Will I be able to take this cheap pneumatic press and turn it into a fancy injection
molding machine? Can I build a CNC and learn enough about die making to make
something for Christmas? What am i doing? Have you ever watched a video and you think
"Oh my gosh, this is going to eat the next few months of my life"? That happened to me. I
was watching a video by Buster Beagle 3D where he was making an injection molding die using one
of those tiny 3018 CNCs. Now, I'd always dismiss those things as kind of toys, but here he was
getting real work out of them so I thought I gotta check this out. Little did i know this
was gonna be the start of a whirlwind romance. I got rid of the original motor and
put in this 500 watt brushless one and I put fatter 12 millimeter rods on the
x-axis. I redesigned the x and y carriages. Then I designed a laser cut enclosure
to cut down on the noise and mess of running a CNC right in your shop. I really
like the way it turned out. Pretty soon I was making things and having a lot of fun, but I
still hadn't made any injection molding dies. Was the machine going to be up for it? AH! We lost power. Like, I'm only 10 minutes
from the end of this thing and we lost power. Well after one more try where our power
stayed on I managed to make what seemed like a functional injection molding die. Like it
looked pretty good. I couldn't wait to try it out, but I was now in the weird situation of having
made a die, but not having an injection molder. So, I decided to build one of the Buster
Beagle injection molding machines, and the thing was great. It's like lightweight,
cheap, easy to build. It checked all the boxes, well there was one important box that remained
unchecked but I'll get to that in a second, but why injection molding? Well I hadn't
really needed a whole lot of parts before. Injection molding is great if you need a lot of
parts, but if you only need one or two parts 3D printing is probably better because you
can just print out one part and off you go. It's like a lot simpler than having to make
a die and have a machine blah blah. When I was working on the computer control loom though I
had to make hundreds of parts for that thing. When i redesigned the way the hooks were I
literally had to print 120 more of these little hooks and it would have been great if I'd had an
injection molding machine because I could have remade them in an afternoon as opposed
to spending a week printing parts. Which brings us back to that missing check box
on the hand injection molding machine, consistency. When I make 120 parts for something
like the loom I need them to all be identical. When I started using the manual injection molder
I quickly learned that there's a lot of technique involved. You have a lot of different variables:
how long the plastic has been in the chamber, how warm the mold is, how fast you pull the lever
down, how long you hold, how much pressure you use can make slight changes in your injection and
a lot of failures and wasted plastic. Frankly. I realized that with that machine if I
really needed to make 120 hooks it was gonna really hurt my arm and I was gonna take a
long time. Now there are fancy semi-automated injection molders that are pneumatic
and I was drooling over those on eBay, but boy even a used one is like thousands and
thousands. Like seven thousand dollars or more and I was like "That is never happening" but
as I was poking around I also noticed that there were these pneumatic punch presses,
and to me they look kind of similar. Like this pneumatic punch press has a big pressure
cylinder, and really it was all it needed was a heating chamber, and a thermostat, and it would
practically be an injection molding machine. So I looked at the punch presses, and I looked at
the injection molding machines and I was like could I add that? It seemed like it was
worth a shot. I tried. I tried to get my friends to talk me out of doing it but they
were unsuccessful so I went for it and I ordered one off eBay. Little
did i know what I was in for! Well the thing was a mess. As the seller said we
were "all victims of rude transport". I was kind of amazed that it arrived in a cardboard
box. I was assuming something weighing 90 kilograms should come in
a crate of some sort, but I tested the cylinder out and it was
free moving. So, I decided to press on! I also needed to machine a
part out of half inch stainless and so i ran some tests on my CNC
and surprisingly was able to do it, but to machine a big chunk of stainless and my
itty-bitty CNC was going to take ... for ... ever. So, I decided to just lay it out by hand
and make this part the old-fashioned way. Welcome to Pneumatics Tower. My
mission is to pull up these tie rods so the new spacer rods can be
installed below the cylinder. whew hmm hmm..... I'm Okay so so so Now one of the few accurate things
you have to do in this whole deal is I have to mount the heating chamber
centered below the pneumatic cylinder, and in order to arrange that you can't just center
it on that rough casting in the top of that thing because that's not accurate you have to center it
relative to the mounting holes for the cylinder. Now that's a little bit tricky. You can't just
draw an x across from the mounting holes because that's floating out in the air over that hole.
So, how the heck am I going to position this thing? Well luckily thanks to the magic of 3d
printing it's pretty easy to print a little jig. do so So the plan for the press is to raise the main air
cylinder up by adding these four spacer rods. Then I can use a stock Buster Beagle v2 heating chamber
and the custom collar I made can be used to mount it under the press. Plastic beads can be loaded
into the top of the chamber where they melt. When the cylinder fires it pushes the plastic out the
small hole at the bottom of the chamber with a great deal of pressure. The heated pressurized
plastic squirts into the die and then cools. I thought the heating chamber could just float on these springs but in the worst case
scenario all the force of the press would be crushing them in a dangerous
way. So, I had to make a couple more parts The chamber can still move but
these standoffs take up the load and prevent the springs from ever being fully
compressed. So, Let's wire up the heating bands, put on the thermostat housing, and
wire up the temperature sensor. do do so Well here goes nothing. Wait did you see that? That could have been a lot worse. I guess
this looks like a job for The Shortenator. Well here goes. Remember at times like this
it's important to use your safety glasses. Oh no! The heating chamber didn't descend. At
least you could tell the shot size is fairly large. Uh, I guess I'm gonna have to clean this
up. Let's see if we got anything in the mold. Well not a complete fill. All I had to do
was unscrew those mounting bolts a little bit so that the mounting springs weren't as
pre-tensioned and then everything worked fine. I made a few other little
improvements, and here it is in action. Well the injection molder was
a success, and thanks to adding both some adjustable exhaust baffles and the
built-in electronic controller it now has uh control over: Injection pressure,
injection speed, uh hold time, release speed. So it's really a very repeatable process and I
and I had a lot of successes in a row I think making a lot of successful injections is pretty
easy and I don't have to act like a gorilla and end up with a sore arm. If I'm going to make
a couple hundred parts I timed myself and at maximum speed making those logos I could
do about an injection every 30 seconds, but I have to admit that's removing the plastic
while it's still pretty hot and I was starting to burn my fingers so i bet maybe 40 seconds or
wearing gloves might be a more practical limit, but it really did a great job. You might be
wondering what happened to the Christmas Project. "I thought you were going to do a Christmas
Project?" Well, I got the injection molder working on December 18th so there were still a few
days left. I thought maybe I could still do this. Ten years ago I designed these Moomin cutters they
were laser cut from acrylic, and although they came out pretty nice they were pretty fragile.
An injection molded cutter would be much tougher and easier to clean. I could do the top of
the plunger and the detail stamp as one die, and the outer cutter as another die, but with only
a few days left before Christmas I needed a design NOW. Thankfully, back then I designed this Little
My cutter but I'd run out of time and hadn't given anyway as gifts. 10 year old design to the
rescue! When I tried to machine the first of the two dies for the Christmas Project I ran into
a whole series of failures or I guess learning experiences. So, although I was learning a lot,
I wasn't making any progress on the Christmas Project and time was running out, and this was
supposed to be the simpler of the two dies! i did eventually get a decent version of the
first die made, but then I ran out of time. Well, so ultimately the Christmas Project was a little
bit of a bust. I ran out of time which was not surprising I knew that a mold of that complexity
was going to be pretty difficult. I will say that I'm super happy with the results of the press.
I think the only real downside now is that it was a little bit more complicated to build than
I'd hoped. Now, I'd kind of been hoping oh you could just have these four rods and this collar
and everything else is just off the shelf and you drill and tap a few holes, but when I did the CAD
model of the press I didn't measure it super well, and it turns out the collar doesn't quite
fit under the casting as is and I ended up having to machine a little pocket out
of the bottom and that's kind of a bummer because not everybody can do that. So, that's
like one thing that isn't very kit friendly, but hopefully you guys can build one. I really
recommend it. It works great. I really think if you're going to make a lot of parts this is
the way to go! So, I'll put all the details up including: injection pressure, maximum shot size,
all that stuff. It's all down in the doobly-doo and I'll also do a cost breakdown, including all
costs including taxes and shipping and blah blah. I'm happy to share all the designs. I'll
put up the design files, the 3d prints, everything so that if you build one let me know
because I really think this is a great way to go!
