Model Construction


1. Paul Breisch 187 W. Ridge Pike Royersford, PA 19468

Mr. Whitey Boswell of Greensboro

Content Tools

2114 Alamance Church Road Greensboro, NC 27406

Many of you will remember the back cover of the August 1987 GEM showing models of the Fuller Johnson engines. Since the magazine came out, there have been inquiries from persons throughout the States wanting information on the casting kits for building those kinds of models. After answering numerous letters and telephone calls about the source of the casting kits, maybe it would be good to mention the names and addresses of casting kit suppliers from which I have ordered materials. Please refer to a listing at the end of this article. Please refer also to April 1987 GEM, page 28, listing model kits and suppliers of that date.

The photos shown on the back cover of August 1987 GEM were made in January 1987. Since that time a headless Witte (De bolt Castings) and two more Fuller Johnsons (Ed Chick's Castings) have been completed. Quite a number of questions have been asked about various machining and construction details, so a few photos were made of these last two Fuller Johnsons to illustrate my ideas for machining and building.

The crankshaft is fashioned from a rectangular cold rolled steel (CRS) bar. (photo No. 1) The selected bar is covered with layout ink (By Kem Blue) and the two centers scribed on the ends of the bar and the entire profile of the crankshaft is scribed on one side. The scribing gives visual guidelines for removing all unwanted metal. As much metal as possible is removed with a band saw and the remainder is turned on a lathe with the 'throw' portion being completed first. As the picture shows, one end of the crankshaft is 'finish' turned then reversed end for end between centers and supported by a steady rest before the other end is completed. An 'oilite' bronze bushing is held by the steady rest to allow accurate alignment of the shaft. As the second end is turned the bending of the shaft due to tool pressure is greatly reduced resulting in a more accurate turned crankshaft.

The next several pictures show the model in various stages as assembly progressed. As the pictures show, all painting and stiping is done before assembly begins. After machining, each casting is smoothed by grinding, hand filing, and sanding as necessary to remove uneven surfaces and parting lines left by the foundry process. All holes or voids and any abrupt changes in surface contour are filled with automobile body filler and sanded smooth. All oils which were used for drilling and tapping are removed by washing the castings with denatured alcohol. Machined mating parts and casting surfaces, drilled and tapped holes, and all functional bores are masked using masking tape. To prepare the metal surface to receive the final paint, all surfaces are primed with gray primer paint (Rust-Oleum or De Rusto), two coats minimum. About twenty-four hours of drying time is allowed between coats. This material is readily available at most hardware stores. Next follows three coats of a chosen enamel paint. Again Rust-Oleum or De Rusto is a good choice. A small one-inch paint brush works very good. Spraying is not necessary to produce a great-looking paint job.

After the paint has dried for about a week, decorating by hand painting, pen striping and various designs can be painted onto the enamel surfaces. This is the ideal time to apply designs since the parts are accessible on all surfaces. Painting is much more permanent than adhesive-backed pen stripes. You need not be an artist since 'air brushes' and 'striping rollers' (see reference 6 for catalogue) are available. For those persons who are artists the regular striping brush does a beautiful job. If an error is made in the decorating immediately remove it with a cloth soaked in gasoline and start over. The gasoline will evaporate leaving a clean surface to try again. All the decorating on the engines shown was done with a 'striping roller' and spray stencils and an 'air brush'. Now for the ideal way to decorate an engine is to have an artistic wife to paint for you as Betty Duggins of Winston Salem, North Carolina does for her husband Henry. They have truly beautiful equipment when engine showing time comes. By the way, Henry and his son Mike build most of their exquisite models without the benefit of castings.

The brass castings are completely filed and sanded after machining, before buffing with rouge (see photos 2 and 4). The sand cast surfaces are filed flat using a medium cut file. One hundred and fifty grit sandpaper is used, then followed with 220 grit. Each time a different grit is used the scratches left by the previous treatment must be completely removed. Since most of the cast surfaces are irregular in shape, this is a hand type operation. Many hours are spent in preparing the brass to give the final buffed shiny surface. All of the other brass parts shown are first machined and then given the same hand treatment as the castings.

The Fuller Johnson's gasoline tank goes into the base. Brass again makes a very attractive container and the base casting can be machined with recesses to retain the gasoline tank to make the mounting brackets invisible from the outside (see photo 3). A check valve is needed between the gasoline tank and the carburetor. Start with a brass 1/8' NPT X 90 degree angle to ?' ferrule tubing fitting, (find at hardware store or plumbing store); turn a seat from brass for the O.D. to press fit into the hole below the shoulder of the ferrule portion of the fitting. Using a #47 drill pierce the seat and complete one side using a 1/8' Dia. ball end mill, machine to about 0.040 depth. After press fitting this part into the purchased fitting complete by adding a 1/8' Dia. brass or stainless steel ball (see Lee Pedersen's advertisements in GEM for the balls). An adaptor of brass will also be necessary to go from ?' tubing size to 1/8' tubing for the connector between the gasoline tank and carburetor. This takes more time than using a plastic tubing but is also more permanent and looks very nice. All the brass parts are polished and buffed before assembly.

The gears are standard stock items from gear manufacturers. In this area there are several suppliers among which are Boston Gear Works and Martin Gear Company. There are three important items to remember in order to select the proper gear pair; these are: pitch of the gears, center to center distances, and the number of teeth. On any 4 cycle gasoline engine, there are twice as many teeth on the cam gear as there are on the crank-shaft gear. The reason for this is the crankshaft must make two complete revolutions each time the cam gear turns one time. For all castings kits worked on to this date, the center to center distance of the gears are already established and a boss is provided in the base frame to accomodate the respective shafts.

When gears are considered different from those specified on the drawings, other factors must be considered such as face width, hub dia. and extension, and bore sizes. To make sure the gears look more like the original cast type of the full size engines holes or slots can be added as desired by the individual (see photo No. 4 showing the cam gear). Usually the standard stock gears are cheaper in price than the customized gears specified on the drawings.

The Fuller Johnson and the Witte engines were both bored to a 2' dia. and standard Briggs and Stratton piston rings P/N 290290 were used. Valves for the Fuller Johnson engine are Briggs and Stratton P/N 23386 modified by cutting the stem to length and threading. Valves for the Witte were turned from CRS bar stock.

Wooden bases are constructed to one's own liking. For the models shown, material for the base of the Witte and one Fuller Johnson is white oak while that of the other Fuller Johnson is black walnut. The shapes are band sawed to pattern and hand sanded to smoothness. The handle ends, which are round, were formed by using a spoke shave and sandpaper. After all construction is completed 5 coates of urethane varnish will give the wood protection from all elements including gasoline and motor oil.

The wooden base as can be seen in photo No.5 is constructed to accommodate all of the electrical ignition components. A standard on/off switch from Radio Shack, a 12 volt automobile ignition coil and a 6 volt square lantern battery is used to supply the voltage to the ignitor. Wire is #22  AWG stranded, and the two ends which terminate on the battery are equipped with alligator clips. These two wires are approximately 2 feet in length so they can be connected to an external battery if desired, either 6 volt or 12 volt. The battery case is a discarded 20 ounce soup can. The battery and coiled-up lead wires fit very nicely into the can. The can is mounted on a 3 degree angle so every-thing will remain in place as the engine vibrates during running. A push-on type wire termination is provided at the ground terminal and on the ignitor. This allows easy removal when the ignitor is disassembled for cleaning the contact points.

The battery and coil box for the Witte was built using box joints. These can certainly be made using the table saw or router, but have you ever thought of using the milling machine? Just cut the four sides to the proper lengths, clamp all four together in the vertical position, and mill 0.250' width slots through all the pieces. Move the table 0.500' and continue this pattern. The corners of your battery and coil box will fit perfectly. Splintering of the cuts can be prevented by adding a scrap of 1/8' masonite to each of the two outside faces of the wood when they are clamped for milling.

The ignitor housing is made of yellow brass, sanded, buffed and polished. The two mounting bolts are 1/4' hex head brass made so they can easily be removed using a ?'  'spintite' wrench. The ignitor will require being removed every day or two and cleaning the points by brushing with a small wire brush to remove carbon. The carbon will build up because the slow speed at which the engine runs does not develop enough heat to burn the carbon away. The contact points of the ignitor are machined from a 1/8' diameter welding rod. This material is soft and a good electrical conductor.

All parts of the carburetor except the metering adjusting needle are machined from yellow brass (as shown in photo #6). Fittings for the gasoline connection are machined to mate with standard 1/8' diameter ferrule tubing fittings. The seat for the metering adjusting screw is made per the drawings and drilled with a #60 drill. The screw thread portion is machined and drilled to accept a 0.040 diameter sewing needle. This needle is cut to desired length and coated with 'loctite' sealant #290 and pressed into the thread portion of the adjusting screw. The sewing needle has a very gradual taper and will allow metering adjustments to be made which are not oversensitive as many of the pointed screw ends turn out to be.

There are new model kits appearing each year. One of these was demonstrated this past August at the Portland, Indiana Show. At the present time, two of these stovepipe Domestic side shaft engines are under construction. Please refer to listing #5 at the end of this article for model information on this kit.

Acknowledgement: The 'good' photographs were made by professional photographer Mr. Whitey Boswell of Greensboro, North Carolina. The remaining attempts at pictures were made by me.