2 January 2013
My loco projects usually stall, literally, at the point of installing pickups.
Prompted by discussion with Alastair Lyall at the Modellers Weekend and Mick Rawlings at West Byfleet I am investigating the use of tender only pickup using split axles. I think there is room in my 3mm tenders for a speaker and micro decoder so with pickup in the tender there is only a need for two wires for the motor from tender to loco. This approach also means that the tender can be optimised for pickup and the loco for traction.
Our 3mm Society finescale tender wheels are designed for a 1.5mm axle. I used a 1.5mm drill to align a wheel under my Unimat milling machine and clamped the wheel to the bed. Then I used a 2mm drill to enlarge the hole and fit a Branchlines 2mm split axle. The fit is ideal, better than with our 1.5mm axles, and seems to be running true.
The axle has two 0.45mm holes drilled through it to take 0.45mm nickel silver wires using the jig shown below. I haven't quite got the holes central but it hasn't been a problem so far.
If I have got that right then the nickel silver wires will act as stops for the proper back to back. The wires are soldered to the rim of the wheel and then filed back to the tread.
I have bought 3 sets of http://www.highlevelkits.co.uk/ 'Miniblox' 2mm hornblocks together with their CSB Jig and Carrier Tags. This jig works in 3mm scale just as for 4mm. Here is my first hornguide fitted to the inner frame of a David Andrews 3mm E1 tender.
Branchlines Split Axles - 7 March 2013
The Branchlines axles are designed for 4mm scale. Some care is required to adapt them to 3mm.
Here are the parts for one 2mm diameter axle and the Branchlines assembly jig.
The pin on the male part is 7mm long and the full diameter is 8mm long. The washer is 0.5mm wide. The female part is 17.5mm long and is bored 8.25mm deep for the male pin.
The axle parts are glued and then held in alignment using the Branchlines jig. Branchlines suggest drilling through the axle to let the air out and the glue in. My tolerances for 3mm use are already tight so I drill a 0.8mm hole into the solid end of the female part.
When the glue is set I remove 1.6mm from the male end and 7.6mm from the female end to give me an axle length of 16.75mm.
As shown in my previous blog entry I drill two 0.45mm holes through the axles for a wire to short the axle to the wheel rims. These holes must not encounter the male pin as this would short the two axle parts.
My first attempt at a jig for drilling the holes for the shorting wires was not very accurate so I made a new one. This is used in the vice to hold the axle and drill the holes as shown below
I am working to the dimensions in the following drawing. You will probably need to click on it to read it. I am working in 14.2mm gauge. You may need to rework this for different gauges and/or wheels. It may be necessary to reduce the length of the male pin. I wanted to avoid that in case it compromised the strength of the finished axle.
Finally here is a wheelset mounting in the 2mm hornblocks from High Level Kits.
As you can see, there is not much space between the shorting washer and the hornblock. I have made four axles so far and they are still insulated after assembly!
An email to Branchlines at sales@branchlines.com will bring a PDF file with details of their split axles.