# Jan Ridders "Stirling Bas" Tea-candle stirling



## shred (Dec 19, 2010)

I didn't take a lot of pictures along the way, so thus no build log, but I did get my version of Jan Ridders Sterling Bas finished up today (started back in Nov, finished just in time for X-mas )

After a little mishap with the drawings, this one turned out "left-handed", like me 







It runs for hours on one tea candle, though it has an interesting habit of slowing way down, then speeding back up for several minutes, then slowing down for a several minutes, then speeding back up, etc, etc.. kinda cool, but a little weird.

I got irritated making graphite pistons and breaking them at the last minute, so went back to brass cylinder and polished steel piston. This time around I chose to work as much in metric as possible, though it occasionally made my brain hurt trying to wangle the CNC into behaving . The threads and fasteners are all imperial, but that's about it (in the future I will also use imperial-sized drill-rod for the axles and rods, or go obtain some metric drill rod first). I couldn't get the specified bearings for the cranks at the local hobby store, so I used some swiped out of a high-end computer fan. Couple nice 5mm/8mm BBs in each. 

Here's the few random pix from the build.

The flywheel was CNC-ed into some plate, then hacked out with the bandsaw and friction-turned round a-la Bog's "Making Flywheels From Plate" article.












Here's how to get a set of crank webs the easy way-- mill up a rod full and then part them off.






This one I posted elsewhere on cutting glass test-tubes.






And a little video (pre-bling)

[ame]http://www.youtube.com/watch?v=MISeGBe10AI[/ame]


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## Blogwitch (Dec 19, 2010)

Very nice indeed Roy.

You kept that one quiet. :bow:


John


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## Maryak (Dec 20, 2010)

Bogstandard  said:
			
		

> Very nice indeed Roy.
> 
> You kept that one quiet. :bow:
> 
> ...



Yep, I agree with Bogs :bow:

Best Regards
Bob


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## Fingers (Dec 20, 2010)

Nicely done another runner for Christmas 
Jamie


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## b.lindsey (Dec 20, 2010)

She's a beauty Shred ! I agree as to how quiet it is running too. Not that its much of a problem with the glass hot cap, but just wondering how much soot develops using the tea candle?

Bill


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## zeeprogrammer (Dec 20, 2010)

That's a beautiful engine Shred.
'Just in time for Christmas' you say? If it's a gift...it's a nice one.


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## shred (Dec 20, 2010)

Thanks everybody..



			
				b.lindsey  said:
			
		

> She's a beauty Shred ! I agree as to how quiet it is running too. Not that its much of a problem with the glass hot cap, but just wondering how much soot develops using the tea candle?
> 
> Bill


When I first assembled it, tuning it up and getting it running, I had to put the candle really close to the glass cylinder and it sooted up immediately. It built-up some impressive soot-stalactites on the glass tube while running. After more tuning and running in, I can lower the candle down so it doesn't soot the tube at all and it still runs fine (although as the other half said.. "that soot's going _somewhere_" as she shooed me away from her cabinets)

One more thing for any prospective builders; it's worth the effort to hunt down Pyrex test tubes for this one. I used cheapy glass tubes from the hobby store and although they work, fallout has been quite high.


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## kustomkb (Dec 20, 2010)

Congratulations Shred. A real beauty.


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## MatiR (Dec 20, 2010)

Nice work, Shred. I'm just starting one. Santa (kustomkb) dropped off a lovely slug of brass for the flywheel, test tubes and O-rings last week; I have the rest in stock, I think, so I'm hoping to make good progress over the holidays. I'm learning to use Alibre Design at the same time which is slowing me down a bit, but hope to post something in January.

Best regards, Mati


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## huse0054 (Dec 28, 2010)

Very cool engine Shred, I am thinking about this engine for my next build and am having a hard time matching up test tube sizes per Jan's plans. Would you mind sharing what sizes you used and where you acquired them from?

Also per Jan's plans he has an ID of the hot cylinder of 17MM and an OD of the displacer of15.5mm. How critical is that clearance and what did yours end up being?

Thanks


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## awJCKDup (Dec 28, 2010)

Very nice Shred. I also have Jan's plans for this engine and will start on it next Jan. so any tips would be appreciated. Did you use graphite or brass?
Again, very nice work.
John


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## shred (Dec 29, 2010)

huse0054  said:
			
		

> Very cool engine Shred, I am thinking about this engine for my next build and am having a hard time matching up test tube sizes per Jan's plans. Would you mind sharing what sizes you used and where you acquired them from?
> 
> Also per Jan's plans he has an ID of the hot cylinder of 17MM and an OD of the displacer of15.5mm. How critical is that clearance and what did yours end up being?
> Thanks


I found "20mm" and "15mm" test-tubes locally in the 'science' section of toy stores a few years ago, but when the last one broke I went back for more and they seem to have quit carrying them (no doubt the meth-cooks found a way to abuse them). Those were thin plain glass and low quality-- they cracked due to thermal stress of the candle. Pyrex and/or Kimax are the ones to get, at least for the hot end. I found a local supply place that would sell me boxes of 72 or multiples thereof, but they're ~$1 ea. I then turned to my brother the biochemistry professor who was able to get me just a few. They're also pretty common on eBay.

As for the displacer clearance, the key is they don't rub on each other. A few mm of clearance isn't a big deal, but a lot of margin gets eaten up if your displacer bearing, rod and tube aren't perfectly straight, so don't go too close if you can help it.

Test tubes aren't precision-made for the most part, so you have to work with what you get. "15mm" is a very common size, "20mm" somewhat less so. Also check O-ring availability as I had to remake the hot end plate after discovering the metric one listed wasn't easy to get here.

As for the piston, this one is steel. I originally had a graphite piston in a glass test tube cylinder, but after breaking a few and getting frustrated with the soft quality graphite pencil I was working with, I went to steel/brass for expediency.


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## shred (Dec 29, 2010)

One more thing that may or may not make a difference is I didn't bother to remove the shields and clean the lube out of the ball bearings like Jan suggests. As-is, they seem to spin plenty well enough.


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