Back to the foundry

[Jammer]

Sounds like you have it planned out, hope it works out for you. Do you still have someone to help you?

[Rasper]

I have always been a one-man foundryman. I use my employee to do some of the dirty work, but when the metal melting happens, I don't want anyone around me. They get in the way, and they distract me. A distracted man with a crucible full of molten bronze is a dangerous thing.

Making the rubber mold today. Here she is almost done.



The rubber will get to cure for 16 hours. On Tuesday I shall make the plaster mother mold and maybe even pour a good wax. It usually takes a few tries to get a good wax.

Richard

[Rasper]

Dateline Tuesday---
I made the plaster mother mold today. Tomorrow is wax day.



Richard

[Rasper]

Well, I took a day of preparation and organization before making the first wax. I made it today, along with the necessary sprues. I won't open the mold until tomorrow. It would be nice if it is a good one. If not it's back in the pot for another pour. No big deal.

I had forgotten how much work investment casting is.

Here are the sprue molds I used for this casting:



and a close-up of the main sprue showing the 3/8 inch steel rod I cast in the center. That allows for wax expansion without any breaking of the investment.



Here is the end of the sprue after I pulled out the steel rod.



Tomorrow I open the mold and look at the wax.

Richard

[latzanimal]

Looks promising but I do not know what I am talking about...

[cae2100]

Looks promising but I do not know what I am talking about...

yea, same here, but just watching and following along with the progress.

With the wax sprues, does the steel rod just slide out of the wax as it's cooling, or do you wait for the wax to solidify and heat the rod and pull it out that way?

[Rasper]

I coat the rod with either a silicone spray or with petroleum jelly before pouring the wax. When the wax is cold and solid I place the end of the steel rod in a vise and pull the wax sprue off of the rod.

I opened the mold this morning and was greeted with a perfectly good wax. Made me happy.





Next step is the final touch-up to the wax, attaching the sprues and the vents, and then to invest it in a sand plaster mix.

Richard

[Jammer]

Looks good, is she hollow as well?

[Rasper]

Very hollow. She is between 1/8 and 3/16 of an inch thick in most places.

Richard

[Rasper]

As I examined the wax closely, I found some problems: several holes and thin spots in her neck. I have made three more waxes. The last one I made this afternoon has no holes and seems perfect. I think I am good to go now. Making waxes is the simplest part of this procedure. With a good mold, which I have, I can turn out waxes in an hour or so each.

Richard