# Murdoch's Oscillating Engine



## SignalFailure (May 6, 2012)

This project has been in my head for four of five years. I started building it about 3 months back and apart from the flywheel is almost complete.

It's my take on William Murdoch's very early oscillating cylinder engine (said to be c1785!) and features a normal piston type valve activated by the oscillation of the cylinder rather than an eccentric.

The original has a wooden cylinder with everything else in iron - as my blacksmithing skills are poor I had to simplify the A frames that support the crankshaft and the main bearings.

As I didn't have any suitable brass for the cylinder or valve chest I made them in mild steel and the piston is cast iron. It's therefore probably unsuitable for running on steam!

It's running on a foot pump here hence the jerky motion - it's not run in enough yet to work off my aquarium pump. 

I've included a picture of the original for comparison.


http://www.youtube.com/watch?v=ny2OehkQdiY&feature=youtu.be


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## cfellows (May 6, 2012)

That's a very nice adaptation of the engine in the drawing. Simple and elegant. I like it, a lot!

Chuck


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## bearcar1 (May 6, 2012)

Glad to see you're still at it Paul. Another nice example of your modeling skills. Thm:


BC1
Jim


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## modeng2000 (May 6, 2012)

Well done Paul.
I wondered what you had been up to!

John


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## SignalFailure (May 7, 2012)

Thank you Chuck, Jim & John ;D

It's crazy but I'm stuck trying to accurately mark out the flywheel - I've tried twice and just can't get it right  I bought two 4" discs of brass at a show last year and with current prices I'm loathe to start cutting until I'm happy with the layout.

Seems I need something better than my wobbly homemade lathe detent. I'm sure I've seen posts on the subject here but damned if I can find them!


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## modeng2000 (May 7, 2012)

It's not like you to make a wobbly unless it's an oscillator 

John


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## doubletop (May 7, 2012)

Paul

Try John "Bogstandards" approach to flywheels worked first second time for me

http://madmodder.net/index.php?PHPSESSID=ri4csmauut6gcsc041i6phdkv1&PHPSESSID=282779f14615aa033c7f5d9e8cca14a2&topic=871.0






Pete


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## ProdEng (May 7, 2012)

Nice to see a fresh design, I like it as well. Oscillating engines are always interesting to watch running.

Jan


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## b.lindsey (May 7, 2012)

Very nicely done Paul, and a great adaptation of the original drawing. Once you finish up the flywheel that will only make it all the more attractive. Nice modeling!!!

BIll


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## SignalFailure (May 7, 2012)

Thanks for the kind comments.

Pete, I'd need to invest an awful lot im equipment to emulate Bog's method - I've got a mini lathe and a poor micro-mill with very little tooling. I plan to mark out the three corners for each space between the spokes then drill & file :big: as I have nothing to hold or align the disc on the mill and doubt if it would cut that thickness anyway.

Watch this space!


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## compspecial (May 7, 2012)

That "Murdoch" guy had some smart ideas for so long ago, I think he was the one with the gaslight and "flier" too.
You have brought his ideas back to life beautifully Paul.. 
             Stew.


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## SignalFailure (May 7, 2012)

Cheers, he also invented the compressed air delivery system used in banks etc! He worked for Boulton & Watt just don the road from here. Genius!


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## doubletop (May 7, 2012)

Paul

Get hold of a copy of the latest model engineer, it may have just the answer you are looking for

Pete


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