Riveting on Attach Angles

[Chris In Milwaukee]

I started getting the ribs ready for the attach angles today. Beginning with the nose ribs, i jigged it up vertically like I learned in EAA SportAir Sheet Metal Workshop so it's more ergonomic. Then I drilled and clecoed the angle to the rib and jig.



I measured the rivet length with the rivet gauge. It was a wee bit long, but I thought it would be okay. Maybe 1/32, tops.



Afterward, I squeezed a couple rivets into the stiffener using the nifty new squeezer I bought from Zane. Turns out that 1/32 too long is still too long.





So it looks like I'll be ordering some shorter rivets tomorrow. Never a dull moment.

This is on the test wing, and it's not going on a flying plane, so not too worried about it. The next ones will be perfect once I get the right rivets in.

So we spent the evening pulling plastic off ribs and angles (pain in the neck) and deburred holes. Still progress!


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[lsa140]

Looking good... I did't realize you were going to build an extra wing for testing, must have read over that on a previous post. It will be really interesting to see how it does in comparision to your calculations. Are you going to test to failure? I've been meaning to call Bob to find out if any testing has been done on the Patrol or LSA wings.

[Chris In Milwaukee]

Yes, that's the plan, testing to destruction. I think this wing will survive at 4000lbs gross @6.6g. But testing will tell. :-). I'm learning lots of little things in this process, too. So it's nice to learn them on this wing, too.

[Chris In Milwaukee]

You'll also notice in the photo the stiffener is a little off center, a bit closer to the bigger lightening hole, and the flange is flipped from the plans. Turns out the stiffener flange was putting itself in the center of the flat area where the skin would rivet to the rib. Flipping the stiffener around and skootching it down a smidge ensured there was clearance for the skin rivets, or more importantly, the bucking bar.

[SC Patrol 253]

Thanks for posting the technique. I think I will be making a similar jig.

[Chris In Milwaukee]

I used MDF because it's what I had. A cheap piece of 3/4" plywood would be a lot easier to drill through. Might give that a try if you have some scrap.

[Chris In Milwaukee]

The rivet gun did a much better job than the squeezer. Maybe I just need more practice with the squeezer.




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[Glenn Patterson]

We have the common aircraft rivet squeezer. The rivet squeezer needs to be pushed firm & square against the rivet head then squeeze all the while keeping the tool square. Pushing it firm helps keep the layers tight so there is no space between the layers for the rivet to swell into. It works best when the gap between the faces is adjusted to be the largest at rest but will make the rivet set. Adjust the riveter with the handles tight together so the gap is about a 1/16" to just touching to get the set. The big gap at rest then makes the handles have to come a lot closer together to contact the rivet. It allows the rivet to be set easier with the both hands working together & easier to keep the tool square. It takes concentration to keep the riveter square as it is easy to put the tool off square while feeding the muscle to it.

The riveting is more difficult if the riveter is screwed out a long ways so that the gap is smallest at rest so the handles make contact early leaving a wide gap between handles. The hands have to work separately because of the spread with pivoting arm off at an angle. The wide handle spread makes it easier to get out off square.

I hope this description makes sense.

A good rivet cutter is a worth the investment. There are lots of odd rivet lengths encountered all along the way & the tool is handy to adjust & trim rivets.

Glenn
BH727

[Glenn Patterson]

One further thought after the photo to measure the rivet. Measuring rivets can drive a person over the deep end if seeking absolute perfection. Close is sufficient. The AC43 requires that the driven side be 1.5x the diameter with the height .5 diameter. The AC43 is a code standard with those dimensions for the proper dimensions for a rivet before and after. That is the "code" minimum. If the driven rivet has a shop head slightly larger than 1.5X dia and slightly higher than .5 then it meets & exceeds the AC43. The code is a minimum so being a whisker oversized is acceptable and reduces the anxiety of pursuing absolute perfection. Once a person has the length right and gets into the rhythm of bucking, they can set the rivets visually w/o having to measure every one & they will measure okay. Bob Barrows told us to set the gun pressure a little lower and it may need a couple more hits but it is a lot more controllable than a riveter running high pressure and hitting the rivets hard. I think if a person has been riveting for years that they can run with higher pressures and can time the gun easily to set the rivets fast & accurately. Speed is more important in aircraft production.

Glenn
BH727

[Chris In Milwaukee]

Thanks Glenn. I think that once I get "the feel" down, it'll take little effort. I'm waiting for a new rivet set to arrive that's the correct size for the -3s. The one an only rivet I set with the gun was set with pressure obviously too high and with a -4 rivet set on some scrap material. Not ideal, but it set nicely, and I can see I need to turn down the heat. It might just be easier to use the gun over the squeezer, but I'll certainly use the techniques you outlined above to see if I can fix that up as well.

[Chris In Milwaukee]

Wow, then I am *way* too high! :-) I'll do some experimenting. I, too, would prefer the squeezer for that very reason. Practice, practice, practice...

[Glenn Patterson]

There is a lot of information out in the world with much higher PSI. My partner was frustrated with the riveting & in a conversation with Bob learned that he used lower pressures & it gave good rivets. It may take a few more taps but it is not as violent & one gets to know how long a burst to set the rivet. If it is under driven then just give it a couple more hits.

[N3UW]

I personally would rather buck than squeeze a rivet. I find bucking much faster and I get more consistent quality. The key for me is the right size gun and the proper pressure. I use a Sioux 2x gun for my smaller rivets and a 4x gun for the bigger rivets in the spar. I also use a separate regulator for the rivet gun. I do not personally like the little screw regulators on the button of guns. I have better results with standard regulators. The other thing I absolutely love are tungsten bars. I do not know how I ever lived without them before, I have two and one of them I use for about 90% of my rivets. I also love the small rectus air hose fittings and hoses that I get from Cleveland aircraft tools.

[Chris In Milwaukee]

I couldn't get the regulator on my compressor to go down to 40psi, but I set it around 50psi, and adjusted rest with the clicky knob at the rivet gun. WAY easier to drive the rivets now. Much better control. And not loud and annoying like when it was much higher.

I practiced on some scrap with an oversized rivet set until my new ones come in. Plenty of smileys on the scrap, but the rivets are squishing really nicely.

[Glenn Patterson]

Chris,

You are on the right path. Take scraps & practice a lot of riveting. It is cheap & a good way to get experience. A good pair of sound muffs makes the work comfortable.

The bucking bar is the critical component, must be kept square and has to be done well so the riveting is successful. The person or hand on the bucking bar makes it win or lose. Each person has to experiment & learn what works best for them.

In our process the rivet gun was pushed tight on the rivet and a light touch with the bucking for a couple taps with the gun. That starts the rivet expansion holding the layers together & seating the head. Then the bucking bar can be pushed firm against the rivet & driven to final set. The light touch with the bucking bar also prevents the bucking bar from pushing the rivet hard so that it backs out on the gun side to get off to a bad start. If the rivet is unseated by the bucking bar then it can swell on both sides so the head is raised. Check the head after the first couple taps and if it is not seated properly then the bucking bar can be set beside the rivet with moderate pressure and a couple taps on the gun to push the rivet in. If it looks good then finish the rivet. If its look bad then stop & remove the rivet. It is a learning process of eyes and ears. Building the Bearhawk is an education and experience. The definition of experience. "Experience is something that a person has when they are finished that they really could have used when they started".

My partners picked up a riveting set exactly like this one at Oshkosh many years ago at a reasonable price. https://www.aircraftspruce.com/catal...clickkey=38078
This set did everything we needed & it is not a big investment. We modified a couple of the bucking bars along the way to fit into tight spaces. We also made a Barrows bucking bar that was in one of the Beartracks once upon a time. We used the Barrows one a lot and it worked really well for a lot of the work especially the spars.
We also had the full set of countersink and dies for the manual rivet squeezer similar to this set. The cost of this set hurts but it did a lot of work. https://www.aircraftspruce.ca/catalo...clickkey=61460 I don't remember as many flats but we had all the dies & used them steady along the way. We built the long arm dimpler with 2" square tube & a pc of 3" channel that was scrap material on hand. The long reach dimpler was at no cost & is easy to fab up. The long reach dimpler uses the same dies as the hand squeezer for dimpling.

A quality regulator & filter close to the compressor is invaluable. The filter will help take water & oils out. Use 3/8 rubber airline with 1/2" quick disconnects. The 1/2" quick disconnects will not restrict flow at the 1/2" QD fittings as they will be full port for the 3/8" air hose. These oversized fittings are bushed down pipe bushings. The oversize QD fittings are the same cost & make a more effective air system. Setting the airlines up like this will allow one to use the same hoses for painting where it is really critical to eliminate all the restrictions in the air hoses so the spray gun works to the full potential of the compressor. Small fittings and undersized hose will strangle the air to a spray gun.

Good luck
Glenn

[Chris In Milwaukee]

My new rivet sets and some rivets 1/32" shorter than the other batch arrived today. Now let's give these things another go, shall we?




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[Chris In Milwaukee]

Great night of riveting. I had planned to try squeezing these by hand, but my practice pieces just weren't coming out the way I wanted them. So using Glenn's advice while riveting, it went crazy fast, repeatable, and fabulous. No squeezer, all rivet gun and bucking bar.

My usual helpers Don, Daniel, and his son Riley were on the assembly line tonight.
















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[Glenn Patterson]

The rivets & ribs look great.
Your knob on the gun probably is dialing down the pressure as well. A good regulator is best as the pressure adjustment can come off the gun so it is left wide open & the air dialed down at the regulator. It is quicker jumping between rivet sizes to simply adjust the regulator as the settings are visible & repeatable. We would push the gun with the rivet driver firmly against a pc of 2x4, pull the trigger to see what the pressure drop was as a check once in a while. Barrows recommended turning the pressures down for the smaller rivets so we used 40 psi for 1/8" & 30 psi for 3/32" at the regulator. The control is so much better & the rivets are perfect as you found. I think we have just the one light smiley. For the larger sizes especially in the spars the pressures need to be up. I had an injured hand when riveting the spars so holding & controlling the bucking bar with two hands was memorable.
Look forward to seeing your Expedition come together.

I wired up our instrument panel & the transponder was not operating properly. We bought a second hand one & it just came back from the repairs. I have to reinstall the transponder. Once that is cleaned up we can take the airplane to the airport to mount the wings & finish it up. Looking forward to getting the airplane done so I can get on to other things.
Glenn
BH727