An Open-Source Rotational Casting Machine

[Aurelio] wrote in to tell us about the smartCaster, an “Open source automatic roto-casting machine.”  For those of you not familiar with roto-casting, or rotational molding, it’s a process whereby something to be formed is placed into a mold and then melted while spinning.  This item is often plastic, but it can be another material such as plaster of Paris or even chocolate.

Naturally, having something made using this process is generally very expensive and generally requires a high volume of parts to be made. The smartCaster Kickstarter project aims to change this. Although in the prototype stage currently, [Aurelio] claims to need only $1571 to finish his project and make it ready for the prospective at-home rotational molder.

Although it’s a much different tool than we see here most of the time, for the right project (custom Easter Bunnies anyone?) it could be quite useful. Check out a video of the prototype in action after the break.


28 thoughts on “An Open-Source Rotational Casting Machine

  1. I’m a bit ignorant about what needs to be done to get a successful rotational cast, but what I see here is two motors, a few planks, some stuff to get power over a rotating axis and an Arduino. Maybe I’m overlooking some subtlities here, but I think I could make that for about $157.10 instead of the $1571 he needs. Am I missing something?

      1. Maybe that is what he needs left to be kickstarted to make it available? It still doesn’t strike me as very um…. robust? User friendly? Isn’t the point of kickstarter projects to wind up with highly polished projects that would not have otherwise been built? Most of us here could build this in a few hours.

    1. I think Hackerspacer has the right idea. Aurelio is looking to turn this prototype into a reproducible set of plans and manuals and a kit form of the device. Hence the higher cost than just building a one-off.

      For the plans, he’d need to test those by getting a reasonably skilled person who is “naive” to this particular project to build it, find out what goes right and wrong, revise and repeat.

      For the kit, he’d probably want jigs to build the parts he fabricates himself, plus setup costs for custom PCBs/labels/etc. that one would expect to find in a kit that one paid good money for. And of course instructions for putting it together.

      $1571 doesn’t sound too bad for all that. (It sure sounds precise, though). Spending the money to make it all refined will save a lot of headaches dealing with users who can’t get it to work through no fault of their own. (He’ll still have to deal with the other kind in either case, though).

  2. There are many other much cheaper versions listed at the end of youtube video. I also don’t understand where his costs are coming from. Yes his is a fancier version, but it doesn’t seem like it should be that much more expensive.

    1. Yes.
      But once you blogged it, and you realise that others who are not proficient enough to make one from scratch might be interested in having one, what do you do? Shrug and be happy you are such a smart person, sulk when someone else comes out with a similar thing, or see a niche and try to get a product out there to fill it?

  3. Prob, to cover the time and expense of documenting the process and putting together the PDF. As well as covering the cost of the hosting and domain name. Build in a little bit to cover his past R&D.

    1. Cost of hosting the website $0.00 google sites are free.

      Shopping cart? Paypal does this free except for taking a cut of each sale.

      So unless he is paying himself $50.00 an hour to write the PDF…..

    1. no motor but other than that, its perfect

      btw, who here with $20 could NOT make this from basic hardware store parts?
      i dont think there is anything that could be done to this simple of a design to add up a sum of $1500

      1. Yep, and adding a motor isn’t rocket science.

        The two easy ways are one of those cheap cordless drills, or even better, one of those motors used to drive microwave turntables.

        The microwave motors are perfect (apart from running off mains voltage). They turn at about 5-6rpm; most people don’t realise you don’t spin these things fast, slow & gentle does it.

    2. Actually a reply to your reply to Frogz (but we can’t stack comments that deep), but the rotational speed comment is a little misleading. At the small scale reasonably slow rotation is fine, yes. But bigger items can need to go faster to ensure even coverages.

      These casters also depend on the mould being roughly even in both dimensions. For objects that are perhaps very long and thin, you might want it spinning a lot faster along it’s length rather than end over end.

      I’m using two gutted battery drill motors to do this. Separate drive and speed controllers on each axis.

      1. There’s always going to be something that doesn’t work, but for most things most of the time a simple design like here will work.

        Mine is about the same size as this, microwave motor with pulleys & belt, casting stuff that’s about hand sized. Works ok, I’ve never bothered to cast cast something long & thin.

        When you hit the limits then it’s time for v2, and even then it shouldn’t be $1,500.

      2. Oh, I forgot to mention my moulds are usually vacuum molded, not big lumps of silicone rubber, so that reduces the weight load.

        Even so, microwave motors have a surprising amount of torque.

  4. “it’s a great alternative to something like a makerbot”
    Except that a 3d printer can be had for around £500 and you don’t need to make a mould and find casting material and heat a whole pile of it, keep it hot and put it in the mould etc… This really looks like more of an industrial process to me, where you need thousands of parts not just one, which is what 3d printers are good at, but this doesn’t look robust enough for thousands of spins.
    And why use an arduino for speed control and timing? Sledgehammer meet nut.

  5. Someone should do an instructable on how to recycle common devices (i.e. broken HP printers) into ABS wire ready for printing.

    Last time I checked the basic plan would be to “shred” the ABS into granules then extrude these as a wire with an optical or capacitance method to ensure repeatability.

  6. Hey guys,

    Thanks for the interest and feedback.

    First I’ll clarify by saying the smartCaster does NOT cost $1571. That amount is a rough approximation on the costs associated with research and development. In the course of developing the smartCaster I tested a total of 8 different motors, numerous gears and pulleys, a few project boxes and a ton of different shaft couplers. If you’re ever done any mechanical work you know that this stuff is not cheap! Include the price for the electronics (the control unit is not shown in that picture) and the casting materials that I have been testing with and this project has seriously cost me a lot of money (and I am by no means loaded).

    The point of Kickstarter is to get help through funding from a community of innovators and entrepreneurs. The smartCaster was not done when I started the project and it still has a few kinks to work out (I’m fully funded btw). Rewards are the ways in which people help fund the project. Some people treat it as a sales outlet, others treat it as a donation structure (which is what I did).

    For exmaple, I put a smartCaster as a $500 reward as a means to get the project funded and recoup my costs. The BOM and hardware won’t be this much because of the experimentation, time and spending I’ve already put into it, but to be honest with you, I don’t want to spend all my time making a ton of smartCasters. I plan on eventually selling an electronics kit for about $150 and a mechanical kit for a little less than that if I can get the costs down but that is the reason I made a reward at that price point (which someone graciously pledged for).

    Ultimately my goal was to make a project that I give back to the community. You guys have cited other rotoCasters but if you look closely you will see they do not do what the smartCaster does (fully automated, programmable and open source). Once I release the building documents you’ll know where you can go to get the parts to build a fully functional device that you know will work, will have easy to understand directions and has been tested with numerous casting materials so you know how to get it up and running as quickly and easily as possible. And for all this you won’t have to give me a dime!

    So why the hate? I can understand why there would be so much but confusion and suspicion about my intent but please don’t be so cynical — I’m definitely not doing this to get rich or rip anyone off!

    Once again thanks for the interest and I look forward to seeing what the community can make with it.


  7. So, how would I make something with this? What would I make the mould out of, and with what material would I fill it? Would I need to preheat the material before putting it in the mould? How fast would it dry? There seem to be a whole lot of unanswered questions here for people unfamiliar with this production technique.

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