Panzer IV

[kentyler]

an old model, and rather poorly drawn
i decided to use it to try an experiment

some parts could be made of bakeable clay

first try at the idler i used pins to give it shape

second try i made a mold from the paper part

since i have to do 4 of them, i keep the short piece of rolled clay as a sample
to be able to maintain something like the same size for successive pieces

[kentyler]

the mold worked better
to make the center, put a ball of clay in, mash it down... but not too hard or it will put pressure on the spokes
an idler wheel

the cap for the large rear idler... this one has a dome center, i left the center of the mold open to make it easier to "eject" the parts

[kentyler]

as in all casting processes, sometimes there are bloopers
i tried making a 2 at a time mold... didn't work well... i think the sides sloped a little as they went down, keeping the pieces from freeing themselves

the molds are "hardened" with a coat of glue

and then before inserting the clay a thin coat of vasoline is brushed on

i don't know if this will actually work out... but i'm learning interesting things

[Zakopious]

What are the molds made from ?

Are you casting resin in the molds ?

[kentyler]

from the paper parts of the model, to be specific

i'm using oven firing clay to do the casting

[Zakopious]

My wife has a lot of Sculpey.

I may snitch some and try this.

[rockpaperscissor]

Interesting technique. I used to resoften old sculpey with corn oil when it got hard. I'm thinking that the vaseline might react with it. An alternate way to "lubricate" the push mold to eliminate the possibility of sticking is to dust it lightly with talcum powder before pressing in the clay.

[Samjacksom671]

I don't know why but unsented talcum powder was always hard for me to find. I get good results with corn starch.

[rockpaperscissor]

cornstarch works well, but your molds smell so much better after using talcum powder

[kentyler]

i'll try talc powder, right now vasoline seems to work fine... the problem i have with the models is when they are undercut... that is, the sides of the parts have to taper out just a little, not in

here's my first try at a mold for the road wheels, 3 layers thick... turned out to be a layer too much
and the mold for the idlers

the first try at a road wheel... the pressed steel shape of the center is a hard one to get

i decided that i needed to try it again 2 layers thick... i cut the bevel the way you'd cut a mast, first the 4 sides, then one cut in between each side