Prone Grip Experiments

The prone grip on our rifle is different than most other biathlon rifles.  A typical stock will have a handstop that slides along a rail.  Our stock uses this rail principle, but because of it’s minimalist design, the handstop also needs to include a shelf for your hand.   To allow for a large area of adjustment, this shelf needs to be cantilevered.  We had to figure out how to keep the grip strong and stable despite a large free-hanging section.

The first step was to create a wooden model of the grip.  This took two iterations and countless hours of sanding.  From there, we made a silicone mold to reproduce this wooden grip.

To accommodate this cantilevered design, we conducted some experiments.  We were pretty sure we wanted to make these grips from a polyurethane foam, but we weren’t confident that would be enough.  So we poured one with just the foam, one with fiberglass reinforcement, and one with carbon fiber reinforcement.

Here is the mold with a carbon fiber weave.

                     

After the parts cured, we did some unscientific flex testing.  In this application, the foam part benefited the most from the carbon fiber reinforcement.

With that testing complete, we made a small batch of carbon fiber reinforced polyurethane foam grips for use on our preproduction models.  After a quick prime and sand, and a textured coating, they’re ready for use.

                  

Milling Bedding Blocks

How do you make something on a milling machine?  If the operation is pretty simple, manual machining is often the easiest.  If, however, the job is complicated or has crazy curves – using CNC is the way to go.

Get ready for some engineering acronyms.  CNC stands for Computer Numeric Control, and means instead of a person standing next to the machine spinning hand wheels, a computer tells the milling machine what to do.  This is great for some complex parts, but it also complicates the process.

First, a 3D model of the end product has to be made in a modeling software.  This is called CAD: Computer Aided Design.  The CAD drawing is then used to generate CAM: Computer Aided Manufacturing.  Here, Ethan is adjusting tool paths to get ready to send over to our milling machine.

After he’s happy with how the program looks, we move over to the computer connected to the milling machine.

This computer uses something called G-code to tell the milling machine where to go and how fast.

Once the part is securely in the vice, cutting tool set, and program loaded up on the computer, all you have to do is hit ‘GO’.

But it’s never actually as easy as that.  Murphy’s Law is always applicable, and we have the scratched up collets and broken end mills to prove it.

After a quick tool change, and redoing all the CAM for the bigger size end mill, we were back in business.

Once the system is working well, it’s a tried and true way to produce- and then reproduce -great products.   These are all well on their way to becoming the bedding blocks/chassis for Anschutz rifles to work in our stock system.  After a quick run through our laser cutter, they’ll be marked and ready for assembly.