So it’s been another batch of cold days, which has kept me from really getting into any work, but I did find time a couple nights ago to pick up some actual body filler to use for pinhole filling and other minor touch-up work. Tonight I made the first use of that by mixing up a small batch and using it to restore that groove I accidentally cut in the rudder tip. Also, another nice touch with the filler is that it sets up a lot faster than micro – the touch-up I did was sandal within an hour or two. That, in turn, allowed me to get my sanding done a lot sooner, and I even shot a light coat of primer just to get a better look at any imperfections. The whole piece needs maybe one more overall sanding and another coat of high-build, but I think at that point these will finally be ready to rivet.

In the meantime, I got back to work on the horizontal tips. The stab tips that I drilled last time needed to be trimmed to length; I made some starting marks last session and tonight extended those around the pieces and got them rough-trimmed and sanded to shape. A test-fit on the actual stab allowed me to finalize the shape and check fit against the elevator tips as well.

Next I worked on cleaning up the elevator counterweights. These are going to get wrapped in fiberglass, but before that can be done the shape needs some fine-tuning to match the counterweight skin. I spent some time working on those with a file, giving them some nice rounded edges, as well as a little inset compared to the counterweight skins, to allow for the eventual glass layup.

Then it was time to prep the elevator tips for glassing in the counterweights. As provided, these pieces are a bit long, actually extending past the counterweight itself. Some trimming is required here before getting to the glassing; here you can see the mark I made about 1/4” back to use as a trim reference:

After extending that line all the way around, I trimmed the tips, then went to work sanding a nice taper to the cut edge. This taper will allow for a good solid scarf joint with the glass plies I’ll be adding:

Now that the counterweight is exposed, I can also see that I’m going to want to work on the stab tips a bit too. The gap is nice in the skin area, but tapers a bit with where the actual weight is. I suppose I could trim the counterweight a bit, but I think it’ll be easier to get a nice edge by working on the tip instead. I’ll be wanting to get that done before I go to work adding glass here.

Also, I still need to drill the elevator tips to the elevators; obviously I’m going to want those clecoed in place before I start adding glass plies. Having the whole thing move around wouldn’t exactly make for a nice shape…

The good news is that it’s warming up again this week, so the weather should be good for getting this glass work done.

Notably, this entry actually covers work done over a couple days – I did bits of work on the rudder tip over the weekend, but at some point it seems absurd to keep making short entries and having to invent new title variations. Hence me combining them instead.

After sanding the epoxy skim coat, I shot filler primer on the tips once again. This revealed a few remaining pinholes in both pieces, but this time, instead of doing a big sand-down operation, I mixed slightly wetter micro and worked it into each pinhole just using a finger, leaving a bit of excess around each spot. After that cured for a day, a quick bit of sanding smoothed everything out, and I shot primer yet again. Finally, at this point, the vertical stab tip was pinhole-free, but I found a few more stragglers on the rudder tip, so I repeated the same procedure again.

As of tonight, the rudder tip was also pinhole-free, but I wanted to do a bit of touch-up on the flanges. The “step” where the flanges begin was uneven in some spots due to buildup from my multiple epoxy coat applications, so I went to work with a bit of 120-grit on a popsicle stick to clean those up a bit and make sure the flanges were nice and crisp. With that done, I shot primer…yet again.

As primer tends to do, it highlighted a new problem I created during my flange work. Looks like I got a little overzealous with the paper here, and now I’ve got a new groove to deal with:

That’s probably fixable with a touch of micro – or maybe I should just go ahead and get some regular old filler for this stuff instead of continuing to make batches of micro and then throwing away 99% of them. Anyway, the rudder trip farce keeps going…

On the other hand, I’m feeling good enough about my fiberglass learning to get going on the horizontal tips. I laid out the rivet holes on the stab and got those drilled in assembly with the tip pieces. For the most part, they seem to fit pretty decently with just the cloches holding them in place, but I think I’m still going to end up adding some support further forward to help them conform a bit better. I also expect that I’ll end up building them up a bit to get a nice smooth transition from fiberglass to aluminum…here’s hoping that process goes a lot more smoothly than the vertical stuff.

Next up will be trimming the horizontal tips and adding the closeouts on the aft ends…then there’s glassing in the elevator counterweights…plus continuing to bang on that rudder tip…

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.