Touchy Feely project materials...

[harryball]

I'm sure some of you saw my show and tell with the 3D carved bat. The bat turned out well and is currently carved from 3/4" Trupan. Everyone that has seen it has loved it and many of the educators want one.

I'm coming to the forum seeking materials wisdom. I know a good sign foam would be the best to decrease machining time, tool wear and provide good detail but I don't think it will survive as the end product. I want these to be able to be touched by the kids when completed. They will rub, push, poke and otherwise feel the surface detail of the carving. I don't think sign foam would survive this... or does someone disagree?

My desire is to either carve them rasied out of a plaque or glue them to a plaque once finished to make them more durable and easier to handle. I'd like to avoid solid wood due to the increased machine time and tool wear. I don't like MDF dust either though... I need to produce them as quickly as possible and keep the cost down.

With that in mind, are their other materials anyone can suggest over Trupan?

Then... there is always the mold method. I've never done that and wouldn't even know where to begin. I could make a reverse mold of an entire plaque and pour something in... if anyone thinks this method would be a good idea I'd appreciate any wisdom they could share.

Robert

[ernie_balch]

look at http://www.smooth-on.com/ for information on making molds and casting plastic models.

Also HDU can be purchased in higher density (25 lbs/cu ft).

ERNIE

[harryball]

Interesting molding site, I'll be reading more.

I've only seen 15 lb HDU before, in fact I don't recall seeing signfoam over 18 lbs advertised by any of the suppliers I've encountered. How durable is the 25 lbs stuff? I'm concerned about fingernails. I've seen lobby signs made from sign foam and most end up with fingernail cuts in them.

Robert

[jim_vv]

Robert,

Look at AZEK.com. It is cellular PVC and comes in all lumber sizes and sheets. (Looks like white plastic MDF) We use it on the outside of houses and buildings in place of wood. I have not tried to carve it yet, but it cuts, nails and routs like wood.

JIM

[billp]

Robert,
You could always go REALLY dense and work with "Butter board". It runs from 48-110 lbs density and is excellent for making masters of molds, etc.A few years back I made that "Dragonslayer" head for the motorcycle out of it... It is pricey, but I think it may still be cheaper, and faster, to machine a master, (or final product) out of Butter board than to do a master out of "something", and then go through the mold making process...
You can get more info at: http://www.goldenwestmfg.com/html/machinable_plastic.html

[jhicks]

Might not be exactly what you want but there are One is a taxidermy clay called magic sculpt. Mark Meggitt of foam carver is well versed on this material and he is also a dealer I think.
The 2nd would be along the molding lines.
Make a positive and have a vacuum form mold made then fill with plaster or other material like the clay. Mark could also handle this for you if its not larger than his vac mold table.
Finally the base material in color core is a polyethylene. Like milk jugs. The good news about it is nothing sticks to it. I have made small molds in the sheet stock, then poured a 2 part epoxy bar top resin called enviro tech into the mold and let it cure. It pops right out. Not great with thick molds but can be built up in thin 1/8" layers or use some plaster or resin to pour it.
I think If I were trying to do it I would call Mark Meggitt and discuss a vacuum formed mold and the taxidermy clay or other molding material options. He's pretty clever with this kind of stuff.

[Brady Watson]

Robert,
What's your material budget?

-B

[harryball]

Well... my budget is cheap to free of course! I was hoping to keep cost around $100/sheet... which probably leaves me with Trupan. I expect to get 4, 6, 8 or 12 plaques per sheet depending on the number of bats presented per plaque. These will have to be hand painted and finished. My retail range is to produce something available from $75 to $500 (possibly more) of a quality suitable for educators with durability to match.

Molding a product is attractive if I can reuse the mold and make copies quickly. My concern is still making it durable enough.

I'm still in the prototyping stage and I never know what will sell until it sells. So until it goes to market... it's all on my dime. That's why I try to make things I can use in my workshops and then make them available.

Robert

[Brady Watson]

Well...as good as Trupan is, it takes some work to get it finished properly. Personally I would machine something out of ButterBoard and make that my mold master. Then create a silicone mold with hard shell to keep it's form. Then 'slush cast' polyurethane resin to coat the entire inside of the mold with about 1/16 - 1/8" of plastic resin. It will kick as you are slushing it around in the mold. Then to save $$$, backfill the rest of the mold with plaster, 2-part foam or other cheap filler. It's doesn't get much cheaper than that.

-B

[myxpykalix]

I can't recommend a material to make the actual bat out of, but if you are wanting to make it so kids can get a good tactile response from this and feel what a bat might feel like couldn't you spray the finished piece with something like (flocking?, sorry i have trouble gettng words out of my head) you spray it on and i thought that might give the feel of bat fur/hair?

[btk]

You could also do a mould and cast out of pottery plaster and have the kids paint them like they do at those birtday parties.

Brian

[harryball]

BTK... now that is a good idea, I've been trying my best to think of a project for our workshops next year in the state parks. Thanks!

For my plaques, I'm researching making a mold and filling it with something to harden. I think in the long run that will be the only thing that will make ecomonic sense.

Robert

[btk]

Robert,

When you start making moulds, you stop really thinking too much about machine time, etc. as all you need is one perfect master:-)

Brian