5.5mm Association

The Harold Minkwitz Archive

Merge Roundhouse/IHC 4-4-0s

This is an old article from the Pacific Coastline site.

The IHC Oldtime 4-4-0 is the right size but it has tender drive and large flanges. The new Athearn/Roundhouse 4-4-0 is a fine example of a 1905 4-4-0 with a motor in the loco and nice flanges. It also has sound and good electrical pickup. Merging these locomotives makes a great 1870's 4-4-0.

The Mechanism

Drill out an remove the valve gear rivet. Cut the IHC frame along the red line even with the bottom of the boiler.
Cut out the opening in the IHC part so it will fit over the Round house mechanism. This shows a 2-8-0 mechanism. For the 4-4-0, the bottom of the running board should be even with the "firebox". Remove material to allow the mechanism to clear the screw for the valve hanger. The boiler should sit on the valve hanger.
Attach lugs to the inside of the cab and tap them for an 00-90 screw and attach the top half of the boiler to the running board section with three screws.
Take the weight out of the IHC tender and bend it to fit the cab roof. Cement it in place to the inside of the cab roof.

Install the Roundhouse pilot truck screw by reaming the hole in the boiler slightly smaller than the screw and "self tapping". Relieve the hole so the screw goes in far enough.
Cut the saddle off the cylinder. Cut the remainder of the saddle off the cylinder block. Use a plastic shim to get the correct boiler placement. Glue them all together.

Mark the wires with white paint and write down where they go. The white mark on the motor indicates the bottom.
Shorten the rear of the frame. The centerline of the smokestack should align with the centerline of the cylinders.

Grind two wire slots in the back of the frame.

Drill two holes in the back of the motor recess and cut out the area with a jeweler's saw.
Smooth out the cutout so the motor slides down into the frame. Grind clearance for the motor wires. Make a light press fit motor mount from .060 styrene and press it up against the motor. Press the worm gear on the motor against the spur gear. Glue the motor mount in place.
Drill a hole to clear an 1/8 square piece in the motor mount. Use an 1/8 square x 3/32 long styrene piece with an 0-90 tap in to make a motor mounting lug. Glue the lug to the bottom of the motor. Make an .060 styrene spacer and attach the spacer to the motor mount.
Make a "washer" out of .030 styrene and shim out of paper to give clearance to the gears and mount the motor with a flathead screw.

Remove the part from the track pickup that goes thru the frame. Relieve the bottom plate and attach the track wires.
Attach the motor wires. I didn't use the wires for the light.

Reassemble the bottom plates and drill a hole slightly smaller than the drawbar screw. "Self tap" the screw into the plates and file it flush.
Make a temporary drawbar out of .030 styrene, mine has a cl to cl of 1 inch.

Assemble the mechanism using one of the IHC tender truck nuts to attach the pilot truck to the frame. Test the mechanism on DC.
A Mantua pilot truck spring is the righ tension. They are available from Yardbird Trains.

Level the boiler on the mechanism using an indicator. Use an 00-90 screw to attach the rear of the mechanism to the frame.
Assemble the mechanism to the tender. Mine pulled 20 cars.

The Tender

Cut the tender at the top rivet line. This will put the lower row of rivets in the center of the body.

Make two slots at the front of the tender back to the bolster for the wires.

Grind the tender frame to allow the sound unit to fit under the tender body and the frame sit flush with the tender body.
Throw away the MRC unit. It will die very quickly. Get a Soundtraxx TSU-750.

Use the lip from the IHC tender on the back to the Roundhouse body. Make a mounting lug in on back corner and a mounting screw at the front on tender deck.
Make a wood load deck and rubber cement it to the tender so the deck can be removed. Make a box to cover the capacitor and paint it black.
Use the tool box covers from the IHC tender. Assemble a wood load on the tender deck by carefully gluing wood. It should be removable. This makes an 1870's 4-4-0. The little guy on the running board is HO.
As a 55n3 4-4-0 compared to Surrey, Sussex and Southampton #2