Jan 27, 2023     Installing fittings on right tank - (0.5 hour)       Category: Fuel Tanks

This was just a quick session to install the fittings into the fuel tank. I used Permatex #3 on the NPT threaded fittings, and then after it had dried, applied some tank sealant around the exterior seams.

  Jan 25, 2023     Finishing the right fuel tank - (1.0 hour)       Category: Fuel Tanks

Tonight I removed the remaining clecos from the holes in the skin that were holding the rear baffle in place while the tank sealant was setting. These remaining holes were the ones that the instructions said to leave without countersinking so that the clecos would have maximum holding strength. So these holes were countersunk to allow flush rivets, and those were then hand squeezed in.

What's next? Both fuel tanks just need their fuel senders to be installed permanently with tank sealant and screws.

  Jan 24, 2023     Closing up the right fuel tank - (3.0 hours)       Category: Fuel Tanks

Tonight it was time to close up the right fuel tank too. Applied a bead of tank sealant around the edge and then squished down the rear baffle against it. Then lots of clecoing and riveting. The rear baffle brackets were also blind riveted on while I still had this mixed tube of tank sealant in a usable state.

It was getting late so I decided to end the work session there, with the clecos still holding the skin through the holes that had been intentionally left without countersinking... Those can be be finished tomorrow.

  Jan 20, 2023     Countersinking the attach brackets - (0.5 hour)       Category: Fuel Tanks

This was just a quick session to countersink the 5 holes in the attach bracket of the left and right fuel tanks. These holes must be countersunk to accept a dimpled skin, so they end up being relatively deep. The holes were then touched up with an Alodine pen to prevent future corrosion.

I also spent some time applying Permatex #3 to the plugs and installing them of both fuel return lines in both tanks.

  Jan 19, 2023     Closing up the left tank - (4.0 hours)       Category: Fuel Tanks

After putting this task off long enough, I decided to finally close up a fuel tank by installing its rear baffle. This has to be installed with tank sealant to ensure no leaks. Since this has to be done without access to the other side once complete, it must be done "in the blind" and without the ability to touch up any of the beads of sealant on the inside. Additionally, all of the rivets along the sealed areas need to ideally be driven while the sealant is still wet, so you're under a bit of a time pressure once you start.

  Jan 17, 2023     Install vent line fittings - (0.5 hour)       Category: Fuel Tanks

Just a quick work session to install the bulkhead-style fittings through the inboard ribs of both fuel tanks that are used for the vent lines. These fittings must be installed with tank sealant, but I also applied some more sealant on top of the nut after it was torqued down.

I also took a Scotch-Brite pad to roughen up the mating surfaces where the bulkhead will be installed, since that will soon be important.

What's next? I think it's finally time to seal up the tanks with the final side.

  Nov 30, 2022     Water leak testing the left tank - (1.0 hour)       Category: Fuel Tanks

I filled the left fuel tank with water and left it for more than a day to see if any obvious leaks were present. Fortunately, nothing seemed to be leaking so I drained the water with a shopvac and set the tank upright to dry. I'm not sure how effective this test would be since it would only detect major drips on the leading-edge portion of the tank.

The build plans don't seem to actually propose this method of initial testing, but I know a lot of builders tend to do it anyways. The real testing will be when I eventually close up final side of the tank and then do an air pressure test.

What's next? I'll be travelling for work next week, so I'm preparing a box of tools and parts for the outboard leading-edge that I can work on while I'm staying at the hotel.

  Nov 28, 2022     J-channel, attach bracket, aft rib half, and nutplates for right tank - (4.0 hours)       Category: Fuel Tanks

After spending a few days away from the plane building for Thanksgiving, I was ready to get back to work.

I started by mixing up a batch of tank sealant and spreading it onto the flange of the J-channel stiffener. Then my friend David helped me slide the J-channel into the right fuel tank. Then he loaded up the holes with rivets, while I followed behind him and bucked that whole row of rivets. The shopheads were then all encapsulated under nice dabs of more sealant.

I then installed the plastic snap bushings into the holes in each of tank ribs, and then slid the soft aluminum tubing for the vent line, making a few gentle bends to allow it to fit into the bushing at the filler cap.

Next was to apply more tank sealant to the attach bracket and rivet that into place, and then do the same with the aft half of the inboard rib. The heavier rivets that attach the two halves of the inboard rib to the attach bracket needed to be bucked using a double-offset rivet set and a bucking bar with an angled tip. Again, the shop heads needed to be covered with additional tank sealant, and then all of the seams and joints were fileted with sealant too.

The inboard lip of the fuel tank then needed the several nutplates attached, which I simply used my hand squeezer to set those rivets. The fuel sender was also clecoed into place and the arm adjusted slightly to allow the float arm swing without hitting anything.

What's next? With that done, now both fuel tanks are up to the same completion stage. I'll try to do a water leak test to see if there are any places that need more sealant before closing up the tanks.

  Nov 21, 2022     Last 3 full ribs in right tank done - (3.5 hours)       Category: Fuel Tanks

Tonight, I had the goal of finishing the last three full ribs in the right fuel tank. Once you get the rhythm down things can move pretty quickly.

What's next? Install the J-channel stiffener, attach bracket, and last half of the first rib.

  Nov 20, 2022     Two more ribs down on right tank - (2.5 hours)       Category: Fuel Tanks

Tonight's session started by opening up a new pint can of tank sealant. I managed to get the 3rd and 4th ribs in the right fuel tank riveted this time, and then fileted the seams and shop heads encapsulated with more sealant.

  Nov 19, 2022     Starting to rivet ribs on right tank - (2.0 hours)       Category: Fuel Tanks

Tonight's session was to start installing the ribs of the right fuel tank. I managed to finish the first (technically just the forward half of it) and the second ribs. Things proceeded smoothly and I finally finished off the first pint can of tank sealant. Fortunately. I already received a second pint of fresh tank sealant a couple days ago.

What's next? Continue on the ribs for this right tank....Maybe I can get the right tank caught up to the left tank before I take a break for Thanksgiving?

  Nov 18, 2022     Bending fuel sender float arms - (1.0 hour)       Category: Fuel Tanks

This was a quick session to prepare the fuel senders, which measure the amount of fuel in the tank by using a float. The fuel senders come out of the box with a straight piece of wire for the float arm, however these needed two 90-degree bends added to each of them using a pair of vice grip pliers. The length of the wire also had be trimmed slightly shorter and the end sanded down to remove the burrs. Then a quick trial fit verified that it properly registered both full and empty positions without any contact or interference of other parts in the tank.

  Nov 13, 2022     Riveting last rib of left tank - (2.0 hours)       Category: Fuel Tanks

In this session, I started by mixing up another small batch of tank sealant and applying it to the flanges of the remaining half of the inboard rib for the left tank. Sliding it into place went pretty smoothly, and so I started bucking the rivets to the skin with the air rivet gun.

Tackling the larger rivets that join the two halves of the rib together to the attach bracket was a little more challenging. I had to use a 6-inch long drill bit to open up the holes slightly more so that the rivets would slide in, and then I had to use the double-offset rivet set in order to have the clearance to buck them. After that, I went about encapsulating all of the rivet heads with more tank sealant and fileting all of the seams where the tank sealant squeezed out. I also applied a bit more along the inner corners where the rib meets the attach bracket. Next, I used the hand squeezer to add on the remaining 5 nutplates along the inboard edge of the tank skin.

What's next? With this done, the major assembly of the left tank structure is basically complete, with the exception of the last baffle that will close in the tank. Once I feel the sealant has cured long enough, I might try filling the tank with water and see if there are any obvious leaks. I still also have to bend the float arms for the fuel sender.

  Nov 12, 2022     Bending vent lines and nutplates - (2.5 hours)       Category: Fuel Tanks

Tonight I worked on cutting and flaring the soft aluminum tubing that would be used for the vent lines in both of the fuel tanks. After flaring, I set aside the tubing that would be used for the right tank for later.

For the left tank, I installed the snap bushings that protect the vent line from contacting the ribs, and then slid the tubing through them. I had to slightly enlarge the mounting clip's hole to allow the snap bushing to fit. A couple of gentle bends were needed on both ends for the vent line to go where it needed to, as described in the instructions. I temporarily installed the bulkhead fitting to check the alignment of the flared nut fitting. This required scraping a little bit of the dried tank sealant that had oozed under the retaining plate and prevented the bulkhead fitting from completely sitting flush. I also scraped a little tank sealant that had gotten into some of the threaded fittings.

Since I was avoiding mixing up tank sealant tonight, I started riveting on some of the nutplates that went along the nose section of the inboard edge of the tank skin. This required me to dimple the nutplate holes along the edge of the tank skin that I had previously deferred (I dimpled the right tank skin too, while I was at it).

What's next? Time to install the last half of the inboard rib, and then probably switch to working on the right fuel tank.

  Nov 11, 2022     Installing J-channel and attach bracket on the left tank - (4.0 hours)       Category: Fuel Tanks

Since tonight's session had the goal of riveting in the J-channel, I decided to try out one of the tubes of tank sealant I have rather than mixing up a batch from the can and spreading it. This was the first time I had used the tube applicator form of this tank sealant, so I had to carefully read the instructions about how to mix it in the tube but this was a pretty easy process. It was definitely nice to be able to squirt a long line of this tank sealant directly onto the J-channel, though I still used a popsicle stick to smooth and distribute the sealant across the entire surface.

Sliding in the J-channel into place while it had the tank sealant applied did tend to leave an excessive amount on the inboard side of the tank (the side it was being inserted from), even though I was trying to avoid letting it drag during the insertion. Riveting the J-channel went pretty smoothly, with only a couple of rivets needing to be drilled out and re-set in order to ensure flush fitment. After that was encapsulation of the shop heads with more sealant and smoothing the top edge of the J-channel. I wasn't able to apply sealant or inspect the underside of the J-channel, so I'll probably have to find a mirror or something later.

Since I still had some tank sealant remaining, I decided to install the attach bracket as well. This went pretty smoothly, though there was one rivet I had to redo as well. The rivets along the mating seem of the first rib's halves were left only held in place with clecos, since the instructions say I need to do some tube flaring+bending before installing the other half of the first rib.

With a little bit of tank sealant remaining from the tube, I went over all of the previously installed ribs and added more along any of the seams that needed more

  Nov 08, 2022     Final ribs of left fuel tank - (3.0 hours)       Category: Fuel Tanks

In this session, I installed the last two ribs on the left fuel tank. Same process as before... Mix tank sealant and spread on the rib flange, insert the rib into the tank skin, cleco, buck rivets with pneumatic rivet gun and bucking bar, encapsulate all rivets' shop heads with more tank sealant, apply and fillet tank sealant along the seams.

I also noticed that I never installed the nutplates on the Z-brackets after I had finished their alodine treatment, so I used the hand squeezer to install all of those rivets. Each of the 12 Z-brackets had 3 nutplates, and each nutplate had 2 rivets, so this was a nice task to get out of the way.

What's next? Probably install the J-channel stiffener, and then maybe the attach bracket and other half of the inboard rib.

  Nov 07, 2022     More fuel tank riveting - (3.0 hours)       Category: Fuel Tanks

Just riveting more of these ribs into the left fuel tank.

  Oct 27, 2022     Second rib added to left fuel tank - (1.5 hours)       Category: Fuel Tanks

This session's task was to install the second rib (first full size rib) in the left fuel tank. This honestly went much smoother than the previous rib, though it became much easier when I started using a pointed awl to help align the holes with the skin. Only one of the rivets had to be drilled out and reinstalled, because I noticed that it wasn't sitting completely flush with the skin surface while cleaning up the excessive sealant that had squeezed-out. Overall, this rib was much less messy to install than the first one--maybe because I didn't go quite as extreme with applying the sealant.

  Oct 25, 2022     Starting to rivet fuel tank ribs - (1.5 hours)       Category: Fuel Tanks

After coming back from several days of travel, it was time to get back to work on the fuel tanks. The first step was to mount the left fuel tank skin into the cradles and test fit the first few ribs into place with clecos. Satisfied with the fitment, I removed the end rib and applied a fresh mix of tank sealant to its flange and started bucking rivets with the pneumatic rivet gun.

This ended up being pretty messy due to the tank sealant squeezing out everywhere--maybe I didn't need to apply as much as I did. In any case, I finished up by filleting the sealant on the internal edge. I also encapsulated the shop heads of rivets, though I'm not sure that was strictly necessary since these rivets are on the "outside" of the fuel containment.

This log entry puts me over the 300 hour threshold.

What's next? The empennage kit finally arrived today, so I'll be trying to verify its inventory before getting back to work on the fuel tanks.

  Oct 18, 2022     Riveting and sealing the fuel filler caps - (1.5 hours)       Category: Fuel Tanks

After re-watching the part of Scott McDaniel's video on fuel tank, I started by cleaning both of the cap flanges and the skins with acetone, applying some masking tape to protect the inner taper, and then mixing up a batch of sealant. I then spread the sealant along the mating surface of the flange, leaving a ridge of more sealant along the center of the contact area and thinning it towards both the inner and outer diameter edges. A couple of clecos at the forward and aft rivet hole kept the filler cap in place during the actual riveting.

Since I didn't have a short enough yoke for my hand squeezer, I had to use the pneumatic rivet gun. Fortunately, the riveting went quite smoothly, and I got all of them set perfectly on the first try. After some cleanup of the excess sealant, I applied a little more over the shop head of each rivet using my drinking straw trick, and then fileted the sealant seams.

What's next? Time to set the skins back in the saddle fixtures and do a final test-fit of the ribs before riveting them in too.

  Oct 17, 2022     Making replacement tube bracket - (1.0 hour)       Category: Fuel Tanks

I decided that I needed to fabricate a replacement for one of the vent tube brackets because the thickness of the edge of the bracket around the hole had become too thin during my smoothing of it. So I grabbed a piece of scrap material of similar thickness, traced out a new one, cut it out, and cleaned it up on the sander. A final fitment check confirms it'll work.

What's next? Time to install the fuel filler caps.

  Oct 14, 2022     Fuel drain flanges and attach bracket prep - (2.5 hours)       Category: Fuel Tanks

Tonight's session started by installing the fuel drain flanges on the underside of each fuel tank skin. These flanges will eventually get the sump drain valves screwed into them when done. I started by applying a layer of tank sealant to the contact surface of the flange and then hand-squeezing the rivets that hold it to the tank skin. Then I cleaned all of the excess sealant and applied small blobs on top of the shop heads since those will be on the inside of the tank.

Next I started the preparation of the attach brackets by hand squeezing on the various nut plates, shims, and bearings. This part went almost perfectly except when I riveted the shim to the bracket first and tried to rivet on the nutplates on its overhanging section. There wasn't enough room to use the squeezer or pneumatic riveter in this assembly order, so I had to drill out the shim and attach the nutplates first. In any case, both attach brackets came out fine and it's onto the next step.

What's next? Attaching the fuel cap flanges, and then maybe a final test fitting of all the ribs before I actually start riveting them in permanently.

  Oct 13, 2022     Stiffeners on right fuel tank - (3.0 hours)       Category: Fuel Tanks

Now that the stiffeners were done on the left fuel tank, I decided to get them done on the right fuel tank too since I had the process figured out. This time I tried applying a little more sealant near the bent side of the stiffener so that there would be enough squeezed-out to avoid the need to add more sealant later. This worked better, but I still needed to a little more in a few spots. I did have to drill out and reinstall 4 rivets because they weren't flush enough--I guess I wasn't pressing down on the backriveting plate firmly enough the first time.

  Oct 12, 2022     Installed lower stiffeners on left fuel tank - (2.0 hours)       Category: Fuel Tanks

This session was about finishing up the installation of the stiffeners on the lower side of the left fuel tank. I've gotten the process down so I can get through these stiffeners much quicker now, even though I did have to drill out one whole stiffener due to the rivets not being set flush enough on my back riveting plate. I think I've found a better amount of tank sealant to aim for, which causes just enough squeeze-out and doesn't require a lot of extra post-processing work to apply more or redistribute excess.

  Oct 11, 2022     Starting the fuel tank stiffeners - (2.5 hours)       Category: Fuel Tanks

I started riveting on the first three stiffeners on the left fuel tank tonight. I decided to re-dimple most of the skin because the rivets didn't seem to be sitting flush enough, so I adjusted the DRDT2 a little deeper. After dimpling, I loaded up all of the holes on the underside with rivets and taped them in place with blue painters' tape.

I mixed up a small plate of the tank sealant and applied it to each of the stiffeners using a popsicle stick, placed the stiffener over the protruding rivets, and then back-riveted them in place. I ended up having to drill a few rivets out because I noticed that they had topped over when my backrivet set slid a little bit due to the slipperyness of the wet tank sealant. Things seems to be more reliable if I use my other hand to hold the nose of the backrivet set against the skin so it can't slide while riveting.

I then covered each of the rivet shop-heads with a small blob of tank sealant by using a plastic drinking straw. I also attempted to apply extra tank sealant around the edge and smooth it into a fillet, but that ended up being pretty messy. I think I will try to apply a little more sealant on each stiffener in the future, so it oozes out under the edges and I don't need to apply extra afterwards.

  Oct 10, 2022     More alodine treatment of fuel tank parts - (2.5 hours)       Category: Fuel Tanks

Tonight was a chance to get back on the work with Aldone to finish treating the remaining skins and baffling for the fuel tanks. By using the undiluted Alodine, I could use brush application method to treat these parts since they were too large for my immersion tanks. Truthfully, the golden color still doesn't seem to be as visible using the brushed application after rinsing, but my understanding is that the application will still have the same corrosion protection capability. Even if the protection is reduced, it is still more than most builders do for the fuel tank interior surfaces (ie: nothing). In any case, this is all done and I can begin actually assembling the rest of the fuel tanks now.

  Oct 06, 2022     Installing fuel tank fittings - (2.0 hours)       Category: Fuel Tanks

Tonight's session started by squeezing on the rivets for the nutplates that will secure the fuel level sender. These nutplate rivets don't require any tank sealant because the fuel sender itself will be sealed when it is later installed. However, installing these rivets was complicated by the fact that they are too far from and edge to use my normal hand rivet squeezer, so I ended up repurposing my DRDT2 dimpler to work as a rivet squeezer and it actually performed quite well.

The next step was to install the fuel bung fittings, which all required tank sealant on their mating face prior to riveting. These were all close enough to an edge that I could use my hand squeezer on them. I did feel that Van's recommended rivet length is a little long for this application because I had a couple of rivets topple over and need to be drilled out.

After those were done, I installed some diamond-shaped anti-rotation plates in a similar manner by applying tank sealant to their mating face before squeezing on the two rivets that hold each one.

After installing those rivets, I encapsulated the shop heads with more tank sealant by using a plastic drinking straw to form a round blob on top of each.

  Oct 05, 2022     Plugging fuel tank hydroforming holes - (1.5 hours)       Category: Fuel Tanks

This session marked my first chance to use tank sealant in this build and a test to see how smelly it would be to use in my indoors workshop. I have a feeling that this Chemseal brand of tank sealant might have less off-gassing than other brands, since it seemed quite reasonable.

In any case, the task at hand was to close up the two large holes in each of the inboard and outboard ribs that had been a result of the hydroforming process used by the factory. This mean installing large diameter (#6, 3/16") rivets while "wet" with tank sealant. I had to buy a larger rivet set for my air rivet gun, since this was also my first time working with this size of rivet. Unfortunately, my first attempt installing one of these #6-5 rivets resulted in a toppled over shop head, so after removing it I decided to try using my rivet cutter and reducing the shank length a little. All of the remaining rivets went in successfully on the first try. I think another trick to success was clamping each of the ribs to the worktable and turning the air pressure on my rivet gun to 90 psi.

After all of the rivets had been wet-installed, I also encapsulated both sides of the rivet with another layer of tank sealant for extra measure. I suppose I probably only needed to cover the inside rivet head (the side I had chosen to put the shop head on) since the goal is only to prevent the fuel from escaping the interior, but it seemed prudent to do both sides.

I did also get plenty of opportunities to confirm that Acetone works well enough to clean up the tank sealant while it is still wet. I had been concerned about needing to locate a local source of real M.E.K. (not the "M.E.K. substitute" that is commonly sold these days) for cleanup, but that now seems unnecessary.

What's next? I have more Alodine arriving today, so hopefully I should be able to try treating the tank skins with the full-strength stuff successfully.

  Oct 04, 2022     Alodine of fuel tank skin - (1.5 hours)       Category: Fuel Tanks

In this session I attempted to treat one of the fuel tank skins with an acid etch and then alodine wash. This was mostly just painting on the solutions and allowing the excess to runoff into the immersion tanks that I was using for the smaller items. Unfortunately, I think my alodine solution is effectively consumed, since it wasn't noticeably changing color any deeper on smaller parts I was trying to immerse. Additionally, the alodine instructions recommend using full strength (not 3:1 diluted) when it will be applied by painting. So I've ordered a fresh quart of Alodine so that I can repeat this process when that arrives.

  Oct 02, 2022     Alodine treatment of interior tank parts - (3.0 hours)       Category: Fuel Tanks

In order to better protect my fuel tanks from possible future corrosion, I decided to treat them with Alodine/Bonderite 1201 (chromate conversion coating) since using primer paint is not an option for the tanks. This process involves immersing and abrading in an acid etching solution the parts for a few minutes, rising in water, then immersion in the Alodine solution for a few minutes, rising in water again, and then letting air dry. I used 3 plastic tubs from Walmart that are normally used for under-bed storage, however their size and dimensions made good immersion tanks. Each tank was filled with about 2-3 gallons of liquid and was sufficient to cover all of these ribs.

The big concern with this process is that the Alodine solution is considered toxic and has waste disposal concerns. The acid bath isn't that great either. However, I believe I should be able to find a local metal plating shop that would be willing to take my waste solutions once I'm done, since they would have to neutralize and dispose of similar waste. I wore double-layer of gloves, and tried to exclusively handle the parts with metal tongs that were left over from parties from long ago.

The intensity of the gold color on some of the parts seems lighter than the others, particularly near the end of the session. I wonder if that was due to the reduced effectivity of the solution as it was being consumed, or perhaps just due to my process inconsistencies. However, I believe this is just a cosmetic concern and not a difference in corrosion protection.

  Sep 29, 2022     Cleaning fuel tank parts - (1.0 hour) Category: Fuel Tanks

This session was just cleaning the aluminum surfaces of the parts I had previously scuffed parts with isopropyl alcohol. This just removes the stray debris and oils that had accumulated during my prep work.

I've also been rewatching the 2.5 hour-long YouTube video by Scott McDaniels of Van's Aircraft about fuel tank sealing so that these processes are fresh on my mine when I start doing them in the next couple of days. Reviewing some of Jason Ellis' fuel tank videos has also provided some more tips, though his techniques were not influenced by having seen Scott McDaniels' video.

  Sep 28, 2022     Scuffing fuel tank parts - (2.5 hours)       Category: Fuel Tanks

In this session I was just working on scuffing all of the internal parts for the fuel tanks. It's necessary to roughen up the surfaces in order to prepare them for better adhesion of the fuel tank sealant.

Then I also needed to countersink the holes in the fuel tank filler cap flanges so that when they are riveted to the underside of the fuel tank skins, they will be able to sit flush. The new material exposed during the countersunking was then treated by an Alodine pen to prevent future corrosion.

  Sep 25, 2022     Close quarters dimpling fuel tank skins - (1.5 hours)       Category: Fuel Tanks

I started by using the hand squeezer to dimple for the large #8 screws along the edges of the fuel tank skins. However, I decided to leave the nutplate holes along the inboard edge undimpled for now, since I wanted to be sure about which holes actually needed dimpling and that edge should remain easily accessible for future dimpling, if needed.

Then I got a box of 6d 2" (#13 6F1) finishing nails from Home Depot under the advice of the Slack group. These fit the Cleaveland Tools close-quarters dimpling dies perfectly and are much more durable than the copper ones that are included, and don't need any grinding to fit. With those, I was able to finish dimpling the hard-to-reach section of each of the fuel tank skins.

Finally, I went back to the fuel tank ribs to start scuffing up their flanges and double-checking that they don't need any more fluting tweaks to ensure their hole alignments are good. I'll need to continue with this though.

  Sep 23, 2022     Dimpling the fuel tank skins - (2.5 hours)       Category: Fuel Tanks

Tonight's session started by final-drilling and deburring of the #19 screw holes on the other fuel tank skin, and then edge rolling the trailing edges on both skins. Since I will need to apply tank sealant to these rivet seams, I decided to use a Scotch-Brite wheel in my powerdrill now to scuff up all of those seams prior to dimpling (which would be more difficult later).

Then I started using the DRDT2 to dimple all of the flush rivet holes in both skins. This was all pretty straight-forward but did require a lot of rotating and flexing to get the skin into proper position for dimpling some of the holes.

What's next? Unfortunately, there were about a dozen rivets near the middle of both skins that are unreachable with the DRDT2 because the rubber handle contacts the skin, so I'll need to locate and use my close quarters pop-riveting dimpler set for those.

  Sep 22, 2022     Countersinking fuel tank skins - (3.5 hours)       Category: Fuel Tanks

This session started by match-drilling the J-channel against the existing holes in the left fuel tank skin. The J-channel is used to add rigidity and avoid oil-canning, but it is supplied from the factory without any holes.

Then the rear baffle is clecoed into place in between the left fuel tank skin so that the skin can be countersunk for flush rivets. I found it interesting that Vans choose to countersink since the skin is dimpled elsewhere for the rest of the ribs, but there's probably some structural or leak-reduction reason for it.

After that, all of the screwholes along the trailing edge and sides were final-drilled to #19 and deburred. The J-channel was also removed, deburred, and dimpled. Next all of these steps were repeated with the right fuel tank.

What's next? I think the instructions call for dimpling of all of the hundreds of holes in the fuel tank skins, so that'll probably consume most of my next session.

  Sep 21, 2022     Fuel tank countersinking and dimpling - (4.0 hours)       Category: Fuel Tanks

The countersinking and dimpling work continues. I started by countersinking all of of the Z-brackets to allow flush rivets to later be installed for nutplates. Afterwards, I used scotchbrite pads to roughen up the surfaces of those Z-brackets.

Next was to cut apart the 4 shims that came as one piece, clecoing them to the tank attach brackets, and marking where they had to be trimmed. I then went over to the belt sander and bench grinder to cut and smooth them to final dimensions. Those shims then had to be dimpled with the squeezer to allow nutplates to later be attached.

Then the flanges of the tank attach brackets had to be countersunk to allow the dimpled tank skins to eventually be attached. I found it easiest to clamp these attach brackets to the side of my worktable so that I could use my drill vertically down into the flange.

Next was moving the tank skins from the garage and into my workarea and removing the blue vinyl from the inside surfaces. I ended up using a Dremel with a cutoff wheel to cut the strips from the edges of the tank skins, since those strips would be needed for the leading edge wing section.

What's next? Time to matchdrill the J-channel and other final prep steps before the glueing starts.

  Sep 20, 2022     Fuel tank dimpling work - (1.5 hours)       Category: Fuel Tanks

The prep work for the fuel tanks continue with more deburring and dimpling of the stiffeners. I also had to dimple the flange on the fuel tank ribs around the opening where the fuel senders will be installed. The holes in that flange could have been dimpled with a very short yoke, but I needed to use my DRDT2 squeezer instead. Then I marked and cut the two pieces of J-channel that will be needed later. I started the counter-sinking of the Z-brackets, but my powerdrill ran out of battery and it was getting late so I'll have to continue with that tomorrow.

  Sep 19, 2022     Prepping fuel tank nose ribs - (3.5 hours)       Category: Fuel Tanks

This session continued the prep of the fuel tank nose ribs. Two of the ribs each needed an additional 3/4" hole made with a step drill, with mounting holes around its perimeter made for a bung hole fitting. The mount holes also had to be match drilled for the bung holes that already existed in each of those ribs.

Then I continued to debur the edges and rivet holes on the rest of the ribs, and then countersinking the flange holes of those nose ribs that would eventually be facing the exterior tank skins. One of the holes in each of two ribs had extremely tight space on the back side that prevented use of my squeezer for dimpling, so I had to figure out how to use the close quarters dimpling tool. I ended up screwing the fixture to the top of my workbench, holding a dimpling die in place with tape, and then using a hammer to repeatedly strike the dimple die through the rib and into the fixture.

  Sep 17, 2022     Prepping fuel tank brackets and stiffeners - (2.5 hours)       Category: Fuel Tanks

This session was just marking and cutting apart the support brackets and stiffeners for the fuel tanks. These pieces ship from the factory conjoined in long strips that need to be separated from each other on the bandsaw and then the remnants sanded off then smoothed on the bench grinder. The edges and holes also needed to be deburred.

  Sep 16, 2022     Fluting the fuel tank ribs, Cutting stiffeners - (3.5 hours)       Category: Fuel Tanks

In this session, I began work on the fuel tanks and started by straightening and fluting the fuel tank ribs. These ribs come supplied with a lot of distortion from the manufacturing process so I had to use the fluting pliers along their flanges to allow them to sit flat. The flanges also have to be bent to ensure they are 90 degrees from their webbing areas.

Then I started marking the cuts I would need to make for the various stiffeners, which are all supplied in long pieces of angle stock that only have guide holes punched in them. I did have time to cut out and smooth some of these ribs on the band saw, but there are still a lot more to go.

What's next? Finish marking and cutting these stiffeners, then prepare more raw tank parts.