Model Engine Works: 00n3 & TT:120 Chassis Conversion

Kato 11-110 Tram Chassis Conversion to 12mm Gauge

It's been a long-term goal of mine to find a readily available economical chassis for 12mm gauge use. This would give 00n3 narrow gauge modellers an equivalent to the Kato tram chassis that 009 modellers have, allowing entry-level tram engines to be accessible at a reasonable price. As a side note, this may also suit modellers of the TT:120 scale.

After working on various alternatives for some time, I finally asked myself: could I convert the Kato chassis and regauge it? So that's what I did ― and it's simple to do, using the new 11-110 version with the cordless motor. The only new bits needed are some small spacers to reset the gauge of the wheels. The rest of the work involves modifying what you have with the existing chassis.

The best way to explain this is with pictures and notes, so I have attempted to do this in the following instructions:

1 Remove the couplings from each end of the upper shell. They are clipped in place, so pull off quite easily.

2 Remove the balconies from each end of the upper shell. I cut these off with a pair of Xuron Track Cutters ― they cut the plastic cleanly and do a neat job.

3 The next step is to remove the four axel boxes from the upper shell. There are two cuts on each one: first a small nick at the inner end, then cut straight across the top. Then clean the cuts off with a craft knife.

This is important as the upper shell needs to be clear of the pickups.

4 The lower shell needs to be trimmed to allow clearance for the bends on the pickups. This requires two cuts in each corner ― it may be easier to cut these with a kraft knife. There is also a bit to trim off each of the end tabs (the small lip that sticks up).

5 Take the metal pickups and using a pair of fine pliers bend these at each end to form a very slight Z. The idea is to induce a 1.4mm offset to work with the wider wheelsets.

I have noted that this can be difficult to get consistent, and I have developed a press to achieve this.

The following shows the method to use the press:

It has a core into which the pickups are inserted with the outside facing the arrow. It will centralize when pushed right down into the slot. Fold up the sides, and press these together to form the bends in the pickup. The metal is soft and bends easily.

I can supply a press on request at modelengineworks@outlook.com

6 Next take the wheel and pull the metal parts away from the central plastic tube and gear. They are only a very good push fit so will not take a lot of force to remove.

7 The next step is to add small packing disks that are 1.4mm thick to the metal wheel pins. This will leave just enough of the pin to push back into the original tube. These can be made from a Plasticard sheet using a hole punch to make the 4mm diameter disk, then drilled with a 1mm central hole so it is a push fit to the axel. I made some on a 3D printer, and can also supply these on request at modelengineworks@outlook.com. The results are similar using both methods.

8 Return the wheel sets to the chassis ― they are not handed so they fit at either end.

9 This is the start of the fiddly jobs. The pickups are returned to the chassis: these need to be kept in their correct position while the bottom shell is clipped on.

10 It is important to get the bottom shell correctly orientated to the metal chassis. There are arrows on the shells that point to the front of the position where the worm gear is located.

11 Before replacing the top shell: as the motor is loose at this point, the red pad on which it sits can become dislodged, so make sure it is correctly positioned in the metal chassis. At this stage to keep the motor in place, I added a small strip of black insulation tape around the hole unit to keep things in place and to test if the chassis runs OK.

12 After testing, the top shell can be returned to the chassis. Look out for the orientation arrow, and then clip this in place.

13 Now test if the chassis runs. If there is a problem: I have found that the areas above the pickups where they are bent out may need more clearance ― they need a bit of free play up and down. The other area that can cause issues is the pickups being too tight on the wheel: these are best with a little free play or less pressure on the wheels and may need to be eased out from the wheels.

The conversion has now been carried out successfully by several other 00n3 modelers.

They have found that the pickup is a difficult part to bend by hand. Also, these must have the correct clearance above the wheels to allow movement. It is also important to get the bottom plastic cover on the right way round, or this will cause the gears to bind with it, or not clip in place.

See the conversion by Paul Titmuss running on his 00n3 layout 'Lispole' on YouTube.

A copy of the press and spacers can be supplied on request at modelengineworks@outlook.com

Tuesday, 31 December 2024

00n3 & TT:120 Chassis Conversion

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