Machining a Billet Baseball Cap Out of a 56 Pounds of Aluminum


Hi! Jason with Tormach. Do you like my
hat? I had the opportunity to make
this from a 56 pound billet. I was super excited to do this project. I
really enjoyed making parts like this. They present some really great challenges
and they’re just fun to make. Holding an organic shape
like this can be rather complicated the head has a 0.004 wall thickness. So you
really want to support the entire surface for stability while you’re
cutting it. This is why we chose to use super glue for the workholding. I only
needed to make two parts so building a vacuum fixture and other complicated
workholding methods was really just outside of the scope for this project. So
we use the superglue, in conjunction with painters tape to see if it would work
for a large organic shape. I’ve used super glue on parts like this in the
past with really good success, But removing the part from the fixture
and cleaning everything up can be a little more difficult without using
painters tape with it. So it really was a good opportunity for us to test the
superglue with the painters tape. To just test everything all out and learn
something new in the process, So for the fixture, we ran a small little test bar
to see how this process would work using a curved shape, before we actually cut
the part. So it’s good practice just to prove out a theory before you you know
try it out on a very large expensive part. We did a separate video on this and
the results of it looked really promising. So we’re pretty comfortable
moving forward with this strategy for use with the hat itself. The fixture was
cut 0.002 undersized to allow space for the glue and the tape. An important
aspect when you’re plunge roughing is how are you going to manage the tool
engagement. We use the one-inch shear hog and with a 5 inch Arbor on this for
all the roughing strategies. This tool can’t handle a full diameter plunge. SprutCAM gives us the ability to create the tool path that only cuts going in the
uphill direction or on a flat surface, and it just does this automatically.
So we’re able to create a couple of roughing passes, starting from different
directions, and kind of approached the part from a couple different angles, and we
were able to successfully, and very quickly rough out this part using that
plunge roughing strategy. For finishing we use a nine millimeter diameter button
cutter. And this uses five millimeter inserts, and it’s great for parts like this. It
gives you a better surface finish than you can achieve with a ball end mill,
since you’re not cutting on the centerline of the tool. But it still has
a nice large radius for that five millimeter insert to be able to effectively finish
the part. So let’s jump to the hat itself we cut the inside as OP 1 and we did this
on a 770M. This was really a quite simple operation. Take everything out on
the inside and make it look amazing with a finish pass. Sounds simple right? The
main consideration for this OP was to roll the outside edge. The radius of the
hat here, as you can see, this is something that I wouldn’t be able to
machine from the second op because it’s an undercut. So I wanted to be able to
roll this edge so that I have a nice smooth radius and deburr, and everything,
right off of the machine. So to accomplish this, when we created the
model, I had the whole block and everything modeled into it, so I…the
block was actually sitting a little bit more than the radius of my tool below
the edge of the hat. So this allowed me to very quickly and efficiently program
op1 without having to come in and try to control my tool paths on a curve shape. It
just made the management and tool pathing and everything very simple. For the
second operation, this is where everything got to be a little more fun. This is where
the nerves come in it’s like the first side went pretty well, everything went
well, tool paths ran great, second op? Now it’s kind of like this crazy idea
actually has to all come together. The good news was, the part in the fixture
fit together beautifully. We set the hat on there. Everything just fit nice, and
located great. We measured up the stacked heights and everything was within a
couple of thousandth of what we expected to see. So everything…we’re very happy
with the results of that. The not so fun part was getting it ready to put on the
fixture. Taping this thing up was a very slow process. The fixture wasn’t too bad
to do since I wasn’t really concerned about scratching the part. I was able
just to lay tape over the entire fixture and then I’d come back with a razor
blade and just trim off the overlap. And that went pretty quick, but obviously
that wouldn’t work for the hat itself, since scratching the inside wasn’t an
option. So I ended up cutting a little strips of tape and fitting them in there,
and it just ended up being a very tedious process. It ended up working out
pretty well in the end, but definitely a time-consuming part of the process. For
us the thought process on this part for both operations were, use a single tool
and don’t worry about it moving, or breaking anything.
I’m only had a couple parts to make so cycle time wasn’t really a consideration.
The only way I really thought about it was is this gonna be finished when I get
back to the shop in the morning, my only consideration with cycle times.
So for the roughing strategies and stuff we used a two flute, Mini-shear, 3/4 inch
diameter, on the long Arbor.We did some real light depths of cut, and we just
roughed this whole thing out with a single tool light depths of cut, just to get it..
get the material off of it, and just to not worry about any process reliability. For
finishing we use the same nine millimeter button cutter that we use on
OP one. And when we started cutting, and finishing on the second operation, that’s
where we started and learning those important lessons. So we’re about a third
of the way through the first..the first hat we had to make, on the finishing pass
and we started to get some chatter in the cut. We tried adjusting speeds and
feeds and everything. We were able to get it better but it was still visible on
the surface finish to the part. So we let it finish up just to get it done. We’re
looking at, and I was debating whether or not I wanted to recut this. With the wall
thickness already being forty thousands thick, I just I had some real
reservations it seemed like kind of risky to try to re-cut this part
again. So we went ahead and removed it from the fixture. This came off a lot
easier than I expected. It’s a big area lots of superglue in there. I kind of
thought it’d come off rather difficult. But this came off pretty easy, which was
a nice benefit, it slid right off. Everything came off without damaging the
part, but this is also where I learned that painters tape wicks up moisture.
I had a small datum hole in the top of the fixture, and it was full of coolant.
So the adhesive on the tape failed and the only thing actually holding the hat
to the fixture anymore was the brim itself. So in hindsight I was quite happy
that it looked as good as it did. That it didn’t come off the fixture or lift it
up and actually like destroy the part on us. But it’s definitely a nice learning
moment. Everything in ended up looking really nice on the first hat. We have a
mold maker on staff..on our technical team, and she felt right at home grabbing
that hat polishing that thing to a near mirror finish, and it ended up looking
really beautiful when it was done. So for the second hat, we knew we definitely
had to make some adjustments, but what options do we really have? The inside of
the hat was already machined. The fixture is already done. I don’t have any more
material to remake the fixture..you know, so we were kind of married, and stuck with
the process that we were using. So sticking with the whole KISS principle
for engineering, it was the simple answer was to just seal the bottom edge of the
hat. I used some putty to seal up the base. The putty was only a few dollars,
and the machine just cut right through all the excess that was sticking out
from the side of the hat, and everything. It ended up working really well. So we
pulled off the second hat off the fixture. The tape was completely dry. It
came off quite a bit harder but still using the heat gun we were able to just
heat the whole hat to about 90 to 100 degrees and I’m just very gently pry it
off with a little piece of wood. And everything came off really nice. As you
can see, the surface finish on the second hat looks really good.
We’re really happy with how this whole project turned out. Again, just a great
experience, and a great opportunity for us to be able to make something fun, and
to share it with a co-worker. So I hope you enjoyed this project as much as we
did and I hope you learned something along the way. Thanks for watching. you

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