Re: home made injection mold

Hi to all you do-it-yourselfer tool makers.

I share similar sentiments with those of you that take such challenges in
making your own equipment.

I built my injectionn modling machine using the same Gingery book as as
guide, after many attempts to do it on my own with little success. I also
started, I suppose with the ovious, a modified heavy duty heat gun in attempt
to build a small machine, but realized that the heating element in such was
not strong enough to melt plastic and I needed bettter info to build
something that will work.

I came accross the Gingery publications in search of information on how to
make useful machines for the home shop. I strongly reccommend these to anyone
with the desire to make your own machines. But you do need a well equipped
shop or know someone that can manufacture some components for the machine in
focus.

In my case, since I had various sizes of aluminum square tubing, I built my
machine from such. I tried making the injector from a chunk of solid aluminum
as well but that did not work well, so I went to a nearby mold making company
and after mentionening to the owner what I was attempting to do and showing
him the aluminum injector block, he gave me some scrap cold rolled steel
chunks much to my surprise of the right dimensions so all I had to do is
drill the injector pin through hole and drill and tap for mounting holes.

I used a 400W cilindrical heating element, surplus thermostat and an oven
thermometer similar to the ones indicated in the Gingery "How to" book.

The machine turned out very simple to use and I was able to make some
aluminum molds by hand (no CNC at that time). Using trial and error to get
the right temperature dialed in and the right amount of pressure to get some
neat molded parts. I did find that if you spray the cavities of the mold
with Furniture Soap a water soluble furniture cleaning soapy spray sold at
supermarquets, the parts come out very easyly from the old. They also have a
better finish, even better if the mold cavities are polished.

Because my needs are constantly changing, after shoping around and searching
the internet, I went on to purchase a custom made injection molding machine
at a fraction of what it would cost for similar equipment. This unit is
extremly sturdy, all steel construction, fits on top of a bench and takes up
2 Sq. Ft. ,has a large air cylinder and a pneumatic switch to raise and lower
the injector into the heating cylinder, the whole thing comes down on the
mold mating the nozzle with the inlet on the mold. This system is spring
loaded so that the injector mates with the part with enough pressure to
provide a good seal without damaging the mold.

Plastic pellets are fed through a 2 inch dia, cup that is concentric with the
heating element cylinder intake. The unit has an industrial type thermo
control. you simply dial the temp and a red light comes on, temp rqanges from
0 to 1000 C.

The Base is steel and has a lever for clamping the mold between steel plates
these are pre-drilled and some of the wholes are tapped , I am assuming they
are for supporting the mold halves and provide some type of semi-automatic
operation.

I have yet to figure these out so I can effectively modifiy it for automatic
clampling of mold and part ejection. The unit operates on an air compressor
of 90PSI.

All I need is a plastic pellets source, anyone know of a source?

Mario.

BTW , does anyone know of a list that is just for Home Shop Equipment
Do-It-Yourselfers, experimenters?