Wednesday, February 29, 2012

Door Window Hinges

 I found the hinges for the Pilot side door window were unusable.  The material for these is MS20257P2 which is aluminum piano hinge1-1/16" wide and .040" thick.  The easiest thing for these was to just make a little jig to hold the hinge while punching the rivet holes.  I used a piece of 1/16" x 1-1/4" aluminum angle, 2" long.  Each hinge is 2" long.The factory used a flat punch about 1/8" wide to lock the pin in one side of the hinge.  I used 2 center punches done with the 5/32" punch from my Whitney punch.  I also hammered the back end of the hinge, like on the flap hinges, to help assure the pin won't slide out.
 The hole fixture is simple.  The 1/8" holes are 5/8" from the corner and 1/2" apart.  There are 3 holes on the door side of the hinge and 4 on the window side.  It's just a matter of positioning the hinge in the corner and punching the holes through the hinge with a punch with the center nib removed, using the clecos to hold the hinge in place as the holes are punched.

 With the hinges and latch installed the window works great.  I was so pleased I decided to replace the old hinges I had installed on the passenger door with new ones also.  Good plan but as I started riveting on the first hinge I damaged the window so I had to remove the glass and start over making a new window.  Oh Well, At least it's all fun no matter how many times you do it.

Saturday, February 25, 2012

Installing Side Glass In Door Frames

 With the roto-tiller done I'm back to the planes.  The door glass is supposed to be .060" thick.  Someone had installed .125" plexi-glass which seems fine but you have to leave out the seal.  Their solution was lots of RTV instead of the electrical tape I discussed earlier.  I'm using the Scotch 2228 Moisture Sealing Tape from Lowes.  Before removing the old glass I drew the cut line on the new plexi-glass so it's 3/32" in from the inside of the stamped part of the frame.
A 1-3/4" radius worked well for the corners.  The top and rear of the frame are straight and square so there are 2 easy sides.  The other edges and the corners I cut with the slow metal cutting bandsaw.  It cut much better than the coarser toothed and faster wood bandsaw.  The edges were finished to the line with the belt sander and a little file work.
To get the piece to fit through the bandsaw I had to cut a piece from the sheet.  I have this nice straight edge with a rubber grip surface, so it won't slide around.  I just used a cheap plastic cutting knife from Lowes to score the plastic and break it.  It work great for doing the same thing on thin sheet aluminum rather than using snips.
The 2228 tape is one inch wide.  By using the straight edge and a sharp knife, with the small breakaway blades, I was able to cut the 4' strip of tape into 2 1/2" wide pieces.  Oh yeah, I have a piece of 1/4" thick glass I bought at the local window place to use for cutting such things on it.  Don't press to hard and you won't scratch it and the tape doesn't stick.  It has a release paper on one side so I cut it with the paper side up.  This stuff will stick to it's self at the slightest touch and never come apart again so be careful.  The tape was stuck to the edge of the window with the sticky, paper side, to the window and wrapped about 3/16" onto both sides.
The window was fit into the frame and everything clecoed together.  The frames were originally assembled with 3/32" flush rivets with the factor head to the outside.  The countersink is very small and appears to have been done on the inside as well.  If you drill out one of these holes to fit a 1/8" rivet you make the countersink almost disappear. Only the top half of this window still had 3/32" rivets.  The rest, on the 2 doors, had been replaced with a variety of 1/8" flat head and universal head A and AD rivets as well as some Pop Rivets.  The rivets need to be flush to clear the door frame nicely when opening and closing so I re-drilled the countersinks to fit the 1/8" rivets.
Because the seal needs to be compressed just slightly to get some of the rivets to line up well there were places where a couple clamps with some duct tape on the faces worked great to hold everything tight while squeezing the rivets.  This is one of those places where a squeeze is the only way to set the rivets.
Click on this picture to zoom in and you can see the difference in the correct and incorrect rivets.

Roto-Tiller Delays Project

 I haven't been getting much done on my airplane projects for the past couple months because I've been busy rebuilding my wife's roto-tiller.  It's a nice heavy duty 8 HP machine built about 1978.  She got it for free and I've been promising for a couple years to rebuild it.  Between the rust and dried grease nothing moved except the engine which turned over with rather weak compression.  The wheels were rusted onto the shafts and had to be cut off and welded back together in order to get the transmission apart.  Other than the tines, tires, hardware, a couple chains and the gas tank which all had to be replace, the rest of the parts just needed cleaning and painting.  A little Marvel Mystery Oil got the rings loose, and with a rebuild on the carburetor the engine runs great.

 The good news is the tiller works great.  I still need to print a couple vinyl labels I couldn't save and make a cover for the pulleys.  The bad news is I spent $900.  Fortunately You can't buy a new one this nice for that price and it was a lot of fun.

Time to plant the garden or we won't have any peas this year.

Sunday, February 12, 2012

EAA Gas Welding Workshop

I've spent this weekend in Virginia Beach practicing welding at the EAA SportAir Workshop.  It was good fun and I learned plenty even though I had to learn to weld to get my A & P back in the 70s.  I don't weld often so I've been practicing on lots of scrap and some tubing from Lowes.  I had lots of questions which I couldn't find answers to on line, in books, or in the EAA welding video.  It really was money and time well spent and good fun.  Now I'm ready to weld up the splices on my bent wing strut.