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Ok Brian's trust.
For those with a jab 3300 USA firewall cowl kit. Did you use the -6 camloc's as mine all sit out about a dash longer and I really need -5. Or did people put an aluminium strip between the fibreglass and the camloc's?
This is what I mean.
Obviously, the cowl's are laid-up by hand and there'll be some variations in thickness of the joggles where the upper and lower cowl meet. I don't remember the specific lengths of my Camlocs, but as I recall, most seemed to be about the proper length. However, I did have to get a few shorter ones for proper seating and fit.
I did not do any shimming of the Camlocs on the cowl sides, but I DID reinforce the back edges of the cowl (top cowl and bottom cowl) where it overlaps the fuselage. My painter felt that the fiberglass was too thin there and some reinforcement would prevent the Camlocs and machine screw holes from cracking the fiberglass or paint. I used .025 bonded with West System's "G-Flex" epoxy. The G-Flex instructions recommended to roughen the fiberglass surface and then apply a wet film of the epoxy to the aluminum and use coarse aluminum carbide abrasive paper to roughen up the aluminum through the wet epoxy and then bond the two materials with plenty of clamps and achieve a slight squeeze-out of epoxy around the edges. Worked great and has not delaminated in 6+ years and 550 hrs!
On my STOL 750, I also noticed the top cowl would develop a depression in-flight from the air pressure at the base of the windshield (don't know if the 601/650's cowls do this or not!), so I riveted two L's together to make a "T" cross-section and after slight metal shrinking of the flanges to match the top cowl's longitudinal curvature, I bonded this down the mid-line of the top cowl to act as a stiffener. I drilled 1/8" holes along the flanges so some of the epoxy could squeeze through and in effect make an "epoxy rivet." Worked great!
On my 601XL with a Jab USA cowl, I put aluminum shims under the camloc receptacles as needed to allow the camloc to have a correct amount of tension under load. The shims were not all of the same thickness, but it allowed me to use the same camloc dash number for all of the side seam locations. I also added an additional camloc along the sides. I felt the Jab USA kit camloc spacing was too far apart and the cowls bowed between them. Fortunately the camloc holes were not pre-drilled so I added one more camloc to cut down on the spacing and I think it looks pretty good.
Thanks I think I will add the as aluminium strips.
Anyone know the thickness difference of one Dash length in thou? .025 or 040?
It looks like they are nominally .030 difference in length from one dash# to the next. The Aircraft Spruce page here shows the dimensional data for the 2600 Camlocs if you scroll down: http://www.aircraftspruce.com/catalog/hapages/camloc2600.php?clickk...