Not much to write about tonight. I spent about an hour sanding down the epoxy skim coat on the two tip pieces. So far it looks like the bits of fiber embedded in the coat aren’t a problem, everything sanded down nicely to a slick finish. I wanted to go ahead and shoot primer again, but it’s been super humid today and so conditions aren’t really that great. I’ll wait until it dries out some tomorrow instead.

I also poked at the horizontal stab tips some more too. I think I’m going to try just drilling the mount holes, clecoing the tips in, and see if they get pulled decently into alignment. If that doesn’t work than I may see about adding a rib further forward in the tip to spread it out, in addition to the rib closing out the rear of the tip. Getting just the right fit won’t be a lot of fun but I think it’s a better option than something like splitting the tip and rebuilding it. Hopefully it won’t be necessary though…

OK, so yeah, the fun times keep on coming. First thing today I set about sanding off all that filler primer I shot Friday evening. That turned out to be more fun than I expected – that stuff really loves to clog sandpaper. I was taking lots of pauses to knock the crud off my paper, over and over again. But finally I got it all removed from both fiberglass pieces – well, mostly. There were some low spots where a layer of primer remained, and I decided that was fine since I’d be covering the whole thing with an epoxy skim coat again.

And so the epoxy dance began again. The idea here is to lay on a series of coats to build up a little thickness, and also to end up with a textured surface to provide a sanding guide (eg you sand the skim coat until the texture goes away). So you mix a batch of epoxy, coat the piece, squeegee most of it off, and then use a roller to even everything out and apply some texture. Then you let that coat tack up (about an hour or so in the current cool temperatures), then repeat this a couple more times.

Now, here’s the fun I had with this procedure today. First off, my nappy paint roller shed a fair bit of junk into the epoxy. That was almost enough to make me call it a day again, but I decided to soldier on, figuring I’d be sanding this down anyway. I guess there are worse things in the world than having odd fibers under the primer. Worst case, I sand it all off (again) and repeat this process (again). I think part of the problem was that the low temperature made the epoxy a lot sticker than it would have been otherwise.

The real fun came when I went out to apply my third and final epoxy coat of the day. I’d mixed up a batch, painted it onto the stab tip, and was just getting started on the rudder tip when…I bumped the stab tip accidentally, sending it off the workbench and onto the floor. Which meant that that epoxy I’d just laid on picked up all the dirt and random stuff on the floor where it landed. At first I tried wiping it off with a dry paper towel, but that wasn’t removing stuff too well, so then I switched to a towel soaked in acetone – which works well for cleaning up uncured epoxy. That did a good job of removing the epoxy I’d just put on, but I think it also removed some of the previous two coats. Kind of hard to tell. In any case, about all I felt I could do was to go ahead with that final coat of epoxy and hope it was enough for sanding later on.

Later, I went and reread some of the VAF fiberglass info, and another recommendation from Dan Horton (a guru-level composite guy) was to skim coat with a different product instead of raw epoxy. System Three Clearcoat is mainly used for waterproofing wood, but according to him a single coat goes in nicely, lays itself down smooth, and has a long enough pot life to have good working time. So I ordered some of that stuff, and will probably try it out the next time I need to shell out a fiberglass part. The whole half-day odyssey of multiple epoxy skim coats just isn’t doing it for me.

Now, let’s just hope that I won’t be trying that stuff on these same stupid tips. I’m really hoping that I can finally get these parts done and mounted, and move on to something else, maybe try that new epoxy stuff on the rubber bottom cap. At least with all this learning I know that the micro I’ve put on there needs more finishing before I shoot primer or anything like that.

So tonight after doing a bit of post-work flying, I got to sanding down my newly-epoxied tips. One immediate problem I had were some runs in the epoxy; it seems my attempts to squeegee off all the excess weren’t good enough. One recommendation for this procedure was to use a nappy paint roller to remove excess, but I didn’t have one so I tried the squeegee method. That, in turn, made sanding a little more fun than it needed to be, and I definitely went through the epoxy shell in a few places. Still, everything felt nice and smooth, so after fine-tuning and doing a final fit check, I decided it was time to shoot filler primer.

Here are the pieces after I shot a couple coats. One thing you might notice on the far left of the rudder tip is…a good-size pinhole. And it’s not the only one. The stab tip has a couple as well. Looks like I’ll be sanding this primer right back off and doing even more epoxy work. Maybe a trip to the hardware store for some paint supplies is in order tomorrow…

The odyssey of the rudder tip continues! I’m starting to become amused by how much time I’m spending on this, though I figure future parts work should go much faster since I’ll know better what I’m doing.

Tonight I sanded the tip down yet again, after last night’s attempt at filling pinholes. Unfortunately, by the time I sanded it back to shape, I uncovered…more holes. It would seem that using micro to fill pinholes isn’t the best approach. So I went back and reviewed a bunch of threads on VAF and decided to take a different approach, namely using a few raw epoxy skim coats to fill the holes. This ought to work better since the epoxy will be a lot less viscous and more apt to fill holes rather than just bridging them.

So over the course of a few hours I applied three skim coats, allowing each one to tack up for about an hour before adding the following coat. Hopefully this will give me a nice hard shell that I can sand down (again) to a nice smooth finish and maybe then I can finally spray some high build primer and think about finishing these things up.

In the meantime, things are looking nice and smooth after the third and final coat:

OK, the arctic front is behind us and I can no longer use the cold as an excuse not to go work outside. Finally, it was time to take that globby mess I made last time around and see if I could turn into something nice. I’m starting to wonder if this is just a normal part of the process, that everything looks horrific when the micro is applied.

Anyway, just like last time it took quite a bit of time sanding and checking and sanding some more and rechecking, but eventually (ie after about an hour and a half) I had a nice pleasing shape:

In the course of all that sanding I removed all the major surface voids, but there were still a fair number of smaller air bubbles and pinholes that had been exposed. So for the last part of the night, I mixed up another batch of micro and applied a skim coat over everything to get all those holes filled. While I was at it, I did the same thing to the back of the stab tip, since it had the same issue and I was going to have a ton of extra micro. So this gets to cure overnight and get sanded again tomorrow, then hopefully it’ll be time for filler primer and one last sanding:

Short night. After thinking things over from last time, I did decide to go with temporarily blind riveting the tip in place for the next batch of micro. First I removed the tip and applied clear packing tape to the inside of the rudder flange, wrapping it around to the outside to protect the metal surfaces here. Then I poked through the rivet holes and installed my cheap hardware-store rivets. One bit of fun I had from this was that about half the rivets had their stems break off above the rivet head. I was able to trim those off with my flush cutters, to avoid them poking through another layer of tape I put on top of the rivet heads.

Here it is all taped up and ready to roll:

Then I got another batch of micro mixed up. Learning from my last attempt, this time I didn’t try so hard to make the mixture super stiff, in the hopes that it would go on better. Working the mix into the interface gap went pretty well, but trying to put a good layer on top of the tip went about as well as last time. It’s just really hard to spread this stuff out without having it stick to the squeegee and come off the workpiece. I ended up having better results spreading it with a wide popsicle stick, and then I ended up sort of massaging it around with a moistened finger to make things look a little less horrific. But I think I have enough material here to work this down to final shape once it cures, even if it does still look atrocious right now:

Finally, before calling it a night, I peeled off my top layer of tape, leaving a nice clean line at the edge of the tip. This interface should look good with just a little sanding touch-up:

So now I wait until I can sand some more. And maybe next time I’ll try keeping the micro mix even wetter; I think there just still be a middle ground here I’m not finding yet. Though I also kind of feel like trying to spread the stuff on a tight curve like this tip maybe doesn’t help.

Oh, hi. Looks like we just had another one of those dead periods where I randomly get out of the habit of building, and then just as randomly get back to it. At least I’ve kind of gotten used to this ebb and flow after all this time, and I don’t feel super guilty about it any more.

Looking back, I actually have done some work since my last post, but I guess I decided it wasn’t enough to merit an actual post. I say this because I’ve had a partially-sanded ridder tip for some time now; after slagging on that last batch of micro, I went back and started rough sanding it to shape, at which point I saw that it might actually be workable as-is to sand to shape.

Thing was, for sanding to shape I wanted to use the v-stab tip as a sort of sanding guide to get everything nice and even – that is, I’d be sanding the rudder tip with both it and the stab tip clecoed in place – but for this to work I needed a way to immobilize the rudder in the centered position. Normally I’d do this by just clamping between the rudder horn and stab, but having a clamp over the top would block the stuff I wanted to be sanding.

After batting around a number of different ideas, I finally came up with something workable. What I’ve got are a couple pieces of scrap angle, with a hole drilled at one end that gets clecoed to the forward end of the horn, while the other end is clamped to the trailing edge of the stab. With one of these pieces on each side, the rudder is held very nicely in place.

Note: after taking this photo, and before actually working, I removed some material from the forward/upper end of the angles, so they wouldn’t protrude above the edge of the horn skin. Didn’t want that interfering with sanding at all:

Next I applied tape to the stab tip so I could lightly touch it with the sandpaper as I worked without removing any material. Scratching here isn’t necessarily a huge deal, as I’ll be refinishing the tip anyway, but I only want to remove stuff from the rudder. Then I went to town with a sanding block, in lots and lots of iterations. In the end, I was able to sand it down to a nice matching contour, which sounds like good news, but the issue was that I found a number of voids (air bubbles) from when I applied the micro.

These are going to need to be filled, which means more micro, and I want to be careful about sanding two different batches of micro at once.Since mixing micro isn’t an exact science, the density of batches will differ, making even sanding possibly more of a challenge. This is probably something I’m being more concerns about than I need to, but oh well.

Additionally, I’m going to need to add some micro down near the flanges of the tip as well. While everything tucks up nicely at the leading and trailing edge, about mid-chord there’s a larger gap here, which I don’t want. So I’ll be figuring out a way to wipe some micro into this gap as well, which overall means that this tip is probably going to just get an all-over batch of micro.

This photo shows both the matching contour, a couple of the voids, and the aforementioned gap:

Anyway, I decided to make this into a sanding training project first and foremost. Even though I wasn’t going to use it, I spent some time with finer paper refining the contour and getting everything nice and smooth, just so get a feel for what I’ll be doing for real later on. Then I went back to 40 grit and proceeded to remove a ton of micro all over the thing, until the contour was about 1/8” below the stab tip. This is to give me the room to cover the entire thing with a coat of micro that I can then sand down. I also scuffed up the entire surface of the tip for proper adhesion of the micro.

Before I do this, though, I need to figure out how to get everything set up for the flange fix. I’m going to need the tip clecoed in place to pull the fiberglass and aluminum tightly together, but doing that leaves the clecoes really close to where I’m going to need to work with the micro. I’ll also need to cover the area with tape to keep the glass from sticking to the aluminum. I’m kind of tempted to temporarily pop-rivet the tip into place with 3/32 rivets, then drill them out later. I won’t have to worry much about munging the holes in the process, since they’ll need to be opened up to 1/8 for final riveting. Still, that’s a decent amount of work for a temporary assembly…

Next, I moved on th the rudder bottom fairing. Last time I added some more micro here to fill a couple pinholes and build up a couple areas. So this needs some sanding attention as well:

It took me about half an hour to work on these fun little compound curves, and get everything nice and smooth. I’m pretty happy with the overall contour here, so I think I’m about ready to go ahead and cut the hole for the tail light here, and get all the mount stuff taken care of.

 Of course, I’ll also be wanting to probably scuff up the entire piece and shoot some filler primer. Question is, should I do that before or after I cut the hole? Bigger question, am I totally overthinking this? Based on personal history, there’s a good chance…

Well, first there’s good news: despite my concern that I’d buggered things up good yesterday, everything turned out just fine. The vertical stab tip ended up actually kinda nice, with the micro just above the level where I’d sanded the glass previously. I knocked that down a bit with a long board and then tested the fit in place on the stab. It’s got some pinholes that will need filling, but I think I’m going to sand it closer to shape before worrying about those.

My real concern, though, was the rudder bottom – but once I got to sanding on that, things started to look pretty decent. Even the relatively complex shape didn’t give me a lot of trouble in the end, though I had to get creative with sanding tools. At one point, I had some 100-grit paper wrapped around a 1/4” docker extension to properly work some of the concave areas. But in the end, all that goop that had dripped down the sides blended pretty nicely into the surrounding shape:

Much like with the stab tip, there are a few pinholes here to take care of, which would just require a little micro. But I didn’t want to mix up a batch of the stuff and only use a tiny amount, so I decided to pick another sizable job – specifically building up the rudder tip to better match up to the stab tip. I marked the general area that needed to be built up, then set to work sanding off the gelcoat in that area to give the micro something to adhere to:

Then I got another batch of the stuff going. Since last night, I did some video watching and got a better sense of what the dry micro should look like, so I added a good bit more balloons to this batch…but I think I might have overdone it a bit. Trying to spread this stuff onto the tip was seemingly impossible, every time I tried to shape it a bit the stuff would form voids, or just decide not to stick to the glass underneath, and the more I worked it the worse things got:

Eventually I just scraped it all off, chucked that batch in the trash, cleaned the part of all residue, and took another go at it. This time I think I made the stuff a little wetter, and while it was a bit easer to work with, it still seems like this stuff is a real pain to work with. After a while I gave up on having anything vaguely resembling a nicely shaped buildup, and instead just went for having enough material in place to shape the thing to near its final state. It looks pretty bad at the moment, but I guess I’ve got to start somewhere:

I suspect that when I get to sanding this, I’ll expose some voids that need filling, but to be honest, I’m not even sure this buildup will be enough to get to the final shape. Roughly, I expect to sand this down to something below the final shape, and then lay on another layer of micro on top to get it to where I actually want it. I feel a little more confident in the results since last night wasn’t the debacle I thought it was.

Oh, and I had enough micro left over from that batch to fill the few pinholes in the bottom as well. Once I sand it tomorrow, I expect it’ll be to the point where I can go ahead and make the mount holes for the tail light.

OK, that title might be premature, but I don’t think it will be. Let’s just say that my first attempt doing some micro filler work didn’t go so well.

First on the docket was picking up with the rudder light cutout area. Ripping off the peel ply revealed a nice new surface, but with a fair bit of overhang. It probably would have been a good idea to trim that glass a bit before it set, but oh well:

Next up, time to remove all that extra material on the edges and sand to roughly match the profile of the bottom. Since my intent was to cover all of this with micro, I also beveled the edges a bit and sanded off the gelcoat a little ways back. I figured I’d have my micro wrap around to the bevel a bit, and then it could all be sculpted to match later on:

It was somewhere along the line here that I started to think that I kinda jumped into the deep end in terms of glass work. The shape here is kind of complex, especially the small-radius inside curves where the upper/lower edges of the light flare meet the narrower main fairing shape. Even at this point I was thinking it might prove to be challenging to sand this back to a nice shape when everything was said and done.

Anyway, I also pulled off the vertical stab tip and examined the bonded-in balsa filler. My intent with this piece was to add some glass plies on the inside to reinforce the joint, and then use micro to fill out the area between the balsa and the actual tip end, which I could later sand down to match nicely with the rudder tip. I went after the plies first, and that part went fairly well, though working with that stuff in the tight confines was a bit fun. Might have been easier if I’d pre-wetted the glass like I did before, but for reasons I’m not sure about I decided to wet the glass in place.

I almost decided to call it a night right there, but I really wanted to get the micro work done so I could have some cured stuff to work with for my next session. The first comical thing here came when I mixed up a couple pumps of epoxy and then started adding the micro balloons. I don’t yet have a good feel of the epoxy:balloons ratio, though some research after the fact suggests it’s about 1:4-5. The punchline here is that a single pump of epoxy and hardener would have been plenty, with two pumps the mixing cup was getting pretty full after a while. That may be why I decided I had a good dry mixture when, in reality, it needed more balloons.

Once I started applying the stuff, after a bit I started to think maybe it was slightly too wet, but it didn’t seem too bad. The main problem I ran into while working on the stab tip – where I started – was that the stuff really wanted to stick to the popsicle stick I was using, which made it hard to put the stuff where I wanted it. That may have been a poor choice of tool, in retrospect. Once I got the stab tip done, I stuck it in the vise with the open end up while I moved on to the rudder bottom. This was even more fun, trying to put a thin layer of micro on the light face, and then wrap it around the edges. Once again, the way the stuff was sticking to the stick made this pretty tough.

I was still thinking I was doing decent until I finished that and took a look at the stab tip. I hadn’t clamped it precisely straight up, and the micro had overflowed the downhill side. That was when I really realized I made the stuff too wet. I ended up creating a sort of dam around the open end of the tip with tape and plastic, then re-clamping it more perfectly vertical, so I hope that will end up mostly OK. The rudder bottom, on the other hand, I don’t really know of a way to control the flow there, so I’m probably going to end up with something disgusting here when it’s all said and done:

The other dumb thing I did was working on this in the evening during a cold snap. When I went to look up info on dry micro consistency, I also noticed warnings about the epoxy not curing right in low temperatures – and it was down in the 40s by the time I finished up. I set up my heat lamp on these two pieces, which will hopefully help, but who knows whether any of this work will be salvageable. Only time will tell.

First goal for today was to see about getting the tail light mount cutout done, so I could assess the annoyance of feeding the wire through without removing the tip. Before doing that, I wanted to get rid of the seam line that runs along the length of the tip, including over the light pad. So I got to spend a decent amount of time with 120-grit working that out to a nice smooth surface. But now the bottom is looking pretty nice:

Next up was the light pad itself. The first thing I noticed was that the pad wasn’t actually flat, on each side of the seam it seemed to slop back a bit. So I started hitting this up with 40 grit, but at first did this while holding the tip. This turned out to noe be conducive to getting a nice square face; I had much better luck with the tip clamped to a work table. Unfortunately the result of this was that I removed more material than necessary, and in the process opened up a few holes:

So I decided to do my first real fiberglass layup, to add some more layers of glass here on the pad. Since I figured I’d have some leftover epoxy after saturating the cloth, I decided to also go ahead and prep for adding the balsa insert into the vertical stab tip. The fun part here is that the tip gets spread a bit when clecoed in place, yet I needed the tip off of the stab in order to fit the insert. So I worked up a length of popsicle stick that I could put in the back of the tip to hold it at the proper size even when removed from the stab:

After cutting and fitting the balsa, it was time for glassing. I made a cardboard template using the perimeter of the light pad, which I’d later use for cutting the layup pieces. For the layup, I put the glass and epoxy between sheets of plastic and moved the resin around with a squeegee until the cloth was soaked, then used my template to draw outlines to be cut out. After that, I just needed to peel off the plastic and put the cutouts in place. After adding four layers, I topped it all off with peel ply and left it to cure:

With the remaining resin, I mixed in some flox to make a nice thick structural epoxy, then buttered up the edge of the balsa insert. That got installed into the tip, with a nice tooled bead made around the mating point, and I clecoed it in place to cure overnight. Later, I’ll add some glass plies on the interface for more strength, then fill out the exterior side with micro before sanding it to match the rudder tip:

So that’s it for today – tomorrow we’ll see how these layups turned out.