Making An Injection Mold For Yourself

Injection molding is the obvious onward step from 3D printing when the making of a few plastic parts becomes their series manufacture. The problem with injection molding is though, that making a mold can be prohibitively expensive. Has the advent of affordable CNC machining changed that? [Teaching Tech] takes a look, and machines a mold for part of a bicycle bracket.

With a diversion into home-made silicone seals for the injection molding machine, he proceeds to machine the mold itself from a block of aluminium. It’s a basic introduction to mold construction for those of us who’ve never ventured in this direction before, and it provides some interesting lessons. As we’d expect he does a rough machining pass before returning with a ball-end tool to smooth off those curves, but there’s a lesson in measuring rather than believing the paperwork. The tool he used was a bit smaller then the spec, so his path left some rough edges that had to be returned to. Otherwise the use of a removable pair of bolts to form holes in the finished part is we guess obvious after watching the video, but it’s something we learned as injection molding newbies.

This video follows on from a previous one we also covered, in which we’re introduced to the machine itself.