Fimo and Sculpey III Tips.

TopRamen · Apr 1, 2016

I need to make some detail parts for a rocket I'm working on, and it was suggested that I give polymer modelling clay a try, so I just got some and am going to try it once I learn what there is to be learned about it.

I understand that it is and will be too heavy for most applications that I need it for, but if I can make a model of the part I need to the exact dimensions I need, I can send that model to someone who can make it out of something much lighter, or I can use the clay model to make a mold once I get that figured out too. One step at a time, but basically I need to make the point that I will not be using modelling clay as an actual structural component of a flying model.

I went to Youtube, to watch tutorials, and while they told me about the properties and handling characteristics of the products, they did not talk about making anything other than jewelry and artsy fartsy stuff. I wand to make geometrical structural shapes and structural members such as struts for boosters and detailed external conduits, you know, rockety things.

Has anyone here used these products to make precision products?

In general, any advice is welcomed in this thread, but keep in mind I've seen the tutorials that talk about making figurines and jewelry, so I already know about getting the clay soft, and stuff like how to make it even softer or stiffer.

hornet driver · Apr 1, 2016

Hey Top, not sure what size things your trying to make. You can make the part out of clay as a male mold. Once it's dry you can press it into some soft clay to make a female mold. I usually make my female mold about the size of a mouse pad so I can make several parts at once. After the female mold is dry, spray it with a couple coats of clear--any brand will do---when the clear is dry you can put a light coat of auto wax on the mold or get your hands on some mold release. I just pour some FG resin onto the hole thing and let is set for a day. Afterwards you can peel the whole thing off the mold and trim out your parts. It might take you a time or two to get your technique down but it's pretty straight forward. . The FG resin is about the same density as plastic so the parts are lite enough for our purposes----H-----------------FG resin= plain ole fiber glass resin

grapetang · Apr 4, 2016

For precision, you might want to use plastic modelling supplies rather than polymer clay. Perhaps use polystyrene sheets & tubing, brass tubing, acrylic, resin, and/or epoxy putties (Magic Sculp, Aves Apoxie)? It even seems like our typical balsa or hardwood blocks and wooden dowels would be better for precision.

Like you've read & seen, polymer clay can get soft when you bake it and it's soft & pliable immediately afterwards. When cool, SuperSculpey & SculpeyIII tends to be a little heavy & brittle. According to Sculpey, Souffle, Premo!, and UltraLight are stronger than the SuperSculpey though I haven't tried them. UltraLight might be an option. I don't have experience with Fimo nor the other brands.

Prior to baking/hardening, you'll have issues making precision parts. Once baked, it's just a hunk of PVC plastic you can sand, file, & carve pretty well. You can add more polymer clay to baked parts & rebake, though the new additions may flake off unless you use liquid clay as a "glue". It might be better to build bigger & then carve down.

Once you have your master part, you can make a mold out of RTV rubber, silicone, latex, or those two-part putties. Support the mold if using latex. Add mold release, and cast in your choice of epoxy/epoxy resin, epoxy clay, or polyester resin. If you use a rubber or silicone mold, you can press fresh polymer clay into the mold, assuming no undercuts, and put the entire thing into the toaster oven to bake (minimizes warping). I don't think part shrinking will be an issue at this scale. Baked polymer clay probably shouldn't be used as a buck for vacuum forming because the heat may deform your master.

Also, if you're making or casting long thin parts like struts, you might want to add armatures to strengthen them, like embedding toothpicks, straightened paperclips, etc.

Tips:
- follow directions for baking and do not burn it (it will give off toxic gases)
- use a dedicated junker toaster oven in the garage to bake
- bulk up the insides of objects with crumpled aluminum foil to save on polymer clay material
- you can add fresh polymer clay onto baked stuff & rebake, though it might flake off; use liquid clay as glue prior to rebaking.

Good luck!

Note: the "antennas" on the figures below are pinned with paper clips and are already cracked from play.

TopRamen · Apr 4, 2016

grapetang said:
For precision, you might want to use plastic modelling supplies rather than polymer clay. Perhaps use polystyrene sheets & tubing, brass tubing, acrylic, resin, and/or epoxy putties (Magic Sculp, Aves Apoxie)? It even seems like our typical balsa or hardwood blocks and wooden dowels would be better for precision.

Like you've read & seen, polymer clay can get soft when you bake it and it's soft & pliable immediately afterwards. When cool, SuperSculpey & SculpeyIII tends to be a little heavy & brittle. According to Sculpey, Souffle, Premo!, and UltraLight are stronger than the SuperSculpey though I haven't tried them. UltraLight might be an option. I don't have experience with Fimo nor the other brands.

Prior to baking/hardening, you'll have issues making precision parts. Once baked, it's just a hunk of PVC plastic you can sand, file, & carve pretty well. You can add more polymer clay to baked parts & rebake, though the new additions may flake off unless you use liquid clay as a "glue". It might be better to build bigger & then carve down.

Once you have your master part, you can make a mold out of RTV rubber, silicone, latex, or those two-part putties. Support the mold if using latex. Add mold release, and cast in your choice of epoxy/epoxy resin, epoxy clay, or polyester resin. If you use a rubber or silicone mold, you can press fresh polymer clay into the mold, assuming no undercuts, and put the entire thing into the toaster oven to bake (minimizes warping). I don't think part shrinking will be an issue at this scale. Baked polymer clay probably shouldn't be used as a buck for vacuum forming because the heat may deform your master.

Also, if you're making or casting long thin parts like struts, you might want to add armatures to strengthen them, like embedding toothpicks, straightened paperclips, etc.

Tips:
- follow directions for baking and do not burn it (it will give off toxic gases)
- use a dedicated junker toaster oven in the garage to bake
- bulk up the insides of objects with crumpled aluminum foil to save on polymer clay material
- you can add fresh polymer clay onto baked stuff & rebake, though it might flake off; use liquid clay as glue prior to rebaking.

Good luck!

Note: the "antennas" on the figures below are pinned with paper clips and are already cracked from play.

View attachment 287214 View attachment 287215

Thanks! That's the kind of info I need.
With the clay I intend to shape the baked parts with files to the final dimensions and measure with a digital caliper that I just ordered for this purpose. It should be here today, so I'm all excited!

I realized that I'de need an excuse to buy a new toaster oven, so I have to get on that too before I do anything. And a thermometer to ensure repeatable results.

grapetang · Apr 4, 2016

You're welcome! A few more thoughts:

I got my dedicated junker toaster oven off Craigslist for $3! My (new) oven thermometer costs twice as much but it's a good idea. Per instructions, do not microwave.

Put your unbaked parts in a cold oven, heating it up with the oven, and start timing once it reaches temperature. When done, let cool completely in the oven before taking it out. Resist the urge to immediately remove your parts; there's a very minute chance they can crack from thermal stress/shock. The bigger the parts, the higher the chance of cracking.

Baking evenly is an issue since parts will have clay at different thicknesses. Thinner, smaller parts are more prone to burning, as are parts closer to the heating elements. You can always shield those parts with aluminum foil and let convection heat bake it.

Parts should avoid touching heating elements or metal parts inside the oven. I bake on printer paper on top of cardboard, or aluminum foil wrapped cardboard. Some people use ceramic tile or woodblocks. Yet others add ceramic tile or broken terra cotta pieces to the bottom of oven to try to even out the internal temperature.

If you happen to burn your parts (like I scorched the little blue figure), open the windows & air everything out. Avoid the fumes & it'll be fine afterwards. While non-toxic in its baked form, I'm not sure I trust the non-toxic label when polymer clay is unbaked. It's probably much safer than the epoxies, resins, paints, thinners, etc. we normally use.

Somehow, I'd still recommend wood, polystyrene, or regular plastic modelling supplies for geometric structural shapes. Clays seem more suited to rounded or organic shapes. Star Destroyer vs Mon Calamari cruiser?

Good luck & have fun!

TopRamen · Apr 4, 2016

grapetang said:
You're welcome! A few more thoughts:

I got my dedicated junker toaster oven off Craigslist for $3! My (new) oven thermometer costs twice as much but it's a good idea. Per instructions, do not microwave.

Put your unbaked parts in a cold oven, heating it up with the oven, and start timing once it reaches temperature. When done, let cool completely in the oven before taking it out. Resist the urge to immediately remove your parts; there's a very minute chance they can crack from thermal stress/shock. The bigger the parts, the higher the chance of cracking.

Baking evenly is an issue since parts will have clay at different thicknesses. Thinner, smaller parts are more prone to burning, as are parts closer to the heating elements. You can always shield those parts with aluminum foil and let convection heat bake it.

Parts should avoid touching heating elements or metal parts inside the oven. I bake on printer paper on top of cardboard, or aluminum foil wrapped cardboard. Some people use ceramic tile or woodblocks. Yet others add ceramic tile or broken terra cotta pieces to the bottom of oven to try to even out the internal temperature.

If you happen to burn your parts (like I scorched the little blue figure), open the windows & air everything out. Avoid the fumes & it'll be fine afterwards. While non-toxic in its baked form, I'm not sure I trust the non-toxic label when polymer clay is unbaked. It's probably much safer than the epoxies, resins, paints, thinners, etc. we normally use.

Somehow, I'd still recommend wood, polystyrene, or regular plastic modelling supplies for geometric structural shapes. Clays seem more suited to rounded or organic shapes. Star Destroyer vs Mon Calamari cruiser?

Good luck & have fun!

Thanks, and yeah, I hear what you are saying about the wood, polystyrene, etc;, I have spent all day watching folks on youtube mold and cast and play with clay and vacuum forming and a bunch of other things.

I'm kind of out of my league here with what I want to accomplish, so I have to try everything I cstartan think of, and eventually I'll have wrapped my mind around the problem enough ways that I find the best solution.

I got some paper clay and sculpting tools today, so I can start futzing around with stuff. I know that the paper clay shrinks a little and is prone to cracking, but it is just to get me eased into the whole idea of working with clay, so I can see how I need to set up to work the media.
I also want to try shaping things with my fingers to see how close I can get to the shapes I need.

I'll take some pics' when I start to play, so you folks can see where I'm trying to go with this, and offer any advice.
The parts I need ofcourse are the struts/lugs that hold the boosters on my SA-5.

TopRamen · Apr 5, 2016

I used the template with the general shape I need to make this little mold box, then filled it with paper clay, and set it inside a piece of aluminum duct that I point my electric heater at to heat my livingroom. It dries in a couple days normally if left out in the open, but this should speed up the process a little.
I made the inside of the box a little large, so that when I break the part free, I can sand it to the proper dimensions afterward.
If the clay acts like glue, and really sticks to the insides, I'll just sand the box away carefully, as it is just balsa, basswood and some cardboard.

Whatever occurs, good or bad, will be beneficial, as I have to start learning somewhere!

TopRamen · Apr 5, 2016

I began removing it from the wood just now, and am liking what I see so far.
Being a thick chunk, it is still soft the lower I went with removing the balsa, so I set it back in my makeshift dryer.
I was able to cut at the clay with my X-acto knife, and I liked the consistency of it so far.

TopRamen · Apr 5, 2016

The molding did'nt turn out so well because I was too impatient, so I went ahead and tried making some shapes like the ones I'll need to see how it works out if I just leave them alone to dry properly, then sand them after.
The rear leg is kinda shaped like a flattened transition, so I made a quick scrap transition, the packed clay inside it to dry.
On the two I made by hand, I threw scraps of metal in there for the detail bit that you can't make of clay. When I eventually make the working model out of FG or whatever, I will use little metal bits like these to secure the booster struts to the lugs on the booster collective ring.

Paperclay tinkering3333 2002-12-31 004.jpg

Paperclay tinkering3333 2002-12-31 005.jpg

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