Sterling Fan Build

[Mike N]

:bow: Awesome workmanship! :bow:

I just ordered a set of plans from Jerry Howell. It looks like a great winter project. Is the crankshaft built up from steel rod & brass?

Mike N

 

[b.lindsey]

Jim,
Its just the 3 jaw chuck from the lathe. There is a threaded adaptor that fits into the mill's T-slots that the chuck screws onto. I lined up one flat with a dial indicator, centered the bore with the mill spindle and then stepped off to drill the holes. One think I will say for Sherline is that they have a LOT of very useful accessories that allow transferring work from lathe to mill without having to rechuck the workpiece.

Regards.
Bill

 

[b.lindsey]

Mike,
Yes, the crankshaft is built up and loctited together since there will be very little stress on it. Jerry calls for Stainless and Drill Rod but I chose to use brass for the disks and drill rod for the shafts. The fan blades and hub will be brass also and I liked the contrast with the otherwise drab gray of the aluminum and steel main body.

Bill

 

[T70MkIII]

A very nice project! I've been thinking of building one of these as my 1st IC engine.

 

[mklotz]

Beautiful work, Bill. I must build one of these for my lectures to the school kids. In those presentations I tell them about the fact that the British, during the Indian Raj, having no electricity, used these fans to cool themselves. For some reason this idea seems to intrigue them greatly. Perhaps it's because it helps them to relate the rather abstract idea of a heat engine to the more approachable idea of doing something genuinely useful. Having one to show them would be a great teaching aid.

One thing bothers me. In all the designs I've seen, including pictures of the ones sold commercially when they were actually used, the hot end is always directly under the fan. This means that all the waste heat rises into the fan air stream and thus is blown about along with whatever cool air is moved. While this makes for a more compact (and probably more stable) design, it seems rather inefficient from a cooling point of view.

A horizontal design with the hot end off to the side, out of the fan air stream would seem to do a better job of providing a cool breeze. Perhaps it doesn't matter. Maybe all they wanted to do was circulate air and didn't care about the waste heat which would be vented to the room regardless of the engine design.

 

[b.lindsey]

Your point is well taken Marv, I can't say I have ever seen one with the hot cap anywhere but on the bottom. Of course even if it were on the side the waste heat would still get in the airstream of the fan I suspect. I definitely agree with the usefulness as an instructional aid. One of the thermodynamics professors saw the finned displacer body a week or so ago and asked what it was. I told him it was a new HVAC trainer for the thermo lab :big: Then again I may try to somehow integrate it into the machine shop practices lecture I teach in the Spring.

Regards,
Bill

 

[rake60]

Bill your web site Workbench Miniatures was in my bookmarked in my favorites folder long before
you joined us here. You never know if the person behind the site is a craftsman or just a salesman.
I am very pleased see that my suspicions were correct on your site.

Beautiful craftsmanship! :bow:

Rick

 

[shred]

One thing bothers me. In all the designs I've seen, including pictures of the ones sold commercially when they were actually used, the hot end is always directly under the fan. This means that all the waste heat rises into the fan air stream and thus is blown about along with whatever cool air is moved. While this makes for a more compact (and probably more stable) design, it seems rather inefficient from a cooling point of view.

A horizontal design with the hot end off to the side, out of the fan air stream would seem to do a better job of providing a cool breeze. Perhaps it doesn't matter. Maybe all they wanted to do was circulate air and didn't care about the waste heat which would be vented to the room regardless of the engine design.

IIRC at least some of the originals had chimneys such that the waste heat exited above the airstream. Beyond that, I've also wondered about why the heat source is directly below the fan blades.

I suspect in the sorts of places these were popular, the heat and humidity were already such that an extra candlepower or two didn't affect anything.

 

[b.lindsey]

Thanks to all for the nice comments. I hope someday to attain that title of craftsman, but until then there is at least a dedicated hobbyist behind the website and I hope to grow the site more over the next year or so and beyond.

Rick...thank you for your kind words as well (and for the plug too ).

Probably won't get much done on the sterling fan until the weekend as we are off to Atlanta for the holiday, but returning Saturday early enough to get some shop time in I hope. Its getting close enough now to really want to see it run myself.

Bill

 

[b.lindsey]

Progress report on the sterling fan...those 13 degree holes in the base and upper leg support were finally done with the help of a new angle plate which arrived this week. All in all it worked nicely with the set-up shown.

Then some of the very small linkage parts were made for the displacer piston and power piston. Most of these were only .125" diameter at the largest section and a couple required remaking the second or third time until I was happy with the results. The graphite piston is also shown with its retainer and rod end fitting attached

The last picture shows the legs installed temporarily in the base just to get an idea of the overall height. Note the power cylinder was removed in this picture as it was being used to properly fit the graphite piston.

Now on to the fan blade hub and blade assembly, the alcohol burner, and one more rod end bearing for the power piston crankdisk.

Regards,
Bill

 

[b.lindsey]

A little more progress has been made....power piston and linkage finished and installed and a start on the alcohol burner (aka door knob). All that remains now is the fan blade/hub assembly to finish and a cap and wick tube for the burner and it will be ready for a first attempt at running.

Bill

 

[rleete]

Can you tell me how you made that burner? Was it hogged out of a solid piece? How do you get the inside and outside profiles to match up?

 

[b.lindsey]

rleete,

It is quite simply a dummy brass doorknob that has been cut down and stripped of its lacquer finish. I will make a brass cap to fit down in the hole and a smaller brass tube extending vertically in this case to hold a wick. For $5.97 at the local home store, its a lot easier than trying to make one from solid brass. The idea isn't original...I fist saw it used in Philip Duclos's fire Eater engine.

Bill

 

[rleete]

Well, I like the idea of using existing things in innovative ways, but I was hoping there was a simple technique.

I'd like to make a shape similar to that, but elongated (think champagne flute). My first attempt ended up cutting through the wall, and destroying the part in the process.

 

[ksouers]

rleete,
The technique you are looking for is called metal spinning. Taking thin sheets of copper, brass or aluminum and forming them over a shaped mandrel while spinning it on a lathe.

Try this web site: http://metalspinningworkshop.com/

It's a very common technique used to make musical instruments, lamps and custom auto parts.

 

[b.lindsey]

Well it is finished other than a few cosmetic things I may still do. Tried running it yesterday afternoon with no success. There was no binding of any sort and I have worked enough with sterlings now that I suspected the power piston wasn't sealing well enough so out to the garage to make another on. Amazing what a difference a few .0001" can have on these engines, but sure enough that was the problem. Another try at running it and it came to life...just needed some running to wear the new power piston and cylinder together. It probably has a good hour or so of run time on it now and I am pleased with the smoothness.

Anyway, here are a few finished pictures, and though I have some committments until mid-afternoon, I wil try to post a video later this afternoon or evening.

Stay tuned

Bill

 

[kustomkb]

What a little beauty!

 

[Metal Mickey]

Excellent work! Looking forward to the video now.........

 

[b.lindsey]

Here's the video. If it seems a bit noisy its because it is sitting on the computer desk and it resonates through the desktop and the empty space beneath. I thought the paper might isolate it better but some press on rubber feet on the bottom of the base should help considerably. If I lift it up off the desk while running it barely makes a sound at all. At the end of the video you can hear me blow out the flame as it coasts to a stop. Interesting to note though that even once the blades stop, the engine backs up a quarter to a half revolution apparently in an effort to seek the lowest volume of air captured within the power and displacer cylinders. It even does this when stone cold so i guess the power piston must be sealing pretty well.

Thanks to all who followed the build !!

Bill

 

[chuck foster]

very nice build 8) :bow: :bow:

chuck