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My Pink Cowl with a Grin

snoopyflys

Well Known Member
I have been working off and on with my pink cowling and I am getting closer to being done. My latest hurdle comes after fitting, riveting and epoxying in the piano hinges that hold the top and bottom halves together. When I put the halves together with the hinge pin, one side crept open a little causing it to have about 3/32nd gap near the front and tapers down to 1/32nd or less towards the firewall. I am struggling with determining how to fill this in to reduce the “grin” or leave it be. I have thought about trying to use packing tap to cover one set of hinges but there’s not quite enough high tab area to hold the tape in place while the epoxy sets. I have looked at Mr Horton’s posts on extending the cowl edge build up methods (which have worked well for me to date), but I just can’t seem to adapt his methods here. Thought I would ask here to find out how others may have solved this inadvertent “grin” issue and keep the halves from binding together.

C4E7398A-ECCC-49AC-8403-CB8ED173FDAD.jpeg
 
Filler

Dan
I'm not in Dan Horton's league but here's a couple options.

1. Any chance packing tape can be slipped between the hinge and fiberglass? If so, slide it in and cut it even to the hinge loop. Repeat with the other half but fold it out so the filler won't stick. Last thing you want is the two halves stuck together. When they are assembled, smush some flox into the gap.
2. Wax the bejeesus out of the hinge but keep the fiberglass clean. Tape the edge you want to keep. Assemble and smush flox in the gap. 3M edge painter tape is pretty good for this sort of thing but I've used black electrical tape with success.
 
Dan
I'm not in Dan Horton's league but here's a couple options.

1. Any chance packing tape can be slipped between the hinge and fiberglass? If so, slide it in and cut it even to the hinge loop. Repeat with the other half but fold it out so the filler won't stick. Last thing you want is the two halves stuck together. When they are assembled, smush some flox into the gap.
2. Wax the bejeesus out of the hinge but keep the fiberglass clean. Tape the edge you want to keep. Assemble and smush flox in the gap. 3M edge painter tape is pretty good for this sort of thing but I've used black electrical tape with success.

I would give Larry's second suggestion a try. Try to do it in these steps:

1) put vinyl electrical tape on the edge of the cowl you want to bond to. wax the hinge. I would do at least three coats of wax with light buffing between coats, to the extent that you can on the hinge.

2) remove that tape.

3) wax the mating hinge, and mask the cowl edge that you don't want to bond to. You could use clear packing tape for that, if it will stay stuck to the edge. If tape won't stay, wax it.

4) assemble cowl halves and put flox into the gap.

5) hope the cowl halves come apart! trim and sand for desired gap and fit.
 
Remove a hinge half, fill the rivet holes with micro, sand smooth, set a new hinge half with slightly different rivet locations.

Plan B: The exact width of a gap doesn't matter much. They all look good as long as they are consistent width along the length. So just sand the narrow end of this gap to match the wide end.
 
Unable - I think

Remove a hinge half, fill the rivet holes with micro, sand smooth, set a new hinge half with slightly different rivet locations.

Plan B: The exact width of a gap doesn't matter much. They all look good as long as they are consistent width along the length. So just sand the narrow end of this gap to match the wide end.

Thanks for the reply Dan. Once the hinges are epoxied and riveted to the cowl and cured, I am not sure removing a hinge halve is an option. But, if there is a way, I am all ears.
Plan B may be my only route if I cannot get Wirejock’s and SCSmith’s (thanks for the replies) suggestions to pan out. I am a little concerned that I may not get the release necessary. May try replicating on a test piece first.
 
Plan B: The exact width of a gap doesn't matter much. They all look good as long as they are consistent width along the length. So just sand the narrow end of this gap to match the wide end.

This, and build on…. Once painted it will look fine. These type of cosmetic issues will fade in your memory over time.

Each RV is hand built. They all have imperfections, some more and some less. I consider these part of the character and charm of the airplane. If everyone built a perfect airplane, it wouldn’t be nearly as fun and interesting in my book.
 
Once the hinges are epoxied and riveted to the cowl and cured, I am not sure removing a hinge halve is an option.

Epoxies tend to have poor peel strength. Unless you used a specialty epoxy blended for increased peel, any wedge shaped tool will separate the hinge and cowl.

That said, I'd just do Plan B. Fact is, I'd open the gap on the other side of the cowl to 3/32. You really need some room for paint build or you'll suffer chipping. I think the absolute minimum is the thickness of a hacksaw kerf.
 
Epoxy

Epoxies tend to have poor peel strength. Unless you used a specialty epoxy blended for increased peel, any wedge shaped tool will separate the hinge and cowl.

That said, I'd just do Plan B. Fact is, I'd open the gap on the other side of the cowl to 3/32. You really need some room for paint build or you'll suffer chipping. I think the absolute minimum is the thickness of a hacksaw kerf.

Dan is right as always. If you wanted to re-do, the hinge will snap right off after rivets are removed. It might get bent in the process. I would fill holes with a flox mix but that's my OCD.
Mine had some gaps. Along the split and the firewall. The tape or wax thing worked just fine. I used flox for that fix too. Just make sure you set up the tape correctly or the parts will bomd. Found out the hard way. I actually bonded a leg intersection fairing shut and had to saw it open with a hack saw blade. G-Flex doesn't let go like West 105. It rips laters apart.
 
If you end up removing both hinge segments, offset the hinge line down below the cowl split line. Then at least the grin won't be so toothy!
Stewart Willoughby, 6 final assembly
 
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