Eccentric cam wing assembly tools

On Monday, October 31, 2016 at 2:35:26 PM UTC-4, JS wrote:
Using excess force with a Schempp dump valve misalignment may end in tears.

Oh dear, how do we know this???

Nope. The best way to incorporate a hex head is to drill an undersized pilot hole in the tool end. Then press in a length of hex bar stock that has a bevel ground onto the end so it won't "shave" the Delrin as it is forced in with a press. The Delrin will "flow" enough and lock the hex in place.

Note I did not incorporate the above on the tool I made as I considered a hex wrench to be too "fiddly" to reverse direction. In use, there are times when the eccentric tool wants to be moved back and forth and the ratchet wrench is near hopeless for this. I (of course!) think my design with the three cross holes is functionally better. The 1/2" stainless steel handle rod is bent at it's center, the bend is such that it splits the angle between the three cross holes that provide 6 handle positions - so with the bent handle there are 12 discrete firm positions, the bend also acts as a handle "stop" when inserting the handle, as designed, it works flawlessly (and I'm not one known for leaving well enough alone - sigh .

Another approach that's worked great for me and doesn't require any extra gadgets is to modify the pins for Schleicher ships. The -20 has enough meat sticking out the back of the spar that simply making it more pointy on a lathe works.

I'll try that on the Duo too.

The 27 doesn't have enough extra length for the sharpening process, so I had an insert made that increased it enough to be tapered. A small amount of spar box removal is required to take the extra length.

KS

KS is spot on with tapered pins. Schleicher pins have no taper whatsoever, just rounded ends. If the spars aren't in perfect alignment, the pins clunk hard into the rear spar. I tapered the pins on my Genesus-2 so that the last 3/4" gently tapered down 1/8". With a little dab of lube on the tapered area and a twisting motion, the taper will force spars into alignment. If your pins go completely through both spars and stick out the rear, then it is safe to taper them in the excess area. You can also make a tapered pin out of aluminum. With the aluminum pin in, raise or lower the fuselage (or tip) to bring the second pin into alignment. With the second pin in, then remove the aluminum pin and insert the steel pin.
JJ

All of these are great suggestions, and could be incorporated on request. Naturally, some will involve more work and a slightly higher cost, but I am always open to ideas. After all, "R&D" in the aviation world often means "Ripoff and Duplicate."

On Sunday, October 30, 2016 at 12:24:13 PM UTC-4, wrote:
Steve Bralla used to make and sell tools used to help align the wing spar pin bushings during assembly. He contacted me recently and said he had lost access to the machine shop. He graciously offered me the opportunity to take over the product line, and I am now in production. I will add them to my website shortly (www.mmfabrication.com) If you need one, please contact me through the website.

And a big "Thank You" to Steve!

Would this work with a Ventus? Do you have any photos?

Dennis

Le mardi 1 novembre 2016 16:21:12 UTC+1, HGXC a écritÂ*:

Would this work with a Ventus? Do you have any photos?

Dennis

Yes, works on my Ventus cM.

On Tuesday, November 1, 2016 at 11:48:41 AM UTC-4, Tango Whisky wrote:
Le mardi 1 novembre 2016 16:21:12 UTC+1, HGXC a écritÂ*:

Would this work with a Ventus? Do you have any photos?

Dennis

Yes, works on my Ventus cM.

OK so I slide both wings into the glider but they are resistive to go the final inch. (Typical for me with my Ventus) Then I insert this tool into one of the pins holes .... how does this effect the pin hole of the wing behind the closer wing?

Dennis

Dennis- The tool has a has a large main body the same diameter of your spar bushing (less a few thousandths of an inch for clearance). Extending from that pin is a smaller diameter pin that is offset to the side like a cam. The smaller pin goes in the second spar through the part of the hole you can see. Using the lever handle, the pin is rotated 180 degrees, pulling the bushings into alignment. Assuming the wings are adequately supported, they will remain in alignment when the tool is removed. You can then install the actual steel spar pin.

Very elegant solutions. I was in a hurry one day and just stuck a length of plastic rod (Nylon or Delrin? Not sure of diameter but maybe 2/3 of the wing pin?) in the overlapped main spar holes and pushed/pulled on the rod to lever the wings of my ASW 24 together the last few mm. Been doing it that way for 20+ years since.

It only works if the wings are within a few mm of being completely inserted in the fuselage. It's not like the Libelle over-center wrench that you could engage when the wings were very far apart. But IMHO, any device like this should only be used to snug the wings together the last little bit.

Chip Bearden