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Building up small areas on cowling - tips?

Flying Scotsman

Well Known Member
I've installed all my camlocs (Skybolt fasteners) on the cowling, and am now ready to fill in some areas with epoxy/microballoons to make all surfaces (top and bottom) align and be smooth/faired/etc.

Any tips for preparation/cleaning/filling/sanding before I start?

I have to build up the top edge of the lower cowl along the split line in a few places just a bit to make the two halves match (riveting on the attach plates caused a little bit of misalignment of the bottom cowl, about 1/16-1/8" in a few places), and I need to fill in and sand down the forward outboard portions of the inlets (which never did match, a much bigger gap there).

Any general tips or tricks are much appreciated!

Steve
 
I hope a picture is worth a thousand words here because I can not remember what I did.....here is the photographic evidence.
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The photos above seem to be showing using micro to build up the areas, which is the normal stuff used for this.

Scuff sand with 80 grit, mix up the micro and epoxy fairly dry----easier to sand later. If you have problems with it sagging when applied to a vertical surface like in the photo, it is not dry enough----or you could use some Cab O Sil to thicken it up.

For areas that will see a lot of stress, like next to a camlock, you could mix in a small amount of flox also-----but flox is a bear to sand.

Be warned, dry micro will leave a pin holed surface, but that is easy to deal with.

Good luck.
 
If its any consolation ...

... that area on the front at the split line is the hardest area to get "acceptable". I used one camlock in that "valley" on each side of the prop, which made building up the low parts tricky. any buildup wants to bury the camlocks in micro. I removed the camlocks completely, and found that a 7/16" socket was the same diameter as the camlock outer ring. I taped up 2 7/16" sockets with packing tape and held them in the two camlock spots with a couple of long screws (like 2 1/2" or so). That allowed me to just goop the micro around them and still leave exactly the right hollow for the camlocks when done. (disclaimer: could be this was a harder process on my sam James cowl than a Vans cowl.) Sorry, no pics ... I was too busy workin'. :D
 
Thanks, guys...this is exactly what I'm looking for!

I will probably just go with platenuts/tinnerman washers/stainless steel screws on the inboard portion of the inlets, next to the prop (the kit from SkyBolt even comes with a bunch of them, albeit they are floating platenuts, which might or might not be the right answer...but nevertheless, the Skybolt folks are great!).

Sigh...time to do some fiberglass/epoxy work, my *least* favorite thing to work on on the entire plane.
 
Jeff...your cowling looks almost exactly like mine! I used #8 screws and surface washers to secure the cowl, and it works pretty good. However, some say I used too many of them (about 1.5" spacing). What is the spacing on your camlocks?

Jim Bower
St. Louis
RV-6A N143DJ
Flying since August 2011
 
This is very timely ............

it is exactly where I am in the process. Thanks for the tips.
 
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