We’re accustomed to covering the use of 3D printing in casting, usually as a lost-PLA former in metal casting. That’s not the only use of the technique though, and perhaps one of the simplest is to use a 3D-printed mould for casting concrete. It’s what [ArtByAdrock] is doing in their latest video, casting an ornamental owl model.
The first part of the video below the break deals with the CAD steps necessary to produce the mould, and depending on your CAD proficiency may not be the most interesting part. The process creates a mould with two halves, a pouring hole, and registration points. Then a 3D printer produces it using flexible TPU. The pour is then simplicity itself, using a casting cement mix at a consistency similar to pancake batter. The video shows how a release spray provides easy separation, and the result is a fresh concrete owl and a mould ready for the next pour.
We can see that maybe readers have only so much space in their lives for concrete owls, but this process could be a valuable part of the armoury when it comes to making some less decorative items. It’s not the first time we’ve looked at this type of work.
Who?
LOL
Have you tried putting the mould over a vibrating surface to get rid of bubbles when the concrete is liquid?
What about a concrete banana then?
I’ve done this
https://youtu.be/4-6nQf7IkfI?si=z6DKlFk6rr1LI6P3
Or you could create a monster… https://dragons-tech.blogspot.com/2021/09/i-created-monster.html
Hehe, I’ll level up from that: I needed a heatproof jig to assemble a bunch of metal parts soldered in a specific complex geometry. I 3D printed a mould, used that to cast refractory mortar, then used that cast for the molten-metal jig. It had a cast-in-place embedded heater and thermocouples to melt the solder. It worked great for the several hundred parts I needed, and would have been a total PITA to have made other ways..
Got pics and/or a write up somewhere? Sounds interesting.
Pics or it didn’t happen. Okay, kidding, but it would be pretty cool to see pics, even if it’s just a screen grab of the model for the 3d printed mold. Also, was the jig the part made out of refractory or did you cast the jig from the refractory clay mold and then make the parts on that? Also, was the “molten metal” a lower temp thing or up in the range of aluminum or hotter, and how much did you have to account for things like part shrinkage? Anyway, if I am being nosy to the point of rudeness, then feel free to ignore me, but it sounds like the kind of project I might be interested in (probably for something different in nature like making parts for a multi-head printer) and it would be great to learn from someone else’s experience.
Kinda curious what kind of heater are you talking about? Is it as simple as nichrome wire cast into the refractory mortar or is it something more sophisticated?
Metal casting sounds very cool to me but the only thing stopping me is having to buy gas operated force/blowtorch and ofcourse the recurring pain of going out to buy the gas itself.
If you are interested in relatively small castings you should checkout electric melting furnaces on ebay. They arent very expensive to buy, or operate.
To answer questions:
– Sorry, no pics or writeup. Just another one of those yak-shaving exercises on the way to getting something done, about a decade ago.
– The heater was exactly that: Nichrome wrapped around a ceramic tube and embedded in the refractory cement mortar. About 50 watts. The mortar was thermally conductive enough to heat uniformly enough, verified by three embedded thermocouples.
– The whole thing was about 8 x 8 x 5 cm, only a couple of hundred grams.
– The jig was the cast refractory. There was no PLA left. The refractory was wrapped in fiberglass cloth so I could still handle it while hot.
– The “molten metal” was plain old 63-37 solder.
– workflow was: load parts in the jig, then warm to temperature, apply solder, then fan-cool to set the solder, remove parts. Rinse, repeat. Cycle time was about 10 minutes. I had to remove parts while the flux was still molten, or they would stick in place. The jig never dropped below 120C or so.
– the jig itself had no moving parts: components just rested in their ‘nests’, firmly enough that solder surface tension didn’t disturb positioning.
– part geometry was not too critical. Repeatability was a fraction of a millimeter, well within requirements.
– it was important to cure and bake dry the mortar thoroughly before putting into service. The first attempt just fell to pieces after a couple of cycles: an overnight room-temp dry was nowhere near enough. Overnight cure, then 70C bake for an hour, then two days ramping to operating temp (200C) worked.
I’ve been dabbling with 3D printed silicone moulds. I am very happy with the newfound ability to make soft silicone parts. So far, I could order 3D printed plastic parts, or even CNC cut metal parts (expensive, but still possible) but “soft” parts were simply out of reach even if I was willing to pay.
Now I’m looking into actually making resin moulds out of silicone moulds, which I make by 3D printing the mould’s mould. Its a long process but I’m quite optimistic. Oh and trying to make parts with plaster-of-paris and cement. Yes, that’s in the to-do list
Its a glorious time when many manufacturing techniques are within reach.
I was looking for a way to cast an abstract owl. Couldn’t find any tutorial yet.
IIRC OWL was a static library.
Seems like a waste. Concrete is much better suited to large, reinforceable, objects. This falls from a foot and it breaks. Also, concrete would not be good anyways, lots of aggregate in the mix, not good for small objects. Cement would be best for surface quality, but again, super brittle. Just cause you can doesnt mean you ahould
I plan to use my pre-ordered orange storm giga to print forms for a life size concrete statue. I anticipate needing to place the forms inside a large box made of plywood so that I can fill the outside of the form with gravel and the inside with concrete. This should keep the forms from blowing out or deforming from hydrostatic pressure before the concrete cures.
In college I was on an American Concrete Institute design team. Engineering schools from around the country competed on pushing concrete to the limits. The year I went to the national competition we made concrete bowling balls that were judged on roundness, strength to weight ratios and a couple other factors. These days there are lots of high tech additives that can give concrete desired characteristics from high-early additives to superplasticizers to steel fibers… there are lots of ways to make concrete a suitable material.
There was another design team that made concrete canoes that they’d actually take down the river in competition.
Take a little time to learn about the possibilities before you say it’s pointless.