Friday, April 29, 2016

A Hinge & Pin Fest

Since it was another rainy day outside yesterday, decided to focus attention on the mounting hardware for the RV-12’s cowling as opposed to getting fiberglass dust all over everything inside the hangar.

The plans call for cutting two sections of hinge material 22" long to create the F-12115 side hinges. These will become the left and right cowl side hinges that will secure the upper and lower cowling halves together. Had a minor issue to sort out … in that the plans are not real clear how to cut the F-12115-R hinge. Only the left hinge is shown and by just cutting two pieces of the hinge material as shown on the drawing and flipping it upside down for the right side it will make the hinges differ because the forward most eyelet will be on the bottom cowl but on the right side it will be on the upper cowl. Not that it makes a difference … but it will just not look symmetrical when the top cowl is off. To remedy the situation, the 22" measurement for the right hinge began 1/2" in from where it shows on the drawing.
My fingers are pointing to the left and right F-12115 hinge halves that will attach to the lower cowling. Note that by offsetting the beginning of the cut by 1/2" now the forward most portion of the hinges that will attach to the bottom cowl on both sides will begin with an eyelet.
By cutting the right hinge material with the 1/2" offset, the right side will be symmetrical to the left side as shown clearly in this drawing.

The hinge pins that come with the hinge material the F-12115 hinges are fabricated from are not used … instead, Van’s supplies two very long hinge pins that has a tabs welded onto them that need to be cut to size. The tabs have holes that will be used as a point to secure the hinge pins to the cowling by using a screw placed through a hole in the tab. The cowl hinge pins are to be cut to 26" so the Dremel (which has been getting a work out the last few work sessions) was outfitted with the cutting wheel to cut the cowl pins.
Using the Dremel outfitted with a cutting wheel to cut the right cowl hinge pin to 26". The tab welded onto the left cowl hinge pin can be seen in the background.
Left and right cowl hinge pins cut to 26" and ready for action.

Next on the agenda was fabricating the pins for the F-1201J & K upper cowl hinges which need to be 27 1/2" and 14 1/2" respectfully. The hinge pins require having a 90 degree bend to form a handle of sorts that is 1 3/16". I found using the seaming tool (which has rounded bills) did a great job of bending the pins by rolling it over on a piece of wood. After the 90 is made on the ends of the pins, the pins are to be shaped to follow the curve of the fuselage.
Using the seeming tool to bend one of the upper cowling hinge pins.
After bending the pins, and shaping the ends per the plans, they both slid through the eyelets without much difficulty.

The remainder of the hinge pins were made using the dimensions in the drawings and the associated hinge pieces were cut to size per the drawings with no issues. Once all the various hinge pieces were cut, rivet hole locations are to be marked on the hinge sections, BUT NOT drilled.
Finished pile of hinges and pins. The four F-12115 side hinge pieces on the right still need to have the rivet hole locations marked.

Ran out of time so will finish up marking the rivet hole locations for the side hinge pieces during the next work session.