Conrod Material For Duclos Oddball

[grubscrewParticipant @grubscrew]

Could someone please advise what grade of steel would be suitable for the construction of a conrod for a small I/C engine, specifically the Philip Duclos Oddball engine? Also, does anyone have first hand experience of making this engine? Are there any pitfalls for the unwary?

Thanks, Grubscrew.

[JasonBModerator @jasonb]

On the open crank engines that I make it is either EN32B rectangular stock or En1A round, never had a problem.

Not made this one but do have the book if you have any other queries.

[Michael GilliganParticipant @michaelgilligan61133]

Now that Jason has answered the question … please permit me a hi-jack

I was interested to find this page:

https://craftsmanshipmuseum.com/artisan/phillip-duclos/

and particularly the link to the short article about his Camera

MichaelG.

[David George 1Participant @davidgeorge1]

Have you thought about using Aluminium for a conrod. H15   (2014A) is strong enough and lighter which will give a smoother run as the weight is reduced going up and down.

David

[bernard towersParticipant @bernardtowers37738]

If you use aluminium I suggest 7075

[Graham MeekParticipant @grahammeek88282]

I built the Odds N Ends engine, by Philip Duclos. Although Aluminium was specified for the Con-rod, I used Brass for this particular engine. As I wanted to run it on diesel. Normally I use Aluminium and have had no problems. I think from memory his Odd Ball also uses Aluminium.

These are Con-rods from the ETW Seagull engine.

 

These are the rods form a version of his Gemini High Speed Steam engines.

Regards

Gray,

 

[JasonBModerator @jasonb]

CRS on the oddball drawings. Quite a long slender one at about 4″ and 3/16″ dia at the small end.

 

[Graham MeekParticipant @grahammeek88282]

Hi Jason,

I stand corrected, my memory is not that good these days and I no longer have my HSM magazines to cross reference.

Sackcloth and Ashes time,

Regards

Gray,

[grubscrewParticipant @grubscrew]

Jason, what’s the reasoning for the different spec materials between rectangular and round stock? Is it down to availability?

Michael, fascinating article, very interesting. Thank you.

David, Bernard and Graham. I hadn’t thought of aluminium, I shall ponder this. Nice work on your conrods/pistons Graham.

Are there any Forumites that have actually built an Oddball?

 

 

[JasonBModerator @jasonb]

That’s it, rectangular tends to come in EN32b but if the part is round then EN1a is nicer to machine. Infact small conrods I’ll often machine from round stock particularly one like this where the big end is not split as that does not need the width.

Steel is also about a 1/3rd the price of 2014.

Looking at the drawings one thing I would watch is don’t just ream the flywheels and expect the CRS crankshaft to be a press fit a sit usually comes in a few thou below nominal. I would use Precision Ground Mild Steel and bore the flywheels to a firm push fit and then use Loctite. Other option is to use a hand reamer but don’t go all the way through so that the taper of the reamer leaves the inside edge of the hole a bit smaller then again assemble with Loctite and a press or vice.

[John HinkleyParticipant @johnhinkley26699]

Grubscrew,

Some while ago, I purchased a book called “Miniature Internal Combustion Engines” by Malcolm Stride*.  From within its pages, I have scanned the following regarding the choice of materials for the con rods as you specified it was an IC engine that you were proposing to construct:

Further on in the chapter, he describes the machining processes required, and the order of operations.  There are separate chapters covering the choice of materials for the various parts of an engine, and I thoroughly enjoyed reading it.  I would recommend it for anyone with an interest in I.C. for an Xmas present, particularly for early learning on the subject.

John

*  Published by http://www.crowood.com   ISBN 978-1-861269-21-8

And no, I don’t get a commission, nor am I in any way associated with the author or publishers!! Just a satisfied reader.

[JasonBModerator @jasonb]

For those that don’t know the oddball is a slow revving open crank engine. With such large flywheels I’m not sure a change to 2014 will make a lot of difference. Don’t seem to suffer much with vibration and any jumping is when they hit rather than related to speed of rotation.

[JasonBModerator @jasonb]

[John HinkleyParticipant @johnhinkley26699]

Point taken, Jason.  I associate internal combustion with higher revving engines than that depicted in the video. Certainly explains the length of the ‘rod!

John

 

[grubscrewParticipant @grubscrew]

Thanks for the link John. I shall put in an order so I have some Xmas reading.

Jason, given the amount of engines you’ve constructed, is there any reason why you’ve not, as yet built an Oddball?

[JasonBModerator @jasonb]

Too many other choices and these days I quite like to design my own more than build other people’s engines. Of His engines, the Victorian would be the one I would most likely go for as it is the least barstock looking engine though redrawn in metric and with a bit less bling.

[Author]

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