Looking to Print a Caboose...

[Lemosteam]

@Maletrain, thanks, yes I think I need some form of pressure and the four holes around the gate are gas vents.  I was hoping to see those fill as I poured, but the passages that the metal is following are pretty small.

Shapeways can produce many types of metal either by investment casting, or by "printing". below are both my designs, and are quite expensive comparatively:

Here is a link to all of the Shapeways materials: https://www.shapeways.com/materials/

Printed "steel" custom tender frame:


Cast brass S Scale tender truck frame parts, although I note there is no evidences of gating or sprues to be found on the final part, all of the sprues you see are part of my 3D model so I honestly do not know how they do it,:

[SkipGear]

There are resins available to effectively print a lost wax style casting simply by printing the master, creating the mold and melting the resin master out. It's becoming very popular in the custom jewelry industry. It saves a couple steps in the process.

[Lemosteam]

There are resins available to effectively print a lost wax style casting simply by printing the master, creating the mold and melting the resin master out. It's becoming very popular in the custom jewelry industry. It saves a couple steps in the process.

Of course, BUT without a gate or vents how did these get filled?  lol.

[SkipGear]

The gates are printed along with the model, just the same as supporting a conventional model.

[Sokramiketes]

Of course, BUT without a gate or vents how did these get filled?  lol.

I'm not sure I understand your question completely, but maybe an overview of the process would help.  I used Perfactory to Lost Wax Brass on a run of 100 Z scale flatcars awhile back, and was working with a jewelry company in NJ.

1) A master was printed with Perfactory
2) An RTV mold was pulled from the master
3) Wax was injected into the mold
4) The waxes were "treed" together with wax sticks
5) They were set in a cylindrical container, and investment (plaster) was poured around.
6) The investment is heated, burning out the wax and leaving cavities
7) Molten brass is poured in
Investment is smashed, reveling the brass parts.  One time use only, and part of why the process works for undercuts just fine.  It even handled cast stirrups!

Z Scale one-piece casting:



It's also correct that there are resins available to skip the rubber mold step and just burn out the RP print.

[Lemosteam]

When the cast your parts in plaster, before they did that they connected each "cavity" with wax sprues and then added a gate.  the gate is where the molten metal is poured in.  The wax disintegrates and the metal is all that is left behind.  Then after that break away the ceramic coating, they cut the sprues and gates off to leave only your parts.

Look at the brass parts above.  Confirmed by the owner, these parts had NO evidence of added sprues or gates cut away from the parts.  The sprues you see are what I designed and sent to Shapeways.  He and i are very familiar with the process and we are both flummoxed by this.

[peteski]

Of course, BUT without a gate or vents how did these get filled?  lol.

Lost-wax brass casting is used for making jewlery, and small model detailing parts (like horns or other similar items).

I believe that they use a spin casting process and the centrifugal force pushes the metal deep into the smallest cavities.  Another thing might be that the "investment" (type of plaster) used for the mold is porous enough to be permeable to air while not to the liquid metal.

@robert3985 is quite familiar with the investment casting process - maybe he'll have some more specific details of how this process works.

[Lemosteam]

Pete, spun or not the mold, whatever material it is made of still requires a gate to let the molten material flow into the mold cavity.  To avoid air pockets there are also tiny vents in the mold to let the material flow to the deepest portions of the cavity,  Spin casing is use only to create a force to pressurize the molten material through all of the passageways.

This one is cool there is a gate point of view while spinning.

[Chris333]

Fast Tracks just came out with cast crossing frogs. In the video it said they bought an expensive wax 3D printer to make the molds.

[Sokramiketes]

When the cast your parts in plaster, before they did that they connected each "cavity" with wax sprues and then added a gate.  the gate is where the molten metal is poured in.  The wax disintegrates and the metal is all that is left behind.  Then after that break away the ceramic coating, they cut the sprues and gates off to leave only your parts.

Look at the brass parts above.  Confirmed by the owner, these parts had NO evidence of added sprues or gates cut away from the parts.  The sprues you see are what I designed and sent to Shapeways.  He and i are very familiar with the process and we are both flummoxed by this.

Ah, I get what you're saying.  Since you created the parts "tree" already, all they would have done is a gate at your central sprue.  I see no reason why the tree you created wouldn't have allowed the parts to fill. 

[peteski]

Ah, I get what you're saying.  Since you created the parts "tree" already, all they would have done is a gate at your central sprue.  I see no reason why the tree you created wouldn't have allowed the parts to fill.

Now I get it too. Yes, Since John already incorporated the "tree"into  his design, they just used them for injecting the metal.

[bbunge]

Certainly no expert, and only know because I follow the industry, and perhaps stating the obvious, but at the high end of things, there are companies that are 3D printing parts for rocket engines and high performance aircraft.  Here is a 2019 article with a video of a metal 3D printer.  There is cost return on the base technology to make a complex component in one piece compared to using subtractive technologies (like machining), several (perhaps hundreds) parts that are then welded together.

https://spectrum.ieee.org/aerospace/space-flight/the-worlds-largest-3d-metal-printer-is-churning-out-rockets

Perhaps Shapeways has something similar. 

Bob

[bbussey]

That is a shapeways process. I believe it is a powdered metal infused with resin that is then fired in a kiln afterwards to fuse the metal together. @bbussey played with it in an effort to make a custom split frame for a diesel but ran into dimensional issues. It shrinks when fired and the change is not uniform. It took 3-4 tries to get the model to print correctly so that it was the expected dimensions after firing.

The stainless steel 3D frame was for the EP-3, and I had it rendered somewhere else other than Shapeways.  They were very consistent as far as tolerance was concerned.  I had revisions due to design errors mostly.  I did have problems with the body, which was printed by Shapeways.  If I ever build another, that and any future bodyshells will be printed elsewhere and probably utilizing SLA rather than a ProJet printer.

[SkipGear]

Certainly no expert, and only know because I follow the industry, and perhaps stating the obvious, but at the high end of things, there are companies that are 3D printing parts for rocket engines and high performance aircraft.  Here is a 2019 article with a video of a metal 3D printer.  There is cost return on the base technology to make a complex component in one piece compared to using subtractive technologies (like machining), several (perhaps hundreds) parts that are then welded together.

https://spectrum.ieee.org/aerospace/space-flight/the-worlds-largest-3d-metal-printer-is-churning-out-rockets

Perhaps Shapeways has something similar. 

Bob

I have spoken with the lead engineer on the team at GE that helped convert them to metal 3d printing for jet engine fuel nozzles. The reject rate went from 30% down to 5% which in a part that had if I remember 15-20 man hours per part, more than justified the added cost of developing the printing process.

He happens to be an avid RC pilot and shops at our store. Having GE jet engine development division here in town brings in some interesting people to the shop.

[Lemosteam]

The stainless steel 3D frame was for the EP-3, and I had it rendered somewhere else other than Shapeways.  They were very consistent as far as tolerance was concerned.  I had revisions due to design errors mostly.  I did have problems with the body, which was printed by Shapeways.  If I ever build another, that and any future bodyshells will be printed elsewhere and probably utilizing SLA rather than a ProJet printer.

Yes, at Shapeways, I had to tweak the 3D model three times in uniquely in all three axes just to get my tender shell to fit. So $70 later I had a final design.