Observations on the FormLabs’ Form 2 printer.

Some observations on the FormLab’s Form 2 printer:

First, the resolution of the objects that are printed is simply amazing. I remember putting together the original Makerbot; this thing prints objects that are absolutely amazing compared to the extruded noodle of the original Makerbot print objects.

For example, I’m able to print 2 millimeter holes through a design and have them come out exactly 2 millimeters in size. I’m printing 32p gears; these are gears with 10 teeth per circumference inch and have them come out perfectly. (I tried the same thing with the original Makerbot; there is no way 32p gears could possibly have worked. Of course the current generation of Makerbots are light years ahead of the box of do-it-yourself wooden parts and gears of the original Makerbot printer.

Here are some parts I printed; they look imperfect because I roughly sanded them using 320 grit sand paper to see how well things would hold up to sanding. (You can get a much better result if you follow FormLab’s instructions.)

IMG 2825

I’m currently writing a Macintosh app which can be used to design gear chain mechanisms using spur gears; the mechanism is the top and bottom of a simple gear chain which performs a clock motion work, stacking two gears with a 12 to 1 ratio, so when one gear (attached to a minute hand) turns one full revolution, the other stacked gear (attached to an hour hand) would turn 1/2th of a revolution.

This is a test mechanism; ultimately I’m looking to design a clock, and I may write more about it in later posts.

The pins are 2mm by 25mm long pins; I was able to specify the holes to an amazing degree of accuracy. I was able to specify the holes in the corners of the frame to a 1/10th of a mm larger than the hole of a standard M3 screw. (Right now I’m waiting for some washers I ordered to insert between the gears.)

It’s stunning how great the quality of the parts printed are.

Of course this resolution and quality has a cost: time. The two frames that I printed to hold the gears (a test of the software that generates Delaunay triangles to triangulate the axle locations for my gears; the resulting frame was bigger than I wanted, so I need to tweak it) took 7 hours to print.

Yes, you read that right. Seven hours.

The four gears inside took around 4 hours to print.

But then, it makes sense. The Form 2 printer takes care to agitate and heat the resin to a consistent state; this allowed me to print some amazing items pretty much right out of the box. After each layer is printed (and each layer is 50 microns thick; about the thickness of a very thin piece of paper), the resin is agitated and the area cleared for the next layer. Needless to say for an object 3 inches tall, building up the part 50 microns at a time takes a while.

The resulting parts come out tacky. Even after bathing the parts in isopropyl alcohol for 20 minutes, the resin is not set or cured; you must allow the parts to finish curing–either in a UV light (mine is on order), or let the part rest for about a day.

Another thing to note is that while the results of using automatic scaffolding helps make the parts print correctly, sometimes with heavy objects the scaffolding can fail, causing print errors. (I tried printing a model of a manatee for my wife, only to have the flippers and head separate from the rest of the body, as the body was too heavy to hold rigid during printing. I fixed the model by gluing the pieces back together.)

Further, the automatic scaffolding algorithm can be a pain; you need to review the parts and edit the scaffolding locations. For example, the above photographed gears have a problem meshing; bits of the scaffolding got stuck between the teeth. So if you have surfaces that must be perfectly shaped and clean, you may need to edit how the scaffolding gets applied.

At some point when I get the gear design software working, I’ll publish a note here.

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