70 Tonner Instructions
Parts Needed
Shell and Chassis (sold here)
Trucks and Motor Clip (sold here)
Handrail Kit (sold here)
6x15mm 12 volt motor from Tramfabreik item 0615S (sold here)
Rokuhan Shorty Chassis B Shinkansen (available at your favorite Z Scale retailer).
Electronic Resistor (330 Ohm 1/4 Watt 5% is recommended)
NOTE: Resistors are not uncluded with the handrail kit.
Tools Needed
Flat Head Screw Driver (5/64 or 3/32)
Phillips Head Screw Driver (#0)
Needle Nose Pliers
Standard Flat Surface Pliers
Soldering Iron
Additional Recommended Tools
Wire Stripper made to strip 30 AWG wire
Primer for Metal
Metal Files for smoothing out print lines if desired
IMPORTANT NOTES!!
This model is compatible only with the “Shorty B Shinkansen” type. The 70 Tonner truck detail parts will not fit on other Shorty models.
You must supply your own electronic resistor. A 330 ohm 1/4 watt resistor is recommended but you may want to use another value to change performance.
Those installing DCC decoders don’t need to install a resistor.
To clean the brass parts you can use house hold brass cleaner. Or you can make your own cleaner by mixing together 1/2 cup of vinegar, a teaspoon of salt, and a sprinkling of flour until it forms a paste. Spread the mixture on the brass and allow it to sit for a few minutes. Rinse with cool water and dry. Another method is to use plain old ketchup. Apply ketchup, let sit for a few minutes, then rinse away and clean with dish detergent.
Parts Overview
Part 1 - Disassemble the shorty
Prep The Shorty
If you have not already done so, follow all steps in the “Shorty Prep” page to prep the motor and trucks. Then return to this page to begin constructing your 70 Tonner.
Click the green button below.
part 2 - Check the 3D Prints
Test Fit The Screw
There is a hole under the chassis for a screw. The Shorty comes with a screw to hold the dummy truck in place.
Before moving on, test fit the screw in the hole.
If the screw turns a few times before tightening, your good to go. It does not need to screw in all the way.
If the screw does not fit, use a drill bit to expand the hole.
If there is NO hole at all, that is a print error and you will need to contact Shapeways and get a reprint.
Square up the Shell
During the finishing process of 3D printing, the foot boards may have been bent out of shape. Use pliers to gently reshape them.
Clear the Headlight Channels
Use a #76 drill bit to clear the channels for the headlights.
1/2 mm Fiber optic filament will fit through these holes.
Check the chassis
The chassis can be bent out of shape during the metal casting and finishing process. Make sure the chassis has true right 90° angles for the coupler platforms.
Also make sure the main body of the chassis is not curved. Gently use pliers to make any adjustments.
Test fit the chassis
Insert the chassis into the shell and make sure the coupler platforms(front and rear) fit in the center of the pilot without touching the sides.
If they touch, pull the chassis out and slightly adjust the shape of the coupler hooks with pliers.
straighten The coupler Pins
The coupler pins should stand up straight from the coupler platform. If they are misaligned, use a small screw driver and/or pliers to gently bend them into shape.
Paint the Lower Details
It is a good idea to prime and paint the tank details on the chassis. In the illustration, the areas in blue can be seen when the shell is mounted onto the chassis. It is recommended that the visible details on the chassis be painted before the motor and other parts are mounted.
part 3 - Prep the motor
Step 1
Take your Tramfabriek 12 Volt motor and cut the wires leads down to 1/2 inch (12.5 mm).
Wire Stripper
A stripper that can strip AWG30 wire is HIGHLY recommended. Otherwise, use a hobby knife to carefully strip the plastic sleeve from the two motor leads.
The tool in the image is the OK Industries ST500 ESD.
Step 2
Strip 1/8 inch (3.2 mm) of insulation from the motor leads.
Step 3
Take the worm gear from the 70 Tonner Handrail kit. Leave the two couplers in a safe place until later.
WARNING: Careful opening the bag. The small parts may go flying if the bag rips while opening it.
step 4
Slide the worm gear over the motor shaft. Push the gear until the shaft slightly comes out the other end.
NOTE: The worm gear will not fit over the Rokuhan Shorty motor shaft. Only use the 0615 Tramfabriek 12 volt motor sold here.
Final adjustment
If the shaft is just slightly poking out from the worm gear, then it’s ready to go.
part 4 - assemble the chassis
Separate The Finishing Parts
Cut off the sprue of truck details from the motor clip. If any flash remains on top of the motor clip, scrape it off.
The parts can be snapped apart if desired.
Tip: Clear the Slots
Use a hobby knife to clear out any left over resin or wax build up that may be in the slots on the motor clip.
This will ensure the metal pickups will fit all the way into the slots.
Motor Orientation
The gear cage is located at the back of the chassis. The worm gear will be facing the rear of the chassis. Position the motor wires just as they are seen in the image.
IMPORTANT: The blue wire must be on the right side of the locomotive and the red wire must be on left side. This will insure the locomotive moves in the same direction as all other z scale locomotives.
Step 1
Slide the motor through the cage at the back of the chassis. Push through the cage and down until the motor clicks into place.
Step 2
Double Check Orientation
Be sure the wires are on the correct side. It should match the image. If not, remove the motor with a small flat head screw driver and rotate it to match the image.
Step 3
Inside the 70 Tonner Handrail Pack, there is a sprue with two metal strips. These are the electrical pickups that fit within the motor clip. Clean the sprue with tarnish remover (or ketchup if you don’t have tarnish remover). After that, clean them again with Dial dish detergent.
Step 4
With a fresh hobby knife, cut the two strips from the sprue. File away any rough edges from where the strips were connected to the sprue.
Step 5
Find the two marks on one end of the pickup strip.
Place the strip on a flexible surface such a cutting mat or mouse pad.
Use a small flat head screw driver to push down and make a bend in the strip.
Step 6
Using your fingers, wrap the strip around the screw driver’s tip to make a rounded fold. Do not crease the metal.
The curved part will give the metal strip a spring like tension to help with electrical pickup.
Step 7
At the other end of the strip, find the two indented lines with the hole between them. At these two lines, make 90 degree bends.
Use pliers or etched metal bending tools for best results.
Step 8
Insert the two pickup strips into the motor clip.
Check the fit
The two strips should fit all the way into the motor clip slots with no overhang. If they are protruding out from the side of the motor clip, there is likely some residue within the slots. Use a hobby knife to clear out the slots until the strips fit with flush edges.
Step 9
Move the motor’s wires out of the way. Press motor clip on to the chassis. Be absolutely sure the wires are oriented just like in the image. Make sure the wires are not pinched by the motor clip.
NOTE: It is highly recommended the clip not be taken off after this step.
Step 10 - Cut the Resistor Leads
Cut one lead down to 1/2 inch and bend it 90 degrees.
Cut the other to 1/4 inch.
NOTE: Electronic resistors are not included with the 70 Tonner handrail kit. The recommended resistor is 330 Ohm 1/4 Watt 5%. You may want another size depending on desired performance. Those installing DCC should NOT install a resistor.
Step 11
Slip the 1/4 inch resistor lead through the hole in the pickup strip.
Snap the resistor in between the two claws on the motor clip.
Step 12
Use tweezers to slip the red wire through the hole in the pickup strip.
Prepare your soldering iron for the following steps.
Step 13
Solder the blue wire and the long resistor lead.
step 14
Tuck the blue wire and resistor lead under the resistor mount. Make sure they don’t stick out from the chassis.
Step 15
Apply soldering flux around the hole where the resistor pokes through the electrical pickup strip(see red arrow in illustration).
Apply a small drop of solder to the soldering iron tip. Quickly apply it to join the resistor to the pickup strip.
TIP: Work quickly so the motor clip does not melt.
Step 16
Apply soldering flux around the hole where the red wire pokes through the electrical pickup strip(see red arrow in illustration).
Apply a small drop of solder to the soldering iron tip. Quickly apply it to join the wire to the pickup strip.
Step 17
On the powered truck, locate the stump that was left over from cutting off the coupler box(See the “Prep The Shorty” instructions if you have not done so already).
Remove the wheels from that side of the truck.
Step 18
Cut the two arms that hold the coupler box section.
Step 19
Put the wheels back on and place the main gear into the center of the truck.
Step 20
Insert the powered truck into the chassis.
Step 21
Insert the truck pin through the hole in the truck and through the main gear.
Slide the pin in until it is centered with the truck.
Step 22
Tightly grasp the dummy truck on both sides. Use needle nose pliers to bend the copper poles toward the middle about 20 degrees.
Step 23
Half way up each pole, bend the pickups outward about 20 degrees to offset the previous bend.
This does not require extreme precision. As long as both poles are sitting at the same height after bending, they will do their job.
Step 24
On the dummy truck there is arm that held the coupler box.
Remove the wheels/axle from under the arm.
Trim off the arm at the half way point(see red arrow).
Replace the wheels.
Step 25
Place the dummy truck on to the chassis and secure it with the shorty’s screw.
Adjust the Chassis
Check that the top of the chassis is level and that both coupler platforms are at the same height.
If the chassis is uneven, remove the dummy truck and adjust the copper poles to raise or lower the front of the chassis. Also make sure the tops of the poles are at the same height. This will take some trial and error.
Test run the chassis while making these adjustments to ensure good electrical pickup.
part 5 - Assemble the Shell
Clean the Parts
To clean the brass parts you can use house hold brass cleaner.
Or you can make your own cleaner by mixing together 1/2 cup of vinegar, a teaspoon of salt, and a sprinkling of flour until it forms a paste. Spread the mixture on the brass and allow it to sit for a few minutes. Rinse with cool water and dry.
Another method is to use plain old ketchup. Apply ketchup, let sit for a few minutes, then rinse away and clean with Dial dish detergent.
Step 1
Use a fresh hobby knife to cut the two large panels from the handrail sprue.
File the edges smooth where it connected to the sprue.
Step 2
Grab the left side panel.
Orient it so that the notch for the staircase lines up with the staircase on the shell.
Step 3
Take the right side panel and orient it so the vent details are on the bottom(see illustration).
Step 4
Cut two of the three grab irons for the rear cab door.
The third grab iron is a backup in case one is lost.
Step 5
Glue the grab irons into the slots on either side of the cab door.
Some paint schemes require masking or decals to be added to the back of the cab. You may want to add these parts after painting.
Step 6
Cut the two pilot handrail sections from the sprue.
Step 7
Bend the parts 180 degrees at half way point of the pilot section. Bend it so the back sides meet and the pilot details are still visible.
Apply CA glue where the backsides meet and flatten the two halves together. Don’t let any glue get on the hand rails or the grab iron above the pilot.
Repeat for both pilot parts.
Step 8
Slide your hobby knife behind the large grab iron above the pilot.
Bend the grab iron 45 degrees.
Repeat for both pilot parts.
Step 9
Glue the pilots to the front and rear of the shell.
Step 10
Cut the two large handrail sections from the sprue.
Step 11
On both parts, find the triangular stairwell handrails at each end.
Rotate them 45 degress as seen in the illustration.
Step 12
Orient the left and right side handrails so that the flat side with no details is facing toward the shell.
Glue both handrail parts to the shell.
Step 13
At this point, the staircase handrails still need to be adjusted (highlighted in blue).
Notice how the bottom of the handrail is floating in the middle of the staircase.
Rotate the highlighted section until the bottom touches the top of the staircase.
Repeat for all four staircases.
Step 14 - Clean Up
Scrape away any excess glue with a fresh hobby knife.
Clean the model with soap and water to remove any oil or residue left on the surface.
Apply a layer of primer before applying paint.
TIP: If using a rattle can spray primer, be sure to follow the label’s directions to avoid applying too much paint.
Part 5 - Truck Details
Step 1
Paint the truck details with acrylic paint.
TIP: Testors Model Master acrylic paints bond especially well to this type of plastic. Primer is not needed. The translucency of this plastic may cause some colors to appear too light. Apply an under coat of gray or white paint to offset the color shift.
Step 2
Snap the painted truck details from the sprue.
Step 3
Test fit each faux truck before applying glue. Due to the printing process, you may need to scrape away waxy buildup much like the slots on the motor clip.
To glue them, use CA glue for best results.
Part 6 - Final Assembly
Install the couplers
Place the couplers on the coupler pins.
The knuckle should be on the left when viewing the locomotive from the front or rear.
Put On the Shell
Straighten the couplers to allow clearance for the shell.
Push the shell into the chassis.
NOTE: The powered truck goes under the cab area.
Check the fit
If the shell is too loose and the chassis freely falls out, glue can be added to the side of the chassis to widen it.
On both sides of the chassis, apply CA glue to where it is highlighted in blue in the illustration. Use a tooth pick to make a very thin smooth flat layer.
Let it thoroughly dry before putting the shell on again.
Repeat if necessary.
Final touches and thoughts
Paint the couplers brown or black. Like the trucks, Testors Model Master acrylic is the recommended paint.
There are parts of the Shorty’s light gray trucks that can be seen under the locomotive. These areas can be painted black to better blend them with the truck details. Avoid painting the wheels.
If you have extra shorty wheels laying around, you can vastly improve electrical pickup. To do this, replace the traction tire equipped wheels with regular metal wheels. This will reduce the pulling power but you may find the performance improvement worth it.