Bog's Paddleduck Engine

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bogstandard:
Kvom,

Are you going for steam or air driven?

I keep asking this question, but it does mean that if you are only going to run on air, then almost anything will do for the main cylinders, even something like nylon could be used if you can get nice smooth bores. I would suggest a nice cheap material like free cutting mild steel. EN1a here in the UK, or ali.

But if going for steam, then cast iron, bronze or brass should be your first choices.

I have included a C-o-C for perusal.

The central mounting bolts do play an important part in the makeup of the engine, in that they stabilise the central portion of the top mounting plate.

But if you can get the hole pattern in like is shown in the bottom sketch, that will do almost the same job, and I wouldn't envisage any flexing problems.

If running on steam, in fact, having a gap between the cylinders will help in the steaming qualities of the engine. It will allow the engine to warm up a lot quicker and produce less condensate. Have a look at how I have seperated the cylinders on the 'blinged' one. That reduces the mass for the steam to warm up, but still retains the one block principle.

Before doing all your final 'exact' calculations for the cylinder bores, settle on a size that matches generally available o-rings. The engine will run quite happily without rings on either steam or air if a couple or three fine oil grooves are put around the piston, but again, if you want to fit rings, if just air, anything will do, but again, with steam, the choice is limited to either Viton (recommended) or silicon (not recommended if WD40 or most other spirits are coming into contact with the engine for cleaning).

I hope this helps you in some way.

Bogs

ozzie46:

John I am building this too. but am have truoble getting a good finish on the bore. I am using imperial and made my cyl 3/8, how big can I ream them and not effect performance?

Ron

kvom:
I will be running strictly on air, and using an oiler-regulator for lube rather than the displacement oiler. For that reason I also plan to make the handle on the control block more like a manual one. I plan to make the pistons from aluminum with oil grooves rather than rings.

I am really wanting to have an "all brass" engine for the look. I could definitely change the mounting hole pattern for more stability. I do have a block of a reddish brass alloy at school that might work, but will have to wait until tomorrow night to get a measurement. It's the same material from which I made the cylinder for my beam engine; someone thought it might be beryllium-copper.

In the meantime I got my 1/2" brass bar yesterday and now have plenty to do making the connecting rods and couplings. Especially since we are having a nice thuderstorm at the moment, so outdoor activites are off for the day.

Thanks for all the ideas.

sbwhart:

--- Quote from: kvom on May 06, 2009, 08:37:09 AM ---I will be running strictly on air, and using an oiler-regulator for lube rather than the displacement oiler.

--- End quote ---

Just out of interest whats an oiler-regulator :scratch: its a term I've not come across before.

Thanks

Stew

Bernd:
Stew,

Trying to figure out how to tell this. It's sort of a small container that is added on after the one that removes water from an air compressor. The unit allows you to adjust the drops of oil into an air line to lubricate air powered tools. I'm sure you've seen them before, it's just our two languages again causing the problem. :)

regards,
Bernd

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