Lock Pins
This week for Capstone adventures, I set out to cast my aluminum lock pins. I have done enough aluminum casting in my day to be comfortable doing this, but this particular technique was a first for me, and as you will see it went awry.
I started out by mixing some plaster up with sand and water. When the mix has the consistency of a Wendy’s vanilla frosty (not required to be vanilla but the mix uncannily resembles a frosty, despite the fact that I am using McDonald’s cups) the mix is ready to set. It sets quite fast so it is important to get a move on. Vamonos!
These pipes are approx. 1 inch in diameter and coated in canola oil to allow them to be removed once the mould (or mold?) has partially set. Now its time to get the forge cooking.
This is my forge (alternately smelter) setup. I am very proud of it. It uses a galvanized steel can as a container, and industrial grade insulation I picked up from a job as the lining. This stuff can take a lot of heat (around 4000 F) without degrading. Inside is a graphite crucible to contain my metals. I have melted metals as high as copper (1984 F) in the past.
These are some aluminum donuts (ingots) I made prior to this. They were melted down from aluminum cans. Once the moulds were partially set, I removed the tubes from them, leaving a negative void to fill. I placed them in my sand bucket to protect my environment while pouring. It was also really snowy out which was a convenience for my high temperature project.
One more note on my forge. It utilizes a custom propane jet that I manufactured in the ITLL. A small brass tube has a tiny hole (1/64 inch) that pushes high pressure propane down this cast iron tube. It draws fresh air after it, creating a perfect flammable mix of gasses.
Pour Time
So long story short, dry your molds. I remember specifically thinking, should I dry these out? And I thought naw, plaster absorbs and chemically removes the water. Not true. I ruined my pour.
Time to rinse and repeat. I still had daylight.
This time we were thinking a little more. I first baked them (pottery style) for some minutes in hopes that the moisture would be drawn out. The crackage is an effect of that, which bothered me at first but I was optimistic that it would turn out.
The second pour still had a little moisture but for the most part it was settled.
The length ended up a little shorter than I was hoping, but these will be usable for sure.
A little bit of honing later and they looked pretty good. I removed the large chunks from the shorter piece and started sanding away.
I still need to work on them a bit more, but I am happy with how they are turning out.
I used the angle grinder to chop them the same length and create a better flat side. I then did some more polishing and am satisfied with the final look of them.
I needed to enlarge the holes they go through on the door, but after that, eureka. They fit beautifully in the door.
Metal Cutting
I managed to leverage some contacts from my construction to obtain some sheet metal at immensely discounted prices. I then used a university connection, fellow ATLAS Capstone student Destin Woods to plasma cut my metal. He brought me to the theater shop where he works, and I helped him cut my metal.
The process went along a simple order of steps. Measure, secure, and cut. We used proper helmets and safety gear, making the job easy.
And finally I have all of my materials. This next progress week should be full of heavy advancements in my project.
Time Management
Goals for week 8
Cast aluminum lock cylinders: 6 hours
Get metal cut: 4 hours
misc. 2 hours
Actual Time Use
Casting Aluminum: 7 hours
Touch-up aluminum: 2 hours
Cutting metal: 3 hours
misc: 2 hours
Reflection
It took much more time to cast than I anticipated. Maybe it was a little cocky to expect to get a perfect cast on the first try, but wow did that not work. I didn’t get burnt and it was kinda fun to watch despite the danger. Everything turned out ok in the end so I will call that success.
ATLS Capstone 