Brownell's BRN-180 Build Part 12 and 13: Finishing the wood handguard cover
When I set out with this project, I had been doing woodworking in one form or the other for quite some time, but I had never done any inletting work before. And after working on this project, I have a much greater respect to amazing stock makers out there because inletting is HARD!
Having already milled out the M-Lock slots, and drilling the mounting screw holes, I was ready to start the process of removing the inner wood.
My plan was to use my floor standing drill press, cross vice and an endmill bit to carve out the first main inner section.
I then planned to plunge deeper to the bottom most depth, while keeping the bit in the center which would leave the material in the corners where the 45 degree cuts were.
I then planned to turn the bed of the drill press at a 45 and carve out the corners.
I spent time measuring everything, using both the actual BRN-180 upper receiver and the 3D printed template, to make lots of pencil markings on the wood.
I used a wide endmill bit and following the lines I drew, I cut out the inner section with the cross vice.
Next I had to carve the very lowest portion while avoiding the corners.
These straight cuts were relatively easy, but I took it really slow and cut down a little at a time, making multiple passes.
Next I turned my attention to the inner corners. What I learned is getting the table of the drill press positioned perfectly for this was very challenging.
Once I got the table at the right pitch and angle, I milled out the inner angles. After cutting the inner angles, I still had to make minor adjustments to the bed of the drill press until the angles where just right.
After test fitting the handguard cover I noticed it fit very well on the sides but the bottom three edges needed to be deeper for it to fit properly. I held up the 3D printed model and used it as a template and made additional markings where I needed to cut out more of the wood.
After cutting the inner area back a bit, it fit perfectly! The only part which was problematic was, when I cut in the M-Lock slot windows, I cut one of the six just ever so slightly too shallow.
The Dremel made quick work of the last remaining M-Lock slot window.
Just when I thought I was completely done with power tools, I noticed I had chamfered the top long edge of the 3D printed model, but I had failed to chamfer the actual piece.
I utilized my oscillating belt sander to carve down the top edge to a nice chamfer, and it turned out really well.
Now that I was finished with all the power tools, it was time for the most arduous task. . . . hand sanding. I utilized a few blocks of walnut I had as sanding blocks and sanded the whole piece down with 220 grit sand paper.
I noticed the insides of the M-Lock windows looked rough and decided the Dremel would be the easiest way to smooth them out. I was really worried the Dremel would remove too much material so I selected a Dremel bit which had a soft, almost rubbery feel to it and it did the trick; it smoothed out the windows without digging in and making any wavy marks. I finished them off with some additional hand sanding with 220 grit sand paper.
Once I had thoroughly sanded the entire thing with 220 grit sandpaper, I moved on to 320 grit sandpaper and went over the entire thing again until it was perfectly smooth. This required a lot of sanding. But the end result was fantastic, the part was perfectly smooth and I could see no real visible flaws.
The part was finally ready to receive its treatment; the awesome Brownell's Boiled Linseed Oil. I started by applying a nice thin coat of the oil with my warm bare hands and massaged it into the wood.
I then utilized 400 grit sandpaper and the oil and sanded the oil into the grain of the wood. I made sure to follow the grain when sanding the oil into the walnut.
The final product turned out WAY better than I ever anticipated. The picture above was taken after just one coat of the boiled linseed oil. I ended up applying 8 to 10 coats the boiled linseed oil over the coarse of several weeks until it developed a beautiful depth and sheen. Because I cut the handguard cover out of the same blank of walnut as the grip, they match super well and the overall look is so rad! I have already started the process of the next step to this build, so make sure to stay tuned!
If you want to watch the video of this portion of the build you can find it at the following link;
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