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Piano Hinge pin Modification

Tcheairs

Well Known Member
I've seen several posts where the ends of the pins were altered (upper cowling) to a "wedge/chisel" shape to help with insertion. Would not an alteration (filing) to a pointed "conical" shape not be a better modification (as if any modification would help with the insertion into the hinge)? Also, what about sanding with a very fine grit sandpaper for the first 5 or 6 inches of the pin and then polishing with steel wool also reduce friction somewhat?

My RV 7A pins and hinges are new, tight fit and my 75 year old hands are having a very hard time getting them started, particularly the short vertical pin on the starboard side.

So, filing end to a point? Sanding and polishing? and of course coating with the Boeing waxed lubricant. Any or all of these?

Thanks
 
Putting a flat edge on a hinge pin creates a very long drill bit that you can chuck into a drill and ream the hinge, in place, in order to make inserting the final hinge pin easier.
Pointing the hinge pin and even putting a slight curve towards the end, depending on the installation, really helps, especially if the hinges are slightly misaligned.
 
I'm going to order a couple of additional pins to modify. My longitudinal pins have the chrome brackets on the end. Other pins are bent at the end.
 
Putting a flat edge on a hinge pin creates a very long drill bit that you can chuck into a drill and ream the hinge, in place, in order to make inserting the final hinge pin easier.
As someone flying a 30 year old RV, I would advise against anything that reams the hinges out at all. They will get loose over time on their own, just through the repeated action of removing and inserting the pins. Don't hasten it.

A light grease once in a while will help with insertion/removal.
 
Drill

Round the tip and lube then use a drill to run the pin in. My wingtip hinge pins were a best at first. Couple of cycles with the drill and they go right in.
 
So, the tips of your pins are such that you can chuck them up in a drill bit? Not bent at 90 degree angles? Or have a flange for the lateral pins? I'll have to buy new ones for that operation in hopes that the ones I use will work better.
 
I understand the tips now. Sorry to be so dense, but where does the drill come into this. How do you chuck the pins to the drill and then run the drill for insertion into the hinge? Sounds like a good way to lubricate the hinge without making a mess and also hone the hinge if only slightly.
 
Kinda off subject but still hinge related. .. where do people get the extruded 1/8 hinge material for the cowl to firewall? Spruce only has the .090 stuff in extruded...
 
As a comment to the OP, making a chisel shape at the end of the rod vice a cone will offset the "point" than contacts the next hinge lug twice as much (assuming you have the pin oriented correctly).

You can chisel shape the end to align withe bend or tab on the other end of the rod for reference. When inserting, ensure the the wedge tip is on the inside of the bend.

Hope this makes sense, but it's pretty simple... and I agree that reaming your hinge lugs is just asking for loose pins down the road. My 2 cents
 

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In addition to blunt taper on the end of the pins, I also used a Dremel tool with a cone shaped bit to taper the inside of the hinge tabs on the side/face the pin is sliding into. Rather than the pin point hitting the blunt edge of the tab as the hinge curves, the taper guides the pin to the center of the hinge tab. It only take a light touch to get a nice taper. I also pre bent the pins to follow the curve which seems to help a little.

John Salak
RV-12 N896HS
 
As much as I hate the piano hinge arrangement the look of the cowl is worth the hassle! It amazes me that the shorter of the two wires that hold the top of my 8 cowl works it's way out after a few hours completly (found once sitting behind the battery!) yet I need a bulldozer to get it on! Grrrrrr.
 
Try 1/8" stainless welding rod, or a McMaster-Carr...?

No, I mean the hinge material itself, not just the pin. I want to use the hinge method for the cowl, but I want to use the extruded stuff that’s stronger than the folded cheaper hinge material that the eyelets break...
 
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