Potty Over Crank Wall Engine

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NickG:
Wow, nice work stew, it's looking like the real deal already.

Nick

saw:
Looking good :clap:

sbwhart:
Thanks for the interest Guys

Milling the valve ports:- this is what I call a **** or bust job its easy to get things wrong then your in it deep.

So I like to mark the ports out this doesn't have to be dead accurate you'r just using this as a guide so that you get the wide port in the middle and the narrow ones at the ends and that the spacing is about right, I also like to make myself a crib sheet showing the cordinates I'm going to use.

I work from the centre of the valve face so first thing is find the centre and zero up the DRO in the x and y.

The middle port is 5 mm wide and the outer are 3.5 mm

Index to the correct cordinate:- centre drill and drill to depth using a number drill, thats just smaller than the slot drill, this stops the slot drill pulling into the corner and giving the port a hockey stick end.

Then using slot drill mill out the ports, as the valve face is angled each port is milled to a diverent depth, I took them considerable deeper than I planned on the drawing but with the actual job in my hand I had a brain wave on how to connect the ports up something that troubled me when I did the drawing as I was unsure how to do it.

Now the brain wave was :smart: drill into the ports from the side, and drill through from the top of the bore to join it up, screw and plug the inlet ports to seal them up, the exhaust is left open.

Finding where to start the drill to join up with the ports.

Drilling through into the ports.

Lining up the cylinder to join the inlet port from the cylinder.

Joining the inlet port up.

And her we have the ports drilled

I'll amend the drawing to reflect this change.

I'll put the cylinder to one side now as I want to make the valve chest and use it to mark of the fixing holes in the cylinder. But before I can do that I've got a huge tidying up job to do in the shop, I'm very much from the:- take it out, use it, put it down school of working as a result I end up with tools and bits of kit spread all round the shop.

Stew

raynerd:
Stew, I`m sorry, you replied to my question and I had not seen it until now.

Thanks for info regarding plugging the bore. I`m sure Harold Hall described a similar but crude method by plugging the holes with cork, marking the centre and then milling. I think this is what you did but more accurately with the aluminium.

Thanks again. Looks to be going great! I`ll be watching...
.
Chris

sbwhart:
This is going :offtopic: but I'd thought I'd show you how the pluging trick can work to get an awkward shape machined.

Some time ago to raise shop funds I machined up a small batch of cylinders for the Minnie traction engine.

These are the castings

The critical features is the position of the cylinder that is dimentioned from the centre line of the boiler the cylinder also has to lie parallel to the boiler centre line.

What you do is plug the bore and stick a bit of wood in the sadle to take the place of the boiler I used No Nail adhesive to stick the chunk of wood where the boiler goes.

Then you mark out the boiler centre line, choosing the best position for the particular casting, all three castings I used were diferent, then you can mark off the position of the cylinder and the radius for the sadle.

Then you pick up the cylinder position and machine it.

Then turn up a mandril to fit the cylinder bore mount this up, setting up on the scribed radius and machine the sadle, this ensures that the cylinder bore sits parallel to the boiler centre line

Her we have one of the completed cylinders.

Stew

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