A reader writes, "I am looking for information on making metallic objects when only a physical part is available. You need a bit of background to answer this though.  I am an editor looking for information to pass on to my readers.  We are interested in antiques, and some parts are simply not available.  I am thinking that stereolithography may be a way to "create" the parts we need--sort of like what they consider to be a prototype.  Most, but not all, would be some sort of metal, but probably would need some basic machining to make them usable (tapping, sizing holes for bearings, etc.)

One of the things I want to find out is whether the stereolithography process is advanced enough to make metallic objects, and whether there is a way to generate a computer file from a borrowed physical part when no drawings of any sort exist.
 
So, which resource would be best to learn the state of the art from?
 

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--Leslie Gordon

Hi Leslie:

If the object is small, I wonder if the dental industry might suggest a solution.  I worked as a dental tech and we used the icky polymer and gelatin mold materials to create plaster models and wax cores.  We also coated these plaster and wax parts with a thin metallic film and electroplated  onto that to build it into a substantial piece, or to fill a mold cavity.

 Think of dental crown and bridge work involving accurate fit and faithful reproduction, and the use of high temp metal casting.

 The key here was creating accurate molds of a flexible material, then ultimately depositing or casting into that mold.  Think Jewelry.

 I found that this technology was so versatile and flexible that I could reproduce a bumblebee in stainless steel, complete with wings.

 You weren't thinking of something the size of a locomotive were you?

Regards,

Colin Caissie, UET mixers, Inc.

There are many ways to reproduce metallic objects, and none of them need be so technically advanced as stereolithography.

Given their unique nature, low demand for the items, and low quantity output needed, I'd go visit a local high school or BOCES organization and talk with the metal shop teachers.  It could become a project for the kids to learn prototype fabrication, and which steps should be done first.  (Should I tap the knob before I turn it in the lathe, or vice versa? How can I speed things up if I have to make 100 of them? 1,000? 10,000?) 

 Even broken parts can usually be used as a master when manufacturing replacements.  One of the sand casting projects I did as a kid was a giant two-headed coin, using the same 1/2 master for both sides of the mold.  We worked with aluminum, brass, copper, and sometimes steel.  We'd use tap and die sets, drill presses, lathes, polishing wheels, and fabricate many, many items. 

 Simply put, they're antiques, manufactured with technology from 100+ years ago - the same technology exists today and is readily available.

I've used RTV silicones and FIMO polymer modeling clay to make molds then pour a wax cast.  Proceed to metal casting in next step. Low tech but it's cheap.

  

I know too

:)

Leslie,

There's no short answer because there's always that, "well it depends on ..."

With regard to recreating an antique part, it would be pretty important to know if we were talking about an antique lamp or an antique car - the difference being a part for decoration or a functioning part subjected to loads, temperatures, pressures, etc.

 I'm going to guess we're talking "lamp" category.  Someone has the top piece of the lamp base and it has an ornate "baroque" design with a lot of detail.  A 'physical part is available' so the next step is to create a solid model of the part.  Since you have the part, a good designer can model it with a pair of calipers or if it's really ornate use 3D Laser Scanning (lots of companies out there).  Once you've scanned it, you clean it up in your CAD software then you can make the part several ways depending on if needs to be solid gold or plastic would suffice.

Since I'm assuming "lamp" category here - YES, you can use stereolithography.  Your engineer would specify the material based on how strong it has to be but yes you can then take a your "plastic" part and have it plated to give it an antique look.

Bad news is you've just spent a bunch of money on a lamp part si it better be a pretty special lamp.  Anything can be done!

MDCMachineDesign.com

"Specialization is for insects"

Try looking up this company: shapeways.com. They can print (or have looked into it) even in titanium. Most of their capability is with sla printing.