Author Topic: Rocker V Stirling Engine  (Read 14090 times)

Offline Plani

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Re: Rocker V Stirling Engine
« Reply #45 on: January 21, 2018, 08:17:37 PM »
Thank you guys for the kind comments! It's very much appreciated!  :cheers:

A short update about the bearing block of the bell crank today.
The upper contour was milled from bar stock. The slot was also milled in this position, using an endmill going back and forth:


While still on the stock, the part was tilted to its side to its side to mill the radius and drill and ream the hole for the pin:


It was the cut off the stock to mill the final thickness and the recess on the backside:


Plani
« Last Edit: May 02, 2018, 06:03:24 AM by Plani »

Offline Plani

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Re: Rocker V Stirling Engine
« Reply #46 on: February 01, 2018, 09:12:32 AM »
Next part to make was the center piece of the expansion piston.
This is the drawing I made for this:


On the left side will be the displacer dome installed and on the right side the piston skirt. It was actually pretty easy to design it like this, but it would been rather difficult to make it and there would also be no way to fit the pin of the small end once the piston skirt is installed. So I decided to make two parts. First The center piece:


And then the small end bearing:


The two pieces will be bolted together using a M3 allen screw which will be loctided into the center piece:


Plani
« Last Edit: May 02, 2018, 06:03:45 AM by Plani »

Offline yogi

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Re: Rocker V Stirling Engine
« Reply #47 on: February 01, 2018, 11:17:22 AM »
You got some good looking parts there Plani!  :ThumbsUp: :ThumbsUp: :ThumbsUp:
I had to go back to your first post to look at the sectioned cad model to see how the parts fit together.  :thinking:
Cool stuff!

Offline b.lindsey

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Re: Rocker V Stirling Engine
« Reply #48 on: February 01, 2018, 12:18:52 PM »
More nice progress Plani. As I see it the  power piston will seal only on that ring around the middle of the piston...is that correct?

Bill

Offline Plani

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Re: Rocker V Stirling Engine
« Reply #49 on: February 01, 2018, 08:23:39 PM »
Thank you, Yogi  :cheers:

Bill, that's exactly how it's intended to work. The lip seal on the compression piston will touch the cylinder only on a very thin line. This needs to be so because the piston is not moving in a straight line but is slightly rocking (that's also where the name of the engine comes from). The rocking motion comes because the piston is driven directly by the bell crank. So to keep tight, the seal has to go out of its round shape and become slightly ellipticall through each stroke. I'm really curious if this will work :headscratch:....

Plani

Offline Plani

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Re: Rocker V Stirling Engine
« Reply #50 on: March 10, 2018, 10:20:22 AM »
Bill, there might been a misunderstanding...
The aluminum part from the last post won't touch the cylinder at all. This is only the center part on which on one side the displacer (deep drawn cup) and on the other side the piston skirt will be glued.

This piston skirt is the next part I made. It's basically only a pipe made of cast iron:


The inner diameter is finished first, then the outer diameter is turned to a close sliding fit in the cylinder:


And finally parting off:


At first all looked good, but after parting off I noticed that the part was slightly out of round.  :headscratch: That means it wasn't moving freely in the cylinder. I didn't expect this to happen with cast iron  :headscratch: :headscratch:
So I had to do it over, this time taking lighter cuts on the finishing passes. That solved the problem. On the next piston of this type, I will either use ductile cast iron or design the wall thickness slightly thicker...

Plani
« Last Edit: May 02, 2018, 06:04:18 AM by Plani »

Offline Doc

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Re: Rocker V Stirling Engine
« Reply #51 on: March 10, 2018, 02:31:16 PM »
Things are looking pretty nice. That fly wheel looks super nice job. I just noticed this build and am watching on the side line.
 :ThumbsUp: :ThumbsUp:

Offline Plani

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Re: Rocker V Stirling Engine
« Reply #52 on: March 21, 2018, 02:57:37 PM »
Thank you Doc  :cheers:

One of the few remaining things left to build is the crankshaft.
The webs were squared and then drilled and reamde together in order to get the whole thing running true:


I then insterted two pins to keep everithing aligned while drilling:


...and tapping:


And finally the slots were cut to get the clamping to work:


That's what it looks like with no bolts installed yet:


For the counter weights a steel disc was turned, cut in half and then cleanded up, drilled and counterbored:


Plani
« Last Edit: May 02, 2018, 06:04:48 AM by Plani »

Offline Craig DeShong

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Re: Rocker V Stirling Engine
« Reply #53 on: March 25, 2018, 11:45:16 PM »
I just caught up with this thread.  Incredible work,  I'll be following  :happyreader: :ThumbsUp:
Craig

Offline Plani

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Re: Rocker V Stirling Engine
« Reply #54 on: April 01, 2018, 12:36:31 PM »
Thank you, Craig.

Closing in on the homestretch  :)
The hot cap was soldered to it's base:


Some brass bushings for several links were made:


Preassembly of the main conrod:


Assembly of the engine started. Don't mind the base, I took what was lying around for a temporary base. A proper board will be made once everything is in place and the burner is sorted out:


Plani
« Last Edit: May 02, 2018, 06:05:15 AM by Plani »

Offline b.lindsey

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Re: Rocker V Stirling Engine
« Reply #55 on: April 01, 2018, 01:29:12 PM »
More beautiful work on this one Plani. Looking forward to seeing how it all comes together.

Bill

Offline Ian S C

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Re: Rocker V Stirling Engine
« Reply #56 on: April 01, 2018, 01:50:59 PM »
Like the hot cap, is it stainless.
Ian S C

Offline Plani

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Re: Rocker V Stirling Engine
« Reply #57 on: April 03, 2018, 07:56:08 PM »
Thank you guys!

Ian, yes the hot cap is a deep drawn cup made from stainless steel.

The engine almost finished, still on its temporary base:


In the meantime a proper board was made to have a clean base for the Engine.


And yes, it's a runner  :cartwheel:


The balance of the engine is really nice. Most of the noise is actually amplified by the table.
Plani
« Last Edit: May 02, 2018, 06:05:36 AM by Plani »

Offline Perry

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Re: Rocker V Stirling Engine
« Reply #58 on: April 03, 2018, 08:38:36 PM »
Wow! Great achievement, what a stirling motor! Where can such hot cap be sourced from?
Perry
« Last Edit: April 03, 2018, 09:19:41 PM by Perry »

Offline yogi

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Re: Rocker V Stirling Engine
« Reply #59 on: April 03, 2018, 09:45:01 PM »
Beautiful running engine Plani! Well done!  :ThumbsUp: :ThumbsUp: :ThumbsUp: