Utah, 2011

A trip to Utah in 2011 laid the groundwork for what would eventually lead to this product development effort. I contracted out with Matt Graham - unknown at the time, but now a TV celebrity on several Discovery and National Geographic shows - to teach me how to live off the land for 3 weeks. Matt's hunting tool of choice is the atlatl, or primitive spear thrower.

The atlatl

Over the course of the trip I became more comfortable with this tool, eventually hunting my own trout with it. And what a lot of fun it was to do target practice with!

And the business was born!

Well, not so fast...but after staying in touch for 6 years and Matt's appearances on Discovery Channel and National Geographic shows, he asked me to develop a commercial product with him.

The originals

The product I set out to build would be carefully modelled off of Matt's favorite personal atlatl and dart set, but mass-produceable, compact, and customizable.

Load-displacement testing

To replicate the arm flex, I did what any good engineer would do - get some test data.

Arm FEA

Using FEA, I then adjusted the arm geometry in CAD to match the desired bending characteristics in an appropriate moldable material to match the wood's natural characteristics - in this case, a glass-filled nylon.

Conformable vs. customizable

The finger holes provided the best throwing accuracy, but were hand-cut for Matt's fingers. I determined that the best solution would need to be either conformable or customizable. I built some crude prototypes to evaluate concepts, including the one shown.

Sizes of the human hand

Thanks to the military, body measurements at various population percentiles had already been documented.

Modular testing system

Using FDM, I rapid prototyped a modular atlatl system that would allow me to evaluate and iterate on finger grip designs.

Winner = Customizable

A customizable finger grip with a few different-sized inserts would result in the best fit with minimal finger play and minimal added cost.

Final CAD

With those decisions in place, the CAD could be finalized. Lots of surfacing!

Prototypes

The first prototype was a very good geometric match - not bad for designing by caliper measurements (let's not get into my failed efforts at 3D scanning that took me all around New England...) Some prototypes were painted for marketing purposes.

Testing

Testing required some more FEA to determine an appropriate plastic rib thickness to run down the back of the arm to create the same stiffness as the wood. The SLS models were not nearly as stiff as the glass-filled nylon would be in the final product. The prototypes functioned nicely and the finger sizing inserts looked great and stayed in place very well yet were easy enough to remove and replace. With that, the atlatl was designed and conversations with potential manufacturers were underway.

The dart

Given that a 7-foot dart is both unwieldy and also expensive to ship, the chosen design was a 3-piece take-down dart with carbon fiber arrow shafts. Lots of sourcing and testing led to an appropriate shaft that could match the flexural spine stiffness at the desired length.

Connections

The threaded dart connections required o-rings to maintain connection and reduce relative motion between the components when loosened. After several geometry iterations an appropriate solution was created.

Fletching

Now, how to fletch a 9-inch feather? A visit to an arrow manufacturer in PA provided some guidance, but it would require a custom fletching jig.

Custom fletching jig

I designed a custom fletching jig that could utilize natural feathers that were long enough to properly stabilize the long darts.

Success

The fletching jig evenly mounted the feathers and would be acceptable for use at a manufacturing facility.

Prototype dart

The first dart prototype was completed and tested.

Dart iterations

More darts were fabricated at different lengths to subjectively evaluate performance.

Dart tips

While we were at it, we quoted some dart tips that Matt had fabricated primitively that worked well in the field.

Soft goods

The goal for the final product was an atlatl and two darts contained in a carrying tube. Having never explored soft goods before, another drive around New England got me connected and a prototype was created.

The full package

In the end, the final design was completed to my and Matt's satisfaction and a manufacturing pathway was in place. Unfortunately, though care was taken during business development and contract negotiations, Matt chose not to fulfill his contractual obligations and the product was not actualized. It was a sobering lesson in business but a positive experience on the whole.