Tip: drilling the hole normal to the surface.

[BonitaRV8]

To help get your holes normal to the surface look at the reflection of your drill bit in the aluminum surface that you are drilling through. When your drill bit lines up with its reflection you are normal to the surface; it will look continuous. Looking at it from two different angles helps. You can see the reflection through the blue plastic as well.

 

[flion]

Great tip. This also works on curved surfaces. But I still had a machinist friend make a drill guide for the steps out of nylon and will have him make drill guides for the cabin top on my -10.

 

[rzbill]

Shades of Bingelis

 

[aerhed]

and will have him make drill guides for the cabin top on my -10.

For drilling the door hinges in the 10 top you can stack hinge halves and drill through the top more square. Hard to stay square through thick curved fiberglass.

 

[Mike S]

For drilling the door hinges in the 10 top you can stack hinge halves and drill through the top more square. Hard to stay square through thick curved fiberglass.

One thing to keep in mind when installing bolts into fiberglass, you want a good fit to the bolt shank. Sneak up on the final hole diameter with a couple sizes smaller drills first. Use a mike or calipers to measure the bolt shank and drill to get the smallest hole that will do the job.

Better still is to ream to final size.