Desert Rat
Well Known Member
I'm really mad at myself, and frankly, a little embarrassed, but I know that I always appreciate it when people post mistakes, so that I can be forewarned if I haven't gotten to that section yet, so here goes.
Located the roll bar / windshield frame this weekend; The mounting hardware for this weldment consist of an AN3 & AN4 bolt on each side through the weldment foot, through the F-721 aft canopy deck and as close to the main longerons as humanly possible without actually touching them.
You accomplish this by laying out locations on the deck, then pilot drilling #40. Theres' lots of match drilling and up sizing after that
The dimension for the front hole (AN3) is a nice big easy to read 7/8" yay! No need to squint and try to get down in the weeds to find 29/32 or something equally hard to read.
In fact this is so easy, that I can likely read the scale upside down, mis-read it, and drill this pilot hole off...not a few ticks, not the width of a sharpie line, but by a full 1/8"
I noticed it almost as soon as it was done, but of course, that is exactly not soon enough. Taking a quick peek underneath, I discovered that I nailed that 6/8" wrong dimension so precisely that I now have 1/2 of a #40 hole in the edge radius of the horizontal leg of the main longeron there between the two vertical members of the center section bulkhead.
1/2 of a #40 hole is about .050. Not even enough to completely wipe out the radius on the edge of that leg, but on the other hand, There's a lot going on in that area and I don't have a good sense of what sort of loads the longerons are carrying through there what with all the structural buildup that's running every which way.
I'll obviously call Vans tomorrow, and I can see a couple of potential solutions, but mostly I'm just sharing to make myself feel better.
The other takeaway from this is that in a perfect world, if you lay out those pilot holes per print, The full size holes will miss the edges of the longerons by 1/16". There's a note on the print that says these bolts should be snuggled up to the longerons as close as possible, but 1/16" isn't much to play with for something that's being drilled through a bunch of layers by hand. In addition to the one I obviously Fubar'd, I had to pull another one inbd will a drill fixture because the pilot hole looked a little iffy. I think if I had this to do over, I'd move all those dimension inbd a fraction more to give myself a little more breathing room.
Oh yeah, I'd also do it right the first time...
Located the roll bar / windshield frame this weekend; The mounting hardware for this weldment consist of an AN3 & AN4 bolt on each side through the weldment foot, through the F-721 aft canopy deck and as close to the main longerons as humanly possible without actually touching them.
You accomplish this by laying out locations on the deck, then pilot drilling #40. Theres' lots of match drilling and up sizing after that
The dimension for the front hole (AN3) is a nice big easy to read 7/8" yay! No need to squint and try to get down in the weeds to find 29/32 or something equally hard to read.
In fact this is so easy, that I can likely read the scale upside down, mis-read it, and drill this pilot hole off...not a few ticks, not the width of a sharpie line, but by a full 1/8"
I noticed it almost as soon as it was done, but of course, that is exactly not soon enough. Taking a quick peek underneath, I discovered that I nailed that 6/8" wrong dimension so precisely that I now have 1/2 of a #40 hole in the edge radius of the horizontal leg of the main longeron there between the two vertical members of the center section bulkhead.
1/2 of a #40 hole is about .050. Not even enough to completely wipe out the radius on the edge of that leg, but on the other hand, There's a lot going on in that area and I don't have a good sense of what sort of loads the longerons are carrying through there what with all the structural buildup that's running every which way.
I'll obviously call Vans tomorrow, and I can see a couple of potential solutions, but mostly I'm just sharing to make myself feel better.
The other takeaway from this is that in a perfect world, if you lay out those pilot holes per print, The full size holes will miss the edges of the longerons by 1/16". There's a note on the print that says these bolts should be snuggled up to the longerons as close as possible, but 1/16" isn't much to play with for something that's being drilled through a bunch of layers by hand. In addition to the one I obviously Fubar'd, I had to pull another one inbd will a drill fixture because the pilot hole looked a little iffy. I think if I had this to do over, I'd move all those dimension inbd a fraction more to give myself a little more breathing room.
Oh yeah, I'd also do it right the first time...
Attachments
Last edited: