[deadalvs]

feels a little awkward, but here we go ..

* * *

well, a friend of mine is doing her architecture diploma for her master degree now. the project is a tiny teahouse here in zurich, in the woods on a little mountain.
now one (tiny) part of the whole project is to find a fitting solution/design for the main door handle.
so she decided to go with something special and chose this squirrel:


the professor for that subsidiary subject is impressed and thinks it's a great idea. now she has to create a 1:1 sample, as close to reality as possible - of course in an abstracted way. it could be wood or a gypsum print for the model, but by far best would be a piece in metal.

now i am trying to find out which would be the easiest way to go.

• gypsum model (two halves), casting in metal
• 3d metal print (positive form)
• 3d gypsum print of the mold halves (negative form)

if needed, i could model the squirrel as a hires poly model.



is there anyone here that has done some metal casting before and could give me some tips ?

or for example could 3d metal printers automatically print with a defined wall thickness to save powder ? or does it really have to be modeled ?

i guess 3d printing is extremely expensive ?

other techniques ?

[ivox3]

clay

[deadalvs]

yes, we talked about clay too.

you think just two halves/molds to simply combine ?

how great is the chance of the molds to burst of heat or something ?

what metal would you recommend ?

[Mihai]

I'd make it plastic and when you squeeze it, it goes sweeeek!

[ivox3]

I'm just saying if you just need a 1:1 model -- use something like a polymer clay, sculpt it -- throw it in a regular oven. Done. Why get all crazy with the money for a model ?

You could also just sculpt it from some polyurethane foam. It's extremely expensive in a whole sheet --- go to a design school and see if you can't snag some.

This is just for demonstration right ?

______________

Demonstration or not, .. let's say you create the model from something like the above methods. Your not too far from creating a master mold to have it done in resin or metal.

** you can make the squeaky sound yourself. Now that's low tech.

[deadalvs]

sure it's just a model, but the appearence should be as close to real as possible. like texture, weight, ..

pu-foam and other plasticcy stuff is not very satisfying.

we're thinking on ..

* * *

though, a squeaky one could be a surprise, like a doorbell ..

[andrebaros]

I'd make it plastic and when you squeeze it, it goes sweeeek!

LOL! Oh my I'm going to cry. I'm going to try suggesting that on a real project. LOL

[mtripoli]

There is a material called "Renshape". It is very popular for protyping as it machines well. It's a bit on the expensive side (relatively speaking).

http://www.wplindustries.com/listing.cfm?id=40



There is also a material called "Obomodulan" (http://www.obo-werke.de/English/Product.html). This is becoming very popular as well.
http://plasticssrt.com/Modulan.aspx

The beauty of these materials is you can finish them any way you want. You could in fact make your "house" from these materials and finish to look like metal. I know of one guy that made a prototype of this stuff and had it chromed.

[ivox3]

There is also a material called "Obomodulan" (http://www.obo-werke.de/English/Product.html). This is becoming very popular as well.
http://plasticssrt.com/Modulan.aspx

Yeah Mike ... that's the exact stuff I was talking about.

Deal ... I don't think your familiar with the material. It's very very dense stuff and great for tooling.

[polynurb]

i can also recommend renshape very much... it is a dream to mill

if you want to use it for casting, get one with density above 0,7 g/cm³ as it has a very closed surface structure.

i think for metal casting the plaster negatives are the way to go.
afaik, there are special types for casting with very fine grain, like "dentists plaster" used for fillings.

but don't underestimate the surface quality you have to achieve on the milled parts, to get a casting negative that makes the final metal look really smooth too... in case that is the effect you want

basically you will need medium-very fine sanding paper to get rid of all toolpaths (use a ballnose tool as large as possible), and some filler ("renpaste" matching the block material type) to glue the parts together and remove the seam.

i only worked on vacuum molding positives not casting... but jewlery makers and sculptors should know about it... if you can find some around.

and then you can always do it the good old way :

http://en.wikipedia.org/wiki/Lost_wax

good luck

[jvanmetre]

It sounds like it is a design detail to a much larger design...deciding on which method to use to create the piece really comes down to what the intent is of making a model? It's clearly not a production piece.

For a quick method of conveying a design.

I'd use blue foam, balsa foam or plaster and work the material to a desired level of detail. I'd then paint it -- using copper paint and gray primer.

If you want to take it up a level...you could take the positive (model) and create a urethane mold and make some castings. You should be able to find cold casting urethanes that allow you to add metal powder. Copper powder embeded in plastic and some gray primer paint can go a long way to conveying that squirrel in your image. It's a pretty low-tech solution and is fairly reasonable in terms of cost.

Here's one of my favorite resources...a company called Smooth On. They even take you through the process of casting step by step.

http://www.smooth-on.com/gallery.php?galleryid=312

Good luck.

jvm