Sphere test

Working on a prototype for a new project, or at least a remake of an older project anyway. This 10cm diameter sphere will be one of maybe seven if I’m lucky for an upcoming exhibition in Santa Monica in November. It is printed in photopolymer resin on a FormLabs Form1 desktop SLA machine. The quality is good but not great… layers are still visible, lines are not that crisp, theres a slight yellow hue to the plastic, where the supports attached there are little bumps, theres a little de-lamination in the print on the seam, and so on.

The two hemispheres are held together with three very strong neodymium magnets. (One of the magnet holders on the top in the back was filled with resin and had to be drilled out – breaking in the process.) Because “complexity is free”, each of the seven spheres will be customized with a different pattern of ley lines on each one. The board is a custom Arduino setup with an H-bridge for controlling the micro metal gearmotor and a charging circuit for the lithium battery. The arm attached to the motor swings around a lead weight acquired from the wife’s lead type collection to create the movement of the sphere.

The ball is overall pretty cool, and definitely not possible to manufacture on my other more traditional FDM machines, but Im not terribly happy with it either. The print quality issues, combined with the print time (16 hours total) and the cleanup involved after the print is done with the cost involved ($260 for 2 liters of resin at discount) on top of everything just has me rethinking it a little. If I’m going to spend some cash on it I might as well do something really cool like this example of polished alumide from Shapeways and not have to do the labor myself.

Option B is definitely not a cheap road to go down but it would be really nice…

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  • Maxim Lobovsky

    Brian,

    Thanks for the review and the really interesting project! It looks like it came out pretty well.

    We’ve got work in the pipeline that will improve most of the remaining print issues you mentioned and will work on the machine you already have :)

    On the print time and resin usage: I’m curious why it required 2 L of resin to print. It looks like those parts wouldn’t be much more than 0.2 L. Also, If it took 16 hours, its likely you were at a relatively small layer thickness (25 or 50 microns). For a part like that, I’d recommend 100 micron layers unless there are some really highly detailed parts. Print time is roughly proportional to the number of layers, so this makes a big difference. As far as we know, we print solid layers at a given layer thickness faster than any commercial desktop 3D printer.

    Thanks,
    Max
    cofounder, Formlabs

    • http://hardwired.cc Brian Evans

      Hey Max. Sorry if that was unclear… I would have to purchase 2L to make the entire set of them not that each individual one would take 2L. Last print was at 85mL with .05mm layers… I had tried .1mm layers earlier and your right for this kind of thing probably not much of a difference. Seems to need a lot of support material but I was tempted to try printing it flat on the platform to see what that would do.

      Overall this is an amazing machine and compliments other more common FDM printers. I cant wait to see what students at the university come up with it. After spending more time with it myself I intend to write up a more proper review as right now my view is more centered to this particular project and may not reflect areas where this machine shines. So in honesty my above comments might sound more harsh than my actual view of the machine. But you’re right – Ive noticed that you might as well load up the machine with multiple prints as it won’t take any longer to print them all at the same time.

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