Reverse engineering

[Binty]

In my zest to have all the various sized PK screw holes in the channels filled by my welder prior to painting, I accidently filled the Plumb bob reference hole (the punch mark is still visible).

As my fuse has now been repaired and is nice and straight, it would be a good to have an accurate levelling reference. I plan to set it up level and hang a plumb over the reference to find the position to drill the new hole.

Can someone please supply some accurate dimensions of their ref hole (and/or a pic) so i know Im close.?

 

[cubunltd]

Forget the hole. level the top longeron on the left side between the throttles.

 

[Binty]

I 'think' this is the reference datum hole I filled...? (smaller one). please confirm.

 

[aviweld]

Level as per cubunltd's suggestion, then use plumb bob to determine where to drill new hole.

P.S. That rear doorpost looks gnarly at the top end where the channel was removed. How's the bottom end look?

 

[cubunltd]

Forgot to mention to level the aircraft side to side by placing level on the rear seat front crosstube. I never use the plumb bulb method.

John

 

[Binty]

you think thats bad... check out what i found at the bottom end?! Piper put the channels on THEN, painted the frame. they rust out from underneath!

I have been levelling my ship laterally with a level through the rear wing attach bolts.

 

[aviweld]

I have replaced LOTS of rear doorposts exactly like that, which is why I asked. I don't even bother removing the channel to look, just cut it out. The bottom end of the front doorpost by the windshield has same issue.

 

[Darrel Starr]

Mine was rusted through too. I only knew to look there because Jim Richmond clued me in to this dumb Piper trick.

 

[Binty]

All sorted. I leveled the AC then found the hole position and re drilled to close tolerances. It is now very accurate. FYI.. the hole pictured is NOT in the correct spot.. its another few inches forward.

 

[bob turner]

Smart Level? I thought the plumb bob and 3/8" blocks and string trick were obsolete.