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3D model to cast silver model


#1

The answer to this may be a “search the archives” type answer, but
I’ll ask anyway. If it’s all already been said, that’s fine, I’ll go
hunting, but timeis in very short supply at the moment.

My hubby is seriously looking into building us a 3D printer in the
near future. This set my mind racing about the possibility of me
being able to make jewellery scale models that I could then cast.

I haven’t done any casting yet (apart from ingots), but I fancy
having a go at Delph casting. Am I correct in assuming that I can
print a 3D model and make either a one-off piece or a silver model
for repeat casts, using Delph clay? If it was something I wanted to
repeat, I would more than likely send itout to have it cast via lost
wax casting, but for a one-off, Delph clay should suffice?

The 3D printers designed for home use seem to use the fused
extrusion method, using PLA (Polylactic acid, which is really a
polyester), ABS (Acrylonitrile butadiene styrene) or PC
(polycarbonate). Could a model made from one of these be burned out,
rather than wax? Apparently PLA burns cleanly.

My head’s all over the place with it all, and it’s very exciting.
But clarification needs to be done of the process I would need to
use.

Sorry if my question is rather vague.

Helen
UK


#2

make sure you check on the fumes from burning it out for toxicity
but I see no reason why you could not use it though I understand it
is not cheap to make prototypes this way if he is building it then
that saves quite a bit. I don;t see why you could not use investment
because both clay and investment contain moisture when casting I
have found a barrier on the item is needed if it is porous material.
If it is not very porous then no reason to change casting procedures
at all wax plastic all used in burn out lost wax casting. I make my
silve master models and then make the molds for waxes. The mold
wears out I have my silver master still.

Teri about 6 months from her new permanent home in the Laurel
Highlands PA YAY a studio again drools pants paces


#3

Hi Helen.

Errrr… ?Maybe?

Delft clay is just very fine oil sand, so it still has to be rammed
up like oil sand. Which means that your model has to be able to take
a bit of abuse while you ram the mold. Also needs to not have
undercuts, so you can get it out after you ram up the mold. Within
those limits, any of the typical home printer products should work
fine, so long as you make it stout enough to survive ramming up.
(Oil sand=normal, generic (read: cheaper) sand casting material. Do
a little online digging on sand casting, and you’ll see what I’m
talking about.)

You could also try burning out one of the plastic parts, to see what
that does. I’d put my first dime on the PLA. I know for sure that
polycarbonate doesn’t burn out worth beans. If he’s going to make
the makerbot anyway, you’ve got nothing to lose.

Best of luck,
Brian


#4

I can tell you one problem with PLA and that it is soluble in water.
You can invest it but you lose fine detail, spruing is a sod and you
get a sugary texture to the surface. Now, using Delft clay may limit
the moisture content enough to keep the surface integrity OK but I
cant say that I would be totally trusting of it.

Nick R


#5

You might want to try steam casting instead of delft clay. I only say
this because if your are going to spend time making 3d printed
models, you should use a casting method that will give you better
results and undercuts. Iuse delft clay all the time and love it, but
it requires more finish work and you can’t use models with undercuts.
Look up the steam casting bookson amazon. With an old hot plate, some
investment, and cans… You can cast great 3d models that will make
the casting equipment dealers hate you. It’s really simple to steam
cast once practiced. The limitations of steam casting with minimal
equipment is that to properly burn out you will have to source the
old hot plates that conduct enough heat, getting the air bubbles out
of mixed investment, and there will be less consistency than
professional casting methods like vacuum casting. However, steam
casting is superior to delft clay when it comes to models. It’s worth
trying. I love my delft clay kit for making ingots and ring blanks
and any piece that has a flat side (back). What a great invention
delft clay is.

Rick Powell


#6

Hi Guys,

Also needs to not have undercuts, so you can get it out after you
ram up the mold. 

About undercuts with fine sand casting, it can be done, and it is
relatively simple, but you need practice to do it. Basically you have
a multi-part sand mould. The cup and saucer challenge is a good
challenge for a sand caster. You need to make a one piece casting of
a cup, and saucer with a spoon it, it takes a lot of practice to get
it right.

Alternatively if you have a CNC machine, and use architectural
polystyrene, as opposed to a rapid prototyping machine, then you
leave the polystyrene model in the sand and it evaporates when the
molten metal hits it. Undercuts, even complex internal voids.

Regards Charles A.


#7
I use delft clay all the time and love it, but it requires more
finish work and you can't use models with undercuts. 

Finishing even Stevens depending on what you’re after. If you put
something highly polished into delft clay you get a better finish
(same as with investment casting).

Again, “yes” you can have undercuts using Delft clay, there are two
good ways to do it, one requires experience, the other just requires
a good polystyrene model, the emphasis is on good, and the
polystyrene is a definite factor in end result.

Regards Charles.


#8
Alternatively if you have a CNC machine, and use architectural
polystyrene, as opposed to a rapid prototyping machine, then you
leave the polystyrene model in the sand and it evaporates when the
molten metal hits it. Undercuts, even complex internal voids. 

Ooh don’t get him started. He already has plans to make a CNC
machine as well!

Helen
UK


#9
If it is not very porous then no reason to change casting
procedures at all wax plastic all used in burn out lost wax
casting. 

Because I could never afford the equipment necessary for lost wax
casting, much as I’d love to.


#10

Thanks for your suggestions Orchid folk. I shall definitely be
looking into steam casting.

Helen
UK


#11
You can cast great 3d models that will make the casting equipment
dealers hate you. It's really simple to steam cast once practiced. 

Just aquote to kick things off - I’ve never steam cast before. I’ll
add that there’s a far greater limitation to using sand casting of
any sort than that of undercuts, which is plenty already. There’s a
definite upper limit of resolution and quality to be gotten from any
form of gravity pour casting. It’s not very high, comparatively -
like for instance one can cast a housefly in a centrifuge, which
will never happen in a gravity pour. Helen can and will do as she
wants - more importantly asshe can afford, I’m guessing. My thought
is that the printer’s output will exceed the casting capacity almost
from day one, using sand casting and similar. We’re not looking for
casting jobs, but when we do them we charge like $40 plus metal. My
platinum caster charges me about the same. Cheap.


#12
There's a definite upper limit of resolution and quality to be
gotten from any form of gravity pour casting. It's not very high,
comparatively - like for instance one can cast a housefly in a
centrifuge, which will never happen in a gravity pour. Helen can
and will do as she wants - more importantly asshe can afford, I'm
guessing. 

Steam produces a hell of a lot more pull than gravity. Steam can
produce in credible pressure and thus capture plenty of detail. I
think steam casting is an excellent option since she is concerned
with cost. It requires minimal equipment as is her case.

Rick Powell


#13

Hi Guys,

You can cast anything with a gravity pour (even a fly), it’s just a
matter of head pressure, meaning more metal. It is more cost
effective to use steam, vacuum or centrifugal because you don’t need
the head pressure to achieve the same result for small items.

Steam casting worries me a little, because I don’t have any
experience with it, and can imagine the possibility of a steam
explosion. The risks are obviously small due to small quantities, but
some nonce will probably try it larger scale :open_mouth:

Regards Charles A.


#14
Steam can produce in credible pressure and thus capture plenty of
detail. 

After I wrote about gravity casting, I realized I might have said
it. I know that Helen isn’t just a smart lady, she’s a real smart
lady, so maybe it doesn’t need to be said. Of course you do what you
need to do every time you need to. Some things can be poured, some
need more and some need even more. It all depends on what’s needed
and what quality is desired and money always is a factor. I can
investment cast an ingot for rolling but of course that’s just silly
when I can just pop one out at the bench. One way or another you
need to overcome the surface tension of molten metal with some
pressure or you won’t get much detail.


#15

Thank you very much to John, Rick and all others who have answered my
questions re casting from a 3D printed model. I’m really looking
forward to having a go.

Helen
UK


#16
I know that Helen isn't just a smart lady, she's a real smart lady,
so maybe it doesn't need to be said. 

Thank you very much John, as I blush in embarrassment!

Been extremely busy with cello and violin practice and orchestra
rehearsals so haven’t had a chance to have a go at steam casting
yet, but I will be doing so very soon!

Thank you John and others for the advice. Currently reading up on
steam casting.

Helen
UK