Instruction Notes
This sequence of instructions is set up to minimize the amount of time spent in setups and task changing; reduce the chance of mistakes, and produce good alignment and neat-looking work. Sometimes the reason is given, sometimes not. The steps should in most cases be followed in exact order; in particular, do not do any task, especially riveting, before it is called for. The order of steps within a task is designed to make each step as easy as possible such as by doing any operation on the smallest possible piece or while it is most accessible. While there are many ways to build an RV, it is fairly easy to get yourself into a place where it may be difficult or impossible to continue without tearing up work you have already done. The sequence of steps and the methods given here represent one possible path that is known to work. There are a number of places in these instructions where you are told to drill some but not all of the holes shown in the drawings; this is because you will be drilling the other holes later in assembly with some other item.
The order of major steps is designed to get each subassembly as complete as possible so that once the fuselage is done there will be very little work left in the final assembly. This is sort of a psychological thing in that you don't want to be looking at another 1000 hours of work when it already looks like an airplane.
I would appreciate any information from users as to errors or easier ways to do things. Also, I am particularly interested in hearing about mistakes made so I can add warnings to the instructions. If you think of a new way of doing something, it would be helpful if you try doing it both by these instructions and by your own way to get a real comparison. This is usually possible as most operations require that you do the same thing twice.
Deviations from the plans
There are a lot of ways in which you can deviate slightly from Van's plans, whether it is to eliminate pop rivets, make the appearance more show-like, make the structure stronger, adapt to tools you have or don't have, or allow easier assembly. These instructions follow the plans as much as possible simply to avoid confusion. I have heard numerous tips from builders about deviations, many of which do not appear to have any significant value, and these are usually not included here. These instructions do try to eliminate those pop rivets which are easy to eliminate, since that seems to be the thing that most builders are interested in. There are also some places where you will find pop rivets must be used but I don’t tell you to; this is because each builder has different abilities and tools to handle hard places. Don’t be afraid to use one or two if it means you will avoid making a mess.
At the moment these instructions do not include the vertical stabilizer and rudder. I will not be able to go back and write these up, but they well enough documented already that there are only a few problems people have with them. I am looking for volunteers to write up these sections for me.
Order of build
With each section there is a file with some notes including the order in which the files within that section are to be used. These files are empkit.doc, wingkit.doc, fusekit.doc.
Revisions
These instructions are constanly being revised as better methods are suggested, kit changes are made, or mistakes are found. For that reason you should pick up a fresh copy of each file as you finish the previous one. Note that the date of last revision is shown at the end of each file.
Hints gathered from various builders and other sources
Most Common mistakes:
Wher more than two pieces will eventually come together, drilling a bolt or rivet hole with only two of them present. Then when you try to drill through the third piece you find the hole is too close to an edge (the metal may split) or too close to something else that prevents access for riveting or attaching a bolt. This is a common problem in the empenage. Always line up all the pieces that go together before locating a hole.
Misinterpreting a drawing is easy to do. These drawings are complex and in some areas actually misleading. Make sure you understand how to interpret section lines and the views that go with them. The horizontal stabilizer will give you fits if you don’t.
Worrying too much. There are many places in the build process where dimensions are not critical. Some are pointed out in these instructions where it is likely that you will have difficulty holding a tight tolerance. I will also tell you where dimensions are critical; most of these are important not for structural integrity but just because later operations will be easier if things are correct.
Countersinking and Dimpling
If you plan to dimple a skin, use a #41 drill bit for all its rivet holes so they will still be reasonably tight afterwards. (Dimpling enlarges the hole) If you plan to countersink, you may want to use a #40 drill instead if your countersink bit tip does not go easily into #41 holes. Also, if you plan to countersink, use a Scotchbrite wheel or fine sandpaper to deburr the back side or else be very light-handed with a deburring bit. Normal deburring with a rotary bit bevels the material and an oversized hole will result in thin material after countersinking. Never countersink without another piece of material behind unless the piece is much thicker than the countersink depth; otherwise when the cutter goes all the way down it will start to enlarge the hole sideways. The backing material must be firmly held to the item being countersunk. If the countersink starts to squeal, stop immediately; it is probably enlarging the hole. Make sure the countersink is exactly perpendicular to the hole, and look at the hole afterwards to make sure the ring is even. Hold the foot of the microstop to keep it from rotating and marring the skin. Use light pressure on the drill so you won't distort the surface of thin material and wind up with the wrong depth, and don't stop too soon. Purchase a good quality microstop countersink tool. Some of the cheaper ones may allow the cutter to wobble excessively or will not hold it exactly perpendicular to the work. Make a countersink gauge by gluing a rivet to a match stick or similar and use it liberally. Do not countersink too deep; you should just be able to see a ring of cut metal around the head of the rivet and the head surface should be a few thousanths of an inch above the skin surface. Go just a little too deep and the head of the rivet will not be tight against the skin after driving and the rivet is more likely to tilt and fold over during driving. When countersinking where a dimpled piece will go into the countersink, you must countersink a little deeper than you would for a rivet.
If the countersink is a little too shallow the top of the head can be shaved down with a rivet shaving tool or a Dremel sanding disk but this is not something you will feel like doing a lot of. To use a rivet shaving bit, put it in a good quality microstop tool and set it to shave only a couple thousandths of an inch at a time. Don't set the cutter down on the rivet head; set the cutter beside the rivet and slide it slowly sideways over the head.
Some dimple die sets do a better job than others, and the more expensive ones that have a slightly curved surface do the best job. If you round off the sharp corners on a cheaper set and use enough force it will do an adequate job. If there is a noticable depression outside of the actual dimple area you didn't use enough force. You should use enough force to get a slight mark on the flat part from the die, but don't use so much force that there is a distinct distinct depression part or all the way around the dimple. For those hard-to-reach dimples such as next to a rib web you can grind a dimple die down almost to the cone on one side. Dimpling of thin skins such as on the control surfaces can be a little tricky; one good way is similar to back riveting. Tape a rivet in the holes to be countersunk, lay the material rivet-head-side down on a hard plate and drive a female dimple die over the rivet shank. This way the rivet makes its own dimple and the metal around it will not be dented or smashed. Then just hit the rivet with a flush set.
There is considerable discussion among builders as to whether countersinking or dimpling is appropriate to use at any one point. In general, countersinking can produce a smoother surface if done right, and the RV designs are conservative enough in most areas that the any loss of strength is not significant. On the other hand dimpling can produce a surface that looks just as professional but it must be done carefully with a lot of pressure on skins that are 0.032" or thicker. An "Avery tool" is essential for this. There are many areas on RV’s where you must dimple; on a finished airplane it is questionable whether it looks any better to have some areas almost smooth if others have dimples. Some builders partially dimple and then put a slight countersink in the hole; this requires a lot of extra work and will still result in a slight depression around the rivet unless the dimpling operation was done almost perfectly to begin with. As for strength, the head on a 3/32" rivet is just about 0.032" high. If the forces tending to pull two pieces of metal apart are tension, then it doesn't matter whether dimpling or careful countersinking is used in 0.040" or thicker material; the rivet head itself is an equal or weaker link. If the forces tend to slide the joined pieces of metal with respect to each other, dimpling will be somewhat stronger because the cross section area resisting this motion is somewhat larger. Most builders who start out countersinking skins wherever they can and end up dimpling wherever they can instead as the project goes on. There is only one area in an RV-6 where dimpling will be recommended strongly as a result of experiences some people have had with riveted skins moving enough to make the paint crack around the rivet heads, and this seems to be limited to airplanes with larger engines used for aerobatics; this is covered in the fuselage section.
How thin a skin can be countersunk is another question. A general rule is that there must still be some of the original hole still visible after countersinking or at least that the bottom of the hole is not enlarged. A full depth countersink for a 3/32 rivet would be about 0.035" deep, so you will hear some people say not to countersink unless the skin is 0.036" or thicker. Since you normally countersink a few thousanths shy of full depth in order to guarantee that the rivet head will be full against the skin after driving, you will also hear other people say you can countersink 0.032 skins. There are some places where you will have to countersink skins thinner than 0.032" but this will be overlapped by another skin which is dimpled so no loss of strength occurs.
Some flush pop-rivets have a 1/8" shaft but the heads are the size of 3/32" rivets. For these, first drill the hole #40 and dimple it. Then drill the hole out to #30.
Last but not least, do not countersink or dimple until you are ready to rivet; clecoes can hold parts in better alignment using plain holes.
Empenage and Wing Jigs
The jigs described in the construction manual are required for only a very small part of the total construction time. These plans are organized in such a way that you will do everything possible before you need these jigs. Do not put up the empenage jig until you are ready to start skinning the stabilizers and do not put up the wing jig until you are at the last stage of assembling the wing skeleton. That way you don't have the jigs taking up valuable space when you don't really need them.
Other Instructions
Whenever a hole is drilled, put a Cleco fastener in it; the exception is that in skins you can often go two or three holes per Cleco. When a step is finished, leave the clecos in unless the next step is a disassembly.
The parts in Van's kits are normally cut very accurately and bent with moderate accuracy. As with any typical moderate precision sheet metal work, any dimension, bend angle, or bend line may be off enough to cause difficulty in getting proper alignment later. Things to watch for will be noted, but there may be a problem with one of your parts that was not a problem in my kit; let me know. Van sometimes has several different vendors for the same part. Measure every part against the plans before starting to work it. There are also a very few places where the parts as supplied meet the drawing dimensions and yet must be trimmed slightly.
Tools and Usage
Tools that I have found that are well worth the money for the time they save are listed below. They will also be useful in many non-airplane tasks.
A light-weight rivet squeezer with a yoke having a three-inch throat, two flat dies and a 1/8" universal head die, 3/32", 1/8", and #8 screw dimple dies. If your rivet squeezer is too heavy you will have to limit yourself to a 1" throat yoke. If the squeezer is awkward for you to handle you will find that the rivets bend over easily. Best tecnique is to hold one die against the shop head forcing it against the material. Slowly squeeze to bring the other die down to the other end of the rivet; watching to make sure that end hits in the exact center of the die. Before buying a squeezer, try one or more brands if you can. Different people have trouble with different brands.
A tabletop belt/disk sander for smoothing heavy pieces
A Dremel tool or equivalent with cutoff disks and a cylindrical cutter bit for cutting where you can't get in with shears and for radiusing after cutting
A four- or six-foot long aluminum ruler
A small-size 3/8" variable-speed battery-powered drill such as Black and Decker makes (the CD5500); use it instead of an air drill because it works just as well, is just as easy to handle, and makes much less noise. Battery powered drills are good, but choose one carefully; it must be very light, balance in your hand, be variable speed, and run as fast as you can get. The CD5500 will only turn 700RPM and that is about the slowest you can use.
Cordless screwdriver, preferably one that will turn several hundred RPM. Use it with a countersink bit or deburring bit held either with a drill chuck adapter or the hex-to-threaded bit tool sold by Avery. Much faster than hand deburring. Not practical for drilling because it wobles too much.
An air compressor is required, but it need not be a large one. Rivet guns do not use a lot of air nor does spraying primer. Air powered die grinders and sanders use a lot of air and require larger compressors, but by using a small high rpm electric drill or die grinder you can do just as good a job. The right battery powered drills as described above are quieter and much more convenient than air drills. The noise generated by the compressor alone when using air tools will get on your nerves quickly.
The "Avery tool", the bench-mounted riveting and dimpling aid that you pound with a hammer. This is used seldom enough that three or four builders can share one. You can get by without one but it will cost you at least 100 hours of work and your quality of riveting and dimpling will suffer. Make a couple of platforms about 1 by 2 feet with carpet on top to lay work on while using the tool. They should be high enough that the work will lay lightly on the tip of a male dimple die installed in the Avery tool.
Drill bits: Either 135 or 118 degree bits will work about as well in aluminum. Cobalt bits don't cut any better or last any longer than standard High-Speed drill bits in aluminum; they are designed to resist the heat generated by high speed drilling in steel. Use split point bits; with reasonable care (start slow, don't push hard) they will not wander when you start to drill, so no need for a centerpunch. They also don’t jam up with bits of metal. For the RV rivets you need drill bits in sizes #40, #30, and #12. You should also get a #41 to use for holes you plan to dimple. You will also need long drill bits, preferably 12", in #30 and #40 as well as a smaller one about 1/16" or #50 to use for drilling pilot holes to help locate rivet lines. A #19 size bit is best for drilling holes for #8 screws. A "D" size drill is used for 1/4" bolts in some cases. If you can afford it, also get one of the less expensive sets of numbered and lettered drill bits for those odd-sized holes. There are several places in the fuselage where you must tap holes and you must use the right drill bit for best results; the recommended bits are always numbered sizes. You must also get Unibits in two sizes; small to 1/2" and medium to 1". Regular drill bits make a big mess drilling large holes in thin metal.
As a general rule, there are very few tools out there that are not worth what they cost, and most of these are the cheapest ones.
rvnotes 1/15/95