A real stainless printed gun!

[JSnover]

http://reason.com/archives/2014/12/06/meet-the-reason

[texassako]

I thought it sounded familiar. He is the same guy that made one last year. Don't some of the large gun companies use sintered parts similar to what his company's laser sintering machine does?

[JSnover]

Don't some of the large gun companies use sintered parts similar to what his company's laser sintering machine does?
Yes... Sort of. It depends on which sintering process they use.

[MtGun44]

Very interesting - BUT - watch out for weasel words. Note that it says: "The weapon
was made mostly from stainless steel on an EOSINT M 280 3-D printer.."
The skeptic in me says the "mostly" didn't include the barrel and possibly the slide.
We know that plastic is fine for frames and many smaller parts, so the sintered
stuff may be only in the low stress areas. Now this is still good, in that if you
want to make your own frames without government control - if the machines come
down in price a whole bunch.

Folks keep want to connect "sintering" with Metal Injection Molding (MIM) and that is
a real mistake. Much of the original use for sintering was to intentionally leave huge
amount of voids in the parts - basically joining a bunch of spheres by just barely melting
them where they touched - so that the resulting part could hold oil (Oilite bushings) or
act as a filter. These parts were usually not intended for any significant structural
applications. The intent for much sintering was to make porous parts.

MIM was specifically developed to make small, high strength parts less expensively than
machining out of solid. Properly done, the finished parts develop essentially the
full strength of cast or machined parts, and have service lives in high-stress applications
that are essentially indistinguishable from cast or machined from solid parts. It is amazing
to me that MIM is still considered to be somehow inferior and makeshift by the uninformed.

As a personal example - I have an early Kimber 1911 that is about 15 years old and has
about 40-50,000 round through it of .45 ACP ammo. When I bought it, I put a 2 lb trigger
pull on the gun and it has remained at 2 lbs and perfectly safe since then. No visible wear
or deterioration in the trigger pull. Hammer, sear and disconnector are MIMed parts.
Done properly, MIM is fine quality. The biggest legitimate complaint is that many parts can
have mold parting lines and small circles where the ejector pins are located, making them a
bit unsightly upon very close inspection in certain external applications.


Laser sintering is intended to make stronger parts, but the key issue will be how much
of the theoretical strength of the raw material does the laser sintered material retain?

The stuff I have seen (a few years ago) was obviously VERY porous, and I doubt that it
developed more than 10-20% of the strength of solid material. No doubt that the technology
will continue to improve.

Bill

[JSnover]

I would have to see the barrel to believe it was printed. The skeptic in me says he bought it. Same for the springs.
Thanks MtG, I was hoping someone would explain a few things.

[MtGun44]

They are continuously improve this technology, so one day we may actually have fairly
high strength metal parts coming out of a 3D printer. What I have seen up to a few
years ago was well short of full strength, BUT that may be strong enough for a lot of
things - especially with a bit thicker structural pieces than might be used with solid
metal.

Also, there is HIPing, which is Hot Isostatic Pressing, which basically takes a porous
part and wraps it in stainless foil, then put into a pressure chamber and heated very
hot, maybe 1200F for steels, less for aluminum and more for high temp alloys, and
the exposed to high pressures - maybe 15-40,000 psi. Lots of variables, but the
basic idea is that voids are compressed out and the material rearranges the grain
structure to become essentially equivalent to a high quality forging.

So, if you laser sintered a part and then HIPed it. . . . could be just like
a forging.

Lots of high tech stuff out there.

Bill