sportflyer-RCU

My Feedback: (35)

I have a horiz stab. ( built up with air foil ) that needs to be attached to the vertical fins of an OV-10 twin with 2 X 4-40 machine screws on each side.

The stab. is already framed but not sheeted. The ribs at each end of the stab. are backed up with hardwood blocks where the holes are to be drilled and tapped with 4-40 .

The question is how to drill the holes accurately at 90 degrees to the end rib at the marked locations.

It was easy with the original flat stab. with no airfoil because I could use either a Robart or Dubro hinge point centering and drilling tool . However I cant use those tools with symmetrical airfoil .

Any suggestions ?

Tks

jester_s1

What I did once on some wing bolt holes was I used my drill press to drill a hole in a small block, which made the hole 90 degrees to the bottom of the block in both directions. I then could place the block onto the surface that I was using my hand drill on and it acted as a guide for the bit.

sportflyer-RCU

My Feedback: (35)

I should have done what you suggested. But now the blocks have been glued to the end ribs. I guess I have to make a jig to keep the stab perpendicular to the drill press . Alternatively make another block with a guide hole drilled then attach it to the drill location for manual drilling.

jester_s1

That's what I meant, using a piece of scrap wood as a drill guide. It works just fine.

combatpigg

My Feedback: (3)

In a pinch I have had my wife sight the angle of my drill bit while she holds a carpenter's square in her line of sight, while I concentrate on maintaining a perpendicular angle as viewed 90 degrees from where she is watching. It's been a good enough method for some jobs where spending time to achieve greater accuracy isn't worth it..