I've used an old 5C spin collet many times for cutting gears, since I lack a D.H.

How does that differ from a dividing head?

I've used an old 5C spin collet many times for cutting gears, since I lack a D.H. 

ah, the dark art of cutting gears, something I need to get my 'teeth' into ......... there you go I said it  .

Someone gave me a dividing head a while ago and it's still sitting on the workshop floor in bubblewrap. I take it one of those is not essential for gear cutting?

My next project is underway despite having only the outline of a plan. As usual it'll be a blocky bar stock build, a variation (refinement??) of the single-acting twin cylinder finished a few days ago. This time there will be a single inlet and no external pipework to the cylinders. I'll also use a scotch yoke to save a bit of space between the cylinders.

Here's all the progress I have made this evening - facing the valve block/bearing and the arms of the frame that the cylinders will be attached to. I planned on using some thinner brass for the frame but couldn't lay my hands on any so this will have to do.

P.S. Don't bother clicking the thumbnail unless you're really bored as there is nothing worth looking at 

Chris, your research, drawings, explanations, construction, just brilliant. 

Thanks Steve!  Guess its the old research engineer in me coming through...