Brownells BRN-180 build part 9: Wood handguard cover

 

The progress on my Brownells BRN-180 build is steadily moving forward.  And having a myriad of tools, especially my drill press, cross vice, oscillating sander, table saw and 3d printer have all proven invaluable.

The goal for this portion of the project was to cut in the six mlock slot windows which I have on the 3d printed prototype.

I was continuing to carve on the blank which I have featured on my last several posts.  The walnut has proven to be a very good choice as it is shaping very nicely. 

After thinking about the best way to mark where the slots needed to be cut on the walnut, I settled on using the 3d printed prototype as a template.  I realized pretty quickly the one side of the prototype would prevent me from marking the opposite side.

I thought I could potentially save time by taking a hack saw to the 3d printed prototype and cut off the part I needed and it resulted in broken part. 

After breaking my prototype, I went back into CAD (Fusion 360) and digitally cut off the parts I wanted and printed them on my 3d Printer (Prusa i3 Mk3s+). After the first printed iteration, I realized I would get  more accurate scribe lines if I printed the the template thinner.

The new thinner templates were perfect.

The thinner overall profile of the templates, made tracing the slots much easier and I was able to achieved very clean markings.

Next I selected an end mill bit which had the same diameter as the inner radius of the BRN-180 M-lock slots.

I decided I should perform some tests on one of my scrap walnut pieces and once I had plunged the first hole and started to drag the bit with the cross vice, I noticed it was pulling a bit cockeyed. I realized I needed to plunge much shallower and make multiple passes in order to keep the bit from pulling.  

I tested my theory and making a shallower pass allowed it to pull straight.  I also choked up on the end mill bit to prevent any flex in the bit.

Because of the shape of the blank, I used a block of wood (actually my V1 grip) so I could clamp the blank in place with out hitting where the hand stop protruded.

I was then able to start carving shallow passes with the cross vice until it was deep enough.

This method took a long time but it was worth the effort, as it turned out nearly perfectly.  I think it might have been better or at least quicker to write down the cross vice measurements instead of relying on my eyes the whole time but it ended up working out.  When I lined up the 3d printed template it lined up perfectly and I think it will look great on the BRN-180 upper. Next step will be drilling out the Mlock screw holes, so stay tuned. 

If you want to watch the video of this portion of the build you can find it at the following link;

YouTube/Faithkillsfear

You can find the BRN-180 lower receiver at the link to Brownells below; Brownells/BRN-180 You can find the upper receiver at the link to Brownells below; Brownells/BRN-180 You can find me at instagram at the link below; https://www.instagram.com/faithkillsfear/ You can find me on Facebook at the link below; https://www.facebook.com/Faithkillsfear/ If you have need of a quality Kydex holster you can find one at the link below and “Faithkillsfear10” will save you 10%; https://legacyfirearmsco.com