Today I found myself making a belt mount for someone and wanted to include integral rivets into the back of it. Because of the semi random nature of the rivet locations, it wasn’t feasible to create a multi part mould so that the rivets could be made and the casting removed easily. So instead tapered hole were drilled into a flat soapstone mould. These holes had the distinct problem of trapping air which stopped molten pewter from actually getting deep into them. To rectify this issue, the holes were drilled all the way through the soapstone, providing an easy path for the air to escape…. Though this also allowed the pewter to escape the same way. So what was the solution to this issue? How can you drill holes all the way through soapstone, and also stop the pewter from escaping whilst allowing the air through?
Bamboo skewers. Yes, bamboo skewers were used to make small little plugs that also allowed air through them. With careful trimming the skewers can be used to provide the correct length rivet too, by altering the length of the skewer filling the hole, you can adjust the length of the rivet on the finished casting. It works well, and is a method I shall be using for future belt mount with integral rivets.
Such a clever idea! I’m surprised that they allowed enough air through.
Me too… But I suspect that there were also small gaps around the edges, that were too small for the surface tension of the pewter to force their way through.
I’m concidering actually making up a small wooden jig on that side of the mould, so that the plugs can all make for easier removal of the finished casting, but allowing me to push it out from the back.
Brilliant.
I just ran into the same problem last night, and that Will Totally Work.
Thinking on this further if you actually file the bamboo skewer bits into a flat wedge and then have that wedge pointing back into where the pewter is coming from you could make easier to flatten split rivets too. Might be worth making the holes larger though to make sure the pewter is strong enough when split to hold onto the piece that it is put through.
BTW, It’s nice to know that people are actually reading this stuff too.