Hey guys,
One of the things I love about YouTube is
interacting with my viewers.
Last week I heard from Dick who lives in Alaska.
He’s involved in a project to renovate an
old steam locomotive. He’s also a model
builder and has taken an interest in Lost
PLA Casting to manufacture some parts for
a 1/8th scale loco.
I loved this idea and asked if he’d got
any files he could share and he sent me this.
This 3D drawing was created by Dick after
researching original builder’s drawings.
It’s a crosshead which I understand is a
mechanism to guide a piston rod.
I just had to have a go at casting it. Unfortunately
the size is right on the limit of what I can
cast at the moment as I’ll explain more
later.
Printing vertically did a beautiful job.
On first inspection this doesn’t look too
bad. The shape is good and the rivets jump
out nicely. But there is some tiny surface
pitting – and I mean tiny. If the intention
is to paint this piece, then it’s fine.
I really think a good primer would flatten
out these imperfections. But if it’s going
to be polished, that could highlight them…
Let’s try it.
Yup, as I suspected, some of these imperfections
were just a little too deep to easily polish
away without damaging the detail, and the
shiny surface does highlight them in my eye.
So what caused these imperfections? Well I
don’t think it’s porosity. If we look
at the sprue that seems fine. There’s evidence
of printer lines, showing good definition,
and no sign of nasty holes.
So what else could it be? Well I suspect it’s
a size thing. When I first spoke with Dick
I told him I’d probably need to scale down
his pattern for casting and I could have,
but I wanted to test my theory.
I’ve noticed the limitations of my casting
set up for a while now and invariably if faults
creep in it’s here, closest to the pour
and furthest from the vacuum.
I do seem to need a little height from the
pouring basin to the pattern, and this project
was right on the line. You can see that one
of the sprues here failed to develop and that
others are also pitted.
At the other end, the sprues seem fine.
So closest to the vacuum seems best and that
would make sense.
The size of my flask is always going to limit
what I can cast, but using a solid flask also
has its limitations. The vacuum is only pulling
from one end. So the pull is bound to be weaker
the further away from the vacuum source we
go.
The way around this is to use a perforated
flask. These holes let the vacuum pull from
the bottom and the sides.
Now I’m not writing off my solid flask.
It’s great for small objects, but if I want
bigger, then I need the perforated flask,
and this requires a different vacuum system.
And as you’ve probably guessed, I’ve already
got one in mind. My new system will cope with
various sizes of perforated flasks, giving
me lots more casting opportunities. It will
also be able to cope with solid flasks.
This isn’t new information to my Patrons.
I’ve already told them about my plans for
a new system, and even hinted about it on
Instagram.
In truth all that’s stopping me now is money.
I’m not a wealthy guy and running this channel
is a surprisingly expensive hobby. The kind
PayPal donations I receive and the regular
support of my Patrons helps me keep going,
but ultimately it still leaves me saving the
pennies.
So if you want to see projects like my new
vacuum system come to fruition, if you want
me to demonstrate how to make equipment far
cheaper than you can buy it, and if you can
spare a little something, please consider
a PayPal donation or even better, a regular
contribution through Patreon. All these proceeds
go towards running my channel and bringing
you original content.
So I hope my flawed casting hasn’t put off
Dick. Just because mine wasn’t perfect this
time doesn’t mean that it isn’t achievable
with the equipment I have here, but I do think
it would be much easier with my future system.
If you’ve got an project that you’d like
to tell me about, drop me a line. If there’s
anything you’d like me to make and sell
in my Etsy store, give me a yell and I’ll
see what I can do.
So that’s it for now guys, take care and
thanks for watching.
