Lost PLA Casting John Wick gold coin – from 3D printer to solid bronze

(Phone rings) Da! – That VegOilGuy is making another video.
– And I want my pencil back! John Wick 3… yes! But I haven’t seen it
yet, so don’t tell me. I love John Wick, so when one of my viewers
requested a John Wick Gold Coin, I leapt at the chance to cast one with the Lost PLA Technique.
I began with Fusion 360 creating something that looks the part. It’s not exact, so
don’t get picky about the details. I knew that the biggest hurdle I had here was in
printing the coin, so I made allowances for that.
It also gave me an opportunity to experiment with print depths. To give the coin a 3D quality,
I worked in layers. Each layer on this side is just 0.2mm deep.
There was a little more detail on this side, so the layers are 0.1mm deep. So I had my
doubts that anything would print. The coin is 50mm or 2 inches in diameter which
is large, but I’ve seen commemorative coins about that size. Bigger would have looked
daft and smaller would have hidden the detail. All in all I was pleased with the coins. Printer
lines were obvious along with a few annoying snot lines, but the Lion looked good. What
I’d planned on being whiskers looked more like an open mouth, so I decided to go with
that. The Lady wasn’t quite as clear, but at just 0.1mm depth between layers, it was
still pretty good. There’s too much for me to try and clean
up here, so I just used the very tip of a file to very lightly scrub away any obvious
imperfections. But that was it… no other clean up.
The prints aren’t too bad. It’s just a standard home printer, a Creality CR10S, so
perfection isn’t possible at this scale. I bonded the two halves of the coin with positioning
wax. I literally smeared it on, putting a very thin layer on each one.
I then used a little sprue wax to fill the join and lightly sanded this smooth.
I decided to do away with the sprue of my printed sprue base, so I just cut this off.
In last week’s video I mentioned that where I had thick castings, I would try to use Risers.
As this coin would be around 6mm or ¼ inch thick, I felt risers would be needed.
At its simplest, a riser is merely a thicker section before a thinner one, so I decided
to use this wax sprue for this purpose. I can’t make my mind up if it looks like
the coin’s going scuba diving, or whether I’m modelling a new Starship Enterprise.
Either way, I was hopeful the coin would have ample feed and resist shrinkage.
Up until this point, things had been going surprisingly smoothly, so don’t blink or
you’ll miss the terrifying bit. Yes, the crucible fell showering thousand
degree puddles of fire everywhere. The reason for this slip is these grooves
on the crucible. I hadn’t noticed previously that these wear away. Look at the crucible
that fell – there’s virtually no groove, so there was nothing for the tongs to grip.
So please be more vigilant about these grooves than I was – and wear safety gear.
In a mad scramble I hopped between the red hot puddles and placed the flask back in the
oven whilst I put out fires, collected the spilled bronze, cleaned it and melted it again.
So about an hour later, still flustered, it’s hardly surprising that I forgot to focus the
camera properly. Now once a flask is out of the oven, it cools
quickly and the plaster can begin to crack. So as my flask had been out, in and out again,
I wasn’t hopeful. But thankfully it didn’t look too bad.
The risers seemed to have done their job. There’s no sign of shrinkage, though perhaps
it wouldn’t have shrunk anyway. So is it perfect? No. There are imperfections.
There always were with the 3D print and the crucible escapade may have taken its toll,
but by and large I was happy. Not bad for home casting with largely home made equipment.
I hope you enjoyed this one guys. Take care and thanks for watching.

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