Tuesday, February 9, 2016

Marking out and drilling Z-brackets - 4 hours

I dove into laying out the center lines on the z-brackets and quickly figured out that if I set the offset 1/16" from the center line, it placed the shoulder of the nutplate into the radius of the corner between the flange and web of the bracket. After taking measurements and drawing it up on AutoCAD. I decided to reduce the offset to 1/32". We are not taking about big distances here, but with these pieces I feel much more comfortable. Seems that this 1/32" distance vs 1/16" is similar to those observed by Mike Bullock in his blog...he too found that the larger offset distance places the nutplate quite close to the web.
This is how things line up with the 1/32" offset from centerline. (Blue is the AN3 bolt. Magenta is the nutplate). 

So...Here is the revised isometric view showing the corrected 1/32" dimension.

Once I had my dimensions all worked out, I marked all the z-brackets out. Then, very carefully i used a center punch and marked the first hole location.


Once all the brackets where marked I set up the drill press and a drill jig, and drilled the first holes with a #50 bit. Then I opened them up to #40. After that...#12.


I bolted the brackets to the spar using AN3-4A bolts, washers and nuts. I snugged them up and then squared each one up to the spar. Using a thin sharpie I marked the edge on the spar as a reference.



All done. Ready to match drill more holes.