Nigel Lawton OO9 Simplex part 3 - swingarm, motor mount and driveshafts.

The swingarm is made up from two etched parts, an axle and a pulley with an O ring fitted. It sits between the motor and the pulley shaft, being driven by the motor shaft and in turn driving the pulley shaft, all by friction. Here's the components that make up the swingarm;

And assembled;

The pulley is secured to the axle with Loctite 603. The axle itself is hardened steel, mine was slightly too short so after a quick e-mail Nigel supplied a replacement. Being hardened means that ordinary files won't touch it so a diamond whetstone was used to file it to length and de-burr it. A diamond needle file would work as well. Note the two inward-facing lugs, these locate in the motor mount.

Next up is the motor mount, which takes the form of a strap...

...which is fitted around the motor;

The strap is then loosened off, the two tabs are bent inwards to form pivot pins, and the assembly is then fitted to the l/h side frame and the strap re-tightened;

With the frames bolted together you can see that the motor sits transversely under the bonnet, as per a full sized Simplex;

Now the pulley shaft needs to be assembled and fitted. Here's the components;

I fitted the pulley to the shaft first, using the Unimat set up as a drill press to make sure that the pulley went on square. The washer sits behind the pulley, and the sleeve holds the shaft in place. First of all though the sleeve needs to be reduced in length, to do this I held a length of 1.5mm dia. bar in a vice. The sleeve was slipped over the bar, which was set to the finished length of the sleeve, and the sleeve filed down until it was flush with the top of the bar;

Easier done than described!
With the chassis assembled, and the etched holes broached out to suit, the shaft can be fitted in place. A tiny drop of Loctite 603 holds the sleeve in place trapping the r/h frame between pulley/washer and sleeve. To make sure that there's enough sideplay to allow the shaft to rotate freely a feeler gauge is provided on the chassis etch to be used between the pulley/washer and frame, which can be seen in the photo below of the shaft in place;

Spinning the shaft showed the pulley to be out of true, due I think to the bore being slightly eccentric. I substituted it for one from my parts box, which ran fine.

Two drive pulleys now need to be fitted to the pulley shaft, these were pressed on using the Unimat. Once they're in place the corresponding pulleys can be fitted to the axles. One wheel needs to removed from each axle (the insulated wheel) and the instructions suggest using a lathe to press the pulleys in place. I chose to broach out both pulleys until they were a sliding fit on the axles, re-fit the wheels, assemble the frames and axles and then the axle pulleys can be positioned and secured with Loctite 603. Note how both axles are driven seperately from a central driveshaft, again following full-size Simplex practice;

The axles are in fact brass, and the ends are turned down to .8mm dia. This means that great care is needed to avoid damaging the journals (turned ends). I did somehow deform one end of one axle, requiring a strip down of the axle and a light skim of the journal in a lathe. In my opinion steel would have been a better choice of axle material, in fact if I were to build another I might just turn up new axles from steel.
Many would no doubt question the use of Loctite 603 to fix the brass axle pulleys in place, as that particular type of Loctite probably isn't suitable as it only sets properly in the presence of steel. In practice though those pulleys ain't moving!

Here it is with all of the mechanical parts in place, note the swingarm and the 'O' ring on the drive pulley;

I took a scale rule to the model and I note that the wheelbase is correct to the drawing in the W.J.K. Davies book, which bodes well for the rest of the model.

The next job is to fit pick-ups, wire it up, and make it go!

Paul.