alpinelakespilot2000
Well Known Member
I've seen a couple methods for tank screw (size 8) dimpling on the spar.
1. Van's method is to attach the nutplate first and then use a #30 cutter and go deep enough for the #8 screw. Here the nutplate serves to guide the #30 countersink pilot, though I've seen other people report that this is not the best way to go because the punched spar holes are already bigger than #30 allowing the bit to wander a little bit before the platenut can engage the cutter's pilot.
2. The other method is to drill a hole big enough for the appropriate countersink in a piece of scrap, clamp that behind the hole to be countersunk, then countersink the spar using the scrap as the guide for the countersink's pilot. People who have used this report the best results. (Dan C. method and others).
** Question on method 2: If I use method 2, will I need to first enlarge the holes in the spar to #19 (to accept the #19 countersink)? #19 is the proper countersink/clearance hole size for a #8 screw, correct? (I got #19 off Cleaveland's pull out chart). OR, should I be using some other size pilot hole drill or countersink cutter.
Votes for method 1 or method 2?
If method 2, do I need to go ahead and predrill all the tank screw holes in the spar to #19 before I begin countersinking with a #19 cutter?
(As you can tell, I'm terrified of messing up the beautiful--and VERY expensive--wing spar. All of the emp. parts that I messed up on were chump change in comparison!)
Thanks,
Steve
1. Van's method is to attach the nutplate first and then use a #30 cutter and go deep enough for the #8 screw. Here the nutplate serves to guide the #30 countersink pilot, though I've seen other people report that this is not the best way to go because the punched spar holes are already bigger than #30 allowing the bit to wander a little bit before the platenut can engage the cutter's pilot.
2. The other method is to drill a hole big enough for the appropriate countersink in a piece of scrap, clamp that behind the hole to be countersunk, then countersink the spar using the scrap as the guide for the countersink's pilot. People who have used this report the best results. (Dan C. method and others).
** Question on method 2: If I use method 2, will I need to first enlarge the holes in the spar to #19 (to accept the #19 countersink)? #19 is the proper countersink/clearance hole size for a #8 screw, correct? (I got #19 off Cleaveland's pull out chart). OR, should I be using some other size pilot hole drill or countersink cutter.
Votes for method 1 or method 2?
If method 2, do I need to go ahead and predrill all the tank screw holes in the spar to #19 before I begin countersinking with a #19 cutter?
(As you can tell, I'm terrified of messing up the beautiful--and VERY expensive--wing spar. All of the emp. parts that I messed up on were chump change in comparison!)
Thanks,
Steve
Last edited: