More Wing Fittings

I needed to make some more wing fittings.  Rich Wilbur was making faster progress on his wings than I was, so I sold him all my wing fittings.  I figured I'd have time to get new ones made before I needed them.  I also need to make fittings for each of us to comply with the spar AD.

There is only one Airworthiness Directive (AD) for the WACO NINE.  The inboard ends of the upper wing spars were prone to splitting.  The Feds believed it was due to poor quality spruce used in the spars.  I happen to agree.  The original spars I have are made from very poor quality spruce.  A repair was developed which clamps the spar ends with steel plates on the top and on the bottom of each spar.  The plates are held in place with four 1/4" bolts.  There are also 2 sets of smaller 3/4" wide straps bolted to each side of the spars.  I think these are intended to assure the wing attach bolts, which run vertically through the spar and the clamping plates, can't pull out of the ends of the spars.

  All these steel pieces are made from 0.090" thick steel.  I don't know anyone with a shear which can cut 0.090" 4130 steel and Aircraft Spruce doesn't sell 3/4" wide strips 0.090" thick.  WACO used 1025 steel bar stock which was rolled to 3/4" wide.  With a good blade in the band saw I can cut about 6" per minute so it goes a lot faster than you would think.

I find that for long straight cuts I do better if I draw 2 cut lines 1/16" apart.  With just one cut line I tend to wander too far from the line.  With 2 lines you can see when you are getting too close to either line.

The 0.090" steel is too thick to punch with my Whitney punch so I drill the holes with center drills so the holes don't wander as much.  All the holes are center punched using templates so they match within a couple thousandths of an inch.  Once the holes are drilled they are reamed to 17/64" to provide clearance for paint and variations in bolt diameter.

The wing strut attach fittings are made from 3/16" thick steel.  I find it helps to cut as much as possible before separating the parts so it's easier to hold them while cutting.

I also grind as much as I can before separating the parts.  It's easy to get small parts too hot to hold while grinding the edges.

I lay out parts with a felt marker so I know everything fits well before punching or scribing the steel.  I drill all the holes to match the template before scribing the cut lines around the templates.  You can see that on the strut fittings above I had one which I somehow mis-drilled a hole.  Because it hasn't been scribed the steel can still be used for some other part.

I only scribe the cut lines, never on the part surfaces which could cause a crack.  Using templates avoids the need to lay out holes, etc. on the part.

These are the top and bottom plates for the spar AD.  They get a piece of 3/16" plywood riveted on before installing.

There are lots of holes.  The 1/8" holes are not drilled with a center drill.  I find the pilot end too fragile to use on anything harder than aluminum.

There is over 9 pounds of steel in the 76 fittings used in the wings.  I need to bend and weld some of these, then paint everything.

Engines on Wood Stands in Shed

John Gaertner sent me a drawing for a wood stand to hold the engines while moving or storing them.  They're now in a better storage shed where I can keep soaking them with penetrating oil.  I like Corrosion-X and I've had some luck with PB Blaster.  I'll pour some blaster in the cylinders a keep spraying Corrosion-X on all the nuts etc.

Wire Dispenser for Wrapping Cable Splices

 I wanted a way to hold the loose coil of 22 gauge wire while wrapping the splice so that I didn't need to cut a piece of wire and risk getting my eyeball scratched again.  The end of a piece of safety wire got around my safety glasses when I was in the Air Force.  I still have a scratch.  I wanted a spool but couldn't figure out how to wind it.  I also liked the packaging of the 20 gauge wire with it's slit on the side to dispense the wire as the coil spins inside.  I figured I could duplicate their idea.

 At the hardware store I bought a 2" PVC cap and a 1/2" coupler.   The coupler has a ledge in the middle so you don't push either pipe in too far.  This made a perfect ledge to set some washers on for a nut on the bolt to hold the coupler in the middle of the cap.  This post helps keep the coil from getting tangled.

 I want the wire to feed out at the edge of the cap so I ground off the raised lettering with the belt sander.  Spin it on the table while holding it lightly against the belt.

 This all leaves a nice square edge.  A few turns of the de-burring tool put a smooth radius on the inside, wire feed, corner.

 A 1/4" diameter hole was located in the center of the cap.

 Some guide lines helped for filing a nice square hole to pocket the carriage bolt which hold everything together.  The carriage bolt assures The cover nut is easy to get off and makes it all a little smoother in the hand.

 You can see how the washers and nut work to hold the center post in place.  I started with a short bolt so I can grind the post to length.  We need a gap of no more than the thickness of the wire.

 I used a thin ruler to use as a thickness gauge drawing a guide line for grinding.

Hold the cap on the table of the belt sander while gently rolling the cap and grinding down the post.  This keeps the top end parallel to the edge of the cap so the cover will have an even gap for the wire.

 I used a hole saw to gently cut out a cover.  The hole saw has a 1/4" drill in the center which is why I used a 1/4" bolt.

To clean up the edge I held the cover on the table with a piece of 1/4" rod and spun it to keep it nice and round.  A little clean up on the edge with a file removed the last burrs and left a smooth edge.

 You need to make sure you have the end where they started winding on the inside and the end where they finished winding coming out the gap under the cover.

I'll look for a nice knob to replace the nut to make loading even easier.  It fits my hand perfectly.

Time to wind some more splices.

Improved Thumb Wheel for the Cable Splicing Clamp

After using the Splicing Clamp to make about 10 cables, for my Fly Baby, I decided I needed to stop and make a larger, easier to grip, tightening wheel.  I originally made the wheel from the same 1/4" x 1" bar stock used for some of the parts.  It seemed clever and would work fine with flexible cable.  With the non-flexible 1x19 cable it was just too hard to get the cable tightened against the thimble.  You could do it but it took a lot of wiggling the cable while turning the wheel.

I decided I needed a wheel closer to 2" in diameter with nice big knurls for a good grip.  I also wanted to keep it 1/4" thick to have a reasonable number of threads.  If it wears out I may need to make one from 3/8" thick steel.

 The only piece of 1/4" steel I had was on some tools for making wire ferrules for the WACO internal bracing wires.  I decided it would be fine with a 2" hole in the base since I just clamp the base to my work bench.

I located a pilot hole for the 2" hole saw then used the saw to draw a centerline to layout a pattern of holes for the knurls.  It certainly took the guesswork out of where the center of the holes should be.

 I center punched a pattern of 12 holes, pilot drilled them with a 3/16" drill and finished them with a 5/16" drill.

 To round the edges of the holes, it makes more comfortable knurls, I countersunk the holes with a 1/2" center drill, steeper flutes.  Then I lightly countersunk then with a 1/2" twist drill.  It really makes a nicely rounded edge to the holes.

 Back to the 2" hole saw to cut out the wheel. I cut half way from each side and when it got close just pounded it out with a light hammer blow.  I didn't want to risk this 1/4" slug flying around.

It's looking like a thumb wheel.

 I cleaned up the outside radius with the belt sander and the chamfered the edge at 2 angles, sort of like with the hole edges.

 The remaining burs were cleaned up with the small sanding drum on the Dremel tool.  It needs to feel good in your hand and no sharp edges.

 The hole was tapped with a 3/8" fine thread to spin on the center bolt.

I had a little trouble getting the 3 bolts apart since I had put Loctite on the threads and cut off the head of the 3/8" both after tightening it in the clamping bar.  A little heat took care of the Loctite.  I greased the threads and the pivot with Molykote to keep the friction low.

I'm ready to make some more cables.  Much nicer wheel.

I'll go back and add this to the original posting.