Question on the best way to extend a fiberglass edge..

[Brantel]

Many times in working around this kit, I have had the desire to want to extend an edge of a fiberglass part.

What is the best method of doing this to keep a nice thin edge but to extend it without having the extention just break off later?

I know it is easy to do when you don't have to wory about the part edge becoming too thick, but what if you need a thin original edge extension?

[f1rocket]

There are a couple of ways to do this and it kind of depends on whether the extended edge needs the same strength as the original or not. For example, extending the edge on the cowl versus extending the edge of a fairing.

For a fairing for example, protect the airplane, epoxy up one ply of glass cloth and lay it down on the airframe where you want the fairing extended. Mix a little flox and put it along the inside edge of the fairing. Press the fairing down into place, pressing the flox onto the one ply of cloth. Make sure the flox squeezes out and extends to the edge you want. Let it set up, remove and sand the edges smooth. Fill any indentations with micro and you should be good to go.

Let me know if you want to extend the edge of a cowling, etc. That's a little more involved.

[Brantel]

Originally Posted by f1rocket

Let me know if you want to extend the edge of a cowling, etc. That's a little more involved.

Yes it is on my cowl, I got slightly agressive with my sanding and took a tad too much off of the right rear of my top cowl right where the forward bend is in the firewall. The pilot side is perfect, the copilot side not so much....Most people may never notice it but I do...

[LifeofReiley]

Originally Posted by Brantel

Yes it is on my cowl, I got slightly agressive with my sanding and took a tad too much off of the right rear of my top cowl right where the forward bend is in the firewall. The pilot side is perfect, the copilot side not so much....Most people may never notice it but I do...

Keep fitting as things will move around until final fit is accomplished. You will want a small gap for the painting process too.

[Bill Wightman]

Brian - The key to doing a good extension is to get alot of contact area between the original piece and the extension itself.

First, sand down the edge you want to extend. I like to sand both sides of this edge at a pretty shallow angle. Your layup for the extension will bond to these surfaces. Ensure everything is absolutely clean before doing the bond. Using several plies of glass on both sides of the part you're extending will yield the best strength.

And since a pic is worth a thousand words:



Nice work on the cowl - keep it up!

Edit: In the time it took to post this, I found out you're doing a cosmetic adjustment to your aft cowl edge. The technique shown here would be used when you're looking for max strength in an extension. For your cosmetic adjustment, I'd still sand the edge you're interested in to get more contact area before doing the extension. Flox should work well for short extensions to your edge. Also, I would stick to a good epoxy in this case, not polyester. These cowlings take a beating - more load on them than you might imagine. Best wishes.... BW

[Brantel]

Originally Posted by Bill Wightman

For your cosmetic adjustment, I'd still sand the edge you're interested in to get more contact area before doing the extension. Flox should work well for short extensions to your edge. Also, I would stick to a good epoxy in this case, not polyester. These cowlings take a beating - more load on them than you might imagine. Best wishes.... BW

Thanks, I was thinking flox for this thin little addition but was not sure if it would hold and no polyester resin in my house!

[Jamie]

Brian:

I made a mistake on my cowl and managed to remove too much material on the bottom. I'm still not sure how I cut too much off, but it happened all the same.



You can go here for the details on my fix.

Best,
Jamie

[Brantel]

Thanks for the link Jamie, I use your site quite often for excellent info! Thanks everyone else for the tips!