(For those who may be interested in the background to the wireless works at Randwick)

In my recent searches for more information on Norman James Phillips (...still working on that), I came across a recent book on Archibald Shaw and the Maritime Wireless Telegraph Company written by Matthew Ryan (ISBN 978-1-7636375-0-4 published by Studio20 in 2024). I have just finished reading it and it appears to be a comprehensive, balanced and well researched book on the subject. It does not help answer directly any of my questions on Star Engineering, but does give good insight into the history of Shaw's Wireless Works at Randwick. It also has possibly provided a few ideas for new avenues to research that may connect a few dots in the future (for example on pg 187 it is stated that in 1915 the Wireless works were making spare parts for P.M.G. (Post Master General) owned motorcycles in 1915, what make of motorcycle were these for? perhaps Douglas?)

I am not sure that any other books exist on this subject (?)

Cheers

Hutch

Another installment has been posted. Castings. HERE



-Doug

The RA brake project required aluminum alloy castings in the form of foundation rings for the friction material and the brake shoes themselves. A fairly complete rear shoe assembly in Australia was on loan and copied. An original sample of the front shoe could not be borrowed, and it was reverse engineered with the combination of photos and field measurements of the one on the Bob Thomas outfit on the I.o.M. The shoe patterns required a core for where they fit down over the brake rings. The vee-shaped valley could have been machined out from solid, however there is an undercut at the root of the vee that would have made this difficult and tedious. Besides, it was hoped that the braking surface would cast close enough to the correct shape that a bit of sanding would suffice in lieu of machining; the rest taken care of by running in.

Like the rest of the brake hardware, the shoes were modeled in 3D CAD software. It was short step to go from that to creating the patterns and core boxes on a 3D printer in a UV cure acrylic material; primarily because I had access to a printer and wanted to see what it could do. The traditional method would have been to machine the patterns from wood. The pattern match board did one front and rear shoe per flask.


The front and rear shoe pattern mounted on a pattern board, but prior to applying gating. The reverse side of the board had the other, identical half of the patterns glued to it.


The core boxes for the front and rear shoe.

A local foundry did the aluminum castings, but they were more familiar with casting small brass hardware and not aluminum and the larger gating required for good flow. As a result, the first batch had to be scrapped and done over. At double the cost. At the same time the foundation rings were cast. The pattern for this was quite simple and just a loose ring laid on a pattern board and hand gated. These did not have to be castings as they are machined all over, but it was more efficient to cast rings than search for a large, heavy wall pipe to machine rings from, or alternately trepan or plasma arc cut them out of heavy aluminum plate.


Raw cast foundation rings.


Raw castings, front shoes and (right) rear shoes from the 2nd attempt.


What happens when the foundry forgets to insert the core into the mold.

The castings were then sent out for Hot Isostatic Pressing (HIP) and then solution heat treatment.  The HIP process involves heating the castings slightly below the melting temperature and then exposing the castings to a pressure of 200MPa or more, usually in an argon atmosphere. Internal porosity that might exist gets squeezed to nil, greatly enhancing the fatigue strength.

The brake shoes required very little machining, just a slot, face, and drill operation; though some substantial fixturing. This comprised of a steel plate held on edge and machined to the form of a segment of the brake ring. Since the rings are different widths, one fixture was needed for the front and one for the rear shoes. The same fixture with engineer's blue, was used to spot the castings and and a four-inch diameter right-angle grinder used to sand down the high spots until the casting fit down upon the fixture to the correct depth. The high spots were primarily at the ends where shrinkage caused the casting to curl in to a sligtly tighter radius.  A pair of clamps wedged the shoe onto the fixture, quite firmly, for machining. 


One of the brake shoe machining fixtures.


The fixture in use. The odd shape to the clamps is because they can be flipped over and used on either fixture to clamp a front or rear shoe.


Though not a lot of machining in the slotting and facing operation, after two dozen castings the chips start to pile up.


A partially machined front shoe next to an original rear shoe.

The same fixture on its side held the brake shoe for drilling and reaming. The ears had to be chocked with adjustable parallels and snubs with a clamp to prevent movement.


Drilling and reaming.

-Doug

Hi, I'm new to the group, I picked up this little Douglas stationary engine at the weekend at a swap meet. I believe it to be an FT35, does anyone have any manuals or information on them please? 

The Q prefix box is for a foot-change 1935 Wessex (600cc sv) or Powerflow (750cc sv).

I will have to pop the cover off my '35 to see how complete (or not!) the positive stop mechanism is.

-Doug



[fix typo, 11Apr25, Doug]

Where I'm stuck is on the selector, the missing gear I can make but somethings missing for the quadrant positive stops?

Wow super informative and very much appreciated 🙏🏻

Eddie,

That is not a "B", the prefix code is an "R".

Steve,

That is a foot-change gearbox for a 1935 OW or OW1 model. A little background first. It was derived from the optional 4-speed transmission offered for the S6 models from mid-1932. In 1934 it changed in detail; mainly the kick-start quadrant mechanism became constant mesh. In (mid?) 1935 they changed from a stub tooth gear form to involute. Now stub teeth are involute with a shifted profile so I am not sure just what they meant; but basically the tooth form changes slightly. Hence, don't run mismatched pre- and post- mid-1935 gears together. It is like running 20 and 14-1/4 degree pressure angle gears together. The 1934 & 1935 4-speed gearboxes were used on both the heavyweight ohv and side valve models; same internals but different gearcases to suit the different mounting points. The foot shift was an option, and entailed a positive stop mechanism built in to the end cover. From what I have heard it was not particularly good, as it was very sensitive to the spring rate being just right, and the springs operating in that curved bronze box in the cover created a lot of friction. They dropped the foot-shift option in 1936. In general the 4-speed boxes not very robust compared to other marques. Which is why a lot of racers and sprinters converted to other gearboxes like Norton. 

By my own list of tracking down surviving OW/OW1 models I estimate they made perhaps thirty total over two years. That would be a mix of hand and foot-change models. I have never seen an advert that said how much extra the foot-change option cost but I am sure it deterred most buyers. So a uncommon gearbox for a uncommon model.

I have a 1934 hand change OW1 and a 1935 foot change OW1. My '35 has a "K" prefix gearbox, so it still retains the older stub-tooth gear profile like the '34.


1934 "G" prefix gearbox.


1934 "K" prefix gearbox.

In the 37 years I have been researching OW/OW1 models I have not yet seen a parts list or exploded views. But the internals, excluding the foot change mechanism of course, did continue on in the 4-speed gearboxes of the Aero 500/600cc models. To be sure some early Aeros flirted with a very terrible floating bronze bearing on the layshaft, but the underlying components were for - and reverted to - ball bearings. So internal views of the Aero gearbox are representative for the 1934-35 ohv gearboxes. So some pics of that are included.


500/600cc Aero gearbox.


500/600cc Aero gearbox.


500/600cc Aero gearbox.


500/600cc Aero gearbox.


500/600cc Aero gearbox.


A 1932 Greyhound gearbox, but shows the same shift drum and forks as used later.

-Doug

According to Jeff Clew's book, that is a 4 speed 'box for 1932 OHV models F or G.

Eddie.

Please assist with manual/ parts list or exploded view
Thanks  Steve