Author Topic: Potty Dake Engine  (Read 52803 times)

Offline sbwhart

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Potty Dake Engine
« on: August 04, 2012, 08:14:45 PM »
I've had an ankering to build a Dake engine for quite some time, when I came across informations on Pat's fathers Dake engine, since then I've researched the engine quite a few times each time I've advanced my understanding and spent a long time thinking about the best way to machine one from bar stock.

Over the last week I've been putting together an assembly drawing I've simplified things quite a bit to suite my methods and machinery. I'm not quite sure when I'll start to cut metal probably in a couple of months when I make more progress on my Simplex loco rebuild.

I've attached the assembly drawing:- comments will be apreciated.

Stew
A little bit of clearance never got in the way

Offline Bearcar1

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Re: Potty Dake Engine
« Reply #1 on: August 04, 2012, 11:03:10 PM »
Oh man, I got the popcorn going and a chair pulled up for this one. I can't wait to see how it develops after your last beautiful S/S build, Stew.  :ThumbsUp:


BC1
Jim

Offline sbwhart

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Re: Potty Dake Engine
« Reply #2 on: August 05, 2012, 07:00:45 AM »
Thanks Jim

I think there are quite a few popcorns out their  :ThumbsUp:

Stew
A little bit of clearance never got in the way

Offline sbwhart

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Re: Potty Dake Engine
« Reply #3 on: August 05, 2012, 07:11:48 AM »
Air passage routes sketch attached

A little bit of clearance never got in the way

Offline vcutajar

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Re: Potty Dake Engine
« Reply #4 on: August 05, 2012, 08:09:14 AM »
Stew

Will be following this one for sure.  I hope Jim brought some extra popcorn.

Vince

Offline BillTodd

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Re: Potty Dake Engine
« Reply #5 on: August 05, 2012, 01:23:27 PM »
Marvellous  Stew! I'll  will be watching with great interest :D



 

Offline sbwhart

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Re: Potty Dake Engine
« Reply #6 on: August 05, 2012, 02:10:54 PM »
Great bit of animation Bill

 :pinkelephant: :pinkelephant: :pinkelephant: :pinkelephant: :pinkelephant:
 :whoohoo: :whoohoo: :whoohoo: :whoohoo: :whoohoo:

Stew
A little bit of clearance never got in the way

Offline BillTodd

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Re: Potty Dake Engine
« Reply #7 on: August 05, 2012, 02:44:22 PM »
Cheers Stew.

The model was loosely based on the Dake patent drawing




BTW Is your outer piston just a rectangle (no back plate) ? 
« Last Edit: August 05, 2012, 02:47:51 PM by BillTodd »

Offline tvoght

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Re: Potty Dake Engine
« Reply #8 on: August 05, 2012, 02:50:04 PM »
Hi Stew,
   I had recently become interested in the Dake engine too, and I'd started
to do some drawing studies of the port timing based on the patent drawings
(US 395,039). When I realized it had already been done, (PatJ's father) I kind
of lost interest.

I was having trouble figuring out the timing, and part of my confusion may
have been with scaling dimensions directly off the patent drawings. For
instance, the center intake port you show (the one on the front cover) is
considerably larger than the one I was using in my studies.

Another point of confusion for me may be that I assumed the engine would use
steam expansively, and so was trying to figure out where cutoff would occur.
In fact, the patent makes no claim of the expansive use of steam (and these
patents often do make that explicit claim).

One thing I noticed is that your air routing is opposite that shown in the
patent (and in Bill's animation). That is, in the animation, the left port is
routed to the top of the pistons, and the right port to the bottom. Left and
right ports are reversed too. Maybe it all comes out in the wash.

Just an observation from someone who's still struggling a bit to understand
the timing.

Of course I'll be watching,
--Tim

Offline BillTodd

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Re: Potty Dake Engine
« Reply #9 on: August 05, 2012, 02:53:33 PM »
I don't think it does have any early cut-off mechanism as far as I can see  (so ideal for compressed air operation). Reversing is a simple matter of reversing inlet and exhaust.



[edit]

Not sure if this shows it better or not ???


« Last Edit: August 05, 2012, 03:09:11 PM by BillTodd »

Offline tvoght

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Re: Potty Dake Engine
« Reply #10 on: August 05, 2012, 02:56:56 PM »
Bill, I had seen the first animation before, but the exploded view, and that last port timing view answer a lot of questions for me. Excellent and thanks,

Oh, and where did I read that the engines did not run as well in reverse as in forward?

--Tim

Offline BillTodd

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Re: Potty Dake Engine
« Reply #11 on: August 05, 2012, 03:12:14 PM »
Quote
Oh, and where did I read that the engines did not run as well in reverse as in forward?

The engine is pretty symmetrical so, unless the porting causes a problem somehow, I'd have expected them to run both ways equally well  :thinking:

We'll know soon enough when Stew finishes his build :) :thewhip:

Offline sbwhart

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Re: Potty Dake Engine
« Reply #12 on: August 05, 2012, 03:18:16 PM »
Tim you spotted the deliberate mistake you win the coconut  :Jester:

I only spotted the mistake after i posted the drawing, I've attached the corrected drawing.

If you do a search on valve steam engine valve timing you should find a site dedicated to the subject they have animation for most types of engines, with features that let you change the perameters, I can think of its name at the moment.

But to be honest for an air powered model I wouldn't get to hung up on getting things spot on from experience air models are not that critical.

I think I've attached the animation as well

Stew







A little bit of clearance never got in the way

Offline tvoght

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Re: Potty Dake Engine
« Reply #13 on: August 05, 2012, 03:46:11 PM »
Thanks for the coconut. The animation I'm most interested in seeing is the one to be taken with video camera complete with exhaust sounds.

--Tim

Offline cfellows

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Re: Potty Dake Engine
« Reply #14 on: August 05, 2012, 04:46:46 PM »
That looks like an interesting engine, Stew.  Still can't quite get my head around how it works, but I'll watch the build and hopefully it'll come to me.

Chuck
So many projects, so little time...

 

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