Eccentric cam wing assembly tools

[[email protected]]

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!

[bumper[_4_]]

On Sunday, October 30, 2016 at 9:24:13 AM UTC-7, 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!

Mark, In 2002, I bought one from Spindleburger that shipped with my trailer.. I made my own "improved" version and sold the one I bought.

Mine was made of black Delrin (as is the original) with the reinforcement a pressed in stainless steel pin. I made the outer large diameter a bit longer and have that cross drilled at 0 - 60 - 120 degrees for 6 handle hole options total, though the handle is rarely used. The 3 cross drilled holes provide plenty of purchase for turning to assist initial pin alignment.

On the face of the handle portion, in line with the eccentric end of the tool, I drilled a small dimple, filled with white paint, it shows where the eccentric is when the tool is fully inserted. This proved to be invaluable when using the tool to show which way the wing needs to be moved.

best,

bumper

[[email protected]]

Bumper- Thanks for the tips. I think the reinforcing pin is a good idea on the pins with a small eccentric. The witness mark on the face is also something I will consider incorporating.

Now that I am going into production, can RAS readers help me by sending me the diameter of their main spar pins? I'd like to set up a glider database so I can anticipate the demand.

Thanks. I can be emailed at: info (at) mmfabrication (dot) com

[Dan[_6_]]

On Sunday, October 30, 2016 at 9:24:13 AM UTC-7, 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!

Mark,
I've been using Steve's alignment tool for several years now on my ASW 20. I love it however I'd like to suggest an improvement. I suggest installing a large Hex head (use a standard bolt/wrench size) on the end. Instead of using the sliding handle/pin which sometimes is awkward, the Hex end would allow the use of a ratcheting wrench. Easier to turn and more leverage!
Hope that helps,
Dan Rihn

[[email protected]]

Dan- The only problem with that is the bolthead would try to unscrew if turned counterclockwise. Schempp-Hirth provided a rigging tool with the Arcus that has an allen head bolt inset in the face of the tool and we ran into that issue.

If you only turn it clockwise, it isn't a problem. I might incorporate that idea if people request it.

[Dan[_6_]]

On Monday, October 31, 2016 at 8:57:02 AM UTC-7, wrote:
> Dan- The only problem with that is the bolthead would try to unscrew if turned counterclockwise. Schempp-Hirth provided a rigging tool with the Arcus that has an allen head bolt inset in the face of the tool and we ran into that issue.
>
> If you only turn it clockwise, it isn't a problem. I might incorporate that idea if people request it.

Sorry, I should have been more clear, I didn't mean to use a threaded bolt per say. I agree it would have to be a "solid" installation that could be turned either way and not unscrew.
It would be a nice option. It's a great tool.
Good luck,
Dan

[Jonathan St. Cloud]

glue the bolt into the threads.

[JS]

On Monday, October 31, 2016 at 10:41:14 AM UTC-7, Jonathan St. Cloud wrote:
> glue the bolt into the threads.

Should it take that much effort to require a ratchet?
For a Schleicher, the hex key used for the tail works in the holes of the Bralla/MM or Cobra wing alignment tools. Sometimes turning the tool by hand is sufficient.
The dump handle should be in the closed position. From experience, ASW27/G29 is more difficult with the valve handle in the open position. Using excess force with a Schempp dump valve misalignment may end in tears.
Jim

[bumper[_4_]]

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 :).

[Dave Nadler]

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???

[JS]

On Monday, October 31, 2016 at 11:48:34 AM UTC-7, Dave Nadler wrote:
> 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???

Someone gave rigging in "dump" position a try on one of the club's Discus 2s.
Seems like a wing panel makes a good hammer.
Jim

[Papa3[_2_]]

This is a fun thread to read. "How many engineers does it take to ..."?? I say that with many smiley-face emoticons.

FWIW, the simple taper pin that my friend made works 10 times out of 10 with my -29. It's just a delrin pin with a solid handle at 90 degrees to the major axis of the pin. If the wing bushing are misaligned by a few mm, the pin pulls the wings together. If they are misaligned by more than that, it's time to make sure a) the flap handle was in -2 or so and b) the stick was more or less neutral and c) the divebrake handle was at the forward 1/4 or so of travel.

P3

[George Haeh]

Steve's tool is a bit undersized on the 20 & 27. No problem on the
20 because there's a reasonable taper at the end of the pins –
not so on the 27 where there's only a rounded corner with a tight
radius; so you have to be really fussy lining up to get the first pin
in.

I would love a pin that's ground off at the end so there's only a
few degrees of arc. Then you could rotate to find if the next hole
is high or low. Fingers are not straight enough.

As for marks, I filed a flat spot where the cylinders line up, and a
notch at the maximum difference.

I find that feel works better than vision on a promising soaring
day because my eyes don't adapt quickly to under the turtledeck
when the sun's out.

[Karl Striedieck[_2_]]

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

[[email protected]]

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."

[[email protected]]

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

[HGXC[_4_]]

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

[Tango Whisky]

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.

[HGXC[_4_]]

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

[[email protected]]

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.

[[email protected]]

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