Split Excentric

[Yorkshireman]

In the Paddleducks build log we just saw the construction of an excentric.

I neet to add a drive pump to a steam loco, to be driven by an excentric. I have no chance to take the wheels off the driving axle, so i will need a Split Excentric (in two halves) to be put around the driving axle.
How do I do this?
What is a smart way to turn the bore for the axle to size, keeping a very strong grip when I clamp the Split Excentric around the axle, so that the excentric doen not slip?
(I dislike grub screws)


Thanks
Johannes

[sbwhart]

You could try putting very thin chim between the two halves before you turn the bore, when you fit it round the axle take the chim out so that it clamps down.

Hope this helps

Stew

[Maninshed]

Hi not easy this, if I had to do it I would:-
a)Make up a bank eccentric rough it out well over size, leave the bore small and the width slightly over width, also rough out sheave diameter.
b)Slitting saw it in half through the centre of the bore.
c)Drill and tap and fix it securly together.
d)Set bore to run as truly as possible around the split bolting line.
e)Bore out to as best you can 1/2 to a 1/4 of a thou under size, true up the front face.
f)Make up an eccentric mandrel with spigot size of you axle.
h)Mount you eccentric on it.
i)Finnish machine sheave dia face off flange on one side.
j)Turn eccentric round on jig and machine other flange to width.
k) Remove from jig fit to axle fix with loctite, and drill anti rotation peg if required.

Martyn.