Twin marine oscillator

[Team ricky]

Hi Chaps,

I’ve wanted to build from scrap stock for a while now !

I thought I would base the engine around the original puffin twin and use some different materials and style , Not sure if it will just be a display or fitted just yet .

The materials used are :

Standard : Cast iron
Flywheel  : Cast iron
Shafts.    : 316 stainless
Cylinders: Cast GM (purchased)
Pistons.  : Bronze 11x5
Base.     : 316 stainless
Bearing block : GM
Crank discs: Silver steel

Bore 11mm stroke 11mm

It should make good power and efficiency

Jobs to still do are :

Calculate the piston rod lengths
Calculate and make the big ends
Make GM throttle arm
Make steam fittings

Not too much more to go !

[crueby]

An excellent start!   

[Sanjay F]

Well, that's impressive you look like you're well on the way with it, should hear that rumble into life soon!

[CI]

Looks nice !
.

[Michael S.]

The motor looks good. A good, robust design. I have a similar motor in my model steamship, and it's very reliable.

Michael

[Team ricky]

Hi Chaps….

It’s been a little while since I have made time on this project!

The engine is now running well and close to final finishing

Without gaskets it runs at 3-5 psi which is encouraging to say the least
I did run the engine partially in on the lathe with the correct shims so to not damage the bearings
All went well so I went straight onto compressed air to keep running in

Now seems well sealed cylinder wise , a little work needed to polish the top of the standard to better seal the throttle arm and I think it’s good to go

So just a throttle arm to make as I’ve robbed one from another model lol 😂 and some gaskets …

I have recently found a lovely little o ring internal booring bar that just fits in an 1/8” hole that allows me to insert o rings on the piston rod to bottom cover, this is a bit of a game changer in terms of leaks and friction, It works so much better than graphite yarn !

[Team ricky]

Some pics

[Team ricky]

Pics

[Team ricky]

Ooh  ,

Just forgot to mention the cylinder security to the standard needs a bit of thought…. Currently cable ties holding them in place for testing !

I have ordered a tension spring to go all the way around both cylinder and I was going to mill a slot in the standard to accommodate the spring and hide it somewhat , alternatively a bracket could be used or peg the cylinders and use two springs between each cylinder…..

Not sure yet but that’s the joy I guess

[Jasonb]

Looking good. A stretched O ring is another option for holding the cylinders.

[Sanjay F]

Nice engine - looking forward to seeing it running 

[PaulR]

Very nice.

I've looked at building this sort of configuration before but was never keen on the methods used to hold the cylinders in place, brackets of some sort being the least worst in appearance to my eye. Another possibility would be uprights at each end of the crankshaft with screws and pads pushing on the outside of the cylinders but I'm sure that wouldn't be everyone's cup of tea!

[Team ricky]

Today I milled the slot each side of the standard to accommodate the spring/oring and made the throttle arm/disk on the rotary table, All went well and I installed an oring for testing

Runs a treat just the right amount of pressure on the cylinders

https://youtube.com/shorts/YuYA7sgmCJo?si=Ct-G4ew-7IOn1jne

[Charles Lamont]

This has made me think about how some means of retaining the cylinders might be built in to the column. Is the porting like this?:

[Jasonb]

Tension spring down the pivot with pins to hook over set into a pivot stub on the cylinders