Gingerbread Cam

a fun Christmas twist on climbing gear

Reno, NV, personal winter break project, 2 week project

Challenge

Create a completely working, edible climbing cam out of gingerbread. Because why not.

Skills

CAD
Baking
Laser cutting

What is a Climbing Cam?

Climbing cams are a form of protection used by rock climbers while climbing cracks. They are spring-loaded devices consisting of four lobes connected by an axle (or in this case, two axles). By pulling the trigger, the lobes rotate and retract, allowing the cam to be slotted into a crack in the rock. When releasing the trigger, the springs force the lobes open again, expanding the cam to fit the crack. The rope is clipped into the end of the stem, opposite the lobes, and if the climber falls the downward force on the stem is converted to outward force in the lobes onto the rock, creating friction and pressure that stops the cam from sliding out.

a climbing cam — see the four lobes on the top connected by two axles

by pulling the trigger, the lobes retract, making the cam smaller

Ideation

Over my three week winter break, I wanted to do something fun. I came up with many different ideas, from a 3D printed mini snowman mold to make a snowman army to a device that flakes your climbing rope into a nice pile and follows you around the crag. However, after many different silly ideas I came up with one that seemed reasonable in the time I had and the materials available: a gingerbread cam. I had previously made a working climbing cam out of cardboard and pencils, so how hard could a gingerbread cam be?

My first plan was to cut the gingerbread pieces before baking using a template based off of a real cam. The axles and stem would be replaced with candy canes, and the trigger wires with twizzlers.

My Father’s Day present: a cardboard cam!

Initial sketches of how to build it out of gingerbread

Prototyping Round 1

My first idea was to make wax paper templates of each piece of the cam, then cut out the gingerbread and bake them. I anticipated the gingerbread expanding while baking, so I made the holes and slots slightly larger than the actual measurements. However, after baking the gingerbread spread even more than expected. Attempting to fix the pieces after they were baked was extremely difficult as the cookies were rock hard and brittle, and I ended up breaking a couple pieces. However, with the pieces that survived I was able to make a first prototype to see if the general idea was right.

pre-baked gingerbread cookies: the dough was soft and easy to deform, making them hard to cut out

the general idea: a two axle system with a slot for the lobe to rotate

post-baking cookies: they were rock hard and brittle, so when I tried to make the holes larger the cookies cracked!

two lobes on either side, with stem connector pieces in the middle

Prototyping Round 2

After realizing that the gingerbread expands more than expected, I created a new set of templates with bigger holes. I also made the pieces larger to reduce the chance of the cookies breaking at their thin points. From these pieces, I was able to build a second prototype with two candy cane axles, two lobes, and a candy cane stem. I used homemade royal icing to glue the pieces together.

However, there were still some issues. One, I hadn’t yet figured out a candy that could be used as a spring mechanism. Two, without the spring mechanism, the heavy lobes wouldn’t stay engaged when held upright. And three, I had planned to tie the twizzler trigger wires to the end of the slots of the lobes, but they were too thick and got caught between the stem and end pieces. I needed a way to make more precise holes and cuts…

On the top are the new templates with bigger holes, and on the bottom, the original templates

Gingerbread cam version two compared to a real cam! I added junior mints to the end of the candy canes to prevent sliding

When held upright, the lobes fall down. Not quite what I wanted

Round 3: A New Approach

After playing with version 2, my dad and I discovered that the pull-apart twizzlers actually worked pretty well as a tension spring! If rotated, the candy had a tendency to straighten back out. With this in mind, we began designing the next version.

I was having a lot of issues with not being able to have precise cuts, since I couldn’t predict how much the gingerbread would spread. But at the same time, if I tried to cut the gingerbread after it was cooked, it would crack. After a spark of inspiration from my dad, I decided to try something new — laser cutting!

With my dad, we designed some CAD parts for the cam, basing it off of both my original templates and the Black Diamond Ultralight Cams.

lightweight lobe design with a hole at the tip to thread the licorice through

trigger with added holes to thread the licorice through

stem attachment piece with one slot for the stem and one hole in the middle for a single axle

end caps with square holes on either side of the axle to put slide twizzlers into

Instead of a double axle design, we decided to instead use a single axle. The square holes on either side of the axle were for twizzlers, which were generally square in shape. Because the twizzlers tended to straighten out, the idea was to have them fixed at the stem and endcaps, but twisting in the lobes when engaged. That way, the twist would pull the lobes back up.

We cut multiple copies of every piece to have back ups in case they broke, and with that began to experiment. We quickly realized that the pieces had softened during cutting, so we baked them again for two minutes and they hardened up again just fine. We also sanded the edges of the lobes to remove some of the burnt edges.

laser cutting the pieces - did not smell very good, but resulted in very clean cuts!

we made many parts in case some broke (which they did)

see the four pieces: lobe, stem attachment, trigger, and end cap

Assembly

After cutting and re-baking each part, it was time to put them together. The final gingerbread cam was made of four lobes, two end caps, a stem attachment piece, and a trigger along with a candy cane stem, candy cane axle, and twizzler “springs” and wires. I slid all pieces onto the axle and inserted the twizzler springs, and then used royal icing to glue the stem to the stem attachment and also to glue the twizzler wires together. After letting it dry overnight, the gingerbread cam was done!