Some of you may have seen my presentation last month on small-scale plastic injection molding. I'm happy to report that the plastic injection molding attachment I've been making for sector67 is complete and functional. I'll try to post some pictures in a bit.
I was able to mold some more wheels, and will be working on some other molds (gears, etc.) time permitting. This design is basically version 2 from Vince Gingery, and is superior to the stand-alone machine I showed at the meeting in several ways:
1) The drill press provides more direct vertical pressure, so the there is no horizontal shear risk as I aptly demonstrated with the previous model.
2) The digital temperature controller (described below) provides much more accurate and repeatable melt temperatures.
3) The larger barrel can shoot roughly twice as much plastic.
Ideally, we'd have a mold pre-heater, so keep your eyes out for a toaster oven on freecycle.
As a part of the project, I implemented a general-purpose 120V temperature controller. It takes K-type thermocouple input and switches a 120V outlet (presumably driving heating elements) to control a temperature quite accurately. My hope is that this can be used directly as a set-and-hold temperature controller for the older of the two kilns for aluminum melting, but the controller could be used to control temperature for nearly any application. It is capable of 20A at 120V and has two outlets.
Many thanks to Chris for his assistance procuring many of the raw materials for this fun project.
If you have any questions on this, or want to get started injection molding plastic, just let me know.
File comment: The plastic injection molding attachment on the drill press with the temperature controller.
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File comment: The temperature controller.
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File comment: The molding attachment with a mold.
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