The Burrell conrod has taken some time to get to as I’ve been waiting to fix the boiler location.
First part to make up was the big end. As this part is so small I decided to make this from a piece of phosphor bronze and not have an insert.
I use an ER25 square collet block to allow me to simply index and machine square faces on a piece of round bar.
The hole through the big end was reamed 4mm in diameter.
The split crankshaft of this Burrell design allowed me to make a solid big end on the conrod.
Jury is out on whether this was the right decision.
I hope this matchstick gives an idea of scale.
Next was the small end of the conrod. Made from brass and shown here with the filing buttons prior to me hardening them. These buttons are made from silver steel with an 8BA bolt through the centre.
Just taking the silver steel up to red hot and then quenching in water. I don’t anneal these as I want them very hard to resist the file as much as possible.
There is a small piece of brass between the fork ends of the conrod end and then a hardened button each side.
I then file and emery the brass to shape.
At this point with both ends of the conrod made up it feels like I’m making progress.
Such a small conrod should perhaps have been made from one piece of brass, however I silver soldered the Burrell conrod from 3 parts.
For silver soldering on this scale the silver solder paste from CooksonGold is perfect. Have to admit that I’m not sure what I would do without it.
Finally a look at the conrod in place.