Piano hinge knuckle damage repair

[rv8ch]

I have a damaged piano hinge knuckle on one of the hinges between my upper and lower cowl. I unfortunately pinched it a bit when riveting it. I can get the hinge pin in and out, but it's very tight. Does anyone have any tips or tricks to "repair" it, or am I faced with a lifetime of stubborn cowl hinge pin insertion and removal? Thanks!

[Ironflight]

By "knuckle", you mean a single loop? If it is just one, you can drill it out - yes, the loop wall material will be thin there, but a single loop won't make the cowl come off. If it is deep in the hinge, take a piece of hinge material, and flatten, then sharpen the end. Maintain the diameter of the pin. Put it in a drill and run it through the hinge to ream out the bad loop.

[rv8ch]

Hi Paul, Yes, I'm talking about the loop. I wasn't sure of the nomenclature for this thing, and the google told me it was a knuckle.



It's unfortunately right in the middle, and really hard to get a drill bit in there. Apologies, but I'm not sure I understand your tip. Are you suggesting that I flatten the hinge loop, and re-roll it? Thanks!

[crabandy]

I've done the same thing squeezing rivets on the cowling hinge, but the eyelet wasn't flattened it was bent out of plane with the other eyelets. It doesn't take 1/32-1/16 off to make the hinge pin hard to insert/remove.

Mark the eyelet with a sharpie so it's easy to identify and look down the edge of the cowling/hinge like you're aiming a rifle and see if the offending loop is in plane with the other eyelets. If it's not insert the hinge pin through the eyelets and gently use a pair of pliers to re-align the eyelet. Make sure to insert the hingepin, it helps with not flattening the loop and realigning the eyelet.

[rv7charlie]

Mickey, I think Paul is describing the technique of using a length of hinge pin material to make a 'spade', or 'paddle' bit (typically used to drill larger holes in wood).

Grind a flat on the 1st 1/2" or so of a spare hinge pin. When you run the pin stock into your hinge and spin it with a drill motor (positioning the flat area in the bent eye (knuckle), the edge of the flat will shave the interior of the bent hinge eye (knuckle) until it's the same inside diameter as the pin.

Charlie

[rv8ch]

Ah, now I get it - great idea! I was looking for super-long drill bits but this idea is much cleverer - exactly what I was looking for!

[rv8ch]

Thanks guys - this worked perfectly. I can now insert and remove the hinge pin by hand - don't need the drill. First time I've made a reamer myself. There's a picture below of the end of the pin. We're learning!