It turns out that updating this blog every time I do some work just isn’t feasible for me. I’m honestly not surprised about this because I’ve never been a big fan of writing. Most of the entries written so far have been written several days later but I change the publish date to make it look like I wrote it on the day I did the work. Plus, not every building session is actually worth writing about. Since my last entry (which was about 2 weeks ago) I’ve had a couple days where I spent hours doing nothing but deburring parts and unless I come up with some magical new technique for deburring I don’t think anyone will really want to read about that. So from now on I plan to update the blog when I feel like it makes sense. Maybe I’ve had a really productive day building, or maybe I’ve completed a part, or maybe I’ve run into a problem and want to help others avoid it in the future. I’ll do my best to not let this blog get so out of date that I can’t bring myself to get it caught up to where I’m at. You may have noticed a link at the top of the blog for my Time Log. If you really want to know how much time I spent each day, what part I worked on, and a short description of what I did, then that is the place to look. I update that every time I build so it will always be up-to-date.
I continued rivet the VS tonight. This time I did everything with the pneumatic squeezer which produced much more consistently round shop heads. Except for the two that wanted to bend over rather then squish down nicely. I drilled those two out. I’m also not thrilled that the squeezer put a small smile around the right side of the hole when it shifted. It’s not too bad but I need to do some research about when I need to be concerned about this kind of damage. It’s not the first time I’ve done it (I know I made at least a couple on the rudder spar reinforcement plates) and I’m sure it won’t be the last time I do it.
I also ran into what seemed like an issue when I was riveting the rudder hinge brackets to the VS assembly. I assumed I squeezed the first rivet way too far because it was way too thin so I adjusted it and tried again. This is what the first two looked like:
Notice how thin that shop head is? Well, that is way too thin to be a structurally sound rivet. The one just to the left of it has the right thickness but the diameter of the shop head there isn’t large enough. This is when I realized that maybe the rivets the plans called for weren’t quite long enough for this spot. I have read on the VAF forums that sometimes the rivets called for in the plans are wrong, otherwise I never would have questioned the plans and may have set all of the rivets like the one on the left. Maybe that is what I was supposed to do, but I opted for drilling them out and using the next size longer rivets. Here is the first rivet drilled out:
When I tried a new rivet in the hole it was a little loose but I think the hole is still ok. It looks offset a little, but I think the impression around the top left of the hole is just the primer that got squished out of the way by the first rivet. Here is the second rivet drilled out after I set a new rivet in the first hole:
This rivet came out much more nicely than the first rivet. I drilled out the manufactured head and then pushed the rest of the rivet out using a punch and a hammer, which is the way rivets are supposed to be removed. The first rivet I ended up drilling all the way out because I couldn’t get it to budge with the punch and hammer. I’m a little scared to really hit it too hard with the hammer because I don’t want to bend the parts.
The new rivets that I set in the bracket holes were much better. The shop head diameter and height were all the correct dimensions, so even if it would have been fine with the rivets the plans called for I’m much happier with these.
I spent a little time last night patching up some spots on the vertical stabilizer parts that I felt didn’t have enough primer. Then tonight I started riveting them together. I back riveted everything tonight, and while most of the rivets turned out well, there’s a few that I’m not too happy about because they turned out slightly oval shaped. I don’t think these are bad enough to need to be drilled out but I think I’ll leave that decision up to a tech counselor when I have one come out. Here are some pics of the work I did tonight.
So I realized that the rudder stiffener being on the wrong side of the shear clip shifted its position just enough to make it very difficult, maybe even impossible, to get all of the rivets through the holes that connect the shear clip to the rudder spar. This made me decide to attempt to drill out the rivets so that I could reposition the parts. I had a couple options on how to drill them out. With a jobber length drill bit I could fit the drill between the other shear clips and stiffeners with no trouble, but because of the diameter of the drill motor, I didn’t like the angle that the drill bit would go into the rivet. To attempt to fix this angle I decided to use a 12 inch drill bit that I would flex, using a gloved hand, so that it would get into the right position to drill the rivet out without turning it into a hole. It seemed like a good idea at the time but in hindsight I should have bought/borrowed a 90 degree drill instead.
This is what my technique looked like. Due to the length of the bit I had to position it between the stiffeners right next to the drill.
I started off slowly and checked my progress on the rivet after a small amount of drilling. Looking good so far…
Got the first rivet drilled out and I’m feeling like this might actually work out.
Three rivets later…
The bottom right hole is the picture above is nearly perfect…I’m not sure how I pulled that off. The other three are not quite as good, with the top left being the worse. The holes in the picture may or may not look very bad to you, but when I insert some rivets to check the size there is a lot of extra room. I’ve emailed Van’s to see what my options are for this part. My biggest concern at this point is that the stiffeners this clip was attached to now have matching holes. It will be really easy to replace the shear clip, but if I have to replace the stiffeners as well that will mean a lot more rivets have to be drilled out which gives me a lot more changes to mess up other holes.
I won’t touch the rivets for the other clip that needs to be repositioned until my 90 degree dill gets here, which I’ve already ordered. Until then I think I might start riveting together the vertical stabilizer.
Today started off simple enough. When I countersunk the trailing edge wedge in the rudder a while back it worked very well on one side, but since the hole was enlarged by the first countersink the countersink cutter ‘chattered’ a lot when I was countersinking the other side. The result was the really rough holes you can see in the picture below.
I cleaned up these holes using a hole deburring tool and some elbow grease. Next my wife and I got everything set up to bond the trailing edge of the rudder together. The plans point out that a straight trailing edges on the control surfaces is very important and can affect the feel of the airplane if they aren’t straight. They suggest bonding the trailing edges together before you rivet them using either fuel tank sealant (which is an old method but still used by a lot of builders) or really sticky double sided tape. I decided to try the sealant this time since it is still a very popular method, and I hoped it would provide a strong enough bond to hide some of the dents I put in the trailing edge of one skin a couple weeks ago.
The basic process when working with the sealant is after you mix the two components together, you apply a thin layer to the trailing edges of the skins and then cleco them and the wedge together. You start at one end and roll on skin onto the other. While you work your way from one end to the other you rivet, using blind rivets, the stiffeners and the shear clips on the rudder skins together.
My wife and I went over the plan a few times to make sure we knew what we were going to do, but despite that we still ran into problems. It’s amazing how thick and sticky the sealant is. This makes spreading a thin layer on the trailing edge very difficult. You really want a thin layer because if it is too think then it can apparently prevent the two edges from coming together nicely. Oh, one more thing, the sealant has a working time of 30 minutes, and it took me about 20 minutes to get the sealant mixed and applied to the entire trailing edge wedge (the plans say to apply the sealant to the trailing edge but I chose to put it on the wedge so that it would be exactly where I needed it). So this meant we really had to hurry to get the rest of the process done, which resulted in some riveting errors.
When I set the first blind rivet the two stiffeners were not as close together as I thought which caused the rivet to expand a little between stiffeners. So now the two pieces are being held slightly apart from each other by the rivet. It’s tough to see but at the center of the picture, where the parts form the sideways ‘V’, is where the two parts are being help apart.
A little bit later I wasn’t paying attention to the position of the stiffener in relation to the shear clip. In the picture below you can see that the bottom stiffener attaches behind the shear clip and the top one attaches in front of the shear clip. Well, both of those should be behind the clip. Unfortunately I didn’t pay attention when I set the rivet that connects the stiffeners together, which is at the left of the picture, and once that rivet is set it isn’t possible to get the stiffener to the other side of the shear clip. Since I was worried about finishing within the sealant’s working time, I just set the other rivets and hoped it would be ok. A couple minutes later I did the same thing to another set of stiffeners…
These are pretty minor problems that I don’t think really need to be fixed. Regardless, I have sent out an email asking some other builders for their opinions on if they would fix them, and how difficult it is to remove the blind rivets. I’m really frustrated that I made these mistakes but it’s also nice to have the rudder that much closer to being finished.
Over the last couple days I got the stiffeners riveted to the other rudder skin, the top rib halves riveted to each skin, and the bottom rib with the rudder horn riveted to one skin. I did skip a couple rivets on the bottom rib because it got too tight to get a squeezer or bucking bar in there so I have to research how to set them. I also got the shear clips riveted to the stiffeners using blind rivets. Blind rivets work a little bit differently than the other rivets I’ve used so far. Blind rivets are like hollow cylinders with a rod that stick through it with a ball on the end. You stick the rivet into the hole and then use a tool to pull the rod which then deforms the bottom of the rivet which creates the shop head which holds everything in place. Once the rivet is fully set the rod snaps off and you’re all finished.
Today I got the second reinforcement plate riveted to the rudder spar and stiffeners riveted to one side of the rudder. All of the stiffeners were done using a technique called back riveting. Basically you put the outside of the rudder skin, where the rudder is flush with the skin, on a steel plate and then hit the other side of the rivet with the rivet gun. This is a very simple way to set rivets and results in a perfectly flush rivet on the other side of the skin.