Another Saltford Simplex rebuild.

This is the second Saltford Models Simplex that I built, probably in about 1988. It was still in one piece, but the motor gave out a long time ago so I decided to rebuild it with a new drivetrain and motor, I've done one before but this time I did things slightly differently.
Here it is before the rebuild;

I machined new wheels from 10mm brass bar (CZ121), pretty much as covered here. There are of course a few differences, these are 6.4mm dia., stub axles are 1.6mm silver steel, the 3 holes are 1mm dia. at a 4.5mm PCD, and as the original wheels were 3mm wide there is a 1mm x 2.5mm dia. shoulder on the face.

The kit originally came with 12:1 ratio gears. I've replaced them with 15:1 gears, from Nigel Lawton, which have a centre to centre distance of 3.6mm, closely matching that of the original gears. The worm gear needed to be drilled out to 2.5mm (or therabouts, the muff was machined to suit), luckily its a nice fit in a 5mm collet. Again I've used Nigel Lawton 3mm root dia. pulleys to carry drive to the front axle along with a 12mm drive belt. Here's the wheelsets ready for use along with the old wheels for comparison;

As before the wheels have been treated with Birchwood Casey Brass Black.

On my last rebuild I replaced the cheapo motor with a Mashima 1015. However, Mashimas are becoming rather scarce now so as an alternative I fitted an open framed Kato motor taken from an 11-104 motorised chassis. These appear to be well made 5 pole jobs, and the whole chassis can be bought on eBay for less that the price of a new Mashima, assuming that you can find a new Mashima to buy of course. The Kato is slightly larger, measuring 16.5mm (34mm including shafts)  x 13.5mm x 9.5mm, with 1.5mm shafts;

Being double ended means of course that a flywheel can be fitted. I had to cut down the shaft, removing 3mm from the top (brush end).

Replacing the motor, drivetrain and wheelsets meant completely dismantling the loco. It was originally epoxied together, and came apart with little effort. I decided to only re-use the castings and replace the plasticard footplate and roof. One problem that I encountered was a loose bearing. When I built this loco I fitted brass axle bearings, supplied seperately by Saltford, rather than run the axles in the whitemetal frame castings. To fit them I had to open out the axle holes in the cast frames from 1/16" to 2mm. But I must have opened up one hole oversize as one bearing was a sloppy fit in the frame, the answer was of course to turn a new bearing to suit. Lathe ownership has many advantages.

Here's the frames with the new axles and driveband fitted;

As I wrote above, the motor needed the upper shaft shortening by 3mm, which I covered here. Once I'd fitted the worm (shortened from 6.5mm long to 5mm, another lathe job) it could be epoxied to the footplate;

The next step was to fit the basic bodywork (remember that only the basic castings were re-used), test run the loco, then fit a flywheel. This measured 11mm dia. x 3.5mm. After yet more test running the couplers, radiator, sandboxes, re-railing beams and front handrail could be fitted. The handrail was formed from .8mm brass rod and blackened with Birchwood Casey brass black. It looks pretty good so I haven't painted it, but the rest of the footplate and chassis is Phoenix Precision Dirty Black acrylic, leaving the original green paint untouched.

The roof is .020" styrene painted whilst off the body first with a coat Hycote auto primer followed by Revell Aqua Color 378 Dark Grey.

It now runs better than it ever did in its original form, the Kato motor, flywheel and 15:1 gearing making a big difference. It still needs to be 'driven', but I like that.

Paul.