410 hours on the hobbs - Replacement ribs and spar arrived

Finally got my replacement E702, E703, and E704 replacement parts from Vans yesterday. I ended up having to re-do about a half a page of prep steps in order to get everything back to where it was before the riveting blunder described in my previous post. When the parts arrived, they were in a very thick cardboard tube. I removed the spar only to find that the flange on the tip of the spar had been badly bent over during shipping. Upon close inspection, and after bending the flange back into place, it looked like the rivet holes were not compromised, and the skin was not creased in any way, so I was able to flatten everything back out with the rivet gun, a flush set, and a back rivet plate. I was beginning to think that this elevator is becoming a bad omen for some reason, but elected to try to push through it and keep working on it.

I also managed to remove the former E703 tip rib from the former messed up spar. Unfortunately the rivet holes where very badly mangled after attempting to set the rivets with a flange that had become badly deformed after screwing up the E704 counterbalance rib (see previous post). I tried to take my rivet gun with the mushroom flush set and lightly bang out the mangled metal around each hole using a back rivet plate, which seemed to work OK, but the rivet holes still appeared to be a bit oblong from attempting to set the rivet in a badly bent flange. I had originally thought I might be able to re-use the tip rib so that I would have less fabrication to do on new parts, but that turned out not to be the case.

Here is a list of all the things I have done in the past two evenings to get all three parts back to the state where I am ready to attempt riveting again:

1. Flute both ribs and straighten the edges with my edge bending tool. I found another tip on a builder web site after searching VAF that reminded me that the real purpose of fluting these two ribs is to make absolutely certain that the webs of both ribs are flush with each other with no gaps. This makes attaching the E713 counterbalance skin a much easier task, since th holes line up pretty well if the ribs  both fit together properly.
2. Remount the E714 lead counterweight so that I could re-drill the bolt holes in the forward flanges of each rib. With the bolt holes already in the counterbalance skin and the lead counterweight, I was able to take a number 10 drill bit and lightly mark the forward flange of each rib by turning the bit by hand. Then I disassembled the rib assembly and step drilled the holes in each rib flange to the proper size using the same technique described in earlier posts when I originally performed the counterweight preparation steps. These new holes actually turned out much better than the previous holes. It's much easier to mark the flange when the holes in the E713 counterbalance skin and the E714 lead counterweight have already been drilled. The new holes ended up much closer to the center of the flange this time, so that was a good thing.
3. Match drilled the rivet holes in each rib web attaching the E703 and E704 ribs together. Also match drilled the flange rivet holes in both ribs. (You know, the ones that totally screwed up when attempting to rivet them previously).
4. Clecoed the entire elevator frame to the elevator skin and match drilled all the remaining spar-to-skin attach holes, including drilling the 4 holes that are not predrilled on the ends of the E703 tip rib. Match drilled the counterbalance skin holes to the holes in both ribs.
5. Disassembled everything, deburred all the holes in the ribs and the spar, and dimpled them.
6. Countersunk the 4 holes on the inboard section of the spar that attach the E705 root rib to the back of the spar.

Now I just need to finish edge deburring the parts, and clean, prep, and prime them, and I will be back where I was a week ago, supposedly ready to rivet. I will tell you that it was not fun trying to cleco and match drill the new frame parts to a skin adn other parts that had already been dimpled. I am a little concerned that the holes and dimples may not line up as well as they did before, but I have done this sort of thing in the past and not had any problems with the parts fitting together correctly, so we shall see....

I went on VAF in search of info about how others had tackled the end rib riveting problems. Not surprisingly,  I found many others that have had similar problems with this part of the assembly going back as far as 2005. Most were saying that the solution is to hand squeeze these rib flange rivets, and to use the tip of riveting the flange of the E704 rib first, followed by the E703 rib, before attaching the two ribs together via the rivets in the webs of each rib. Van's instructions still say to attach both ribs together first, and then attach the whole assembly and rivet the flanges to the spar, which just does not work out if you try to do it that way. The problem is that while most were describing using the workaround, I could not find any pics of the yoke, rivet sets, and positioning they used to set thse rivets. Then I finally found one. You need to use a flange yoke, a 1/8 inch x 3/8 inch AN 470 round head rivet set, and a 1/2 inch x 3/8 inch flat rivet set on the other end. It is always a little harder to squeeze 1/8 inch rivets with a hand squeezer, but it can be done, and you have much better control with the hand squeezer. You have to leave the tip rib off when you set the flange rivets for the counterbalance rib, because the thickness of the squeezer prevents you from being able to get the round headed set over the head of the rivet due to lack of clearancefrom the tip rib. All you have to do is flex the counterweight rib out of the way just a bit, adn you can set the rivets correctly.

I bet I could convince Vans to give me job where my sole responsibility would be to evaluate and identify all of the latest build issues from their current set of plans for every airplane kit that they provide, determine the work arounds that are being used to correct the problems, and update all of the plans for each aircraft to incorporate the new and better building techniques. The fact that they seem to have no interest in receiving this info and making the changes to their aging sets of plans really pisses me off.

Anyway, I digress. For the record, I wanted to include some "before" pics of the fit of the flanges for both tip ribs against the spar before I rivet them together. If you compare these to the pics at the end of the previous post, you will see just how messed up the flanges of both of the ribs are. The way they appear in these next pics is exactly the way they should look after the flange rivets are set:

Notice that there are NO gaps in between the flanges in the above pics. Everything is nice and flush. Should be ready to try this again tomorrow, after verifying the correct rivet lengths, ensuring the parts are clamped tightly to the table, grinding down my yoke just a bit more, and borrow another set of hands to help hold the rib out of the way. Maybe this time it will work out......MAYBE.

405.5 hours on the hobbs - prep parts for primer and start riveting

Nothing posted for a while. Short story is that I prepped and primed all parts with primer, nad began to rivet the tips to the lef elevator E702 spar. I bucked these rivets just as I had done before on the right elevator, expecting the results to come out the same. What I got instead was severely clenched rivets, followed by less than succesful attempts to remove the rivets, followed by more unsuccessful attempts to drive new rivets, followed by badly deformed holes, and severely deformed aluminum resulting from the attempts to drill out and remove multiple rivets . As a result, the spar is trashed, as it the counterbalance rib, so new parts are on order. Not happy about this at all, since this will seriously challenge the accompishment of my goal to be finished with all the tail pieces by the end of the year.
This will set me back by at least a week if not more.

First is a pic of most of the trim tab and elevator frame parts all cleaned and scuffed and ready for primer.

The only thing that was not prepped was the other half of the trim tab hinge that still has to be fitted and drilled. And of course, now I will have to prepare a second spar, third counterbalance rib, and second tip rib when they arrive from Vans.

Next is the trim tab and elevator riblets, the trim tab control horn halves, and the trim tab-half of the hinge, ready for priming on my makeshift priming table.

Next is all the other parts hung up on the wire and ready for priming. Lots of parts for both the elevator and trim tab.

And now for the really funny part. Normally I have been using my expensive two part self etching primer for the larger pieces of aluminum. The only realt reason for this was to avoid having to buy cases and cases of NAPA 7220 primer in the can. When I went to open the quart can of the primer base, it looked more like the material used to make Silly Putty than primer, and had about the same rubbery consistency. Needless to say that this was not going to go through a spray gun, no matter how much I tried to reduce it. So another $64.00 down the drain. This pic was of the setup for the two part primer application just before I discovered the primer was bad.

So the solution to the problem to avoid any further delays was to go ahead and use the 7220 primer for all the parts. Here they are all ready for riveting:

Next is a more close up pic of yeat another attempt to instroduce an adequate amount of light to one side of the parts that are strung up on my priming wire. My garage lights are closest to the work benches, and I string the wire up on the opposite end for ventilation and to prevent priming other things not intended to be primed, but I then suffer a penalty for lack of light on this area. The problem is that I get great sun light from the open garage door, so I can see that side of the parts very well, but I get shadows and severe lack of good light on the other side. So I tool part of the wing jig, mounted two of my High intensity reflector lights to the angle, and that seemed to work OK.

And finally the crappy rivet on the top that has set me back yet again. I can't even begin to tell you how sick and tired I am of trying to buck rivets in all these teeny tiny places. You do everything absolutely correctly to get to this point, and then it all goes to shit in a heart beat. Really sick and tired of this. Oh well, get new parts and try it again.

Followed by the crappy pic of the other side of both rivets. Really really bad.......No chance to salvage this - they had to come out, which lead to the distortion and final demise of the spar web in addition to the rib flange. If your shop heads end up looking like this, then they need to come out - no question.

Another one of the shop heads. Here is where is starts to get strange. It's hard to see in the pick, but if you look at the top rivet head, and then notice the bottom rivet head appearing at a slightly different ange than the one on the top, this is how the rivet shafts were sitting in the metal before I even began riveting them. They were obviously at different angles to each other, implying that something was wrong with the spar web or spar flange, or both. I noted that the manufactured heads on both rivets were not sitting at the same angle either. I ahve no idea why or how this section of the spar would ahve become so messed up, other than this possibly happening at the factory when they were forming the part on the bending break. It would not be the first time I received a badly formed part from the mothership, and probably won't be the last. Of course, it's much easier to blame them than it is to blame me, right?

And here is the setup I used - same as I did for the right side.

For whatever the reason, I decided to go ahead and set the two rivets that attach the tip rib to the E702 spar flange which is 90 degrees opposed to the other flange that attaches the counterbalance rib to the spar. Those were set with the pneumatic squeezer using the flange yoke without any problems. Unfortunately they will have to come out since the spar is now damaged from the failed attempts to drill  out and re-set the rivets for the counterbalance rib. I was so disgusted at this point I just decided to order all the tip ribs and a brand new spar:

And the final pic that shows just how messed up the fit of the two ribs is against the spar. None of the flanges are lying flat against the spar or the ribs. This was totally messed up and I am still at a loss as to the reason why. The counterbalance rib flange was bent while trying to move it out of the way to drive the rivets with the double offset rivet set, so I can explain that one, but the fit of the tip rib flange to the spar is also messed up.That one I cannot explain. Hopefully the next post will be a better one.....

402.5 hours on the hobbs - fabricated 3 riblets for trim tab and elevator

After a ton of research on Steve Riffe's and several others builder sites and logs, and a break in our super chilly weather here in Denver, I was able to fabricate the two end riblets for the trim tab, as well as the end riblet for the left elevator cutout which sits adjacent to the outboard edge of the trim tab. I also have to say that I did get a little distracted listening to our Denver Broncos pull out another miracle finish against the Chicago Bears this afternoon, to take sole possession of first place in the western division. Go Broncos!

This weekend was slow in terms of airplane building. Had to do the annual Xmas shopping yesterday, and got a new Smart phone as an early present, which I of course I just had to mess around with this morning. So the weekend airplane work did not actually commence untlil about noon today.

As a preface to the coming photos, let me just say this: Did I save any time on my build by choosing to make riblets instead of bending the dreaded tabs - NO! Did I end up with more piece of mind using the riblet solution without ruining any parts, or having to build a second or even a third trim tab in the process -  YES! So, if you are builder who seeks info about bending the tabs, do not waste any time hunting my blog for that. However, if you choose to cut the tabs off and make the riblets, then read on.

During the process of making the riblets, I encountered many twists in the road that most other builders don't seem to comment about, and I have tried to mention them in this post for the benefit of future builders. If you read my blog, you know by now that I like the details, and I also like to dispell as much of the doggone mystery about some of this stuff that I can.

Here is what I learned and how I made my riblets:

I had already trimmed the edges of the trim tab skin very close to their final state, but I needed to trim the edges of the elevator cutout where the trim tab resides just a bit more to allow enough clearance between the trim tab and the elevator. In this pic I have the skin laid out on my table with the 2x4s slid underneath. I then clamped everything down, and performed a bit more "dremel surgery" with the cutoff wheel to carefully trim away about another 1/8 inch of material from the top and bottom outboard trim tab cutout edges of the elevator skin. My measurements for the long edge of the trim tab cutout were about 17 and 22/32 inches, so this is the minimum amount needed to allow the trim tab to just fit inside the cutout in the elevator so that the edges of the trim tab will line up with the edges of the elevator.

This setup provided enough stiffness and separation of the edges of the elevator to allow me to keep two hands on the dremel tool to keep from making a costly mistake. One slip up here and you will order a new skin, so take your time, secure the work, and move slowly with the dremel tool, and it works out fine. I cut just outside the reference line I drew to leave a bit more material than desired, and finish trimming by using a file to trim away the remaining material up to the reference line.

Next is something I am a bit concerned about, and I will need to talk to Vans tomorrow, before removing any more material on the edge. Vans has you draw a line on the elevator that is perpendicular to the long trailing edge to determine the bend/cut line for the tabs. I expected that the corresponding matching edge of the trim tab would also be perpendicular to the LE of the trim  tab so that both edges would line up evenly. Unfortunately, I found this not to be the case. Upon trial fitting the trim tab in the cutout of the elevator, I found the outboard edges were not aligned as expected, and the trim tab edges are anything but perpendicular.

You are supposed to end up with a minimum gap between the elevator edge and the outboard trim tab edge of at least 3/32 inches. To correct the problem,  I think I will be able to trim the extreme trailing edges of either the elevator or the trim tab to even out this line, and still have the appropriate gap. SO much for cutting straight lines on everything. The next pic shows the additional amount I originally marked that needed to be trimmed from the elevator. Advice to future builders is to avoid trimming anything additional from this area until you actually start fitting the trim tab and hinge assembly in place.

And here it is after cutting and filing the excess down to the new line:

Next, the riblet fabrications begins. What do you need?

2 Vans practice Kit ribs (I don't know the part number but there is one for them - call Van's to find out what it is. thanks again to Mike Rettig for providing me some brand new untarnished ones so I would not have to tear apart my completed practice kit like Steve did!

The riblets fabricated from the ends from these two ribs will go in the OUTBOARD edge of the trim tab and in the edge of the elevator that sits next to it.

1 E703 elevator tip rib. Order one from Vans, or use a discarded one if you messed one up during elevator construction.

The riblet fabricated from this rib will go in the INBOARD edge of the trim tab, or the edge closet to the rudder when mounted on the fuselage.

Here is a pic of the remnant from all three ribs to give you some idea of where I made my initial cuts.

Now to describe the process I went through. This was a bit painful, and involved a lot of measurements of the gaps between the skins, and length measurements from leading to trailing edge, followed by transfers of all those measurements onto the rib stock, followed by more measurements, and more trimming, etc. I must have measured everything about 20 times before deciding where to make the first cut to separate the ends of each rib from the original part.

I essentially used a "more is better" approach, meaning that I took my original measurements, and added a bit to them just to be sure I did not cut anything too short. The elevator riblet pretty much gets cut symetrically off the end of the practice kit rib, while the other one for the outboard edge of the trim tab tends to have a bit of an angle on the leading edge due to the angled nature of the trim tab forward spar. The web on that spar, which has a Z bend on both ends for the flanges that attach to the top and botttom of the trim tab skin,  is not vertical, but sits at an angle.

Next I will go ahead and provide some "finished" photos of each riblet. First is the OUTBOARD or smaller end riblet for the trim tab. On the bottom of the forward part of the riblet you see a small cutout for clearance of the trim tab spar flange. You have to make this cutout to clear the edge of the trim tab spar flange. I suggest measuring to obtain about a 1/8 inch clearance, which is a standard clearance for most other non-attached rib-to-spar clearances. The hole that you see is a tooling hole from the original rib - I consider it a lightening hole (haha). Just debur the hole, and that is all you need to do with that.

Also notice the clearance from the end of the riblet to the trailing edge of the trim tab, and a slight rise in the forward flange of the trim tab skin where it joins the top flange of the trim tab spar. I was not very happy about this. It seems that the angle of the prefabricated practice ribs does not quite perfectly match the angle of the trim tab skin after attaching it to the forward spar. I will need to decide how to manage this, but for now some scuffing for primer and trying to work the edge of the flange of the riblet a bit more to reduce the width are all I can think of. The trailing edge of each riblet will sit just a bit forward of the trailing edge of the trim tab and the elevator to achieve the correct angle to fill the gap between the skins. Of all three riblets, this one does the worst job of mating correctly to the trim tab skin. Options are to make a wood form, take some of your spare metal, and form your own, as many other builders do. I'll have to ponder that this week to decide what I will do - leave it as is or form my own.

You should also know that I did not trim anything off of the trailing edge of this riblet - I used the original trailing edge and only trimmed the forward portion to fit it. Lastly, and this is a personal choice - you can face the web of the riblets inward or outward. For the trim tab I chose to face the web of the OUTBOARD riblet toward the outside to create a difinitive edge that will have the same effect as bending the tabs.

Next is the other side of the trim tab, or the INBOARD side. This riblet is made from the E703 Elevator tip rib, and is much longer and a bit wider than the one on the outboard edge.It will be placed as shown with the web facing inward, to match the edge of the E705 root rib, and allow solid rivets to be used on the flanges instead of pop rivets.

Oh, I guess I should have mentioned something about the rivets. Some holes will be drilled in the flanges of the riblets, and in some cases existing holes will be used. Then they will be dimpled for flush rivets. On this one I can set the rivets with a squeezer, but on the other two, with webs facing outward and flanges facing inward, I will need to use flush pop rivets for those, since the web will close off the access to the flanges. This is all by design.

Again, notice the slight cutout on the bottom forward portion of the riblet, and the clearance from both the web of the forward trim tab spar as well as the bottom flange. Also notice where the riblet trailing edge ends, forward of the actual TE of the trim tab. For this rib, I actually had to trim off about 1/4 inch or so of the end to preserve the correct angle of the trim tab skin without bulging it. This one actually sat much better inside the skin without bulging the leading or the trailing edge too much.

One other very important thing about making this riblet is that you end up utilizing one of the existing holes in the original part without needing to drill a different one. this is the hole on the bottom where one of the two halves of the trim tab control horn is mounted to the bottom of the trim tab. In other words, You will be setting a rivet through the control horn, then the skin, and then the riblet flange which is directly underneath. You can use this existing hole as a reference mark to determine how much to trim off of the front an rear portions of the riblet. Just keep lining up the existing hole in the bottom flange of the riblet with the existing hole in the skin, and put a cleco in there once you get it lined up and trimmed up enough. Then you can fine tune the LE and TE of the riblet accordingly.

One other note - - The rivet holes for the OTHER half of the trim tab control horn assembly end up being very close to the web of this riblet. I will need to decide if I am going to cut a recess on the webof the riblet in order to clear that area, or if I will simply put some RTV over that rivet to prevent any potential cracking from vibration, etc. It appears as though it will sit just on the edge of the dimple in the skin, so there is just enough clearance for the shop head of the rivet, but it is VERY close to the web of the rib.

You may need to trim the flanges a bit to line them up with the edges of the trim tab skin. All rivets that attach the control horn, skin, and this riblet can be set with a squeezer using solid rivets. Just be sure to increase the rivet length where necessary to account fo the additional depth of the flange of the riblet.

Lastly is the riblet that goes into the end of the elevator. This one was fairly easy to fabricate from the other practice kit rib. You do NOT have to cut a fancy recess in the bottom of this riblet like you do with the other ones, but you do need to ensure that there is sufficient clearance from the edges of the spar flanges on the front of the riblet. Again, notice the gap in the trailing edge of the riblet. This one also used the original trailing edge from the original part. I did not have to trim any of the trailing edge off of this rib.

So here are a few more pics to point out specific areas of interest in this process. Here is a blurry pic (sorry) of the cleco inserted into the INBOARD root riblet hole of the trim tab riblet I mentioned earlier.

Next is a close up of the forward portion of the same riblet to show the clearance from the spar web and the bottom flange of the spar of the trim tab. This gap is only 1/8 inch or less, so don't let the close up fool you into thinking that it is bigger than that.

Next are the two trim tab riblets by themselves. The pic on the top is the outboard riblet, and the one on the bottom is the inboard riblet.You can see the original hole in the bottom of the flange of the inboard riblet. You can also see more detail of the recesses I cut in each forward portion to clear the bottom trim tab flange, and the two original holes in the outboard riblet. Not sure if I will be using these or not, but will let you know what I decide. The upper flange holes in the inboard riblet (bottom) are a different story. I may use the most forward hole, and then make new holes and space them evenly along the flange accordingly. It is OK to leave existing holes and make new ones as long as you maintain proper clearance of each hole.

Next are the same two parts flipped on the other side, again for better clarity.

I was able to rough cut the recesses in each flange using the dremel cutoff wheel, and cleaned up each cut and trimmed it to final size with the Scotch Brite wheel. I ensured that each part was securely clamped, and that I could keep both hands on the dremel tool at all times. Had to keep a close eye on each cut, so safety glasses were a must. Also wore ear muffs.
Next is the elevator riblet. This one ends up with three rivet holes that I will most likely use, but if I need to space them out differenty I will do that.

And here is a shot of the trailing edges of each riblet so you see the difference between the ones created from the practice kit ribs and the one from the E703 elevator tip rib.

And finally a pic of the inboard riblet that shows both the top and bottom original holes in each flange.

I ended up doing a lot of cutting and trimming and cutting and trimming. I wish I could spew out exact measurements for everything I did, but you really end up doing most of the fitting on a trial and error basis to get the exact fit that you desire. I ran out of steam after getting them to fit where I wanted them, so I will finish fitting everything tomorrow. The hard part is done. The only other intense activity is the measuring of the other half of the hinge that attaches the trim tab to the elevator, and positioning the trim tab servo mounting brackets. Then I can drill and dimple holes for all the riblets, prime everything, and finally get around to riveting this bad boy together.

397.5 hours on the hobbs - trim tab reinforcement bracket platenuts installed

So today I tackled the dreaded nut plates on the trim tab support bracket that I had previously back riveted to the elevator skin. Several notes again about this - MAKE SURE TO INSTALL THEM IN THE BRACKET BEFORE MOUNTING THE BRACKET TO THE ELEVATOR. Next, BE SURE TO GRIND DOWN ANY EDGES OF THE NUT PLATE THAT STICK OUT BEYOND THE EDGE OF THE MOUNTING FLANGES OF THE MOUNTING BRACKET BEFORE YOU INSTALL THEM ON THE PART.

If any of you future builders stumble across this part of my blog, be sure to use the tips above to avoid the hastle that I went through. The good news is that the nut plates are successfully installed. I was able to reach all of the rivets with my hand squeezer and a combination of the flange yoke and the standard 3 inch yoke, and had to use my C frame tool to set the rivets on the last nut plate on the side where my yokes would not reach from inside the access hole in the bracket.

Here are the yokes I used in the hand squeezer to rivet the nut plates to the bracket.

Note that I used a 1/2 inch wide x 1/8 inch flat set over the manufactured flush rivet head and the smaller diameter 3/8 inch x 1/8 inch flat set for setting the shop head of the rivet. I did this to ensure that the flat set would not interfere with with dimpled for the screw in the center of the nut plate. turned out to be a non-issue but I wasn't sure in the beginning so I opted to be sure. Using the smalled rivet set definitely adds more challenge, especially when you using it to set shop head. You have to ensure that the rivet shank is pretty much dead center on the rivet set to avoid setting a bad rivet.

Next shows the process I used to set each rivet. You use once cleco to hold the nut plate in place while you insert the rivet into the other hole. then you slide the yoke onto place, ensuring that each flat set is where you need i to be, and squeeze the rivet. Definitely chose the hand squeezer over the pneumatic one for control reasons. I had to heep the larger diameter rivet set away from the edge of the elevator skin to avoid damaging the skin, while ensuring that the smaller rivet set on the other side was adequately centered over the rivet shank. Had I used the the pneumatic squeezer for this I most certainly would have damaged something.

You can see the completed rivets on acouple of the nut plates at the bottom of the previous pic. Once you set the the first rivet, you remove the cleco, insert the final rivet on the other side, and set it exactly the same way you set the first one. Wash, rinse, repeat. Also note the flanges of the rounded nut plate slightly sticking out beyond the edge of the flange. These will absolutely interfere with the clearance of the trim tab servo that will be mounted to the access plate, so you have to file these down to match the edges of the opening.

Next is my setup to hold the skins out of the way while I set the rivets for the nut plates:

Next is another concern about the clearance of the trim tab servo case from the lowest edge of the mounting brackets as shown. Not a lot of clearance for a rivet head, much less a dimple. Thanks to Steve's builders log post, I found out that he simply countersunk the metal for the flsuh head rivet so that no dimple was needed, and he then used a 1097 rivet that has a smaller head on it to avoid interference with the output shaft of the servo. I will do the same.

Note the angle of the mounting brackets in the next pic. The wires are also routed through the access hole that is precut into the bracket.

Next, all the nut plates rivets were set with the hand squeezer except for the last one. The yoke with the shortest span that I possess is the flange yoke. Unfortunately, even that one cannot fit inside the access hole at a point where it allows the last set of nut plate rivets to be squeezed. So I needed another solution. Enter the C Frame....

So I need to take some time to explain how I set this up. One nice thing about the C frame is that you can use it to set rivets as well as make dimples. I used 2 1/2 inch x 1/8 inch flat rivet sets. I decided not to use the smaller 3/8 inch diamter flat set because to set the rivets you ahve to bang on the ram with a hammer, similar to setting the dimples. The parts will inevitably move a bit while you are banging on the rivet, so I wanted a little more leeway on the rivet set to allow for this movement.

The setup was C frame perpendicular to the long edge of the table, set on top of a 3/4 inch piece of plywood. On the opposite side, I stacked two 2x4s on top of each other, long side down, and placed a blanket over the top to prevent sratching the outer surface of the skin.  Then I placed the skin on top of the 2x4s. Again, the idea is to get the skin at approximately the same height as the bottom set in the C frame.I could ahve used the C frame table for this, but because the dimple dies and flat rivet sets are different dimensions, I would ahve had to adjust all the legs on the C frame table for the flat rivet set, which is much lower than the dimple die. This jury rigged setup took much less time and trouble and worked out well enough.

Next, I took another 2x4, short side down, and slide it uder the skin next to the C frame took for additional support. I used rivet tape to hold the manufactured head of the rivet in place, with the cleco in the other hole, just as I had done with the hand squeezer setup. I may have reversed the cleco so that it was as out of the way as possible from the rivet while positioned in the C Frame. The last step was to borrow another set of hands from my son to hold the top skin out of the way while I bang on the rivet to set it. I used a ball peen hammer for maximum affect and energy transfer to the rivet with each blow. I took 1-2 blows, and then checked the clearance of each rivet set on the top and the bottom as well as the depth of the shop head of the rivet, and re-positioned the skin as needed. Then I followed up with another 1-2 solid blows to finish setting the rivet. Worked out fine.

So here are all nut plates installed on the flange of the trom tab mounting bracket:

Now the only problem was the excess portion of each nut plate that is hanging over the edge of the flanges. I took a square file and proceeded to file down all of the nut plate edges until they were almost flush with the edges of the flanges of the bracket. I stopped just a bit short to prevent myself from accidentally filing away part of the flange itself. I may need to fnish up the last but of filing with sand paper, a scotch brite wheel, or a dremel tool of some sort. The trim tab and its mounting brackets just barely fit into this access hole, so every edge dimension has to be spot on.

Lastly are top and bottom shots of the nut plates after being filed down flush with the flanges:

396 hours on the hobbs - Dimpled trim tab skin and spars

Disassembled the trim tab spar and E721 hinge from the trim tab skin and deburred, dimpled, and countersunk the appropriate areas per the plans. Used the same technique to countersink the top flange of the trim tab spar that I used for the top flange of the rear spar of the elevator. In fact, the same hole spacing was used, or very close to it, so I was able to resue those same holes in my drill board to cleco the spar down and complete the countersinking. Bottom of the spar was dimpled, and the hinge was only deburred (no dimpling or countersinking on the hinge).

I also filed down the edges of the elevator skin where I remove the tabs. Looks like I may still have at least another 1/4 inch of skin to remove, but I won't know that for sure until the trim tab hinges are being lined up for final assembly.

I tried to get to several builder sites using Kit Log Pro for their builders logs, but they must have had server problems, because I could not access anyones info. I wanted to check Steve Riffe's log because he mentioned the problem that I am curious about regarding the trim tab servo and the two Z mounting brackets that are used to install it. The servo sits in these brackets, which get riveted to the bottom of the trim access cover plate shown in my previous posts.

While checking the trial fit of these brackets on the servo, I noted what Steve had also pointed out in his log - that there is not much clearance between the bottom of the servo and the two most forward rivets that attach the brackets to the cover plate. It seems that the servo case will end up hitting the dimple and the shop head of the front rivets because the mounting brackets do not provide enough clearance. I tried to check VAF posts for some answers, but was unsuccessful in finding exactly what I was looking for.

Tomorrow I hope to start setting the nut plate rivets that will hold the screws that will attach the cover plate and trim servo. Also, now that the 3 Ds are pretty much done, it is time to scuff and clean the parts for primer, so I may get started on that as well. I also need to fab the three riblets and will get started on those. Still a lot of steps to complete to finish the tail kit, but you just keep knocking them out one by one....

The third of three weather systems is going to move through tomorrow, so I don't expect I will be able to do any priming tomorrow. Single digit temps tonight. We have already cleared about 15 inches of snow from the first two systems, and we are expecting another 3 inches tomorrow. I have had enough snow for a while.

395 hours on the hobbs - Last few elevator holes dimpled

Got out the old close quarter tool again from Cleaveland tools. If you have read any of my other posts about this tool, you know how much I cherish and utilize it to get into places that are just too small for conventional squeezers and dimple dies. I dimpled the two TE holes on the elevator tip using the back of a chair as a support for the elevator skin. Worked out quite well actually. It left both my hands free to focus on making the dimple, whereas previously I had to enlist the help of a friend to hold the skin for me.

Then I had to get creative. I needed to dimple 4 more holes deep inside the skin that attach the rear trim tab spar to the skin - two on the top and two on the bottom. The problem was that the stiffeners get in the way of trying to dimple these holes. I needed to find a way to elevate the tool enough to allow the skin to slide over the tool and sit flat over the top of it. I had a cedar 2x4 about 3.5 feet long in the garage that looked like it would work perfectly. Other builders that are obviously more intelligent than me have figured out that they needed to dimple these holes much earlier in the process. Oh, well, builds character I guess, if nothing else.

I removed the tool from the edge of the table, and re-attached it to the end of the 2x4. This elevated the tool enough to keep the flanges of the stiffeners from interfering with process to make the dimples as shown in the following sequence:

Here is the setup with the skin in postion over the tool ready to dimple the remaining spar attach holes:

and a shot from the side. Notice how the 2x4 slides nicely between the stiffeners, which allows the tool to be able to reach the holes and keeps the skin level over the tool:

This pic shows one of the two holes dimpled successfully. the ring around the dimple is normal. It is just slight impressions made by the edge of the dimple die on the alclad layer of aluminum that tell you that the die was seated over the hole correctly. It usually cleans up with Acetone or soap and water quite nicely:

and both holes dimpled:

Here is how I attached the tool to the 2x4. Again, I needed to elevate the skin somehow so that the skin would sit flat on the tool. Had I not done this, I would have had to force the skin down over the dimple die, putting pressure on the flanges of the stiffeners on either side of the hole, which might not have allowed a good dimple to form, and may have damaged the skin or the stiffeners in the process - not good. In actuality, a 2x2 would have been more than perfect for the job, but I used what I had in the shop at the time. As long as it slips in between the stiffeners on either side, it will work.

I quickly realized that I also needed to put the tool on one edge of the tool or the other of the 2x4. I had to move it to both sides of the 2x4 in order to allow it to reach all the holes on both sides of the skin. You can see the other mounting holes I drilled for the other positions that I used. The reason it has to be on one side or the other is to allow the die in the end of the tool to align with the holes that are closest to the stiffener flanges on either side of the hole.

And here is the entire setup. I just clamped the other end of the 2x4 to the table. I set the end of the tool from the edge of the table so that it would allow the front edges of the skin to lay down on the table to provide support and help level the skin out across the dimple die  in the tool.

Here is the chair "tool." Hehe. Amazing what you can rig up if you put your mind to it. I used a blanket to keep the skin from getting marred up on the back of the chair. This ended up leveling the skin out just enough to keep it in proper position over the tool. In this situation I was attempting to dimple the last remaining nut plate rivet attachment holes with the 3/32 #40 dimple die. This did not work out as well as I had hoped, because the dimple has to go into the trim tab support bracket, which has very thick skin - much thicker than the elevator skin. The rivet gun just did not form the dimple very well, and I did not want to turn up the juice (air) on the gun as I did not want to damage the part. I have had quite enough of that over recent weeks as you well know.

Next is a close up of the not-quite-formed-yet dimple after attempting to form it on the tool. I had to revert to the C frame tool to resolve this. I could not get a squeezer into the access hole to get to this last set of nut plate holes. This was the only set of holes I could not get to with a squeezer. Lesson learned here is to attach the nut plates first, BEFORE attaching the support plate to the elevator skin. I still can't believe that Van's does not clearly explain this in the instructions. Enough ranting, I found a work around for the problem, so all is well. The hole in question is on the top of the pic.

Hmmm. I just realized I did not take pic of the C frame setup. So I will describe it here. Since the close quarter tool would not set the dimples very well, I removed the skin from the table, placed the C frame tool on the table, put the #40 dimple dies in the C Frame, with the male die sticking up as I usually do for the skins. I used the chair back to support the skin. I did NOT use the dimpling table - too much trouble to set it up for three lousy holes. Instead, I needed to slide the 2x4, long side up, under the skin near the edge of the table so that the skin would sit relatively flat over the dimple die in the C frame. The top skin was draped over the top of the ram after positioning the hole in the dimple die, so I held the top skin out of the way while I hammered the C Frame ram to create the dimples. I then needed to switch the dies from #40 to the #6 dimple dies for the hole in the middle that will accept the #6 screw.

Here is a blurry pic with all of the nut plate holes in the trim support bracket dimpled (finally!) The set of holes I dimpled with this technique are the ones in the top middle of the photo. The shiny spots around some of the holes are where the primer has sadly flaked off. I will touch up these areas later when I am in full primer mode for the rest of the parts. The flaking primer does not concern me much. Normally all the holes are drilled, deburred and dimpled prior to applying the primer, but in this case the dimpling was done after the primer was applied. All that banging and bending of metal can certainly take a toll on any surface coating. Just reprime it and no problems.

And here is a trial fit of the trim servo access cover plate with the screws inserted into the holes just to check for hole clearance and flushness of the screw heads inside the dimples in the cover, which are inserted into the dimples in the support bracket underneath. This should work out nice after the nut plates are riveted in place, which is my next challenge.

And lastly a blurry pic of the #6 dimple die in the C frame. I was trying to show the flat side of the male die that I grinded off so that it would clear the elevator skin that overlaps the trim support bracket. Hopefully you get the idea behind why I needed to do this by looking at the screw hole locations and edges of the cover plate in the pic above. There is not a lot of material sticking out from underneath the skin to hold all the nut plates, dimpled holes, and rivets in place. The dimple dies are just a bit wider than the amount of material sticking out, which is why I had to grind down one side of the dimple die. The flat spot is on the male die on the bottom, on the left side. I did not have to grind it down very much to clear the skin, but it still needed to be done.

I think I have resolved how I am going to set the rivets for the one nut pate that I cannot reach with the squeezer.  I may use the C frame to set the two nut plate attach rivets. Sure wish I would have attached these confounded things before I attached the support bracket to the skin. Sorry, I said that already, didn't I?

I will have to get used to dealing with nut plates. they seem to require a lot of prep work, and that kind of sucks. When you start building the wings your very first step is to counterskink a million holes for the fuel tank attach brackets on the main wing spar. OK so maybe not a million holes, but you get the picture, right?

I then plan to use a ton of nut plates in the fuselage in the floor panels, as well as hinged access plates, so that I can gain access to critical areas of the plane without having to drill out rivets. This will add a lot of work to the fuselage build, but in the end it wil be worth it.

Some builders comment that it is easier and takes less time to drill out the rivets than to install nut plates and screws. What they don't understand is that if you are stuck  in nowhere USA one day, without a rivet gun, compressor, drill, spare rivets, and a bucking bar, it is very difficult get into the critical area to troubleshoot the problem, and remove, replace, or repair a component, and then close the floor back up again, unless you have access plates or panel doors installed.

393.5 hours on the hobbs - Countersinking the elevator rear spar

So yesterday I continued with dimpling the elevator skin adn the E702 front spar. I then hung the top flange of the E606PP rear spar over the edge of my particle board drilling board, and match drilled #40 holes through the existing holes in the spar into the particle board. Then I clecoed the spar to the particle board in every other hole so I could use my microstop countersink with the number 40 countersink bit to countersink all of the holes on the top flange. Worked pretty good.

I still don't like the inconsistent countersink results that I seem to get with this tool. Some holes end up a little more countersunk than others - not sure if it is due to an incorrect angle of the bit in the hole, too much pressure while drilling, or holding it on the hole for too long. Probably a combination of all three. Anyway, they came out acceptable enough for me. The trick is to countersink them just a bit further than the point where the flush head of the rivet is exactly flush with the top of the skin. You take it just a bit deeper to allow room for the dimple to sit down completely inside the countersunk hole. This then also allows the dimpled skin or part to sit flush on top of the countersunk part, making a strong joint in the process.

Here is a shot with several holes already countersunk. I placed a rivet in each one to check the depth. On other note about this. You need to do one of two things when you set out to use the countersink tool:
1. Make a test piece and check the countersunk depth on the test piece before doing it on the actual part, or
2. Start out with the countersink tool set to a depth that you know is much much too small so that there is no way you will remove too much material when you start out. Then adjust the depth of the tool until you get it where you want it.

Either method will work, and will keep you from damaging the part by drilling too deeply.

And a little closer shot to show how each head is just a bit deeper than flush with the top of the skin:

And the end result - both the top and bottom flanges of the rear spar sit nicely against the top and bottom of the elevator skin.

Tonight I would have finished dimpling a few areas in the elevator skin that require the close quarters tool or the C frame, and may have even finished countersinking the forward spar of the trim tab, but with the weather down to 5 degrees I decided to stay indoors tonight and get some non-airplane stuff done that I had been putting off long enough.Even if I get all the prep work done I still have to wait until the weather gets warm enough to prime the parts. My little radiator heater just can't keep up with temps that low, and I don't want to take a chance on screwing up anything on this part of the build because I was shivering from the cold.

Hopefully I will finish the remaining prep work and the riblets this weekend. There are two more weather systems waiting to hit us here in Denver over the next two to three days, so it may be next week before I can prime everything and start final assembly.

On another note, I have finally purchased my builders insurance policy. too much invested in everything at this point not to protect it.