I love watching what, and how, people on this forum build.

[jamesbeat]

Nice mortar, and nice project!
Will you be casting this yourself?
What alloy will you be using?

[KABAR2]

I have a small electric furnace for jewery casting, it can handle bronze, and I have a small supply of that metal and will have some more on the way in the near future..... this will be my first attempt at lost wax I have only done sand casting in the past... mainly brass pans for flintlocks and sword & dagger parts.

[KABAR2]

Well tonight I will try to give a quick explanation on making a silicone mold.....

This is my molding set up from right to left two part silicone mold material, mold, scale, mixing container, vacuum pump & vacuum box.   

Product: SMOOTH-ON  OOMOO two part silicone mold material, mixing ratio 100 part A to 130 part B by weight hence the scale.

Thorouhly mix both parts, the mixing process will fold air into the mix..... you have about 15 to 20 min.  pot time, I then put this in the vacuum chamber to de-gas for about 5 min.

While waiting for the pot we can prepair the model with mold release they recomend after spraying to brush it around to be sure all the surface is evenly covered.....

 
Once de-gassing is done pour mix onto model.... I am not sure of the outcome on this one the mold material is over a year old and was a little stiff on pouring we will see...


place models in vacuum chamber for further de-gassing..... 

I would normally wait till tomorrow to de-mold but with the stiffness of the pour and how fast it set up solid - under 2 hours..... the mold was suspect.... as feared it is not a usable mold the keys (red X's) did not form properly and along some of the moldings ( red <) there are gas bubbles/holes ..... So things don't always turn out just the way we want them.....even with the issues the mold did show the all the engraving I will adjust the mixing time and forgo de-gasing until in the mold .... this might give me a little more time on the pot life. Tune in tomorrow same Bat time same Bat station..........
Allen <><

[Cannon Cocker]

Nice project.  Silicone mold making, and bronze casting are on the list of things to learn this lifetime and I often look for information on these topics.  I may not get to it for a long time, but I like to learn what I can until then.  I look forward to seeing the process shown by someone like you who knows what they're doing.  Thanks for the step by step descriptions.