355 hours on the hobbs - Pounding rivets on the right elevator!

Airplane building notes aside, I am going to start a new Label called Motivation. VAF often has motivational posts like this on their home page that include scenic in flight photos with awesome scenery backdrops, and tug-at-your-heart pics like dog rescues. So here is some "off-into-the-sunset" motivation that I hope to chnage into a reality one day when the plane is finally done. One of reasons I love living in Colorado is that the Fall season is absolutely spectacular. The temps are just right, the air is calm and still, and the sunsets, similar to the one captured in the next two pics, are also spectacular. Just picture my RV flying off into the sunset to some exciting destination, just me, the plane, and the sky, all to myself........

Now back to "reality," or the unfinished airplane. Have to finish it to allow the motivation described above to become a reality. As the caption states, I finally got past the priming fiasco - sort of. I finished one can of my expensive two part self-etching primer, and opened up another quart can that I purchased some time ago. As stated in the previous post, The first coat of primer was less than desireable, so a second coat for some of the parts was absolutely necessary. I opened and mixed the primer, and expected it to apply in a similar manner as the first coat. Unfortunately, this primer came out a slightly different color for some reason. So now I have some two-tone colors on my parts here and there. Not a big deal for me, as the only reason is it there is to provide some means of corrosion protection.

Right elevator parts primed:

Removed all the vinyl from the inside of the skin:

And now on to the next challenge, or as we are often told at work, "opportunity":
I still had some work to do on the lead counterweight. On the right elevator only, the plans call for removal of a specific amount of the lead so that the balance point on the elevator is as close to correct as possible before it gets painted. The left elevator has more overall weight due to the addition of the trim tab and supporting structure, so none of the lead has to be removed for that side. Vans provides the same size counterweights for both sides in the kit, so the one used for the right elevator has to be trimmed down for it to be properly balanced. Just how to perform this removal was not described in the plans, so once again I had to resort to the methods of others that had gone before me.

I checked Steve Riffe's builders log (He uses Kit Log Pro as many other RV builders do), and found that he drilled a 1/4 inch hole after marking the weight for the area to be removed, and then said he used a hack saw to trim the lead. So I started this same approach, and had a terrible time getting the blade on my saw to remove any material once it was deep into the lead. The lead weight is very heavy, and is also oddly formed to match the curvatures of the rib flanges that it rests against, so it is not easy to clamp down and hold in place on a flat surface either. It is so easy to distort the soft lead and ruin the required shape of the counterweight, so you ahve to be careful when securing it. In fact, during this process, I actually dropped the weight onto the concreate floor of my garage, and, you guessed it, I deformed the lead just a  bit. It messed up one of my screw holes, and the countersink for that hole, which also became distorted. Here are just some of the tools I started with to perform this job:

Then I had another brilliant idea - why not use my jig saw and a metal cutting blade. Only problem was, I did not have a blade long enough to penetrate the two inches or so of lead that I would be slicing through, and that would spell disaster. If you have ever tried to do this on a piece of wood where the wood is thicker than the blade, you know what I am talking about. So that was out of the question. How then was I going to get this done without further screwing everything up? Answer, my 14 inch RIGID band saw. Even though it had a wood cutting blade, and the speed is designed for cutting wood and not metal, it worked like a charm, and cut through the lead like a knife through warm butter. Just be sure to lubricate and clean the blade afterward to prevent fouling the wheels on the saw. So I turned a 45 minute fiasco into a 5 minute success. I was even able to re-drill the damaged hole and countersink it again as well. Amazing stuff, lead is...even if California doesn't think so.

Here are pics of the counterweight before and after making the cuts and smoothing the edges. First is the 1/4 inch hole. I decided to be brave and not step drill this since there seemed to be enough material to be able to drill the hole to the final size from the beginning, and I was not drilling through any additional metal. This was a pain in the ass. I used my cordless drill for this task, as I knew I might need the extra torque. I drilled slowly, lubricating the drill bit with oil and then drilling small amounts and backing the bit out repeatedly as I went. Problem was after you get about 3/4 inch in, it gets very hard to turn the bit, and even harder to get it out if it gets stuck. I had to manually back it out several times since the chuck of the drill would only spin around the drill bit, no mater how tight you tried to chuck it. I drilled about an inch on one side and then turned it over and drilled from the other side, hoping that I would meet in the middle. The plans call for 5/8 inch or at minimum 1/2 inch of material as measured from the TOP of the counterweight as drawn in the plans. Both my drill holes ended up right where they needed to be.

Not shown in this next shot are all the preliminary cuts I made with the coping saw and a double sided hand saw. This pic is after I sliced it using the band the saw, which is the preferred method for this task:

And another view:

I purchased a very expensive set of files whne I ordered my original tool kit, including a vixen file, from Ceaveland Tools. This was the first time I actually used several of the different files in the set to finish dressing out the lead after the cuts were completed. I used a flat file to smooth out the recessed area where the lead had been removed, and I used a tapered round  file to remove the cut lines and radius the 90 degree cut lines just a bit. Then used a straight file again to smooth the edges and remove excess slag from the cuts.

Proof that my measurements were pretty good on both sides of the lead. The drill went straight through both sides.

Shows some of the cuts I was making before the lightbulb went off and I decided to push the easy button and use the band saw.

When I dropped the weight, it landed on one end. Here is blurry pic of the damage that I was able to repair:
Note the slightly oblong looking edge and countersink on the end:

Everything all filed clean, holes and countersinks repaired:

Bucked all these rivets for both back plate support brackets and nut plates, similar to what was done on the Rudder.

And the other side

And on the inboard plate:

Time for another area that I have not had much success with until lately - riveting the ribs to the spar. Got a great tip from Steve, who got it from someone else, for the end ribs. The plans say to rivet the end rib E703 to the counterweight rib, and then rivet that whole assmebly to the end of the E702 spar. Problem is, if you do it in that order, you have problems getting a squeezer or even a bucking bar in there to do the work.

Due to the many major problems I have created for myself in the past, I refuse to use the air squeezer in areas where the risk of damaging parts or screwing up AN470 rivets is a very real possibilty. Instead I use my double offset rivet set and buck ALL rib-to-spar AN 470 rivets to ensure they are set correctly. Steve also points out that the rivet call out for this area tends to leave rivets a little bit long. If you use an air squeeezer on these rivets they most often times will clench, or lean over to one side.

If you take your time with a rivet gun and bucking bar on these same rivets, I have found you can actually correct a clenching problem as long as you catch it early enough and maneuver the bucking bar to force the shop head of the rivet back on the right track. I also use a lower pressure than most when I drive these rivets, as I have found that this, in combination with using masking tape in the head of the rivet set, helps prevents smilies in the metal, should you not hold the rivet gun exactly straight on the rivet head while riveting.

 

 Here is the counterweight rib. The trick is to attach this rib by itself to the end of the spar first. Do not rivet the end rib to the counterweight rib as the plans describe.

One rivet set..... E704 Counterbalance rib is show on left side, and the E702 spar is shown in the middle to right side of the pic.

And the other side with shop heads after both rivets are set:

Manufactured heads look good:

Now you cleco the end rib to the counterweight rib, and also to the other spar flange. This allows you to get your squeezer/bucking bar in there...

Securing the work as you rivet the two ribs together...This keeps the ribs from flexing too much which caus smilies on the skin or the rivet from the rivet set not being firmly placed against the rivet head. You need the proper amount of resistance on both sides of the part to ensure a nice, clean, correctly driven rivet. I just used some shims and some 1/8 inch thick hardboard plates from the packing materials that I had lying around the shop.

I like to work on the top side rivets, and then turn the work over and reclamp everything, so that I can clearly see are the rivets that I am about to buck or squeeze. So I do one side of the rivets, the turn the work over, reclamp, and do the other side. That way the other rivets do not get in the way of me being able to see the bucking bar position on the rivets I am driving.

I need to get a pic of the modification I made to my no hole yoke. I needed to put it on the grinder to trim the sides down and to also grind down the top. I should have done this way back while fnishing up the leading edge rivets on the Horizontal Stab, before I screwed them up so bad. The problem was that the no hole yolk still has a significant incline associated with it, so I found that it would still not work very well for close quarter riveting, since the yolk would still bottom out on the other side of the rib or skin. I finally came across some posts on VAF where they explained that they ground down the taper on the yolk so as to allow it to fit inside smaller areas where riveting needs to occur. The pic will explain it better than the text.

Anyway, My immediate need is to make the yoke skinnier so that I could get it into the area of the E709 root rib and E702 spar. This rib flange is angled over 90 degrees to allow for the proper amount of rudder travel on either side of each elevator, and it makes riveting the 4 flush rivets that attach this part a bit of challenge. After grinding down the no hole yolk I was able to get it onto the flush rivets using a half inch long by 3/8 inch wide rivet set in my hand squeezer, without having to bend the rib out of the way to set the rivets. Here are the shop heads of all four flush rivets after squeezing them.

And finally, once the flush rivets are set, you get to attach the control horn onto the end. The pushrod from the control stick in the fuselage attaches to the control horns and allows the elevators to move up and down. The control horns are powder coated and welded pieces of steel. The rivet call out in the plans is for AN470AD4-4 rivets, but these end up being a little short. I have had this same experience when riveting other powder coated parts. I don't think that vans allows for the thickness of the powder coat, and this is why the call out seems short. If the rivet is too short you will not get a proper shop head on the rivet. So I finally experimented with my rivet cutter for the first time. Since a 4-4 rivet is too short, and a 4-5 rivet is too long, what I really needed is a 4-4.5 rivet. Problem is that the cutter is not set up for such odd dimensions. So what to do? I determined that my ruler is about 1/32 inches thick, and so I used that, in addition to a 4-6 rivet, to create the proper sized 4-4.5 rivet. The cutter defaults to a 2/16 inch cut on the end of the rivet without using any of the spacers, which are each 1/16 of an inch thick. This seems to give me just about the right rivet length to work with, and they appeared to set just fine.

I should be able to finish up the control horn and start riveting the frame to the skin tomorrow. Felt good to set some decent rivets again.