<October 26, 2005>
Drilled Tie-Down Brackets
I have to take my wife to the airport at o-dawn-thirty tomorrow morning so it was a short night in the shop, but I am happy with what I was able to accomplish. I focused on the tie-down brackets (7-731) and spacers (W-726) tonight, and took lots of pictures. You can thank me later. =8^)
I started by drilling the 1" lightening holes in the W-726 spacers. I put this off last night as I needed one more low-profile c-clamp (foreground) so that I could hold the spacer and still have room for the spinning circle cutter. I found my circle cutter was having problems if I tried to go straight through the spacer, so after I was halfway through, I flipped it over, reclamped using the center hole as I guide and finished it off from the other side... problem solved.
Here are the spacers. What a mess on the drill-press to clean up! Before moving on to drilling the bolt holes in these, I hit the surface of the spacers with the deburring wheel to remove any sharp edges from the drilling that might nick the spar.
I then marked the guide holes on the W-731 tie-down bracket (or whatever it is called) and drilled them to a #12. Just one hole per bracket for now, the other seven are match-drilled with the spar and spacers.
Next it was time to align everything and match-drill. I started by positioning the spacers according to the plans.
The instructions then say to clamp the W-731 Tie-Down bracket to to the spacers/spar, but before I did that I put a layer of masking tape over the spacers to hold them in position as I aligned and clamped the bracket... pretty smart huh?
Then I placed the bracket in place and inserted an AN3 bolt into the drilled hole, then using my roofers square, I aligned the braket perpendicular to the spar. Wow, I am getting even smarter as the night goes on!
I then carefully clamped the bracket/spacer/spar assembly together in preparation for drilling. This picture was taken after I had clamped then flipped the spar over.
I then drilled the four spar/spacer/bracket holes in the center. After each hole I inserted a 3/16" cleco to hold it all together and alinged. After drilling the four interior holes (the ones with the clecos), I moved onto the three remaining outer holes, one of which can be seen being drilled here.
Here is what the first one looked like when I flipped it over. All the holes look good to me.
This is the best part, the holes in the spacers are exactly where they are supposed to be! Be sure to mark the orientation of everything before you disassemble it all. Before calling it a night, I did the other wing exactly as I did this one, only in half the time.