Building a 31/2" Gauge Locomotive Engine

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Stilldrillin:
I often don`t know whether I`m coming or going, been or gone! ::)

Was that a lightbulb moment Stew? I wish I`d got half your patience...... :wave:

Good luck, again, this time....... :thumbup:

David D

bogstandard:
Sometimes Stew, it is better to put it under the bench for a day or two, then come back to it with a fresh mind, and check everything methodically from start to finish.

I didn't even spot anything wrong in that department, but we only looked at one eccentric anyway, just to see if the timing could be obtained, and of course we found the jamming problem.

I bet that once you have those swapped over, and the hack off mods we talked about, you will have no more troubles in that department, except for the locking system for the eccentrics.

John

NickG:
Well done on finding the timing problem Stew! It will be fine now, it is still a silly way of locking the eccentrics though. I wonder if it might be worth drilling and pinning permanently once in the right position. Then any overall timing can be adjusted by moving the valve on its spindle as Bogs suggested?

NIck

arnoldb:

--- Quote ---I bet you'd thought I'd given up on this, old Stew's not beaten that easily.
--- End quote ---

What? :scratch: :scratch: If you give up, you'll be getting a lot of :whip: :lol:

Going great guns Stew :thumbup: - when it's running, it will be worth so much more , unlike easy come easy go ::)

:beer:, Arnold

sbwhart:
Well next instalemt of this epic

I put the valve linkage right, things were better in that the linkage was moving in a logical way, but still couldn't get the timing correct, when John had a look at it he said he thought that I needed to take a couple of mm off the slide valve. :hammer:

Before I started on such drastic action I decided to go back to first principles and work the valve sizes out for myself, so looking on my book shelf, found these two books with detail info on slide valve design.

They were saying the proportions of the slide valve should be as sketch:-

I know that these proportions are not set in stone, and there are countless variation on this to meet variouse design criteria, but for me this was a good place to start.

So using these criteria I worked out some sizes for the slide valve and low and behold they said I needed to take 1mm per side off the valve (Johns 2mm :bow: :bow: :bow:)

Not wanting to jump in with 2 feet and start cutting the valves about, this morning I made a dummy valve out of some brass to these calculated sizes tried it out and it looks like it will work may have to take a little bit more off so I'll give it a go on the dummy to see how it looks.

Fealing hopefull

Stew

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