How to make easy "form fitting" molds... (1 Viewer)

[Captkronos]

In my never ending quest to save money, I am trying to move past the standard square/rectangle shape of molds, since there is much dead space which equals silicon going to waste. I am trying this, clay walls fit around the figure, with spray foam sealant behind the clay. The only problem will be when drop casting, the mold won't have a flat edge to lay on the table, I will probably just put the mold in a pan with sand all around to support it. I'll update this thread with more photos and results. By the way, my secret tip of the day, Play-Doh works incredibly for simply pushing your master into it to get the first half of the mold. It does not contain sulfur and does not affect the curing of the silicon. I'm giving you gold, Gold, I tell ya'!

Yours in home casting cheapskates,
- Captkronos

 

[Wraith]

Thanks for the Gold! Neat idea. Re the lack of a flat base, if the clamping boards are slightly bigger, then shouldn't this overcome the problem?

Not tried Play doh. I've used plasticine, is there much difference?
We have Play doh in the UK, just trying to establish if it's the same product.

Cheers
Simon

 

[thebritfarmer]

Thanks for the Gold! Neat idea. Re the lack of a flat base, if the clamping boards are slightly bigger, then shouldn't this overcome the problem?

Not tried Play doh. I've used plasticine, is there much difference?
We have Play doh in the UK, just trying to establish if it's the same product.

Cheers
Simon

PlayDoh and plasticine are similar. Play Doh comes in yellow cans and is much softer and easier to work with.

 

[Wraith]

Ta Scott, guess it's the same product then.

 

[Captkronos]

Yes, you are right, the clamping boards would work fine. I've used that trick before when I would have odd shaped edges. Play Doh is incredibly soft. If you re-can it after taking apart your mold "box", you can re-use it maybe once before it starts to get too hard. Here we have stores where you can get a generic version of Play Doh, 4 little cans for $1. I'm going to pour the silicon on the first half now. After curing I will post a pic.

 

[Wraith]

Look forward to the results mate.
From plenty of experience with the kids leaving the lids off the pots, I can guess at it's lifespan, but as you say, it's cheap enough.
Cheers
Simon

 

[Martin Tabony]

Instead of "Plastice" which is oil based try "Plastiline" which is wax from Alex Tiranti of London. Plastiline comes in different grades of hardness and if you get any bits in it (guaranteed when mould making) you can melt it in a pan and seive it.
Also if you are trying to save the amount of rubber you use, try a shell mould. Or use a thixotropic agent so that you can butter on the rubber.
One other thing if you have old moulds of the same material, cut them up and use it as a filler for the new moulds.
The problem with Play doh is that it can dry out and grip to the silicone!
Martin

 

[Captkronos]

okay, rubber cured, part II....

 

[maddadicus]

In my never ending quest to save money, I am trying to move past the standard square/rectangle shape of molds, since there is much dead space which equals silicon going to waste. I am trying this, clay walls fit around the figure, with spray foam sealant behind the clay. The only problem will be when drop casting, the mold won't have a flat edge to lay on the table, I will probably just put the mold in a pan with sand all around to support it. I'll update this thread with more photos and results. By the way, my secret tip of the day, Play-Doh works incredibly for simply pushing your master into it to get the first half of the mold. It does not contain sulfur and does not affect the curing of the silicon. I'm giving you gold, Gold, I tell ya'!

Yours in home casting cheapskates,
- Captkronos

Love the new figure. Put an egyptian head on it and you can add it to your Sudan line. Of course now, every time I make a suggestion, it costs me money^&grin. Michael

 

[Captkronos]

This figure is the first to be made from my rider skeleton armature, so there will be many variations to come, including Egyptian...naturally

 

[Captkronos]

I love it when everything goes right...

 

[christopher]

captkronos hello, I also make my own forms I build a wooden frame and fix my character in children's play dough. I notice that at least 1 cm margin is around the figure. I can pour without risk.
Save to a tip from me to Slikon. but do not throw away old forms into small pieces or cut into thin slices dei can be processed safely with the new silicone.
It greets Chris

 

[Wraith]

The casting is looking pretty crisp! Nice job.

 

[Captkronos]

I've always cast in single pieces, so I have no experience with rods and all that. A detached arm would offer even more possibilities of couse.
Also, even with this one, you can see there wa a lot of unnecessary rubber, so yes I will likely start to minimize the room around the figure in the future, as suggested with a 1 cm boundary for example.

 

[kilted vampire]

This is one of the most helpful mold making threads to date. I firmly endorse it.


'' KVs' bite of approval !

 

[PJDeluhery]

Great thread and very helpful. I'm a little suprised at how well the metal flows into the extremities without vents. Any tricks to share here?

 

[Captkronos]

I would say the fact that I use low melting bismuth in my pours helps a lot with the flow into tight spots without cooling. I use bismuth with tin and lead, play it by ear sort of, but a little bismuth lowers the melting temp of lead and tin, and helps the flow also. If necessary I use the razor knife to cut small vents to allow for air flow, but you also kind of develop an eye for what should work and what won't. I have some older stuff that didn't pan out no matter how many vents I cut into it. You can also see the big sprues going into the feet on this piece. Using the weight of the metal to help push it through helps, and you can just re-melt those sprues for the next guy of course.

 

[PJDeluhery]

Interesting response. Thanks.

I don't have much experience with metal, but what you say makes perfect sense.

 

[kilted vampire]

I would say the fact that I use low melting bismuth in my pours helps a lot with the flow into tight spots without cooling. I use bismuth with tin and lead, play it by ear sort of, but a little bismuth lowers the melting temp of lead and tin, and helps the flow also. If necessary I use the razor knife to cut small vents to allow for air flow, but you also kind of develop an eye for what should work and what won't. I have some older stuff that didn't pan out no matter how many vents I cut into it. You can also see the big sprues going into the feet on this piece. Using the weight of the metal to help push it through helps, and you can just re-melt those sprues for the next guy of course.

I had that problem then realised my metal content had changed. Where do you get bismuth? How much would you add to 10lbs of metal?

 

[Martin Tabony]

Be careful not to add too much bismuth, it will make the castings britle.

Martin