Hey guys, today I thought I’d do a metal casting experiment.
Obviously, I’ll be using a 3D resin printer, but to be different, I thought I’d include
some gemstones.
Now in theory some gems can be included in the casting process, actually left in place
whilst the metal is poured around them.
Suitable gems include Diamonds, rubies, sapphires, some synthetic gems and garnets.
Garnets, of course, are nice and cheap, a bit like me really, and these two were just
£4 each.
They’re Indian Garnets, a bit cloudy with a basic stone cut, but ideal for this kind
of experiment.
Obviously I needed to design something to hold the gems in place, and a sensible person
would probably opt for a simple ring design or similar.
But I think it’s fair to say sensible and me are barely acquainted, so I decided on
a skull ring design because, as we’ve already established, I like skull rings.
There are no prizes for guessing that I intended to use the garnets as eyes.
But I needed to hold them in place.
So I gave him some hefty eyebrows and again a sensible person would have left it there.
But I got carried away with my ZBrush work.
So, two days later, I finally remembered the purpose of the experiment and decided to stop
designing.
One thing I hadn’t considered at that point was how I was going to fit the garnets.
How could I fit them beneath these heavy eyebrows?
The way I came up with was to approach from behind, a process that’s often brought me
great personal satisfaction.
So I cut away some of the back section of the ring and cut circular shapes to give access
to the gems and stop them falling forwards.
Of course the gems could still fall out the back, so I designed a simple insert to fill
the void and most importantly gain a good firm grip on the backside of each gem.
I was very chuffed with this idea and congratulated myself heartily – until I realised a blatant
flaw with my plan.
During the burnout process, the resin print supporting the gems would vanish.
Some plaster would lightly grip the front and some side edges of the gems, but the all
important backside would remain completely bare, and that would allow the gemstone to
break free of the plaster long before the metal was actually poured.
So more plaster was needed to support the pointed part of each gem, and this could easily
be achieved by creating two holes in the insert.
I added a large sprue to aid the casting process and did a test print using my Phrozen Mini
8K.
Here you can see the insert has been printed in a different colour.
The gems would need to be sandwiched between the purple insert and the grey skull ring.
Happy with fit and theory, I decided to print in castable resin.
Now again, a sensible person would use a tried and trusted castable resin.
But we’ve established that I’m not sensible and so I opted to use a resin that I cannot
name at this point.
It’s not yet on the market and I’m helping the company concerned by testing it for them
– for which I’ve been paid the grand total of one free bottle of resin and no printing
instructions at all.
Y-es…
There’s one born every minute and this one runs a YouTube Channel.
So after several days of misprints and failures, I finally achieved a print that I was happy
with.
This grey colour is very easy on the eye, which I like a lot.
It’s quite supple and whilst it needed large supports with this print, the supports clipped
away easily without snapping and tearing.
After a very generous UV curing because, as I said, no instructions, the print became
a little patchy in colour, but I’ve experienced that with other resins, so I wasn’t flustered.
The resin also sanded nicely, allowing me to remove support nubs and ensure a perfect
fit with the insert.
I couldn’t show the fitting process as there were too many fingers and too little space,
but you can see the theory has worked nicely.
The insert clamped the gems firmly in place.
And if you think there’s quite a gap there, this was on purpose.
Using sprue wax I was able to melt a little into the gap to bond the insert in place and
prevent plaster getting anywhere it wasn’t wanted.
And with that done, it was just a matter of casting.
Well, that looks promising.
The gems were certainly where I wanted them to be, though there did seem to be a colour
change.
The insert had bonded as one with the ring, leaving holes reassuringly filled with plaster.
To remove this, I opted to give the ring a 60-minute dip in my ultrasonic cleaner.
Oh dear.
It seems that both of the garnets had somehow been coated with a microscopically thin coating
of bronze, hence the colour change, but the ultrasonic removed this only to reveal that
one of the garnets had broken.
I tried to gouge out both gems but only succeeded in damaging the broken one further.
It does look as though the garnet of your left has the thinnest of cracks running across
it, but it may be just a scratch and the gem certainly won’t budge.
So the design concept was a success at least but the garnet victory was 50% at best.
Admittedly these were low quality gems, so maybe that had something to do with it, or
maybe my clamping system left too little room for movement and expansion.
Hopefully some of my casting buddies out there may have the answer for me.
I’m not going to polish this one any further as it’s just scrap, so why waste resources
on something that’s going to be recycled.
They can’t all be winners, but I’m encouraged by the design idea which held up nicely, showing
an alternative method for novices like me to fit gems.
And at least the resin which cannot yet be named seems to work okay, but more testing
is still needed.
So I hope you enjoyed this casting experiment guys.
Take care and thanks for watching.