The most common (cheapest and easiest to use) material is PLA (polylactic
acid), and next is ABS. I think both of those respond well to an acetone
vapor soak, which melts the surface a tiny bit so it flows and becomes
smooth and shiny. Kind of like fire polishing glass. Also, someone talked
about places to get stuff printed, besides the local makerspaces and buying
your own printer. One company that prints your files is shapeways.com,
charging by the volume of material and what the material is. They also have
a storefront where you can sell your printed items. You upload the file,
set the selling price, they put it on their web site storefront, when they
get an order they print it, ship it, and at the end of the month send you
your money minus the printing cost and a handling percentage. Pretty clever
business model, I think. Not a customer, just saw their site.

-----
Regards,
Carl Ijames

"Tim Wescott" wrote in message
...

On Thu, 14 Aug 2014 13:51:01 -0500, Dave M wrote:

I'm starting to get interested in 3D printing. My primary purpose would
be to make parts for obsolete equipment, and other parts that are no
longer available. These parts often have imbedded metal parts, such as
a metal ferrule inside a knob, or an imbedded nut or mounting tab.
Can 3D printers make such parts? If so, is any additional equipment or
unique model of 3D printers required?

Monoprice has a model that appears to be a clone of a Makerbot printer
at about half the price. Reviews seem to indicate that it is an
excellent printer, although not perfect. I guess that 3D printers are
relatively new on the scene, and will improve in time.

Thanks for any insight,
Dave M

Before you contemplate investing much money in 3D printing of knobs, check
out the surface finish attainable by your intended 3D printer. The ones
I've seen all have some sort of pattern left on the part, as an
unavoidable consequence of the printing process.

You may be able to print a knob and then sand it and polish it, but I
don't think you'll be able to just print a nice shiny knob.

--

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com