1:8 scale Koban Model Documentation

Transcription

1 1:8 scale Koban Model Documentation Gear-foot assembly The gear foot consists of three parts, the gear-foot, prop shaft, and propeller. Clean flash from castings being careful to keep the mating surfaces of the prop and gear-foot flat. Trim the prop shaft about 1/32 inch and make sure that it is an easy fit into the prop. The large end of the prop shaft should be flush with the prop. Use a Dremel and a tiny drill to make a hole from the inside of the bottom rudder pivot hole to the prop shaft hole. This hole will allow glue to secure the prop shaft. When gluing the prop shaft be careful not to glue the prop.

2 Lower unit The lower unit consists of the parts in the picture. The brass parts are as follows: Shaft tube K&S 3/16 brass tubing long Rudder shaft is Special shapes or K&S brass 1/16 square stock long Large bush is.500 diameter X.202 inside diameter X.200 long 2 Small bushes are.250 diameter X.230 long with 2-56NC thread NC X1/4 long brass screws Cast parts include: Gear foot assembly rudder transom clamp 2 transom clamp screws 2 transom clamp screw pads flange rudder crank shaft and pivot casting Assembly insert the two small bushes (leave screws off) and glue into the shaft and pivot casting being

3 careful to keep the end flush with the casting and keeping glue out of the threaded hole. Place the shaft tube on the peg protruding from the shaft and pivot casting and glue in place. Insert peg on gear foot into shaft tube being careful to keep the gear foot aligned with the shaft and pivot casting. Glue in place. Smooth the outside of the rudder crank so that it is an easy fit into the hole in the shaft and pivot casting. Insert the bottom pivot of the rudder into the hole on the bottom of the gear foot. Thread the rudder shaft through the hole in the shaft and pivot casting through the hole at the top of the rudder and into the larger hole on the top of the gear foot. Push the rudder shaft through the hole in the shaft and pivot casting and over the rudder shaft. Glue the rudder shaft to the top hole in the rudder being sure that both the lower pivot and the rudder shaft are seated in the holes in the gear head. DO NOT GLUE THE RUDDER CRANK!

4 Screw the transom clamp screws into the transom clamp all the way. Screw the transom clamp pads onto the transom clamp screws being sure that the screw does not protrude beyond the pad. Apply a drop of glue to secure the pads to the screws. Position the transom clamp on the small bushes and screw to secure.

5 Set aside the lower unit, flange and large bush.

6 Crankcase The crank case assembly consists of : Crankcase/cylinders (one piece) 2 Cylinder heads Carburetor 2 Spark plugs Exhaust manifold 2 pcs Muffler - piece of K&S brass tube 11/32 X.014 X.950 long (see note) Top crankcase bearing 1-72X1/4 or 1/72X3/16 NOTE Muffler length may vary due to variance of castings/holes. Suggest making 5 test mufflers with two.005 over/under, two.010 over/under and one to.950 dimension. Check which test muffler fits and then cut appropriate size.

7 Prep and assembly: Clean up the ends of the cylinders and crankcase. Check to see that parts seat properly and that mating surfaces have been scratched with sandpaper or a file to assist bonding of glue. Using #1-72 taps thread the hole for the tiller. You may want to start with a spiral point tap and finish with a plug tap. Trim carburetor and spark plug pegs so that they do not protrude into the cylinder or crank holes. Test each to be sure. Position, align and glue the top bearing making sure the top gas tank mount is parallel with the mounting lug on the crankcase. Alignment is critical. Glue one of the exhaust manifolds to the brass tubing. Insert the other manifold into the tubing and fit the assembly into position on the crankcase. Glue the second manifold to the brass tube while in place. Remove the assembly from the crankcase and set aside. Fit and glue the cylinder heads Fit and glue the spark plugs in place. Using a # 60 or a #59 drill, drill the hole in the carburetor for the gas line. The #59 drill will provide a loose fit and the #60 a tight fit. Your choice. I would opt for the #59. Glue the carburetor in place.

8 Flywheel There are three flywheel options as shown in the picture. The flywheel with spokes, the magneto type flywheel with the knob, and the top hat wheel. The top hat and the magneto types use the advance lever with the coil plate. The wheel with spokes uses the smaller advance lever. The spoke wheel is pretty simple. Just clean it up and thread the crankshaft through it and the advance lever. The magneto wheel has a knob. Clean up the knob making sure the shaft fits the hole in the flywheel. The knob shaft is pushed into the hole till it bottoms out on the nut. The knob shaft is glued into the hole. The shaft is trimmed flush with the bottom surface of the flywheel The top hat wheel is made up of two parts. The flywheel needs to be filed flush to remove the nut and any bosses so that the rim will fit flush. The top of the flywheel then needs to be gently slid on 220 grit sandpaper on a flat surface to give glue tooth. The rim has two different sides. The top side does NOT have a raised bump. The bottom has a very small raised bump. Use a small chisel to remove the bump. Sand the central portion of the bottom surface to accept glue. Apply thick CA glue to the flywheel. Use a 1/8 dia. Teflon peg (included in with the flywheels) to center the rim onto the flywheel. Wipe off excess glue. Shoot with zip kicker.

9 Gas tank The gas tank consists of three parts. Top, bottom and gas cap. The top half needs to have the flash removed from the hole so that the gas cap fits and the sprues filed flush. The mating surfaces need to be scratched up with sand paper to aid glue adhesion. The bottom half of the gas tank needs to have the sprues filed down and the mating surfaces scratched up to aid in glue adhesion. DO NOT REMOVE THE EXTRA MATERIAL AROUND THE SHARP EDGE. Glue the top and bottom half together using medium or thick viscosity super glue. Shoot with zip kicker. Use Xeron flush cutters (model railway rail cutters) to nibble away the extra material leaving it just a bit larger than the top half of the tank. Then file or sand the extra material till it is flush with the side wall of the top half of the tank.

10 Assembly Drill one end of the steering link #53 and tap the other end of the link Use a 0-80X1/8 screw to connect the link to the tiller as shown. Position the large brass bushing in the crankcase flush with the bottom edge of the crankcase. Glue in place. Position the flange centered on the hole in the bushing. Use a piece of 18ga copper wire form the intake water tube. DO NOT GLUE IN PLACE. Set the water tube aside.

11 Clean up the flange and glue in place as shown being careful to keep the top surface of the flange perpendicular to the axis of the peg. Apply medium viscosity glue to the inside of the hole and surface of the brass bush and insert peg of lower unit and carefully/quickly align the lower unit with the crankcase. Fit the previously formed water tube to the crankcase and glue in place. Fit the rudder linkage and tiller and screw together. Holding the gas tank with the mating surface up, apply medium viscosity glue to the two recesses. Keeping the gas tank in that position fit the crankcase to it and allow glue to dry. Fit the lower water intake tube (18 gauge copper wire) and glue in place. Cut two pieces of 18 gauge copper wire for the exhaust water tubes and glue in place. Cut to desired length and bend the ends down. Bend about 1/8 of a length of 18 gauge copper wire 45 deg and insert into hole in bottom of gas tank. Bend and cut to form the gas line and insert the other end into the hole in the carburetor.

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