GALLOWAY 5HP HIT & MISS BUILD IN 1:3 SCALE
By Jason Ballamy 
Part ten - Push rod and brackets
M4. C4n

The push rod slides in a pair of brackets, these are supplied as a single bronze casting which was first held in the 4 jaw to get a flat reference face. Although it looked fine from the outside some holes soon started to appear.

With the now flat face against the vice fixed jaw and a bit of aluminium on the other side to take up any unevenness the 4 sides were squared up but left oversize at this stage.
I could then hold it by these faces to bring it down to thickness and shape the governor arm pivot that is part of the bracket nearest the crank.
The slot for the pushrod was then milled which revealed how cheesy the casting was, followed by adding the mounting holes.
The slot for the governor arm was added, then the pivot hole and finally the brackets were taken to size.
Then onto the rotary table to add a bit of shape.
There is a little block of steel on the end of the pushrod that engages with the governor latch, the ‘dovetail’ shape of this was cut with a flycutter.
And here is the rod assembly complete with cam follower wheel and adjustable fork. Most of the holes are out of sight in the surfaces that the rod runs against so I don't see it being a problem as there is still enough meat to give a decent bearing area.
The ignitor trip is another bronze casting, this time it seems a bit more solid.
I started by machining the top and sides to give me some flat surfaces to do some rough marking out on.
I then started to machine to size but left the angled faces square for now.
I could then indicate off these faces to locate the pivot hole...
...followed by the slot so it can slip over the push rod. Also drilled and tapped for the stop screw at the same setting.
I then roughed out the top and cut a rebate (rabbet) for the steel tip.
An oversized piece of steel was silver soldered in place before being machined off flush with the bronze.