The Kato 11-104, along with the similar 11-103, is a popular chassis among the OO9 fraternity being a cheap reliable motor bogie. Many kits have been designed for it, and a fair few others adapted to sit on it, usually steam locos with the mechanism hidden by side skirts (ho hum). I have one fitted to my
Rushby's Resins battery loco, but I feel that its let down by the small wheels. So I decided to turn my own.
First job was to measure the stock wheels and make a simple back-of-an-envelope sketch;
The wheels are solid metal with stub axles which fit into insulating muffs with the drive gear moulded on.
I started by making the stub axles from 1mm silver steel. These have pin points on the outer end, and there was much experimenting done before I found a method that gave me results that I was happy with. I ended up using a sharp 'V' tool in my
compound slide (set to 30 degrees) and turning away from the chuck (i.e. moving the tool to the right). The machine was set at 4000rpm and only light cuts taken. I also found it best to cut the material a couple of millimetres overlength, turn the pin points, then face to length rather than my usual method of losing a long bar in the chuck spindle and keep drawing it out and cutting the part from the bar as I progressed. This was to stop the bar whipping around inside the headstock spindle and getting bent.
Here's a poor shot of the set-up;
There's only 2mm of material sticking out of the collet.
I made 6 stub axles, so that I could select the best 4 to use.
The wheels themselves were turned from brass. Nickel silver would probably be better but I have brass in stock, and its easier to turn. As I wanted 3 hole discs I started by facing the ends of 2 lengths of 10mm rod, then drilling 3 equally spaced .9mm holes in the ends at a 4mm(ish) PCD (pitch circle diameter) on my SL, set up as a drill press with the bar held in a
dividing head.
Then the bar was transferred to the U3. First I turned down the end to 8.7mm dia. by 4mm long;
Then I used a 1.5mm grooving tool to cut a relief groove 2.5mm from the end, to 6.6mm dia.;
Next the profile tool came into play. This cuts a NEM 310 profile, with a flange depth of .8mm. So as I wanted a wheel that was 6.9mm diameter I plunged the tool in until the flange diameter was 8.5mm (.8 x 2 = 1.6mm. So a 6.9mm dia wheel would have a flange that measured 8.5mm.). I touched the tool on the end of the workpiece and moved it along 3.5mm, which put the flange in roughly at the right place at the end of the bar (although I still had to skim the end of the bar to remove a witness mark);
The wheel could then be drilled for the axle, I used a .8mm drill followed by a .9mm. This is so that I could finish to size with a 5 sided broach. I did originally try a .95mm drill when practicing but it cut slightly oversize. Rather than using a Jacobs chuck I held the drills in my collet chuck, which I find to be much more accurate when using small drills.
Once drilled the wheel could be parted off, slightly overlength. I remounted the wheels in a stepped chuck (from
Fohrmann) and faced them to length. I wanted a groove in the face of the wheels, so used a tool that I originally ground when turning a
Swedish spark arrestor chimney to cut a shallow groove. Again the wheels were held in the stepped chuck;
Here's a shot of the wheels and stepped chuck, the upper pair have been grooved;
To get this far I've had to use 5 different turning tools;
From left to right; turning and facing, grooving, wheel profile, parting off, face grooving. Its when doing jobs like this that you find a
quick change toolpost invaluable. Spindle speeds used were 1500rpm for drilling turning and facing and 150rpm for grooving, profiling and parting off.
Here's a closer look at the wheel profile tool along with the holder that I milled for it;
Once I had carefully broached out the axle holes so that the stub axles are a light press fit I pressed the stub axles in place using the lathe. To ensure that the axles only went in as far as neccessary I turned a spacer to act as a stop, this sat behind the wheel as the stub axle was pressed into place from the inner face.
Here's a photo comparing the original Kato wheels to my new brass turnings;
The spacer can be seen at the bottom of the photo.
And here's a spare Kato chassis with one set of my wheels and one set of Kato wheels fitted;
The 3 holes and the groove can hardly be seen. I blackened the wheels with two applications of Birchwood Casey Brass Black then left them overnight. In the morning they were thoroughly cleaned with lighter fluid and cotton buds and re-fitted to the gear muffs;
And finally the wheels fitted into the loco;
Was it worth it? Well, yes. Despite the new wheels having a chunkier look the difference is hardly noticable to be honest unless it was pointed out but that wasn't really the point. I have successfully turned my own wheels (although one wheel has a slight wobble, probably due to a wonky pin-point on the stub axle) which opens the way for all sorts of possibilities and means that I don't have to rely on commercial products (as long as I don't mind using plain discs and am not bothered by spokes).
And finally, my apologies for the less than perfect photos, I find lathes and shiny brass to be a pig to photograph. Don't forget that you can click on any pic. for a larger image.
Paul.
Update April '19. Instead of turning new stub axles its far easier to press the ones out of the stock wheels and re-use them. Quite why I didn't do that in the first place...
