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Lost Foam Casting is a process in which a foam pattern is made of what ever object is desired then the part is cast and the foam is burned off in the process. It is a type of investment casting, similar to lost wax casting. Since one of the types of foam used is ABS, I thought I would try lost ABS casting where instead of foam a thin filament of ABS is used. So using a Think-o-Matic 3D printer, which extrudes ABS, I printed up a few things to try casting. My first attempt did not go well, actually the results were dismal. Since I was using greensand and I did not vent the sand well enough, the ABS did not have enough oxygen to achieve combustion properly and the smoking continued. Back to the printer.

My second round of testing I received more of the results that I was looking for. First, I limited the amount of ABS in the print (no more than 5% fill) and I reused the sand that had dried from the first attempt. The first part, an android head, came out with good detail and only minor artifacts.

The android body did not do as well. I did not settle the sand well enough and the result was a compressed casting, something else to watch out for. I will be doing some more testing in the near future to refine my process and see how patterns with thin sections will turn out. Maybe a T.I.E Fighter Advanced will be the test for that.

We have been enjoying the Thing-o-Matic (a Makerbot), printing new things and experimenting with settings for good prints. While I was poking around the web I found a site makerblock.com that has a Profile Maker that helps you adjust your settings in Skeinforge. So, I am giving it a try but since I am at work and printing remotely I will not know how the new settings turn out until I get home. Never the less, it will be interesting to see how they improve (or not) the print quality.

This is all a prelude to moving to the Skeinforge44 code which is supposed to fix several bugs and have some good improvements. I will have to mess around with it before doing some ‘serious’ printing. I have found that printing a calibration cube is fine, but I like using a block that resembles those ones that click together (while not naming names). Not only does this model have the straight sides and corners, but also small bridges and round tubes (and nubs).

I have to admit that my son loves the printer, but is easily distracted (what 10 y.o. isn’t). So we are behind on having him print his own designs. We are working on it though.

Makerbot has a 3D printer called the Thing-o-matic. The printer extrudes plastic (ABS or PLA) through a nozzle and deposit’s the plastic in whatever shape the model is (oversimplified explination). It was a gift for my youngest son; who has a great imagination for creating things. My son and I assembled the printer over two weekends, then started printing. I have to say that it is fun, although it can be loud while printing (I have had complaints from the other occupants in the house). Add in Thingiverse, and you have a plethora of pre-modeled things to print. Darth Vader, Yoda, the Millennium Falcon, and a 3D knot, were some of our first prints. We also designed our own Lego type block which turned out well, but is not as refined as the injection molded version. I have also been playing around with some designs; a compressor air filter bracket, a webcam mount (articulated of course), a CD/DVD spindle all have come off the printer and are in use.

Additionally, the printer can make some of its own upgrades. X & Y axis belt tensioners and adjusters, filament guides, spool holders, and the like have all been printed and installed. While the possibilities are not limitless, there restrictions on size of the print is the only current hard restriction. This printer can be a stepping stone to larger printers, open source of course, as there are currently other projects that have much larger build platforms (print area) and multiple extruder options (2 extruder heads at one time).

From my sons point of view this thing is “COOL!” (his words). Now comes the need to teach him how to design his own models for printing. Of course, some of his skills will spill over to the CNC Mill, and maybe to the foundry. We will see…

You can watch the Thing-o-matic live stream here when it is printing.