Moriya Stirling Engine Build

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NP317
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Re: Moriya Stirling Engine Build

Post by NP317 » Tue Apr 20, 2021 9:12 pm

The crankpin is best screwed solidly into the crank arm. The bushing should float on the pin.
And I suspect you already know that.
RussN

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rmac
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Re: Moriya Stirling Engine Build

Post by rmac » Wed Apr 21, 2021 12:33 am

NP317 wrote:
Tue Apr 20, 2021 9:12 pm
The crankpin is best screwed solidly into the crank arm.
I think my jam nut gives the same effect? Maybe? This arrangement also allows adjustment of the axial slop between the conn rod and the crank pin.
The bushing should float on the pin. And I suspect that you already know that.
I did not know that! I have the plastic bushing threaded onto the crank pin and sized so the bearing on the connecting rod rotates freely about it. Can you explain why having the bushing float on the pin would be better? Should I be thinking about remaking these parts before continuing?

-- Russell Mac

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NP317
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Re: Moriya Stirling Engine Build

Post by NP317 » Wed Apr 21, 2021 9:51 am

Russell:
Your setup should work fine.

In general practice, having a plastic bushing on a threaded rod may be hard on the bushing where the threads make contact.
But the forces involved are likely low enough in this use to not be a problem.
Time will tell, and it is easy to make a new pin and bushing if required later.
RussN

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rmac
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Re: Moriya Stirling Engine Build

Post by rmac » Wed Apr 21, 2021 12:41 pm

NP317 wrote:
Wed Apr 21, 2021 9:51 am
In general practice, having a plastic bushing on a threaded rod may be hard on the bushing where the threads make contact.
Interesting. I was thinking that with the bushing threaded onto the rod, there wouldn't be movement (and therefore wear) between them. But there is a little bit of play there, so I can see what you're saying.

Every morning when I get up, there's always that risk of learning something new!

-- Russell Mac

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rmac
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Re: Moriya Stirling Engine Build

Post by rmac » Sat Apr 24, 2021 8:25 pm

Progress Report #15

Here are a couple of power pistons and a couple of homemade 1/4-28 x 3/8" bolts for the port plugs. The other little fitting temporarily screws in where the port plugs go so I can pressurize the engines to locate any leaks.

For the record, it took me three tries to make the two pistons. I made a bonehead arithmetic error and undershot the OD on one of them. Grumble, grumble.

-- Russell Mac

pistons_and_port_plugs.jpg

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NP317
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Re: Moriya Stirling Engine Build

Post by NP317 » Sat Apr 24, 2021 8:46 pm

"For the record, it took me three tries to make the two pistons"

Meh. Welcome to life. No harm no foul And education. And eventual success.
Yea!
We just blew into the port openings to test for gross leaks. You are going a Step Above.

On my pistons I counter sunk the bottom hole that secures the interior pivot for the rod, for a CS screw.
That provided additional clearance in the power cylinder, and increased allowances for tolerance issues.
Maybe not required. But remember that I had inexperienced students machining these projects.
You are obviously not in that category...
RussN

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rmac
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Re: Moriya Stirling Engine Build

Post by rmac » Sat Apr 24, 2021 9:35 pm

NP317 wrote:
Tue Apr 13, 2021 4:16 pm
When reassembled I attached an electric drill motor to the engine shaft and ran in the engine for several minutes until it was turning smoothly.
I read somewhere that if you do this, a temperature difference will develop between the hot side and cold side of the engine. I can't remember which side gets cooler and which side gets warmer. Anyway, have you ever noticed this when running in an engine like you're talking about?

-- Russell Mac

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NP317
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Re: Moriya Stirling Engine Build

Post by NP317 » Sat Apr 24, 2021 9:54 pm

Nope. Not noticed this, and I was not paying attention to that possibility.
However, I think I need to do some more break-in of the repairs, as the engine is not running with heat now.
I obviously messed it up...
To be continued.
Russo

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rmac
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Re: Moriya Stirling Engine Build

Post by rmac » Sun Apr 25, 2021 11:32 pm

Progress Report #16:

Here's a group shot of all those parts I've been babbling about for weeks. Today I put the engines together enough to see that the displacers weren't going to rub or bottom out in their cylinders. Then I went ahead and put the caps on the displacer cylinders, assembled the engines completely, and fired them up with a flywheel borrowed from a model my dad made.

The first one ran right out of the chute! That was kind of a surprise. I expected to have to do at least a little troubleshooting to get them to run. The second one didn't run on the first try, but only because I hadn't tightened the screws that hold the power cylinder to the base. Once I fixed that, it took right off, too.

The engine with the aluminum displacer will run on its side, but not very well. The other one won't at all, most likely due to the heavier stainless steel displacer. I want to fiddle around with this to see if I can do anything to make it better before I start worrying about the parabolic mirror and all that.

Anyway, it was a good day. Many, MANY thanks to RussN for all the encouragement and "been there, done that" advice. It's really helped so far.

-- Russell Mac

first_run.jpg

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NP317
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Re: Moriya Stirling Engine Build

Post by NP317 » Mon Apr 26, 2021 12:24 am

Great to see an operating engine! Well done, Russell.
And Thanks for sharing your journey.
RussN

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GlennW
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Re: Moriya Stirling Engine Build

Post by GlennW » Mon Apr 26, 2021 1:34 pm

Great job, and very nice finish on all of the parts.

Well Done!
Glenn

Operating machines is perfectly safe......until you forget how dangerous it really is!

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rmac
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Re: Moriya Stirling Engine Build

Post by rmac » Mon Apr 26, 2021 5:55 pm

Thanks, Glenn.

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