Author Topic: The McOnie Oscillating Engine  (Read 27252 times)

Offline Ramon Wilson

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The McOnie Oscillating Engine
« on: March 19, 2013, 10:07:35 AM »
Hi guy's,

I began this engine a while back and it's one of two ongoing projects that  are currently 'rather dormant' - the Bentley being the other - so before we go any further I should point out this is likely to remain so for a while.

Why bother to post then? Well commenting about some images on the crank build on Robert Hornby's excellent thread on the Windemere Steam Launch he has said he would like to see them so I thought it might be worth putting it up as a separate thread rather than encroach on his.  Coincidentally on Sunday I caught up with some old friends from the Norwich SME as they put on a display of members work. One of the exhibits was a nicely made version of this engine which made me realise it's too nice to leave languishing
Who know's then - it might just provide to be the encouragement required  to pick it up again - but not before the Eta engines are finished  ;)

These pics then are for Robert and anyone else who may find them of interest. As always, if theres anything not understood please do comment.

The crankshaft provided in the kit of castings is a flame cut blank of flat mild steel. Having made several other crankshafts by the composite method using dowel pins and high strength Loctite I decided to go that route. There's a spare blank should anyone want one then  ;)

The tapered crank webs were made from mild steel and shaped and finished except their inner faces. Because the original shaft was probably a forging it was felt that the holes should be blind so as to give that effect. The small feet left were to retain squareness for pressing in the shafts (using the bench drill) and would be removed later


The shaft ends and crank pin were turned from mild steel the ends reduced to a tightish hand push fit into the webs. The shaft ends were assembled to their respective webs using Loctite 638, each spigot having a very small flat filed on to allow the air to escape from the blind holes in the webs (the red line)


After assembly the webs were drilled for a mild steel dowel pin. I know I've said this before on more than one occasion but if you wish to plug a hole like this without any sign of it after finishing  the hole should not be deburred - in any way at all - to do so will, without doubt, leave a witness


The dowel is fitted with Loctite also, tapped home and slightly peened to swell the end. This is then filed off to blend in with the web.
The web in the rear has had the pin fitted and been filed off. 'Inking' up around the pin will give a good indicator as to how close the file is getting.


The crank pin was then fitted to one web in the same fashion then two vee blocks were set against a back stop on the mill table and the two half shaft assemblies brought together loctiting the pin in the second web. It helps if this fit is slightly less tight as this needs to be carried out quickly before the Loctite grips.


Finally finished and fitted with no discernable run out -


So far I have had no failures using this method - indeed the crankshaft on the Lang Bridge engine took some of the impact when I dropped it and though it distorted slightly it was easilly tweaked back to truth once set up in the lathe and runs as well as it ever did. What I like personally about this method is that all parts can be 'finished' before assembly, theres no distortion likely from heat sources ie silver soldering and providing it hasn't really got to work for a living then is more that adequate for the task.

I hope that helps you Robert and anyone else with similar interest

There are some further images of the build which I'm quite happy to post about if that's what you or others would like but as I said this is a dormant project until at least those Eta's are finished

Regards - Ramon

"I ain't here for the long time but I am here for a good time"
(a very apt phrase - thanks to a well meaning MEM friend)

Offline Jo

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Re: The McOnie Oscillating Engine
« Reply #1 on: March 19, 2013, 10:44:39 AM »
Ramon,

I would be interested in seeing more of your photo's because as you may be aware Santa brought me one of these castings sets for Xmas  ;D

Jo
Enjoyment is more important than achievement.

Offline zeeprogrammer

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Re: The McOnie Oscillating Engine
« Reply #2 on: March 19, 2013, 10:46:43 AM »
Beautiful looking crank and a very interesting post. Thanks.
Carl (aka Zee) Will sometimes respond to 'hey' but never 'hey you'.
"To work. To work."
Zee-Another Thread Trasher.

Offline ths

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The McOnie Oscillating Engine
« Reply #3 on: March 19, 2013, 11:38:09 AM »
Hi Ramon, thanks for that post. A few questions:

Are the holes in the webs only drilled, or drilled and reamed?

How do you go about ensuring that the holes are equidistant on both webs?

Wouldn't a tight push fit exclude any Locktite and therefore be ineffective?

Hugh.

Offline b.lindsey

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Re: The McOnie Oscillating Engine
« Reply #4 on: March 19, 2013, 11:58:40 AM »
Beautiful work Ramon. I too would love to see more pictures of your build.

Bill

Offline black85vette

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Re: The McOnie Oscillating Engine
« Reply #5 on: March 19, 2013, 01:05:25 PM »
Impressive work.  Love the looks of the crank.   :ThumbsUp:

Offline tvoght

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Re: The McOnie Oscillating Engine
« Reply #6 on: March 19, 2013, 01:55:56 PM »
Highly educational as always. I really like the way the clamps work on those v-blocks. Wish I had a pair like that.

--Tim

Offline Ramon Wilson

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Re: The McOnie Oscillating Engine
« Reply #7 on: March 19, 2013, 10:17:13 PM »
Hi Ramon, thanks for that post. A few questions:

Are the holes in the webs only drilled, or drilled and reamed?

How do you go about ensuring that the holes are equidistant on both webs?

Wouldn't a tight push fit exclude any Locktite and therefore be ineffective?

Hugh.


Hi Hugh,

The holes in the webs are drilled and reamed to ensure a uniform size (the spigots on the shaft and pin stopping short of the chamfer left at the bottom of the hole - the wall thickness left at the end of the hole is minimal to get maximum surface contact.

The webs were prepared first as rectangular slabs to block size and then the hole for the shafts were put in first. A small flat piece of steel held in the mill vise had a round counterbored button (a thou down on spigot diameter) bolted to it using a cap head which the webs were then located on and clamped to the plate. The hole for the pin was then put individually without moving the table setting. I'm afraid I don't have many pictures of this early stage - it appears I was doing this as far back as 2008 - where's that time gone :o

Even though the fit is a tight hand push fit the Loctite, though pushed ahead to some extent as you rightly state, will still leave sufficient residue in the microscopic tooling marks to work. That's why I prefer to 'press' it in even though its a tight hand fit - if the Loctite goes off before you get home it's a 'start over' but with heat probably involved. I have seen some reference by others of turning a very shallow recess for the Loctite to sit in but have never felt this neccessary - if anything I prefer to make the fit slightly tighter and remove a very small amount by filing (in the lathe) - a thou or so at most - from the front of the spigot and let the shaft tighten near the shoulder as as it pushes home.

The drawings for this engine do have some errors in which, (unless they have been rectified since my version) could lead to some problems for the unwary. Looking at the folder tonight I surprised myself at the amount of 'red ink' on a few of the drawings. I would have to refresh my memory by going through it all again but if I remember right none of it caused any real difficulties once I became aware of the need to check everything before machining.

The casting quality was superb though a little tight on machining allowance in a couple of places. The gunmetal is very homogenous and machines well with sharp cutters but it's a material I don't enjoy machining - this felt too 'soft' but that's not a criticism probably just my dislike of the stuff - I would have much preferred these basic castings to have been in Cast Iron. The iron flywheel turned beautifully without any hard spots.

This is where it's at at the moment - I'll post some of the pics and cover some of the 'trials and tribs' a bit later


Thanks for the kind comments - much appreciated

Regards - Ramon
"I ain't here for the long time but I am here for a good time"
(a very apt phrase - thanks to a well meaning MEM friend)

Online steamer

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Re: The McOnie Oscillating Engine
« Reply #8 on: March 19, 2013, 10:23:36 PM »
Nice tutorial Ramon!   Thank you very much for sharing that on the forum!   It will be a great help to many as time goes by. :praise2: :praise2:

Dave
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Offline Don1966

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Re: The McOnie Oscillating Engine
« Reply #9 on: March 19, 2013, 10:48:09 PM »
As always Ramon, your work is inspiring and educational. Thanks for the blow by blow, I learn from all your threads. I will be following till you complete it.

Don

Offline NickG

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The McOnie Oscillating Engine
« Reply #10 on: March 19, 2013, 11:17:51 PM »
Fascinated by proper replicas of oscillating engines as usual see them as simple beginners engines but love the look of this, is a complex beast.

Offline ths

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The McOnie Oscillating Engine
« Reply #11 on: March 19, 2013, 11:28:45 PM »
Thanks for that reply, Ramon, the process is clear, and the explanation logical!

Hugh.

Offline ScroungerLee

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Re: The McOnie Oscillating Engine
« Reply #12 on: March 20, 2013, 03:43:56 PM »
Thank you for pointing out the use of V-Blocks to align the crank, that will be very useful.

Lee
Mmmmm.... Shiny!

Offline ref1ection

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Re: The McOnie Oscillating Engine
« Reply #13 on: March 20, 2013, 07:33:30 PM »
I'd be more than happy to see more of your setups. They always give me new ideas that come in handy if I remember them.

Ray
Indecision... the key to flexibility!

Offline Bearcar1

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Re: The McOnie Oscillating Engine
« Reply #14 on: March 20, 2013, 07:42:42 PM »
What a beauty Ramon, thanks for taking us for the ride. Purty, purty.  :ThumbsUp:


BC1
Jim

 

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