Hi YouTube, my name’s Geoff and I’m the VegOilGuy.
It’s challenge time!
And this is it, a coin.
Perry at SWdweed came up with the coin challenge idea.
For my contribution, I designed this little YouTube Casting logo, but all credit for putting
the coins together lies completely with Perry.
This challenge for me at least is all about detail and there’s a lot here in something
that’s really quite small.
Look at all those tool marks.
I could try and clean these up, but instead I want to try and cast something that shows
them and for such detailed work, I opted to try Lost Wax Casting.
Now I’m a complete newbie to Lost Wax Casting so I’ve been picking the brains of my betters
to help me along the way.
Their details are on the screen now and I’ll be referring to them throughout.
So to start with, I glued the two halves of the coins together.
I also added a little car body filler to the sides to blend the join mark and shortened
the feeder and vent sections.
From here I needed to make a silicone mould.
This empty sealant tube was a perfect size.
Cut down, it needed a base and plastic cut from a washing detergent bottle worked nicely.
It just needed rubbing down with a little fine sand paper and bonding with a few spots
of super glue.
Or in my case, a pigs-ear mess of superglue.
This was unlikely to be water tight, so some plasticine / modelling clay / play doe, whatever
you call it can be firmly squashed around the edges.
Some might call this play doe, but this was serious work.
You won’t catch me playing about with this stuff – ahem.
I needed to attach a sprue and a sharpened stick slotted nicely into a small hole I’d
drilled.
Superglue will held it firmly.
I also glued a cross piece to the stick and added a small amount of plasticine for extra
support.
The crosspiece suspended the coin fairly centrally within cylinder ready for the silicone.
Now this is the silicone inside my vacuum chamber.
After mixing, the chamber is used to force out any trapped air.
It expands up to five times its size and once in collapses, it’s ready to pour and form
a mould.
The mould was then vacuumed to pull out all the air and pick up every detail of the coin.
And here it is 24 hours later.
The plasticine was pulled away along with the plastic bottom.
A sharp utility knife sliced through the sealant tube and was peeled off.
Now for the tricky bit.
With a very sharp blade, the silicone was sliced through until the blade gently brushed
against the edges of the coin.
This opened the mould and allowed the 3D coin to be removed, leaving a perfect coin-shaped
void behind.
Personally I only sliced one side and left the other as a kind of hinge.
The sealant tube can be added to support the mould and a little tape keeps things in place.
Here’s the hole where the sprue was.
I needed to inject wax in here.
This is casting wax.
And if you ever doubt my commitment to you guys, remember this – this is my wife’s
saucepan!
Once the wax was molten, I sucked some up with a cheap syringe, then I injected this
into the mould – making quite a mess at the same time and winning no filming awards.
Once this had cooled, I peeled everything back and, well, not brilliant.
And I never really managed brilliant either.
Such injections are usually vacuum assisted and done with professional machines which
I didn’t have access to.
But despite this, the level of detail was excellent, but the results were lacking.
Still, for a first attempt this wasn’t too bad and I was keen to move on to the next
stage, building a wax tree.
A cheap alcohol burner provided heat and any suitable metal tool helps melt the wax in
place.
The trick is to melt both faces of the wax when trying to join them.
Historically the branches of wax trees go upwards, but I pointed my downwards – an
upside-down tree if you like.
Professionals like Paul Hamler use vacuums at the metal casting stage and I don’t have
any equipment like that, so I designed my tree to vent air.
My theory was that the metal would enter from beneath the coin voids, pushing any air up
and out as it went.
If nothing else, it made a bizarre looking wax sculpture.
I needed a flask to hold the wax tree and I began this with a piece of broken CD case
as a base.
A food can was used for the main body and I traced an outline around this.
Three small holes were marked and drilled for the vents.
The trunk of the tree was pressed firmly to the centre of the base and the thin wax sprues
were pushed through the drilled holes.
Wax underneath and a smidgen above sealed these holes.
The food can slid neatly over the top of everything.
A series of large holes were drilled through the can before it was attached to the base
with more plasticine.
Then all these holes were taped up and investment was thoroughly mixed according to the exact
specifications of the manufacturer.
This was vacuumed before being poured into the flask.
The filled flask was then vacuumed and tapped to release air and ensure there were no voids.
The investment sets in minutes but needs to be left 2 hours before cooking.
Obviously I don’t have a burnout oven, but the wax needs to be cooked out of the mould.
So I used my electric foundry and increased the temperature 100 degrees every hour until
I achieved 630 degrees Celsius.
I let this cook for 4 more hours then left everything the cool as I was shattered and
needed to go to bed.
The next day the flask was sitting at around 80 degrees so I placed it in my Kitchen Oven
and reheated to 275 – this being as high as my oven will go.
Meanwhile I melted some aluminium and got ready to pour.
I placed the hot flask on some dry sand and poured…
it was over a little quick if I’m honest.
The vents seemed to work a treat though an overspill of metal choked one off.
I waited half an hour to dunk the flask in a bucket of cold water and waited for the
much anticipated frenzied hissing.
It was quite the anti-climax.
It must have cooled off too much.
This meant I had to spend time soaking and brushing away the investment, but eventually
a shiny tree was revealed.
With the sprues cut away and filed down, here are the results.
I know, they’re a little disappointing, but for my very first ever attempt at Lost
Wax Casting, they’re not too bad I suppose.
The coins haven’t taken all of the detail, but there certainly was evidence of the tool
marks.
So where have I gone wrong, how can I do better?
Well, when it comes to wax injecting, lack of professional equipment was always going
to be an issue, but Martin the Olfoundryman and his friend John Dersch suggested using
talc and making vent holes, and since making this video I’ve seen improvements in my
wax injections – though still not perfect.
However, most importantly, John felt I was using the wrong sort of wax and that I needed
one for fine jewellery making.
For the investment powder, John again recommended fine grade Jewellery Investment, to ensure
better detailing and also mentioned that the flasks should not really be allowed to cool
after the burn out, but used as soon as possible.
Paul Hamler echoed this sentiment and stressed the importance of vacuum equipment at the
metal pouring stage to force the metal against the mould and pick up additional detail.
Martin also felt the metal was wrong.
He reminded me that my choice of extruded scraps was unlikely to get optimum results
and suggested I buy proper alloys instead.
For me the feel of the coins was all wrong.
Being aluminium, in the hand they felt like toy money.
It’s a strange thing to describe, but it left feeling deeply disappointed.
So I had another go.
The wax coins were still a little flawed and I decided to use my old nemesis copper for
a heavier feel.
I changed the design of the tree to add a little pressure well above the coins, even
though I know the will annoy Martin, and a recast everything.
Again the pour was very short lived and the crucible got in the way… it was much too
large for the task.
Again I’d left it too long for a fizzy, exciting dunk in the bucket afterwards.
But the results weren’t too bad.
Sure there’s still gaps from the wax pattern, but you can see the tool marks there.
There’s really not meant to be any winners or losers in this challenge, but I don’t
think I’ll win any prizes for the prettiest coin.
But I think when it comes to picking out very fine detail, I think Lost Wax Casting is the
real winner.
Martin in his Bitcoin video showed how it was possible for an expert sand caster like
him to obtain this level of detail.
But Martin’s got years of experience behind him and a skill set most of us will never
achieve.
But with Lost Wax Casting, me – a complete novice – managed to knock out something
with plenty of detail in just my first and second attempt at the technique.
Imagine the sort of thing experts like Paul Hamler and John Derche can achieve with it.
Well actually, you should go and look.
So for me that’s it.
Don’t forget there are other competitors in this challenge, so look out for their videos
and give them a thumbs up.
I hope you enjoyed this challenge guys, and if you did, please drop me some comments.
Your support means a lot and encourages us YouTubers to keep going.
Hopefully there will be more challenges in the future, but I think we’ll need to see
how this one goes first.
So that’s it for now guys.
Thanks for watching.