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I am sure the "brains trust" has developed a full proof technique for drilling the hinge pins used in flight control surfaces, etc

Hole needed for small cotter/split pin to secure hinge pin in its working position.

So far have broken several new HSS drill bits and hardly made a dimple in the hinge pin.

Please advise

My foolproof way was not to drill the hinge pins at all. I made a 90° bend in the end of the pin and locked it in place with a small joggled plate attached by the next rivet. It's easy to inspect and if you need to remove the pin it only needs drilling out one rivet, which I have never needed to do. If you do need to remove the pin the 90° bend part makes a nice handle.

Peter

I hope I misunderstand your question and you are not trying to drill through the hinge pin. The hinge pin should be 1/2 inch shorter than the length of the hinge so that it is 1/4 inch short on each side of the hinge. Check the plans for the actual dimensions in case my memory is failing. But the key point is the hinge pin is shorter than the hinge. Then you just drill through the aluminum hinge round in front of the hinge pin. That prevents the pin from sliding out each end. Don't drill through the pin. I hope that makes sense.

Matt

Peter/Matt -

I need to secure the hinge pin on two modified inspection door hinges (engine cowling). Your advise, (drill the hinge not the pin) is correct for almost all application bar this one.

The pins have been "L" d at one end this can not be done on the other end, due to installation limitations - solution is to drill and cotter pin the other end OR Matts suggestion: shorten the pin and drill the hinge at both ends so as to fit two cotter pins per hinge.

The pin material is very very hard ie resistant to drilling.

Have been trying to drill with HSS bits without success - just come back from purchasing a "cobalt" drill bit - will give it a go

Hi Sean,
Here's how I made my cowl doors. I wanted to hide the hinges like a kitchen cupboard or car door. I figured that people would be so impressed with my doors they'd miss the runs in the paint. This way it's simple to just 'L' the hinge pins and lock wire them in place.

Yes, just lock wire the end of the pin. For the fuel door you don't even need to do that. If the pin is installed from the back, once the cowl it fitted the pin isn't going anywhere.

Peter

Nice work Sonex 1566.

Problem solved - replaced min material with aluminium welding rod - easy to drill and actually makes for a better fit than the hinge pin.

Why not just follow the plans? The steel rod is a little shorter than the hinge and you only drill and safety the hinge loop, not the pin.

Please don't use aluminum welding rod on any control surfaces or to hold the cowl/canopy on.

Bryan - As previously mentioned - this application is for a engine cowling inspection door.