# Single cylinder solonoid engine design and build



## AllThumbs (Mar 22, 2008)

I drew this one up last night. I need a diversion from a stubborn twin 4 stroke I am trying to start so here it is:







I teach electrical to college students so this one could be used as an object lesson when teaching electromagnetism.

The coil is located under the aluminum cyclinder cover. Cast iron piston and cylinder. Bronze flywheel, the rest aluminum.

E


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## AllThumbs (Mar 22, 2008)

Hey if you want to see the model dynamically, download the free viewer here: http://www.solidworks.com/pages/programs/eDrawings/e2_register.html Select edrawings viewer only and download and install. Then click on 
www.ody.ca/~envanandel/sol.EASM to see the model and be able to manipulate in in all kinds of cool ways, including making parts transparent etc.

E


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## DICKEYBIRD (Mar 22, 2008)

OK, now you've started something. It is officially your solemn duty to detail EVERYTHING about this engine. Coil wire gauge & turns, switching, timing, the works.

_I'll be watching._ ;D


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## AllThumbs (Mar 22, 2008)

Ok I will try. This is new for me so we can learn together. The plan is to use whatever wire I can find, wind it onto the cylinder, measure the resistance and figure out a safe voltage to use.

E


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## DICKEYBIRD (Mar 22, 2008)

Cool! Sounds like a fun project.


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## Bogstandard (Mar 22, 2008)

Now watching with great interest.

John


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## cfellows (Mar 23, 2008)

Aaah, great minds think alike! Here are drawings of a 3 cylinder Fairbanks I'm starting on that will be powered by Solenoids. I'm planning to use ready-made Ledex solenoids that are 3/4" diameter and 1.5" long. According to the nearest specs I can find, each of the three solenoids has 1904 turns of #31 copper wire. I plan to run the engine in 4-stroke mode which means the solenoids will be energized about 25% of the time. With a 25% duty cycle, I should be able to run the engine on up to 31 volts which would be a little less than 1 amp. Amp turns at that voltage would be about 1700.


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## Brass_Machine (Mar 23, 2008)

I will be watching this one with great interest!

Eric


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## DICKEYBIRD (Mar 23, 2008)

cfellows  said:
			
		

> Here are drawings of a 3 cylinder Fairbanks I'm starting on that will be powered by Solenoids. I'm planning to use ready-made Ledex solenoids that are 3/4" diameter and 1.5" long.


Mornin' Chuck, where does one get solenoids like that? Are they reasonably priced?

Also, what are you fellows going to use for switching...points, transistors? Anybody have any details yet? I think I have some old Lucas MG points around here somewhere. I guess they should work.

Milton


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## Bogstandard (Mar 23, 2008)

Milton,

In the UK solenoids are fairly easy to get hold of. Your Radio Shack or similar might stock them. A search on google will usually give you enough leads.

You should be able to use standard micro switches for the switching, but they usually only have a guaranteed life of about 3 million cycles, so a couple of spares would be called for if it was to be run for prolonged periods.

John


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## AllThumbs (Mar 23, 2008)

I was planningon using a standard set of points and a cam. KISS.

E


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## cfellows (Mar 23, 2008)

I bought my solenoids on eBay. They usually cost 3 or 4 USD apiece. I'm still undecided on what to use for switching. I'd prefer to have something hidden or not out of character with the engine. I've also thought about using push rods with some kind of contact points closed by rocker arms.

Chuck


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## cfellows (Mar 23, 2008)

AllThumbs  said:
			
		

> The coil is located under the aluminum cyclinder cover. Cast iron piston and cylinder. Bronze flywheel, the rest aluminum.



Allthumbs,

You have to use some kind of nonferrous cylinder liner or the engine won't work. If you wrap the coil around the outside of a cast iron cylinder liner, the cylinder will conduct the magnetic lines of force and there will be no attraction for the piston. You could use aluminum, brass, or even plastic for the cylinder liner. Also, you should try steel or cast iron casing on the outside of the coil. I believe that will increase the attraction for the piston.

Chuck


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## cfellows (Mar 23, 2008)

I have an Excel spreadsheet with copper wire tables and formulas. You can input the wire size you want, coil length, form diameter, overall diameter and input voltage. The sheet will provide answers to overall resistance, length of wire required, current, and amp turns. I can upload this to the files section if anyone is interested.

Chuck


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## rake60 (Mar 23, 2008)

I've always been fascinated with solenoid engines.
They've been around for longer than many realize.
The switch on this old model is nothing more than a 
kink in the crankshaft that make contact with spring steel
tab. It might add to the thought process.
[ame]http://www.youtube.com/watch?v=8aWobDU0Cm0&feature=related[/ame]

Rick


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## AllThumbs (Mar 23, 2008)

cfellows  said:
			
		

> Allthumbs,
> 
> You have to use some kind of nonferrous cylinder liner or the engine won't work. If you wrap the coil around the outside of a cast iron cylinder liner, the cylinder will conduct the magnetic lines of force and there will be no attraction for the piston. You could use aluminum, brass, or even plastic for the cylinder liner. Also, you should try steel or cast iron casing on the outside of the coil. I believe that will increase the attraction for the piston.
> 
> Chuck



Wait a second here. The plan is to use cast for the liner to increase the magnetic flux. The coil will be wound around the back half of the cylinder. The forward half is just a guide for the piston as it extends out of the coil. Iron cores are used all the time because they are great conductors of magnetic lines of force. As far as I know the more iron, and the less non ferrous material between the coil and the piston the better.

Eric


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## cfellows (Mar 23, 2008)

Eric,

I believe that most if not all the magnetic lines of force will be conducted by the cast iron cylinder wall and none will get through to attract the piston. However, I could be wrong and perhaps the best thing would be to try it.

Chuck


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## shred (Mar 23, 2008)

rake60  said:
			
		

> I've always been fascinated with solenoid engines.
> They've been around for longer than many realize.
> The switch on this old model is nothing more than a
> kink in the crankshaft that make contact with spring steel
> ...


Yeah, I was thinking it would be trick to do something with a spring finger running on the flywheel as a switch and either do some clever cuts or conductive/non-conductive treatments to direct the current.


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## AllThumbs (Mar 23, 2008)

Cylinder raw material:




Cylinder complete:


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## AllThumbs (Mar 24, 2008)

"Piston" and aluminum coil cover. This part is mostly cosmetic, alto it will help cool it a little and provides a means to mount it.


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## Powder keg (Mar 24, 2008)

I'm keeping an eye on this build. I'm intrigued with these little engines. I hope to have one soon. Can you control the speed on these?

Wes


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## AllThumbs (Mar 24, 2008)

I may build a little RC timer circuit to control the speed. Another option is mechanically adjustable "timing". For now, I will try to get it to run. 

No picture but I made a cast iron "washer" that slips over the cylinder in order to make it "spool" shaped. Red locktight will hold it in location. 

Next will be some tape insulator over the cast, then as many turns of wire as I can get on there. More pics tomorrow I hope.

E


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## AllThumbs (Mar 26, 2008)

I wound the solenoid today with whatever wire I could find. It was pretty heavy wire (#20) so the coil ended up being 1 ohm. At 6 volts this is 6 amps which caused the coil to become very hot very quickly (in about 30 seconds it was too hot to hold) The iron core does not pose a problem as far as I can tell. The coil had lots of power, sucking the piston in instantly.

At this point I have 3 options: 

1) make a bigger coil to get more turns on - not my first choice really. It would mean major design changes to my engine, and I wanted to keep a "scale" looking cylinder size.
2) run it on 3 volts - I could live with this if I have to.
3) find a lighter gauge wire. I think this is the best option. This gives me more turns in the same physical space. Also the smaller wire has more resistance and would be longer, causing it to have more resistance again. This would reduce the current.

I will try option 3 as soon as I can find the wire.

Eric


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## cfellows (Mar 26, 2008)

Eric,

What are the dimensions (ID, OD, length, & Flange diameter) of your cylinder? Also, how much of the cylinder length did you use for the coil? I'd like to do some similar experiements with an iron cylinder.

Thx...
Chuck


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## AllThumbs (Mar 26, 2008)

Here is a drawing:

The piston is 1" long and at TDC is flush with the back of the spool. The forward part is just a guide. The stroke is 5/8"

The 1" piston will want to be centered in the coil, so that is why I made the coil 1" long.


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## cfellows (Mar 26, 2008)

Thanks, Eric.

According my calculations, if you use a #25 wire, you'll need about 120 feet which will give you a resistance of about 3.8 ohms. This would limit the amps to 1.573. #25 wire is rated at a maximum of .64 amps for continuous duty.

I think you would be OK as long as you didn't run the motor 24 hours a day. You could drop down to #26 wire which is rated at about .5 amps and would require about 150 feet. Resistance would be 6 ohms.

Chuck


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## AllThumbs (Mar 26, 2008)

Some things to consider:

The power in watts (which is all heat) equals the current squared times the resistance. This means if you keep the same winding, but reduce the current (you can only do this by reducing the voltage), the heat will be reduced by the square of the current.

So for my coil:

at 6 volts I had 6 A and 1 ohm: 
Power = (current squared) x resistance = 6x6x1 = 36 watts

If I reduce the voltage to 3 volts, coil is still 1 ohm:
Power = (current squared) x resistance = 3x3x1 = 9 watts

That is 300% less hot. Still too hot? maybe.

Chuck, where do you get your current carrying data from? Do you have a link? #20 wire is good for 11 amps in free air, but I have no idea what it's good for in a coil.

E


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## cfellows (Mar 26, 2008)

I uploaded an excel spreadsheet that contains a wire table I found on the internet. I added the calculations and formulas. It shows that number 20 wire is good for about 2 amps, continuous duty, presumably in coil form. So far, my experiments seem to validate the numbers in the spreadsheet.

Chuck


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## AllThumbs (Mar 28, 2008)

Ok, so I only have two sizes of wire. #20 and #33. The 20 is too heavy and the 33 is too small. I am going to run the #20 and try various voltages once I get is assembled. I think the #20 would be ideal on a much larger engine. Maybe the next one.

Here are some pics of the coil parts. This engine will definately run, but probably only for a few minutes before it gets too hot. 

E


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## AllThumbs (Mar 29, 2008)

One more part


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## cc61 (Mar 29, 2008)

If your are running it as a 4 cycle your average current is .5 amps and the heating will be ¼ of the constant 2 amp current. I think you will see it will run cooler than you think it will. 

Chuck


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## AllThumbs (Mar 30, 2008)

I will run it as a 2 cycle. I can play with the timing one it's running to minimize the "on time" of the coil and still allow it to run. I find an engine that just ticks over more interesting anyways. Performance is not what I am after here.

Sorry that the progress is slow. Life has been interfering again. :-\

E


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## AllThumbs (Mar 30, 2008)

Another part made (flywheel support), and the solonoid cylinder assembled. Just the base and a con rod to build. The flywheel is one I am recycling.


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## Powder keg (Mar 30, 2008)

Looking great!!! I want to build one of these, so I am keeping a close eye on this build)

Wes


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## AllThumbs (Apr 1, 2008)

Well, I made the base. I just need to make the con rod. No picture today. Too boring. More soon.

E


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## AllThumbs (Apr 2, 2008)

It runs! Video soon. Just a pic for now. Still need to clean up the wiring and add a switch and wooden base! Gets hot in a couple minutes.


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