RCM Fuselage Jig (oz11465)
About this Plan
RCM Fuselage Jig. Note this is not a full-size plan. This is not a plan at all. This is an article describing in detail how to build a fuselage jig.
Quote: "RCM Fuselage Jig, by WA Thienes.
The majority of RC'ers who build their airplanes try to divise building and finishing methods that will enable them to complete an airplane in a shorter time. Using conventional balsa and plywood fuselage construction methods, and assembling the fuselage sides and formers 'in the air' using rubber bands, pins, diagonal braces and appropriate language, it is difficult, if not impossible, to obtain a properly aligned fuselage. This fuselage building jig will provide the means to obtain a straight centerline, no twist, and have all formers at 90 degrees to the centerline of the fuselage.
Figure No.1 is a photo of the completed jig. The cost is very nominal, as all there is to it is a piece of 3/4 x 12 x 48 inch warp-free pine or plywood, 16 five-inch long 1/4 in carriage bolts, washers and wing nuts, and some 1/8 in hardboard and 1/4 in plywood slotted jig blocks.
The 12 x 48 in base has a centerline the length of the board with three parallel guidelines on 1 in spacing on either side of the centerline. Crosslines on 3 in spacing are marked off at right angles to the centerline, this is a sufficient number of guidelines, although some builders may desire to add more guidelines, or actually glue a graph paper grid to the board. A carriage bolt is located every 6 in, starting on the first crossline from the end of the base board. The bolts are located 4 in out from the centerline for the first five pair of bolts while the last three pair are located 3 in out from the centerline. The bolts are inserted from the underside of the board in 1/4 in holes drilled through the board. This spacing should allow sufficient opening and closing of the slotted jig blocks to construct a fuselage for any of the R/C airplanes in the air today. The carriage bolts serve as guide pins for the 3-3/4 x 4 in slotted jig blocks. Figure No.2 is a drawing of the base board showing the alignment grid and the carriage bolt guides.
The slotted jig blocks are made from 1/8 hardboard with a 1/2 in wide spacer of 1/4 in plywood glued and nailed at each end of the spacer. The plywood spacer permits a nice smooth fit of the jig block over the carriage bolt guide. The 3-3/4 in depth allows sufficient threads of the carriage bolts above the jig block for a washer and wingnut. Figure No.3 shows a drawing of the slotted block... "
Quote: "RCM Fuselage Jig, by WA Thienes, from RC Modeler.
This jig came out of the now defunct and sadly missed RC Modeler magazine; the photo showing the jig in use [see morepics 003] is from RCM's review of Midwest Products' 74 inch semi-scale Cardinal Squire. I'm not sure when the jig was published (or even how long ago I scanned the article), but it has to date back to some time before 1975 [edit: now confirmed: Feb 1972], as that is when the updated (but harder to store in limited space) Fuselage Jig II was done.
Similar devices have been asked for recently on 'social media' so I hope this is helpful for many of our model building friends.
Direct submission to Outerzone.
Note main pic of RCM Fuselage Jig in use was found online on brner's RCGroups thread at https://www.rcgroups.com/forums/showthread.php?1812128-Fuselage-Building-Jig which also has some useful templates to download for the grid layout.
Note for the companion article on the RCM Wing Jig from Aug 1967, see RCM Wing Jig (oz6524).
Supplementary file notes
Planfile includes article.
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User commentsGood Day Mary. Attached is a photo of a modification that I made to my version of the RCM Fuselage Jig, plan oz11465 [more pics 004]. Originally I built the side pieces square. When I went to get the carriage bolts to assemble the jig, I found that the length of the bolts required cost twice as much as somewhat shorter ones. So I thought about it and cut the square sides to the shape as per the attached picture. It meant that each square side piece could be cut to make a pair of the revised shape. I then found that the shorter bolts were just right and 1/2 the price. It also had a big advantage when building. You can swing the sides around so either the tall or short end faces the fuselage. So when making 049 size planes the short end of the square works for the tail and nose area. The tall side works in way of the cockpit.
Also there is another very subtle modification to the edge that sits on the jig base. The outer ends are sanded to allow for fuselage bottom sheeting to slip under the fuselage and pass under the edge of the side frame of the Jig. So if you make up cross sheeting slightly oversize for the fuselage bottom, it can be put on the base and still allow the Jig side brackets to be positioned against the fuselage. For the base I find that laminated stair treads tend to stay flatter than plywood or a large plank. The treads are generally available in 36", 42", and 48" lengths. They are nice and thick, so you can counter bore the underside to recess the heads of the bolts. Make sure that you use the edge glued pine or spruce treads. They are less expensive than fancy veneered ones. They also are more moisture resistant than those with particle board cores.
Just my 2 cents worth of revision.
Jim Haliburton - 24/08/2019
Nice work Jim, that's a very neat design. You gain additional flexibility with the two heights of jig-block, plus save money (and weight) by using shorter bolts. Have to admire your thinking there.
SteveWMD - 25/08/2019
Instead of coach bolts, use 1/4" all thread (that is threaded rod) and tap threads in the holes. You will discover this increases the versatility of this jig immensely. I also have various height jig blocks to suit different depth fuselages.
Andy Luckett - 26/08/2019
Steve, 6 inch bolts are cheap [more pics 005]. Best Regards,
Jim - 27/08/2019
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