Darjeeling B Class Instructions

Instructions and notes for building our B class kit go here

Revised Motor/Worm Mount

A recent change in what we could get from our gear supplier has resulted in a slight change to the gearbox assembly. You may have received a brass worm gear that is a sliding fit in the motor shaft. Leave fixing it until the last minute as you can slide it on and off as you adjust the mesh and with it off it allows you to freewheel the chassis and gearbox.

When you are ready to fit it read the instructions below on how to use Loctite 603. When you are happy centre the gear over the spur gears and add a drop of Loctite 603 to the outer end of the shaft and let it wick into the join.

Have a brew. In an hour it will have a grip so that you can handle it but a full cure takes 24 hours.

Revised Gearbox Assembly

Its almost inevitable that the contents of a kit will evolve over time as parts originally sourced cease to be available. In this instance the gears we provide with the Darjeeling kit have changed. As a result the gearbox needs assembling slightly differently. The new set up is shown below.

What you get in the kit

These are the parts supplied in the kit. The item that has changed is the final drive gear which is now thicker and secured to the axle with a grub screws. There is an Allen Key included for tightening the grub screw.

* you may also get a brass worm that is a sliding fit on the motor. Read the notes below about using the retaining compound and use compound to fix it to the shaft.

Tools Needed

  • Assorted files
  • 1/8″ reamer (in the tube at the top)
  • Big taper reamer
  • Small taper reamer

Instead of the big taper reamer you can file the holes but if you’re doing a lot of kit building its a worthwhile tool to have.

Potions

  • 145′ solder. This lower temp solder flows real easy without getting too much heat in to the model.
  • Powerflow Flux
  • Loctite 603  [not superglue –  look for it on Amazon]

Preparation and Folding.

Clean up the etch removing the etch tabs an the cusp around the outside.

Don’t clean out the motor mount holes at this stage

I missed a picture here and its not something you can go back to take so I’ll just describe it.

Open the holes out to take the top hat bushes with the big taper reamer or file. Take care to open the holes out concentrically. Particular care if using a file.

Insert the bushes such the flange is on the inside. Flux generously and solder the bush in running a good filler of solder round the outside. File the flanges off once its soldered.

Fold the gearbox etch into its U shape, make sure its square and then run a fillet of solder into the join.

Another thing I forgot to photograph – cut the 2mm shafting in to two and file the ends to a slight taper to remove any burrs. This so that the end are the same size or fractionally smaller than the body off the shaft. Using the small taper reamer open the smaller holes so that the shaft just pushes through as a tight fit

Gear Assembly #1

Using this view (and ignore for now that the shafts are already cut) to assemble the plastic gears and 2mm bushes as shown.

Pull the shafts through to be almost flush with the surface.

Make sure the gears have slid away from this surface so the heat doesn’t get them.

 

Add a decent amount of flux.

Quickly run a fillet of solder around the ends of the shafts as shown

Next…..

Turn the gearbox over, cut the shafts just clear of the etched frame and solder the ends of the shafts.

TOP TIP – before soldering the second side of the shafts insert the final drive gear and a sheet of paper to ensure the soldering leaves a running clearance for the gear.

If you don’t there is a tendency to squeeze the frame too narrow for the gear

Loctite 603 – Its magic…… …. but its not superglue

Its way cleverer than that. Officially its called a retainer but what does that mean.

  • its low viscosity – it flows into gaps
  • its activated by metal – so it doesn’t start to cure until its on the shaft
  • Its bigger in its solid form than liquid
  • It acts concentrically

It will get a hold in an hour and cure fully overnight

So, it doesn’t take much, it wicks into a joint, doesn’t start to go off until its in the joint, swells up to make a tight retained fit and in a bush/shaft situation it keeps the shaft concentrically in the middle of the bush.

Application – don’t squirt it from the bottle onto the work.

In the above picture my applicator is 0.35mm wire in a bbq skewer. I squeeze some 603 on to a lid and then pick up a blob on the wire

Follow the procedure below….

  • Centralise the single gear
  • Move one bush up close
  • Move the gear away
  • Add a small drop of 603 to the shaft between the bush and etch frame. It will wick into the bush and moving the gear away stops it getting in the gear.

Put the kettle on and have a brew. Leave it an hour.

  • Move the gear back against the first bush, move the second bush up to the gear then back it away about a paper thickness
  • Add a drop of 603 between this bush and the frame allowing it to wick into the bush.

Have another cuppa or, better still leave it overnight

Whoops – Lets back up a bit

Concentrating on building the gearbox I forgot that the back end motor shaft needs trimming off. You need a motor tool, carborundum cutting disk and some tape.

Oh, and don’t forget the safety glasses

First carefully bend the motor electrical connections down.

Warp the motor in tape to prevent cutting dust from getting in the works. I used some Tamiya masking tape but any tape will do.

With the motor tool running as fast as it can cut the shaft about 1mm from the body. Don’t linger as the cutting process makes heat which could damage the motor. Running the disc fast it should be through the shaft in moments.

You may be able to saw the shaft but its hardened so likely to be as hard if not harder than you blade.

Completed Gearbox

There you go, one completed gearbox. The Delrin gears are self lubricating so the finished gearbox needs only a very small amount of oil applied to the final axle bearings and on to the intermediate shafts.

See the images and text above on blob sizes. Adding more oil or grease just invites it to attract gunge into the gearbox.

I run them in for an hour or so at this stage just by hooking the motor to a battery.

the only additional thing I would do to the motor and gearbox is to not permanently fix the driving wheels into the loco until close to the end after painting. Then as you put it to get it together for the last time wash the gearbox out with thinners and then re-lubricate it to make sure its got no construction muck in it and has fresh oil.