Casting weights from 3D printed molds

[Lemosteam]

I started this in the 3D printed caboose thread, and decided I had hijacked that topic long enough.

Not a complete success, but worthy of additional effort.

The cope and drag:


The flat car needing a weight. Grooves are inside the ribs under deck.


The mold closed and aligned. Center hole is the sprue. Four other holes are vent/ mold full holes


The tools.


Mold closed and clamped.


After pour.


Part from mold;


Mold did not melt, crack or fail. Otherwise decent casing that pulled right out do to the draft angle used. Not sure how many castings it fill handle, but I can always print more.

The casting filled about 75-80% of the mold cavity. Need to figure out a way to get more pressure during the pour. Maybe need to heat up the mold first in an oven so make less diparity in temperature between the mold and the molten metal.

Was worried that the part would not eject but it popped right out of there.

Proof of concept is valid IMHO.

[Lemosteam]

As an update, I am up to my sixth pour of 300+ degree pours, modifying the drag a little each time till I achieved a complete casting.

The lowest casting is from the first try.

The second try I tried helping push the metal down using a rod. No help.

Third try I realized material was cooling too quickly in the gate, so I doubled the diameter of the gate inlet. Helped but not quite

On the fourth try, I made some small grooves for each side wing because they were not filling, much better

Fifth try, I increased those same groove to the length you see, but the long wings were not filling completely.

On the sixth try, I added grooves for the long ribs and boom. I’m there.

At the very end of the pour, I use a medium sized Phillips head driver so I can twist off the excess material from the gate to get the part out.

I am very surprised at how long the mold has lasted. I love testing ideas like this. Think of the custom weights that could be cast  for use in infilled areas of a stem locomotive shell. A few measurements and a cad model later, an open pour or split cavity could be printed in a jiffy.

BTW, Thanks @SkipGear for the gentle prod that was the last straw to finally put me over the edge to buy a printer. To do crap just like this.

[John]

this might be a good way to replace those atlas C55 frogs

[Lemosteam]

this might be a good way to replace those atlas C55 frogs

Pretty sure NIckel silver has a much higher melting temp than what I am using!

Also, it is NOWHERE near the quality of a good pressure die-cast part. It is very crude, to put it mildly.

[metalworkertom]

Pretty sure NIckel silver has a much higher melting temp than what I am using!

Also, it is NOWHERE near the quality of a good pressure die-cast part. It is very crude, to put it mildly.

Nickel silver is much higher. I have had very poor results in even larger simple items.

[ednadolski]

Pretty impressive meatalworking!   No way tho that I'd want to try pouring molten metals myself (except when defending the castle).

Ed

[Lemosteam]

The volume is so small.  All I use is a plumbing torch with MAPP gas sitting on the ground.  The small stainless ladle contains the metal, and I place it over the flam till it melts, I have a cast iron plate on my desk.  Once melted just pour in the hole.  It's not a big deal at all. The metal cools so quickly wit these small parts its really remarkable.  The ladle stays hot longer than anything else.  its kinda fun.

[Lemosteam]

Guess I should show what this weight is for...

I am prototyping a design for a very small PRR flatcar, potential KD offering to compare this weight with a different method.

[GimpLizard]

John,

You may have already mentioned, but I couldn't find it... what is the resin you printed the molds from?

Thanks
Mike

[Lemosteam]

John,

You may have already mentioned, but I couldn't find it... what is the resin you printed the molds from?

Thanks
Mike

I did not mention that. This is straight Siraya Fast. I like it very much so far.

[GimpLizard]

I did not mention that. This is straight Siraya Fast. I like it very much so far.

Very good. Thank you

Mike

[daniel_leavitt2000]

I really want to try a lost resin casting in brass or pewter. This could open up some really interesting possibilities.

[Chris333]

Have you tried casting the whole underframe?   

[Lemosteam]

No, but I think it would be very difficult with a gravity pour.

[metalworkertom]

No, but I think it would be very difficult with a gravity pour.

Just need a larger well to receive the molten metal above the sprue.