Chuck and Ryan's Build Tips

[ceslaw]

More Riveting Information

This is a ridiculously little tip.

When pulling the Cherry Max rivets on the aft spar reinforcement strip the rivet puller would occasionally want to ‘bounce’ and contact the spar reinforcement strip. To protect the reinforcement strip from an errant ‘scratch’ a large fender washer was placed over the rivet when it was being pulled. No more scratches.

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The same trick was used to protect the forward skins while riveting the stainless-steel rivets

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[ceslaw]

Drag Tube Notches.

The angled drag tubes require a notch on one end to clear a bolt per the manual. It can be notched with a file or Dremel. But if one has access to a mill it is a thirty second job that results in a perfect notch.

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[ceslaw]

Skins: Seventeen Tips, Part I

Reading various posts, the manual, and watching videos, it seems there are as many different techniques and tricks as there are Cubs for installing the forward wing skins. Seven years ago I posted twelve tips. Time to add a few more.

The approach suggested here is a bit different than the manual. It has the advantage of visually assuring the forward ribs are straight, perpendicular to the spar, and that the rivets are perfectly centered into those ribs. It has the disadvantage of being more time consuming.

1. Confirm that the washout is correct. Again.

2. Do NOT use masking tapes to align the forward ribs, contrary to the manual. Do make sure they are generally straight.

3. Mark the pattern provided for locating the two upper attachment holes with two additional holes 1.75” from the top. These holes are used instead of the top holes on the inboard section between ribs 1 and 3 where the extended fuel tanks set.

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4. Mark a line along the center of each rib about six inches from the top down with a fine point Sharpie. Also mark the center point of each rib on the aft side of the spar.

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5. Set the skins in place, using clamps to hold them temporarily to the spar, starting from outboard to inboard. For now, the aft edge needs to be elevated about a quarter inch so the mark on the back side is visible. Referencing that mark, place a mark directly above it on the top edge of the skin. A small square is helpful. Now use a square to draw a line with a fine point Sharpie about six inches forward on the skin. This line now defines the perfect location for the rib, perpendicular to the spar. Now make sure the aft edge of the skins is tight against the inside edge of the spar in their correct position using spring clamps.

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6. Using the pattern provided by Cubcrafters, mark the holes. Note that the primary ribs get a top rivet and a second rivet per the pattern, but the intermediate ribs omit the top, inner rivet. Use the line made in paragraph 5 to assure the holes being marked are exactly on the line.

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7. Mark the rivet locations at the top of ribs 1 and 3 and the bottom of rib 1 with a distinctive mark so they won’t be inadvertently riveted for now. These rivets will be added when the cap strips are in place.

8. Now remove the skins and take them to your work bench. Using a #40 bit, drill and de-burr the holes.

To be continued . . . . .

[ceslaw]

Skins: Seventeen Tips, Part II

9. Put the skins back in place. Wiggle the ribs a bit to line up the top hole with the vertical line previously placed on the ribs. I drilled a guide hole with a #40 bit and then match drilled with a #30 and clecoed in place. Now line up the next lower hole wiggling the ribs as needed with that line, drill and cleco. You now have perfectly aligned ribs, perpendicular to the spar, with hole locations centered on the ribs. Now take the skins off again and de-burr the holes you just drilled in the ribs.

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10. The ribs where the skins overlap need a bit more attention. After drilling the holes in the top skin, use them to mark the location of the holes in the lower skin. The skins need to be removed. Again. (I warned that this approach takes more time). Now drill out these holes with a #40 bit. Set the skins back in place. Again. Line up the overlapped sections. By using a #40 bit match drilling through the rib with a #30 bit will keep the holes lined up.

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11. Remove all the skins again. Using compressed air, thoroughly blow away any debris.

12. Replace the skins and cleco in place for the second, third, or however many times it may be. Now starting at the outboard end set the clamps starting at the center of each skin and working your way outward. I generally placed the clamps midway between the ribs. It takes a bit of creativity to get the clamps secure in some locations due to the drag wires and compression tubes. We used spacer blocks only on the web of the spar, not the spar caps. Before securely tightening the clamps, rivet the first and second row of rivets (except the two that join the next adjoining skin). Then tighten the clamps until they are snug, with no gaps, but only finger tight.

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13. The pattern noted in a prior post was used to line up the bottom rivets. Check to make sure the ribs are within the vertical opening of the skin at the bottom rear of the skin. Drill starting in the middle, cleco, and work your way out, left and right. Then rivet. Before putting that first bottom rivet in place take a flashlight and look inside to make sure the leading ribs are still properly aligned and not distorted.

14. Get the jig for drilling the top vertical edge of the skins to the spar. It makes drilling those holes go much faster and there is no question about properly alignment to avoid hitting a spar bulb. It is available from Aircraft Tool Supply Company. https://www.aircraft-tool.com/shop/d...aspx?id=AE1145 Clamps were used to hold down the skin, especially where the fuel tank straps are located.

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15. We wiped down the skins with alcohol to remove the marks. Running a finger down the leading edge we could feel the ribs so we are confident it is nice and tight. The seams are all flush. There is no ‘tin canning’ affect

16. Since we built the EX five years ago, Cubcrafters added a metal reinforcing plate that goes between ribs number 2 and 3 to better secure the door latch. This will result in a gap between the skin and the adjacent ribs on the bottom surface, which may be seen on rib 1. That should not be an issue.

17. Admire your work, take the rest of the day off, have a beer.

[ceslaw]

One more skin tip, Part III

A question on the FB site prompted this, hopefully, last skin tip. This is a good point that should have been mentioned earlier.

18. The placement of the skin around the light fitting may be an issue for two reasons. First, the adjoining outboard skin needs to be trimmed about an inch to avoid interfering with the light. The skin needs to be flush with the inner side of the sixth rib. A common tin snips worked fine to trim it.

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Second, the light fixture may need to be trimmed slightly to clear the adjoining rib. But about a quarter inch minimum needs to be retained to assure there will be enough for the rivet on the leading edge to grab.The trick is to set the skin with the cut out for the light and the adjoining skin temporarily in place to check the alignment. This will determine the amount needed to be trimmed off the skin and then the light fixture.

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It is helpful to clamp the light fixture in place before the final riveting of the skins. The lower section of skin –about an inch wide – likes to distort and clamping the fixture in place helps minimize that. It will be glued with methocrylate in a later step. A little bit of distortion may be hard to avoid.

We added a couple of additional rivets on the bottom when the light fixture was glued and riveted in place to minimize the distortion. Fabric covers a host of minor anomalies.

[PBY Catalina]

...
It is helpful to clamp the light fixture in place before the final riveting of the skins. The lower section of skin –about an inch wide – likes to distort and clamping the fixture in place helps minimize that. It will be glued with methocrylate in a later step. A little bit of distortion may be hard to avoid.

We added a couple of additional rivets on the bottom when the light fixture was glued and riveted in place to minimize the distortion. Fabric covers a host of minor anomalies.

I fully agree with that, I did the same !
And I put a lot of little clamps to avoid the lower part to distord.

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[ceslaw]

That's an impressive collection of clamps!

Here is a pic of the two rivets added to the bottom. Extra security to keep things in place.

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[ceslaw]

I Pad

The back seat passenger may want to know what is going on, so we mounted an I Pad mini to the back of the front seat. The Mini is the ideal size for this application.

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The parts needed came from Airgizmos, which we discovered at EAA Airventure in 2019. Two parts were needed: the I Pad mini clip and the base mount.

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Here are the links.http://www.airgizmos.com/iPad-mini-c...nd-5_p_72.html
http://www.airgizmos.com/Base-Mount-Tilt_p_46.html

Two holes were drilled in the base mount aligned vertically and nutserts placed on the back of the seat. This held it securely in place. The tilt base permits angling the I Pad in relation to the seat back. The base can be positioned four ways, so make sure it is positioned so the I Pad viewing angle can be adjusted up and down, not left and right.

When linked to the Garmin G3X using Foreflight it essentially duplicates the information on the panel, less the engine data. Here is a screen shot on the I pad. Even the ADSB data shows up.

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We will be adding a nearby USB power source so the I pad can be externally powered for longer flights.

[ceslaw]

Tool Tip

You just sent a check for thousands and thousands of dollars to Cubcrafters for your kit and now you find more bucks need to be spent on an assortment of tools to properly build the plane. Ouch.

One of those tools is for aligning the three holes needed to install nut plates: a larger one in the center and two smaller on either side. Making matters worse, there are different sizes of nut plates so you made need several of those alignment tools. Ouch again.

Here is a simple solution. Take a nut plate and remove the nut. Once removed, a cleco should center nicely between the tangs in the space where the nut once resided. Drill the center hole, set the nutplate on top, cleco it in place, match drill the two side holes, and you now have three holes perfectly space, ready to have a fresh nut plated riveted on the opposite side.

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Feeling a little better about that check you just sent to Cubcrafters? Yea, me neither.

[PBY Catalina]

Tool Tip


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Feeling a little better about that check you just sent to Cubcrafters? Yea, me, neither.

Excellent ! (both the joke and the tip !) Thanks !