Brownells BRN-180: Part 15 - Finishing the Cheek riser

 

When I embarked on this Brownells BRN-180 retro build, I knew adding a wood cheek riser was in the plans. And in one of my previous posts, I outlined my process of designing and 3d printing a physical prototype of the proposed cheek riser. What I didn’t anticipate was being able to cut it out, drill it, and shape it all in one day. It either went smoother than I anticipated, or I have improved throughout this project; It is most likely a combination of the two. 

I started by measuring the 3d printed prototype, and again checking and measuring the dimensions of the receiver extension (measure twice, cut once). 

Using the measurements I just took, I utilized the micrometer to draw exact measurement lines on the walnut blank I was going to use for the cheek riser. 

My plan was to cut the walnut blank in half and use both sides to create two identical parts. My thought process was to make two blanks and get them all the way to the point where I would start shaping them, so if I screwed up while shaping them, it would be easy for me to try again.

I started my work on the table saw, and used my micrometer again to get the perfect width. I then ripped it down the center to the perfect final width. 

I then measured again for my final desire height utilizing the micrometer. 

I cut that width twice, and after trimming them to length, I had to completely identical blanks. 

After taking many measurements and finding the center of each blank I used an end mill bit of the same Diameter as the head of hardware I would eventually use to mount the cheek riser to the top of the receiver extension, to drill some wider holes, so the hardware would be countersunk. I utilized my floor standing drill press and cross vice to get everything lined up perfectly and plunged the holes. I was able to set my depth stop so each hole was equally plunged. 

I then swapped out the end mill bit for a regular drill bit and once I had it perfectly centered, I drilled it all the way through each blank. 

I was left with two identical blanks which were both ready to be shaped. Well I guess one was ready to be shaped and the other one was ready in case I screwed up the first. 

I turned once again to my 3D printed template and used it as a guide to shape my final product. 

I used my oscillating belt sander and rolled the piece by hand to achieve the top rounded radius. 

To shape the angles at the front and back of the part, I held up the 3D printed template to the correct angle and mirrored the angle to sand the front and back. 

I essentially eyeballed the angle and continue to compare it to the 3D printed model until it matched fairly perfectly. 

While I was planning how to shape the inner radius, I encountered a problem which required a custom solution. I decided to use the drum attachment for my oscillating sander, but the nut which secured the drum was wider than the 1/2” drum. This became problematic because the cheek riser was longer than the shaft of the drum. 

My solution was to take the plastic nut over to my Ben h grinder and grind the heck out of it until it was the same circumference as the metal washer. While it wasn’t the prettiest of repairs, it fixed the problem. 

I used the 1/2” drum and was able to sand the inner radius by periodically flipping the part to evenly sand the entire underside. 

Sanding the underside was the last time I used power tools. At this juncture the piece was looking very good and was virtually identical to the 3D printed model. 

The last major step before starting the finish work was to hand sand everything. I started with a 320 grit and then moved to a 400 grit. Some areas (like the front and back angled areas) had sand lines from the belt sander which required more attention/sanding. 

The final look and fitment was fantastic. 

I utilized the same finish method for the cheek riser as I had done with the other parts; hand finishing the walnut with the awesome Brownells Boiled Linseed Oil. 

After applying some of the oil with my bare hands, I essentially wet sanded the wood with first 400 grit and eventually 1000 grit sandpaper. 

After more than a month of adding very fine layers of the boiled linseed oil, and polishing with the fine sandpaper, it developed a beautiful depth and sheen which speak for themselves. 

I am so stoked with how this turned out and I can’t wait to complete this build!