Custom Hamburger Mold

Where is it written that hamburgers must be round?

I had learned how to use the Vacuum Former at TechShop San Jose, and needed a project to make sure I remembered how to use it.  Also, I wanted to test the theory that a hole in the center of a burger will help it cook more quickly and/or evenly.

Herewith, the delicious results of my experiment.

To make the positive for my mold, I used the ShopBot at Techshop.  I still had a "gear" file from class, and made several 4" gears, some with holes in the center, others solid.  I had guessed that a 4" gear would yield a four ounce burger, i.e. a quarter pound, and they came out pretty close. 

I placed the positives in the vacuum former, secured the PET-G food-safe plastic, heated it and vacu-formed the molds.  The hardest part was extracting the gears from the plastic, as the sides were perfectly vertical. Normally one adds a bit of a "draft angle" to the positives, so that they are larger at the base than at the top to ease extraction.  Since I was not in a hurry, nor was I doing a production run of the molds I just dealt with the annoyance.

After a few minutes of flexing and pushing, I had molds for my gear-shaped burgers.

Back home, I mixed up a batch of burger meat.  I used 15% fat hamburger, and added some salt, pepper, garlic seasoning and some italian bread crumbs to add a little structure to the mix.

First, I sprayed a little non-stick spray into the mold. Next, I smushed the meat into the mold, flipped it over and flexed it until the burger popped out. 

I made a couple each of the hole and non-hole burgers.

Off to the barbecue. 

I grilled a couple and flipped them at the same time.  Once done, I cut them open to check done-ness.  The ones with a hole in the center were more done, but there was not as much difference as I had expected.  Both styles were delicious.

One surprise was that the patty with a hole in it was more recognizable as a gear after cooking. 

Bon Appetit!