![\"DSC_0559\"](\"http:\/\/www.balsaworkbench.com\/wp-content\/uploads\/2017\/08\/DSC_0559.jpg\")
<\/a><\/p>\nI’ll start by making a set of ribs. \u00a0Sometimes you get the rib outline from the fuselage side view, but this plan shows an empty wing profile there instead. \u00a0Complete wing rib templates are in the upper right area, as shown in this photo.<\/p>\n
Typically, a set of ribs is made in two steps. \u00a0First a master rib is made, and then the rest of the ribs are made from the master rib.<\/p>\n MAKING THE MASTER RIB<\/strong><\/span><\/p>\n The first step in this process is to get a piece of paper to trace the rib outline. \u00a0I have a box of used office paper for this purpose.<\/p>\n The wing rib outline is traced with a pencil. \u00a0Note that it is traced on the inside of the wing sheeting, to make a rib the correct size.<\/p>\n Sorry about the dirty fingernails. I changed the oil in my wife’s van today.<\/p><\/div>\n Next, the traced template is cut out with scissors. \u00a0It doesn’t have to be super accurate, so don’t worry about it.<\/p>\n Here’s a photo of the template, placed over the outline on the plan. \u00a0You can see that it’s a fair representation, but not super perfect.<\/p>\n The ribs of this plane are cut out of 3\/32″ sheet. \u00a0The template is placed on a piece of balsa, and the outline is traced with a ballpoint pen.<\/p>\n Next, the rib is cut with a knife. \u00a0Don’t worry about getting it perfect. \u00a0Theoretically the part should be cut on the inside of the line, but if you try to do that you will inevitably cut it too small in one or more spots.<\/p>\n When the part is placed on the plan, it’s obviously too big. \u00a0You can clearly see that the rib is covering the wing sheeting in the drawing.<\/p>\n The rib will need to be sanded to make it fit correctly.<\/p>\n Sand it in one area until that part of the rib fits inside the line.<\/p>\n Then sand the next segment, and recheck the fit. \u00a0Sand a little bit more, and check again. \u00a0Keep doing this until the entire rib is the correct size and shape.<\/p>\n MAKING THE REST OF THE RIBS<\/strong><\/span><\/p>\n Now you need a whole stack of these. \u00a0For many planes there will be two or more specific rib outlines. \u00a0In the case of the Guppy some ribs go full length, some are short to make room for the flaps, and some are just different because they go in the rounded wing tip. \u00a0When cutting ribs for this type of wing, it makes sense to cut the biggest ones first, then trim the master rib for use as a template for the smaller ones. \u00a0You probably noticed that I made the short rib first in the above sequence. \u00a0Well, you caught me not following my own advice. \u00a0So I made a full size master rib for the following tutorial, and I’ll use photos of it now.<\/p>\n Before I go any further, I feel like I should mention that there is no one right way to do things. \u00a0Most of the time when you ask how to cut out a set of ribs you will hear answers that involve\u00a0a\u00a0disc sander, a band saw, or a sanding block, and a stack of balsa blanks secured tightly with a couple of screws. \u00a0The master rib is attached on the top of the stack, or one on the top and one on the bottom, and the whole stack is cut on a saw, or block sanded, or held on the flat table as the edge is formed by a disc sander.<\/p>\n I don’t have a band saw or a disc sander, and for some reason the block sanding method never really inspired me. \u00a0So I’m going to tell you how I made all of my wing ribs for literally hundreds of planes that I built over the course of thirty years. \u00a0I’m one of those guys who always had a building project on the table, at least one a month, and and for many years it was at least\u00a0one plane per week. \u00a0Have I built a thousand planes in my lifetime? \u00a0Probably not, but I’m getting close. \u00a0I tell you this\u00a0because although my rib cutting method sounds kind of funny, I can assure you I have cut out a whole lot of ribs this way. So without further ado, here it is.<\/p>\n First, I harden the edge of the master rib with thin CA glue. \u00a0It helps to make the first rib from rather robust wood, because you don’t want a fluffy rib with a crispy edge. \u00a0Such a rib would come to a bad end.<\/p>\n After the CA treatment, the edge will be bumpy and grainy. \u00a0A light touch with a sanding block makes it nice and smooth.<\/p>\n Next, the master rib is placed on a piece of balsa sheet for tracing. \u00a0As you can see, I’m using a piece of laser cutter scrap because I’m cheap. \u00a0There is no compelling reason to make small parts from\u00a0new wood if\u00a0you have scraps.<\/p>\n “If you have laser cutter scraps, why don’t you just cut the ribs on the laser cutter?”\u00a0 Good idea, but you probably don’t have a laser cutter, which is why you’re learning one way to cut ribs out by hand.<\/p>\n The outline is traced with a ballpoint pen. \u00a0Accuracy is not critical.<\/p>\n Next the ribs are all cut out. \u00a0If I were using a new piece of wood I would pack the outlines really tightly to use the wood as efficiently as possible. \u00a0But these are scraps, so I’m not going nuts for this demonstration. \u00a0If you’re on a tight budget, you can splice scrap wood for your ribs. \u00a0These Guppy ribs are over an inch tall, but let’s say you have some strips that are less than an inch wide. \u00a0You can edge-glue another strip to\u00a0make it wider and it will work as well as it needs to.<\/p>\n These ribs are easy to work with because they are straight on one side. \u00a0For the next step I take one of my rough cut ribs and align the straight edge with the straight edge of my master rib. \u00a0Check your wood to make sure the straight edge is actually straight. \u00a0If it isn’t, straighten it with a sanding block.<\/p>\n Holding the ribs together tightly with my left hand, I then cut the protruding edges flush with the master rib, using a new, sharp hobby knife. \u00a0Don’t let go of the ribs. \u00a0Trim all the way around before you allow them to separate. \u00a0Otherwise you’ll have to realign them.<\/p>\n You have to pay attention to grain direction when doing this. \u00a0If you cut into the grain you’ll force your knife into the master rib and damage it, and you may dislodge a sliver of the target rib. \u00a0It’s best to start at the crest of the airfoil and work toward the leading edge, then the trailing edge.<\/p>\n The rest of the ribs are held against the master rib one at a time and trimmed in the same way. \u00a0When all of the full length ribs have been made, then the master rib is cut to make a pattern for the shorter ribs in the flap and aileron bays.<\/p>\n When all the ribs have been formed, spar notches are cut in the master rib. \u00a0You could use a ruler and mark a quarter inch square notch, but there is a much smarter way to do this. \u00a0First the spar locations are marked. \u00a0I always mark the rear edge of the spar with a ballpoint pen.<\/p>\n The spar notch is traced around a piece of the material to be used for spars. \u00a0In this case it’s a piece of 3\/16 square bass wood. \u00a0The location is marked with a knife on all three sides of the spar.<\/p>\n You can see the spar location in the following photo.<\/p>\n The notch is cut out with a hobby knife, preferably one sharper than the one I’m using.<\/p>\n Here is the finished notch.<\/p>\n The notch is hardened with thin CA glue, and then each rib in turn is held against it while the notches are marked. \u00a0Don’t cut through the target rib at this time. \u00a0Just mark the notch with your knife, and try not to enlarge the notch in the master rib.<\/p>\n After you have marked the spar notches on all of the ribs, then go back and cut them all out. \u00a0You really want a sharp blade for this. \u00a0It will make your life easier. \u00a0Here’s what it looks like when you use a not-so-sharp blade.<\/p>\n If I were just building this plane without doing a tutorial I would do it all in the correct order, but the process of taking photos\u00a0sometimes makes me forget what I’m supposed to be doing. \u00a0Normally I would make all four spar notches in the master rib, then hold each target rib tightly against it in turn while marking all spar locations. \u00a0Then after all ribs have been marked I would then cut the notches out of each rib, until the entire stack is finished.<\/p>\n There you have it. \u00a0That’s how I make a stack of ribs for a plane. \u00a0It seems kind of labor intensive, and it seems like a band saw or sander would be easier. \u00a0Maybe it would be, but with some practice it becomes easy and quick.\u00a0\u00a0I can make a set of 20 ribs in about half an hour, during which time the band saw guy and the sander guy are pinning a stack of blanks together and gluing paper templates to the top rib with contact cement.\u00a0 Six of one, half a dozen of the other, I say.<\/p>\n Part II: Fuselage<\/a><\/p>\n","protected":false},"excerpt":{"rendered":" Here’s a plan that I bought from RCM in the 1990s, the Guppy. \u00a0It’s a really cool plane with flaps but no ailerons. \u00a0I built it with flaps and ailerons, and it was a really great flying airplane, on land … Continue reading <\/a><\/p>\n<\/a><\/p>\n<\/a><\/a><\/p>\n<\/p>\n<\/a><\/a><\/p>\n<\/a> <\/a><\/p>\n<\/a><\/p>\n<\/p>\n<\/a><\/p>\n<\/a><\/p>\n<\/a><\/p>\n<\/a><\/p>\n<\/a><\/p>\n<\/a><\/p>\n<\/a> <\/a><\/p>\n<\/a><\/p>\n<\/a> <\/a><\/p>\n<\/a> <\/a> <\/a><\/p>\n<\/a><\/p>\n<\/a> <\/a><\/p>\n<\/a><\/p>\n<\/a><\/p>\n<\/a><\/p>\n<\/a> <\/a><\/p>\n<\/a><\/p>\n