Building a Small Coal Tender

(This project is in progress.)

Figure 1: Hardaway Construction Company 5 with tender


I needed extra electrical pick-up and a place to install a sound system for use with my Bachman and LGB Porter 0-4-0T locomotives. The solution was a 12 foot long coal tender. I modeled by tender after a 12 foot coal tender pulled behind Hardaway Construction Company 5, a narrow gauge Vulcan 0-4-0T in operation at Agrirama in Tifton, Georgia. HCC5 is nearly 19 feet long which scales to about 11 3/8 inches in 1:20.3. The older Bachman Porter is about 10 ½ inches (17 ½ scale feet) long and the LGB Porter is about 8 ½ inches (a bit more than 14 scale feet) long. So a tender 12 scale feet long would be nearly as long as the LGB Porter. I considered shortening the tender, but the LGB ball bearing wheels I wanted to use would look very large on a much smaller tender. Looking at the tender (Figures 1-4) we see that its 12 foot flat bed extends behind the coal box in front, in back, and at both sides. The coal box itself is only 8 feet long, a bit more than half the length of the LGB Porter. I decided this would work visually with these small engines and based my plans on the prototype's 12 foot length.


Figure 2: right side of tender

Figure 3: right front of tender

Figure 4: right rear of tender


The wheels are attached to the prototype by leaf springs bolted directly to the bottom of the base plate. I decided this would be hard to model and would probably not produce a very strong structure. So I opted to use standard pedestals and to add a frame below the base plate to hold the pedestals. I also wanted a Kadee knuckle coupler on the rear of the tender. Other than these changes, I would try to model the prototype as closely as possible.

Figure 5: base assembly

Base: Cut one piece 7 x 4 inch from 2.5 mm styrene sheet and cut two pieces 7-1/8 x 4-1/8 inch from 0.5 mm styrene sheets. Sandwich the 2.5 mm piece between the two 0.5 mm pieces, allowing each 0.5 mm piece to extend 1/16 inch beyond each edge of the 2.5 mm piece. This will form the edge shown on the prototype in Figure 3 and on the model in Figure 5.

Figure 6: top of coal box assembly

Figure 7: bottom of coal box assembly

Coal Box: Cut two 5 ¼ x 2 3/8 inch coal box sides and one 2 1/2 x 2 3/8 inch coal box rear piece from 2.0 mm styrene sheet. But the sides against the rear piece at 90 degree angles and weld them together. To strengthen the joints, cut two 1 1/2 inch lengths of 3/16 inch square styrene rod and glue them inside the corners about 3/16 inch above the bottom of the coal box. (A screw anchor made from 3/16 inch square styrene rod will be attached to the bottom of these supports later.) Cut a 2 5/16 x 1 1/2 inch piece of 1.0 mm styrene sheet 2 5/16 inches long to form the front floor of the coal box. Weld this piece between the two coal box sides flush with the bottom of the coal box and with its front edge flush with the front of the coal box.

Next construct a foundation for the coal load which will also serve as a box to hold the electronics. Cut two pieces of 2.0 mm styrene sheet, one 2 5/16 x 2 1/2 inches and the other 2 5/16 x 2 3/4 inches. Weld the smaller piece 1/2 inch from the top of the coal box, making sure that it is parallel with the top of the coal box. Weld the other piece to the front of the first piece and slant it down to meet the piece making the front of the coal box floor. We will cover this later with coal.

Cut two 5/8 x 2 3/8 inches of 2.0 mm styrene sheet and attach them to the front of the coal box. They should be welded to the sides and to the front floor of the coal box, leaving an opening of about 1 1/4 inches in the front of the coal box. Figure 5 shows the top of the coal box, sitting on the base we built previously, after these steps. Figure 6 shows the bottom of the coal box and the space that will hold our sound system. There is room for a 2 inch speaker and a good-sized circuit board.

Do not attach the coal box to the base at this time. We will need access to the cavity underneath later.

Figure 8: coal box corner

Figure 9: front of coal box with bracing and rivets

Figure 10: rear of coal box with bracing and rivets

Angle Iron Bracing: Use 1/8 inch styrene L-angles for the braces at the corners and around the base of the coal box. Begin with the base. Cut two pieces a bit more than 1/4 inch longer than the sides of the coal box and weld one side of each L-angle to the bottom of a side with the other side extending out from the bottom of the side. Each piece should extend a little more than 1/8 inch beyond both ends of the coal box. When both of these pieces are firmly attached, trim the corners. The vertical part of each L-angle extending beyond an end of the coal box should be trimmed until it only extends beyond the coal box by the thickness of the L-angle. When we attach the pieces of L-angle to the ends of the coal box, the vertical parts will meet to form a corner (Figure 8). Also file or sand the bottom part of the L-angle extending beyond the end of the coal box until it is perfectly flat and has no ridge left from the material that was removed. Now measure two pieces of L-angle to fit at each end and weld them in place. Cut the strip of 1.0 mm styrene sheet or strip to fit in the gap between the front of the coal box floor and the L-angle brace on the front of the coal box and weld it in place. Figures 9 and 10 shows the coal box after the angle iron braces and the rivets (next step) have been added. Weld strips of 1/8 inch x 0.5 mm styrene to the edges of the front of the coal box (Figure 22).

Rivets: There is a row of rivets around the top rear and sides of the coal box in line with the bolts holding the tops of the braces in place. These rivets do not appear on the front of the tender. Draw a line 5/8 inch (about 30 scale inches) below the top of the coal box on the rear and both sides. In the original high-resolution photographs, I count 12 rivets on the rear panel and 16 on each side. The ones on the sides are spaced further apart. I reduced the number, putting 9 rivets spaced ¼ inch apart on the rear and 13 rivets spaced 3/8 inch apart on each side. I placed rivets 1/4 inch apart on each side of each corner braces, staggering them between the two sides of the brace. I placed a row of rivets 3/8 inch apart around the entire horizontal part of the bottom coal box brace. I placed another row staggered between these in the vertical part, leaving out the section between the two front side pieces of the coal box. Figures 9 and 10 show the coal box after the rivets have been place.

I used a technique recommended by David Fletcher in his" MasterClass 2001 - Build a Baldwin 8-16-D 2-6-0" on for the rivets. Cut pieces about 0.8 mm long from 0.5 x 0.8 mm styrene strip. To apply a rivet, dip a small brush in plastic solvent, put a drop where the rivet goes, pick up one of the small pieces of styrene with the brush, and work it into place. After applying several rivets, I come back and paint each one again with solvent to secure and round them.

Figure 11: rear screw anchor

Figure 12: front screw anchor

Installing the screw anchors. We will use screws to attach the coal box to the base. First cut the rear screw anchor from 3/16 inch square styrene rod to fit inside the back of the bottom of the coal box. Weld it in place flush with the bottom of the coal box as shown in Figure 11. (Notice in the photograph that there is a gap between the corner supports and the screw anchor. This was a mistake; if I had positioned these supports better, they would have also supported the screw anchor.) Cut a support from 3/16 inch square styrene rod to fit between the rear screw anchor and the top of the coal load. Weld this support in place. Cut the front screw anchor to fit between the sides of the coal box just behind the front coal box floor plate. Weld it to the sides and to the floor plate, flush with the bottom of the coal box. Cut two 1 inch supports from 3/16 inch square styrene rod and weld them to the sides of the coal box and the front screw anchor as shown in Figure 12.

Figure 13: marking the base

Figure 14: coal box taped to base for drilling

Drilling the screw holes. Mark the top and bottom of the base by drawing pencil lines 3/4 inch from each side and each end. The coal box will fit approximately on these lines on top of the base. With the bottom of the base up, place the base on the bottom of the coal box so you can see the screw anchors (Figure 13). Center the coal box using the two lines drawn 3/4 inch from the ends and mark the locations of the screw anchors on each long edge of the base. Draw in lines to indicate the locations of the screw anchors. These areas are marked with hatched lines in the photograph.

Drill four 1/16 inch holes through the base at the locations for the screws. These are marked in red on Figure 13. For the rear screws, they are 1/2 inch from the lines we drew parallel to the long side of the base. The middle screws need to be 3/4 inch inside the lines to allow room for the wheels.

Carefully center the coal box on the base and tape the two assemblies together (Figure 14). Turn the model over and drill four 1/16 inch holes through the screw anchors using the holes in the base as guides (Figure 15). Remove the tape. Use a 1/2 inche 2-56 bolt to tap the four holes in the screw anchors. Redrill the holes in the base to 3/32 inch. Now you can four 1/2 inch 2-56 bolts to attach the base to the coal box. (I used 1/4 inch 2-56 bolts to assemble the model at this stage since I expected to be taking it apart frequently.


Figure 15: the speaker grill

Figure 16: speaker mounted

Figure 17: mounting the frame to the base

Mounting the speaker. If you are going to install a sound system, now is the time to mount the speaker. Place the speaker on the top of the base between the screw holes you drilled in the last step, leaving room to clear the screw anchors in the coal box. Draw a circle around the speaker, then mark four "compass points' on the circle to locate the positions for the mounting screws. Drill a 1/16" hole at the top two marks, then place the speaker on the circle again to check the bottom two marks. You want the screw holes to be just outside the rim of the speaker. When you are sure about the location, drill the bottom two 1/16" holes. Use the speaker again to check the location. If you are off on any of the holes, just mark and drill another one a bit further along the circle. Use a 1/2" 2-56 bolt to tap the four holes. Next, drill about twelve 1/4 inch holes inside the circle to form the speaker grill (Figure 15). Finally, use 1/4 inch 2-56 bolts to mount the speaker to the base (Figure 16). Tighten the bolts snugly, but be careful not to over-tighten and strip the threads in the base. Once you are sure everything looks okay, remove the speaker to make the next step easier.

Building the frame. Cut two 4 3/4 inchlengths and two 2 1/2 inch lengths of 1/4 x 3/8 inch rectangular styrene rod. Weld the pieces together to form a rectangle with the shorter pieces between the longer pieces (Figure 17). On the outside of this frame, mark lines 1/2 inch from the corners. Use CA to attach two journal pedestals (I used Ozark Miniatures OM-05CS, but there are many choices) to one side of the frame so their outsides edges touch the two marks you made. Using the other two pedestals and the wheel sets, check to make sure everything will go together properly when you assemble the wheels. The axels should fit tightly in the journals. Since you are using ball bearing wheel sets, the axels do not need to turn in the journals. Weld the frame to the bottom of the base, being sure to get it centered. (Notice in the photograph that I did this step before drilling the speaker grill and mounting holes. I have reversed the order of these steps in these instructions because it would have been easier to drill the speaker holes before mounting the frame.

Figure 18: wiring for power under base

Figure 19: joining power wires above base

Wiring for power. We will need to do some wiring to get power from the wheels to the sound system and the locomotive. First, drill four 1/8 inch holes in the base at the locations indicated by the green arrows in Figure 18. The power wires from the wheels will pass through these. In the photograph, the right side of the tender is at the bottom and the front is to the left. The left front hole (the upper left hole in Figure 18) will need to be enlarged since the wires for the connector for powering the locomotive will also go through it. Also drill a 1/8 inch hole through the left side of the front frame. Dill this hole close to the base. Run the wires for whatever connector you decide to use through the frame and then through the left front power wire hole. Then attach the connector to the base and the frame using AC. The connector is indicated by the red arrow in Figure 18. Solder about 5 inches of thin wire to each of the four connectors that come with the LGB ball bearing wheels. I used red wire for the two connectors on the right side of the tender (bottom of the photograph) and black wire for the two connectors on the left side of the tende. Run these wires up through the four holes in the base. Turn the base over and strip about 1/2 inch of insulation from each of the wires going to a wheel connector and from the two wires going to the locomotive connector. Take two more wires about 3 inches long and strip them similarly. Join the wires to the right hand wheels and the right side of the locomotive connector to one of the short lengths of wire and twist the bare ends together to form a "pig-tail". Solder these wires together and cover the connection with shrink tubing. Form a pig-tail with the other wires in similar fashion. The result is shown in Figure 19 with the extra wires stripped and ready to connect to the power leads of the sound system.

Figure 20: the sound system

Assembling the sound system. I used a SoundTraxx DSX sound-only decoder for my tender. A picture of a DSX decoder is on the left in Figure 20. It has red and black power leads, two purple speaker wires, and a brown wire that will be used to synchronize the chuff sound.For use with large scale voltages, a resister has to be put in one power lead. A capacitor is also used in one of the speaker leads. These are mounted on the small piece of circuit board shown in the photograph. I used double-sided tape to attach the decoder to the back of the speaker, then more double-sided tape to attach the circuit board to the top of the decoder.

Figure 21: wheels and steps in place

Figure 22. front and top details

Install wheels. If you want to paint the wheels, do it now. Now is also a good time to paint the bottom of the tender since it will be more difficult after the wheels are installed. Apply CA to one of the remaining pedestal journals. Place one end of an axel in one of the journals, then place the other end in the journal with the CA on it and place the journal in place on the frame. Remember that you want the edge of the journal exactly 1/2 inch from the end of the frame. Install the other wheel set the same way. After the CA has set up, attach the wires to the power leads on the wheel sets.

Strap steps. I used strap steps that mount under the frame (Ozark Miniatures OM-02B). Drill 1/16 inch holes in the step supports using the dimples as guides. Use these as a guide for the holes in the base of the tender. Drill all the way through the tender base, far enough from the edge that you go through the core as well as the 0.5 mm top and bottom plates. Use nut-bolt-washer castings for 1 inch bolts with 2 inch nuts (Ozark Miniatures OM-7A or OM-7B) and AC to pin the steps to the bottom of the base. (I use Blacken-It on all castings before attaching them to the model.) Cut the heads from brass eschutcheon pins and glue them in the holes in the top of the base for the bolts.

Top bolts. It appears from the photographs that there are rods running through the sides of the coal box. The bolts for these can be seen on the top edge of the coal box at the corners, with three more along each long side and one more on the rear. I did some compression here and only installed two between the corners on the long sides. There do not appear to be any bolts at the top of the front opening in the coal box. Take a sharp hobby knife and place the point exactly where you want to install a nut-bolt-washer casting. Twirl the knife to make a hole to guide your drill. Use a 1/16 inch bit in a cordless screwdriver to drill the holes for the castings. Needless to say, you must be extremely careful since the sides of the coal box are barely wider than the drill bit. Again, use nut-bolt-washer castings for 1 inch bolts with 2 inch nuts (Ozark Miniatures OM-7A or OM-7B). Cut the pins on the castings to about 1/8 inch long, particularly on the castings that go into the sides of the tender. It is easier to drill a deeper hole in the corners and I did not shorten the bolts on the castings for these locations. Glue the castings in place using AC (Figure 22).

Figure 23: braces, doors, grab rail

Figure 24: corner detail

Braces. If you haven't done so yet, fastened the coal box to the tender base using 1/2 inch 2-56 bolts. Run the brown wire from the DSX decoder (the wire to trigger the chuff sound) through the hole for one of the power leads on the right hand side of the base, leaving about an inch sticking below the base. We will attach this later to the chuff-trigger. Cut eight 2 1/8 inch lengths of 1.5 x 3.2 mm styrene strip to make the side braces for the tender. Using pliers with smooth jaws, carefully bend one end of each brace back into a U. This will relax into the bend for the bottom of the braces shown in Figure 23. Bend the other end of each brace gently for the top angle. Test fit and weld to the sides of the coal box and flush with the edge of the tender base. There are four braces on each long side of the tender and two more on the rear. Add a rivet to each brace at top and bottom.

Doors. In all the photos I have, the doors on the tender are open. It appears that the hinges are on the outside of the iron strapping riveted to the sides of the door opening. I decided to model the doors in the closed position since I would add a full load of coal later. Cut a 1 5/8 x 1 inch piece of 1 mm styrene sheet. Cut eight 1 inch lengths of 0.5 x 1.5 mm styrene strip. Locate the center of the door and weld the strips to each edge of each door, front and back. Weld the doors to the front of the door openings. The support strips on the back outside edges of the doors should fall just outside the strap iron supports on the edges of the door opening.

Grab rail. Fashion a grab rail from 1/16 inch brass rod. Mark the location for the ends on the right front corner of the coal box. (There is no grab rail on the other side of the tender.) Then take a couple of nut-bolt-washer castings with large washers and file a groove in one side of the washer to fit around the 1/16 inch brass rod. These casting should be placed tight against the grab rail so they appear to be part of the rail. Drill four 1/16 inch holes for the brass rod and the castings. Use Blacken-It on all parts and attach them to the model using CA.

Figure 25: coupler mount

Figure 26: coupler combination

Couplers. Mount the couplers of your choice. I decided to use talgo link-and-pin couplers (Ozark Miniatures OM-06) with a modified Kadee coupler inserted into the link-and-pin coupler at the rear of the tender. The talgo coupler provides some swing to move around tight curves. First cut two pieces of 1/4 x 3/8 inch rectangular styrene rod to fit between the end frame and the edge of the tender base. Use the link-and-pin coupler to mark the spot for the mounting hole on the wide (3/8 inch) side of the coupler mount. You want about 1/8 inch between the the back side of the coupler pocket and the end of the coupler mount. Drill a 3/32 inch hole through both sides of the coupler mount and tap with a 1/2 inch 6-32 bolt. You may need to enlarge the hole a bit by twirling a hobby knife in it to get it large enough to start the bolt. Weld the couple mounts under the ends of the tender base, being sure to get them centered (Figure 25). Attach the talgo link-and-pin couplers using 6-32 bolts of appropriate length. (You can get by with a 1/4 inch bolt if you don't use any shims. A 3/8 inch bolt will reach the other side of the coupler mount making a stronger connection.) I will connect the tender to my locomotive using a link-and-pin, but I want to be able to use cars behind the tender with either link-and-pin or knuckle couples. To do this, take a short, straight Kadee coupler and cut off the wings and pins on the side that hold the springs in place. Then cut and file the back of the coupler until it will fit far enough into the link-and-pin coupler to get a pin through the mounting circle in the Kadee coupler (Figure 26). The Kadee coupler may be a bit high, and you may have to shim the link-and-pin coupler to get it exactly right.

Figure 27: LT&S 7 with the new tender

Last comes the painting and lettering. I wanted the name of my railroad to appear on the side of the tender, but it didn't look right behind the body braces. So I put the lettering at the top and put one of the LT&S hobbit logos in the middle of the side. Here is the tender behind LT&S 7. I hadn't added the coal load when this photo was taken. The locomotive is an LGB Porter with a Digitrax DCC decoder installed. The pilots have been modified, but the footboard has not been installed on the rear pilot and the whistle and other trim have not been put back on the engine after repainting and relettering. You can see the power wires connecting the locomotive to the tender.


Copyright 2004 Donald Nute

This page last modified: 2/9/2004.

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