Brazing, heating and machining 3D printed items

This forum is dedicated to the Live Steam Hobbyist Community.

Moderators: cbrew, Harold_V

SG3950
Posts: 18
Joined: Tue Mar 03, 2015 10:50 pm
Location: Milwaukee

Brazing, heating and machining 3D printed items

Post by SG3950 »

I'm putting this out there for everyone's information. A lot of questions get asked about Shapeways 3D printed stainless steel. I have a lot of it on my engine so I thought would share some insights based on my experience over the last few years.

The material is basically made up of stainless steel dust fused together with bronze. It will not flex or bend, it will crack when significant pressure is applied. It does not anneal. You can heat it cherry red and apply mild force, it will crumble, not bend. When it cools back off it is just a tough as when you started.

You can braze it with either 15% or 45% silver but you must use a white brazing flux. You don't need the part red.

It will machine beautifully. I have only tried carbide tooling, non-indexed end mills and boring bars. Use surface speeds similar to a hard bronze. Keep your chip loads about .003" per tooth. Take shallow cuts to minimize tool deflection. Make sure your tooling is ground sharp. I am torn on coolant at this point. It does not seem to make a difference when using non-contained tooling (if a tool breaks off and its not still in your part its non-contained) Plus, because this stuff is not cheap, I am usually only taking off .050" or less total. So I haven't really hogged out a part either.

Drilling, tapping and reaming (contained). I have found carbide is not your friend. It is too brittle for the small bores holes we use in modeling. Anything you buy at the local hardware store will become part of you part when it breaks, don't waste your time. Quality HSS drill and taps with TiCN coating for lubricity helps. Use a heavy thread cutting oil and keep it flowing to remove chips. OVERSIZE your tap drill! On a normal 5-40 hole I wold typically drill a .101, make it a .106 or .110. Lastly, use your mill as a rigid fixture. Center drill, tap drill, and then use an old counter-bore to center the tap handle. If your tap handle dose not have a tapered guide hole in the top then get one that does. All of what I am recommending for drilling and tapping is limiting two things: Torque and deflection. The amount of force you must apply to cut this stuff is higher than most people are used to. When applying that force to small tooling you want to minimize deflection. I do not recommend tapping freehand or with an auto tapper.

It grinds pretty easy with a standard wheel and will not gum up the stone.

I haven't tried to ream it really so I can't help much there. Nor have I tried to forge or harden it.

I hope this helps anyone who may be considering or struggling with this material.

SG
User avatar
Dick_Morris
Posts: 2841
Joined: Sat Jan 04, 2003 2:09 pm
Location: Anchorage, AK

Re: Brazing, heating and machining 3D printed items

Post by Dick_Morris »

Thanks. I have been curious, but this is the first time I've seen a description of what can be done with the 3D printed SS.
User avatar
NP317
Posts: 4557
Joined: Tue Jun 24, 2014 2:57 pm
Location: Northern Oregon, USA

Re: Brazing, heating and machining 3D printed items

Post by NP317 »

In the early 2000s when I was working for the Unv. of Washington Seattle Mechanical Engineering Department,
one of the profs was experimenting with developing printed stainless steel powder, fused with bronze!
My job was to test machinability of the product.
I discovered that same issues with tapping holes as described above. It was really tough material to tap!!

So follow the recommendations provided by SG, and you should be OK.
Interesting to read that today's printed SS+Bronze has the same characteristics we determined.
RussN
Sandiapaul
Posts: 567
Joined: Wed Jan 07, 2004 8:04 am
Location: Princeton, NJ

Re: Brazing, heating and machining 3D printed items

Post by Sandiapaul »

Thanks for taking the time to write this up. One thing I have thought about but not tried is to use form taps. But after reading your descriptions I don't think they will work well.
User avatar
Chris Hollands
Posts: 546
Joined: Thu Mar 26, 2009 8:38 am
Location: Vancouver ,Canada

Re: Brazing, heating and machining 3D printed items

Post by Chris Hollands »

I tried formed taps and just about everything else on the stuff , I think the term is you have your heart in your mouth every time you use small taps and drills on this stuff , as stated you really have to oversize your tapping holes - or you will hear the dreaded sound - PING - and then the really bad words start to fly .
FKreider
Posts: 338
Joined: Fri Feb 02, 2018 8:44 pm
Location: Massachusetts

Re: Brazing, heating and machining 3D printed items

Post by FKreider »

Can you post pictures of the parts on your engine?

Pretty expensive way to build a locomotive however I guess having almost finished parts arrive in the mail is pretty convenient! 8) :lol:
-Frank K.
SG3950
Posts: 18
Joined: Tue Mar 03, 2015 10:50 pm
Location: Milwaukee

Re: Brazing, heating and machining 3D printed items

Post by SG3950 »

Here is a few pics. The pilot is printed as well. Do a search and you will find pics

Exhaust Pipes
Trunions
Rod cover

Mostly detail stuff. Everything else is machined.
Attachments
20200802_185053.jpg
20200824_154738.jpg
20200405_225630.jpg
apm
Posts: 391
Joined: Sun Jan 05, 2003 12:21 am

Re: Brazing, heating and machining 3D printed items

Post by apm »

With the relative high cost of the stuff as well as the challenges in machining it does anyone offer a more economical service where you go from 3D print to investment casting and then they send you the finished part?
User avatar
Bill Shields
Posts: 10460
Joined: Fri Dec 21, 2007 4:57 am
Location: 39.367, -75.765
Contact:

Re: Brazing, heating and machining 3D printed items

Post by Bill Shields »

sure - but I never considered prototype investment casting to be cheap.

Just look at what Jack Bodenmann is doing....
Too many things going on to bother listing them.
User avatar
Fender
Posts: 3084
Joined: Wed May 02, 2007 8:33 pm
Location: Chattanooga TN

Re: Brazing, heating and machining 3D printed items

Post by Fender »

apm wrote: Sat Jul 24, 2021 9:21 am With the relative high cost of the stuff as well as the challenges in machining it does anyone offer a more economical service where you go from 3D print to investment casting and then they send you the finished part?
Some people have used Shapeways to print a design in plastic, then taken that to a foundry to be invested and poured. If the right plastic is chosen, it will burn out just like wax would.
Dan Watson
Chattanooga, TN
apm
Posts: 391
Joined: Sun Jan 05, 2003 12:21 am

Re: Brazing, heating and machining 3D printed items

Post by apm »

Fender wrote: Sat Jul 24, 2021 2:09 pm
apm wrote: Sat Jul 24, 2021 9:21 am With the relative high cost of the stuff as well as the challenges in machining it does anyone offer a more economical service where you go from 3D print to investment casting and then they send you the finished part?
Some people have used Shapeways to print a design in plastic, then taken that to a foundry to be invested and poured. If the right plastic is chosen, it will burn out just like wax would.
Yes that's what I have in mind I am just surprised no one has put in place the whole turn key solution from online quote to investment cast part showing up at your door. It wouldn't take much for shapeways to partner with a foundry. Or I am surprised there isn't a good foundry who has their own 3D printer who could do it all for you preferably with an online rapid quote too.

Does anyone know of such a website where one could find such a service?

I have a few parts in mind myself where even aluminium would work. It would be nice to find a 3D print to foundry service.
rrnut-2
Posts: 691
Joined: Mon Jul 18, 2011 7:40 pm
Location: Bennington, NH

Re: Brazing, heating and machining 3D printed items

Post by rrnut-2 »

I did get a quote on a printed sand mold for a cylinder casting. Had to pick myself up of the floor after reading the quote. $3500 for the first mold, price break after 10. No thank you.

Jim B
Post Reply