piston valve engine-cyl glands

[bentprop]

A question for John(Bogstandard).
I recently started on your engine from scrap.After buying $50 worth of brass and a few days playing,I have the block done.pistons and rods done,as well as caps and glands.However,now that I've had the time to read through the building instructions,I realize I've made a boo-boo(That's polite speak for cock-up :big.
I failed to leave a spigot on the cylinder side of the glands!This means there is no way to centralize the glands to the bore.
Will I have to redo them,or is there a quick and dirty save for my incompetence ;D.
Thanks for any advice.Regards.Hans.

 

[Bogstandard]

Hans,

There is no incompetence at all, just show me a person who has never made a mistake. We all do it.

As long as you haven't put too much of a chamfer in the ends of the cylinder bores, you can easily rescue the glands. There should be enough meat on the flange to put say a 15 to 20 thou spigot on there. It won't make any difference to the running of the engine, in fact it will give a little more clearance in other places.
But because you might have concentricity problems as you will be turning off the outside spigot, I would make it about 2 or 3 thou undersize from the bore diameter, doing it that way will allow a bit of tweaking on final assembly, to make sure that the piston runs up and down and turns in the cylinder without binding.

I made this engine with the beginner in mind, nothing is written in stone. Make it so the bits fit together. The only real critical parts are the two eccentrics, which are dead easy to make, the way I have shown, and the spool valve spacing, again this is described in a lot of detail on how to measure and make the parts fit together perfectly so the engine runs.

Hope this has helped.

John

BTW, if you are running this engine on air, you can use almost any materials for making the parts, I only used brass and cast iron because it will run on steam, and because it looks pretty. If you are happy making say the crank discs out of steel or ali, then do so. The world won't come to an end because you have decided to use something different. It is all about enjoyment and getting a running engine you are happy with at the end.

 

[bentprop]

Thanks for your reply,John.I will give it a go.
I bought the brass mainly because it looks pretty.I did use cast iron for the block,and will probably use steel for the crank discs.I have aluminium,but it has some sort of coating on it,and I'm not sure if I'll be able to clean it all off.
I'll push on,and take a few pics when I have something worth showing.
Hans.