# Plan it, build it



## SignalFailure (Apr 24, 2009)

I want to make an uber-simple double-acting piston-valve engine so I thought I'd draw out some plans for a change before cutting any metal ;D

Can someone who knows about such things please cast an eye over this initial drawing just to see if it looks about right? 

I know that the eccentric/strap isn't shown the right size or position at present and that there's bits missing from both elevations (to avoid clutter) but I thought I'd get it checked out before going any further. Ignore the colour too, it's just there to help my slow brain. Oh and please excuse the fact that I probably haven't stuck to any drawing conventions and that the design is rather ugly!

Thanks in advance!


----------



## tel (Apr 24, 2009)

Looks OK to me Paul. At least you have got it down on paper, the furthest I get seems to be a rough, back-of-an-envelope, sketch of the odd part - the overall plan is usually stored in wot passes for my brain.


----------



## SignalFailure (Apr 24, 2009)

Cheers Tel, whether or not I'll have the stamina to draw all the parts out properly is another matter altogether ;D


----------



## tel (Apr 24, 2009)

More productive to be cutting metal any'ow!


----------



## Maryak (Apr 24, 2009)

Paul,

Looks good, the only thing I can't see, (doesn't mean it isn't there), is some form of piston rod guide.

Best Regards
Bob


----------



## abby (Apr 24, 2009)

Paul I have some cylinder castings of similar size to your drawing , although they are for a G1 loco they would be an easy start for a stationary engine with the bonus that the ports and passageways are already cast in. If interested PM me.




This is as fitted on loco frames.








a little ingenuity would soon adapt them!


----------



## Paolo (Apr 24, 2009)

Hi abby are you interested on steam loco?
Cheers
Paolo


----------



## SignalFailure (Apr 25, 2009)

Maryak  said:
			
		

> Looks good, the only thing I can't see, (doesn't mean it isn't there), is some form of piston rod guide.



Thanks Bob, I was in two minds about that. For simplicity I'd like to omit it as the maximum extension of the rod is only 14mm. I've seen a couple of similar engines with no cross-head guide so assumed they must work reasonably well. A simple guide (block underneath, 'rails' on top) would be easy to insert I suppose. What do you think?

Abby, thank for the offer mate but I haven't got the gear for machining castings... it's bar stock all the way here  !


----------



## Maryak (Apr 25, 2009)

Paul,

With the small travel/extension of the rod (14mm) the best thing may be to make the stuffing box as long as you can and leave it at that.

Hope this helps ???

Best Regards
Bob


----------



## SignalFailure (Apr 25, 2009)

Thanks Bob, I think I'll try it without first... it can always be added later if necessary ;D


----------



## tel (Apr 25, 2009)

They're very nice cylinders Abby - 'ow much for a set posted to Oz?


----------



## SignalFailure (Apr 25, 2009)

For them wot's interested, here's where I'm at so far... blimey this CAD is slow compared to ordinary vector drawing/DTP! 

View attachment pveV2.pdf


----------



## SignalFailure (May 25, 2009)

Built most of it so thought I'd post a picture (should probably be in 'work in progress' but thought I'd keep it with this thread). Please excuse the finish and temporary fasteners! Just need to finish the valve rod fork and make the eccentric.

Decided to call this engine 'Pug' as it's small, chunky and pug-ugly!

Once it's done and (hopefully) running I'll post the final plans.


----------



## SignalFailure (Jun 4, 2009)

Uploaded the plans to the download section for anyone what wants 'em!


----------



## Groewrs (Jun 4, 2009)

Cheers for the plans, Paul! Downloaded for future use (hopefully!)

Gordon


----------

