Author Topic: The Artful Bodger might, might, make a little engine!  (Read 9261 times)

Online John Hill

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The Artful Bodger might, might, make a little engine!
« on: June 15, 2009, 01:54:09 AM »
So I am thinking of a little engine, I suppose one really should build a little oscillator engine as a first engine but the Artful Bodger is never one to follow custom and common sense.

I am thinking of a steam (air actually) engine with piston ported valving using a technique someone must have used before but I have never seen described.  What I have in mind is a piston with a very deep skirt on the top side that will act as a sleeve valve.  As the piston moves it will open input and exhaust ports.  The feature that will (might?) make it interesting is that the piston will both reciprocate (that is, move back and forth) and will also partly rotate about its axis,  sort of twisting one way then the other about 70 degrees or so.  The rotation of the piston will be caused by having the crank pin inclined in relation to the crankshaft axis and the connecting rod will have Hook's joints at each end.  Having the piston partially rotate in this way means that a point on the surface of the piston will prescribe an eliptical path and I can drill the ports to give a suitable duration of input and exhaust openings.

So far I have made a cylinder and started to turn the piston though that is quite difficult requiring a small boreing bar that I dont dont have as yet,  I need to turn a fairly deep 22mm into the head of the piston and that will form the sleeve.

So far I am thinking of steel for piston cylinder etc.

There is a long way to go on this one and I am currently travelling on the Mainland for a couple of weeks.

Cheers

John
a.k.a The Artful Bodger
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Offline sbwhart

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Re: The Artful Bodger might, might, make a little engine!
« Reply #1 on: June 15, 2009, 03:21:09 AM »
Hi John

That sounds an interesting engine  :headbang:

You could try making the small boring bar out of some silver steel (drill rod)

Good luck with the project

Stew
A little bit of clearance never got in the road
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Location:- Crewe Cheshire

Offline NickG

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Re: The Artful Bodger might, might, make a little engine!
« Reply #2 on: June 15, 2009, 04:10:10 AM »
Hi John,

Don't know if you're aware but there is already a recognised design of a slight variation on that theme. I know you said you're going to come up with your own design but it may help?

http://www.homemodelenginemachinist.com/index.php?topic=3382.0

http://www.workbench-miniatures.com/opv.htm

Location: County Durham (North East England)

Online John Hill

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Re: The Artful Bodger might, might, make a little engine!
« Reply #3 on: June 15, 2009, 04:56:36 AM »
Thanks Nick, that is a good explanation of something I had heard about but not previously seen in such detail.

Although the motion of the pistion is similar that explanation states the valving is symetrical and the engine will run equally well in each direction.  In my design I am hoping for a quite long exhaust duration and a much shorter input duration, that should be like a conventional engine fully 'notched up',  high speed and not so much torque for minimal air/steam consumption.

My valving concept is much more complex than their's, not to say that mine will necessarily be better though!
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Online John Hill

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Re: The Artful Bodger might, might, make a little engine!
« Reply #4 on: June 15, 2009, 05:07:51 AM »
Stew, I have a 10mm bore I need to enlarge to about 22mm and it is about 40mm deep, blind hole.  Thats the size boreing bar I need to make but I dont have brazing facilites right now so I need to scratch my head a little to make a suitable tool.
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Offline sbwhart

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Re: The Artful Bodger might, might, make a little engine!
« Reply #5 on: June 15, 2009, 05:29:50 AM »
Hi John

For that size you could use a bit of round tool steel in a holder.

The holder can simply be a bit a square bare with a hole down the middle and split down it length. the tool post clamps pinching the holder on the tool keeping it where you want.

Hope this helps

Stew
A little bit of clearance never got in the road
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Location:- Crewe Cheshire

Offline NickG

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Re: The Artful Bodger might, might, make a little engine!
« Reply #6 on: June 15, 2009, 06:17:59 AM »
John,

Sounds great, looking forward to the project!

Nick
Location: County Durham (North East England)

Online John Hill

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Re: The Artful Bodger might, might, make a little engine!
« Reply #7 on: June 16, 2009, 06:08:40 AM »
Stew, I found a 7/8" drill in a junk shop today so I will be able to make a decent hole that wont need much to true it up,  it might be a millimetre or so more than I intended but that wont be a problem as the design is not really finalised yet.  I had tried a bit of 3/16 tool steel but it was too springy at the length required but with a bigger drill to start I should be able to get something stiff enough into the hole.


John
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Offline dsquire

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Re: The Artful Bodger might, might, make a little engine!
« Reply #8 on: June 11, 2010, 12:02:07 AM »
Hi John

I was just curious if the Artful Bodger might, might, did make a little engine? Enquiring minds want to know and it will refresh the topic. :ddb: :ddb:

Cheers  :beer:

Don
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Online John Hill

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Re: The Artful Bodger might, might, make a little engine!
« Reply #9 on: June 11, 2010, 01:52:00 AM »
Hi Don

Sure did make the little nutating engine and it runs. :ddb:

My very first engine


http://madmodder.net/index.php?topic=1389.45
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Offline dsquire

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Re: The Artful Bodger might, might, make a little engine!
« Reply #10 on: June 11, 2010, 02:03:41 AM »
Hi John

Well now I have my answer and have the topic refreshed. We will see how many viewers we get on the 2nd go round. It looks like a pretty sharp little engine. Thanks for the picture John.  :ddb: :ddb:

Cheers  :beer:

Don

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Offline Chuck in E. TN

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Re: The Artful Bodger might, might, make a little engine!
« Reply #11 on: August 05, 2010, 05:01:54 PM »
Where's the video?
I have made 'emergency' small hole boring bars from allen keys...

Chuck in E. TN
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Offline dsquire

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Re: The Artful Bodger might, might, make a little engine!
« Reply #12 on: August 05, 2010, 09:27:06 PM »
John

Well, we haven't generated many replies but at least we have raised the read total from 254 to 595 so I guess it helps to bump some of the older topics once and a while..

Cheers  :beer:

Don

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Online John Hill

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Re: The Artful Bodger might, might, make a little engine!
« Reply #13 on: August 06, 2010, 12:24:35 AM »
From the den of The Artful Bodger

Offline dsquire

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Re: The Artful Bodger might, might, make a little engine!
« Reply #14 on: August 06, 2010, 12:40:49 AM »
John

Oh my. Now we have a video. Definitely Oscar material. Great little runner John.  :ddb: :ddb:

Cheers  :beer:

Don
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Offline Stilldrillin

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Re: The Artful Bodger might, might, make a little engine!
« Reply #15 on: August 06, 2010, 01:56:57 AM »
Nicely done John!  :clap:

Thanks for showing.....  :thumbup:

David D
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Still drilling holes... Sometimes, in the right place!

Still modifying bits of metal... Occasionally, making an improvement!

Offline ozzie46

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Re: The Artful Bodger might, might, make a little engine!
« Reply #16 on: August 06, 2010, 08:16:48 AM »



  Good little runner John. Well done.


   Ron

Offline Bernd

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Re: The Artful Bodger might, might, make a little engine!
« Reply #17 on: August 06, 2010, 01:10:33 PM »
Very interesting action on that piston turning like that.

I think you should get an Oscar for that.  :)

Bernd
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Offline jim

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Re: The Artful Bodger might, might, make a little engine!
« Reply #18 on: August 06, 2010, 03:11:08 PM »
brilliant!
if i'd thought it through, i'd have never tried it