# Electromagnetic Rocker Engine



## 4156df (Jan 7, 2009)

Technically this engine may be a motor and so is not entirely appropriate to this site. Here goes anyway.

The engine can best be described as an electromagnetic rocker. It is loosely based on early (circa 1860) models of devices developed during the transition from steam power to electrical power.

The engine base is 4 in. x 2.5 in. and the flywheel is 2.5 inches in diameter. Each coil is wound on a 5/16 core with 300 turns of 22 AWG magnet wire. 






















In the following video, the motor is running on a 6V lantern battery. Speed is about 340 rpm.

[ame]http://www.youtube.com/watch?v=vQkI2UcCeK8[/ame][youtube=425,350]

Its a good runner, but contact pressure and timing are really touchy. If I were building it again, Id figure out a more precise method of adjusting the contact position and pressure. Also, Id make it a double contact so it would have reverse.

As far as the build goes, theres really nothing too unique. However, a few things that might be of interest are:

Flywheel
Flywheel construction followed Bogstandards treatise found elsewhere on this site. When it came to bling though, instead of painting or polishing the spokes, they were beadblasted. I used a little hobby air eraser I got at a swap meet. I like the texture and it contrasts nicely with the polished rim (photo is pre-polish).






Upright
The upright was my first shot at free-form brass turning. I started with a piece of brass hex. First I cut the major diameter and then used the parting tool to cut the minor diameter of the curves.






Then I moved to the wood lathe and shaped the curves using HSS wood turning tools. The lathe was run at slow speed (500 rpm in my case) and I made very light cuts. It worked pretty well and I wouldnt be afraid to try a more complex shape. The key is keeping a negative rake.






Pushrod
The pushrod was fabricated as shown in the following photos. The part was first turned as a cylinder and the ends rounded with a file.






A very minor tipWhen I filed the lower round, I slipped a piece of tubing over the small shaft to protect it from the file.






The flats were milled using soft jaws in my mill vise. Did one side, then flipped it over.






Cut out the center,






and, voila!






Terminal Screws
I wasnt up to attempting single-point 4-40 threads so the terminal screws were made as an assembly. The screw head was turned, tapped, knurled and parted off.






Then I screwed it on a 4-40 screw, soldered it and faced it off.






This is an overly long post, so thanks for bearing with me.  More importantly, thank you all for sharing your knowlege with us. This site is fabulous. Im happy to answer any questions you may have.

Regards,
Dennis


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## Brass_Machine (Jan 7, 2009)

I think it qualifies for the site.

Very nice!

Eric


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## stevehuckss396 (Jan 7, 2009)

4156df  said:
			
		

> Technically this engine may be a motor and so is not entirely appropriate to this site.



What would be inappropriate is not sharing pictures of work this nice.

Thanks!

Steve


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## Brass_Machine (Jan 7, 2009)

stevehuckss396  said:
			
		

> What would be inappropriate is not sharing pictures of work this nice.
> 
> Thanks!
> 
> Steve



Well said Steve.

I agree.

Eric


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## cfellows (Jan 8, 2009)

Nice looking engine. Very nice build.

Chuck


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## Maryak (Jan 8, 2009)

Great Motor, :bow: :bow:

Best Regards
Bob


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## Kludge (Jan 8, 2009)

4156df  said:
			
		

> Technically this engine may be a motor and so is not entirely appropriate to this site.



Dennis, if this *engine* is inappropriate for this site then I'm in deep doodoo. Most of my recent sketches of been for electric engines instead of compressed gas (air, steam, etc) or IC because they're fun and can be even more completely off the wall than usual. Well, usual for me. 

Okay, guys, I hear you clamoring to see one! I may be able to accomodate fairly soon!

Anyway, this one looks like one I saw in a very early book I downloaded from google books and thought particularly interesting. Your execution is absolutely beautiful and we (well, I) hope to see more like this in the future. 

There was another one that used a series of bar magnets in an armature of sorts from about the same era. I kind of remember how it worked but I also remember it had a real problem starting under certain circumstances. I figured out a cure but never did anything with it. 

Keep up the excellent work!

BEst regards,

Kludge


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## BobWarfield (Jan 8, 2009)

I love it!

Very Jules Verne/Steam Punk!

BW


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## Kludge (Jan 8, 2009)

BobWarfield  said:
			
		

> Very Jules Verne/Steam Punk!



I avoided mentioning that ... but you know it's a favored style, right? 

Best regards,

Kludge


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## NickG (Jan 8, 2009)

Nice work. That free form turning looks scary to me but the finished pieces are great!


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## malcolmt (Jan 8, 2009)

Hi Dennis
How could there be any doubt that this would fit in here, The name of this site is Home Model Engine Machinist.

This beauty qualifies on all counts, An excellent piece of work, we like to see lots of pictures and build stories. Couldn't get nearer the mark than this.
Thank you for sharing.

Kind regards

Malcolm


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## McNeillMachine (Jan 8, 2009)

Motor, engine, potato potahto.

Very cool regardless of what you call it.

-Phil


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## rake60 (Jan 8, 2009)

Great Build Dennis! :bow:

Rick


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## firebird (Jan 8, 2009)

Hi Dennis

I made one a while back when I was experimenting with electro magnets/solenoids. Not as pretty as yours but good fun. heres the link if you want to take a look.

http://www.homemodelenginemachinist.com/index.php?topic=1824.0

Cheers

Rich


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## 4156df (Jan 8, 2009)

Guys,

Thanks for the compliments. You've made my day.

BW....Great comment about the Jules Verne/Steam Punk look. I hadn't thought of it that way, but you're right.

Rich...Believe me, I looked at your post many times before I started this. I should have credited you for the inspiration.

While I'm at it...Thanks for the cfellows "Coil Calculation Table" in the downloads section. It really helped me nail down the coil configuration. Also, thanks to Marv for his flywheel calculation program.

Dennis


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## cfellows (Jan 8, 2009)

Dennis,

Can you go into a little more detail on how you beadblasted the flywheel? I like that finish.

Chuck


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## cfellows (Jan 8, 2009)

One other question. Are the coils energized twice per full revolution or just once? Looks like it would work to energize it on each side of dead center so you get two power pulses per rev. Or maybe you're already doing that, can't tell from the pictures or the video.

Chuck


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## 4156df (Jan 8, 2009)

Chuck,
I beadblasted using a Badger Hobby Abrasive Gun Model 260. I found mine at a garage sale, but they're available on line for less than $30. The blaster comes with an aerosol propellant, but I hooked mine to the air compressor at 30 psi. It also comes with aluminum oxide media, but I happened to have some glass bead media, so that's what I used. Blasting was done way, way out on the end of my driveway and I used a carboard box as a cabinet. It's messy, but you're not blasting long. Just stay far away from your machines. 

I had planned to paint the spokes so the flywheel had been masked using blue masking tape when I decided to try the beadblast.  The tape seemed to be a good maskant for the beadblasting and makes me think there may be some neat applications where designs could be masked over polished brass....(stop me, please!). Before blasting, I filed/sanded off gross tooling marks and relieved sharp edges. I'm guessing it was about a 220 grit surface. It hardly took any time at all to get to a matte surface.






Regarding the coils...yes, they're energized twice in a full revolution by a two lobed cam. One power pulse is less effective though, because the push point is lower down on the push rod lever. I guess this is would be considered a "double-acting" engine.

Regards,
Dennis


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## cfellows (Jan 8, 2009)

4156df  said:
			
		

> Chuck,
> I beadblasted using a Badger Hobby Abrasive Gun Model 260. I found mine at a garage sale, but they're available on line for less than $30. The blaster comes with an aerosol propellant, but I hooked mine to the air compressor at 30 psi. It also comes with aluminum oxide media, but I happened to have some glass bead media, so that's what I used.......



Dennis, 

Can you capture and re-use the glass bead media?

Chuck


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## 4156df (Jan 8, 2009)

Chuck,

Yes, the glass bead media can be captured and reused. I didn't in this case because it was such a small job. At 30 psi, I suspect the beads will last quite awhile. I've used beads in the past in an industrial recirculating sand blast cabinet. When they turn dusty & powdery they need to be replaced.

Dennis


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## Philjoe5 (Jan 8, 2009)

Cool motor Dennis. Thanks for sharing some very useful machining techniques with excellent photos. Call it what you want - it's a very cool machine :bow: :bow: :bow:

Cheers,


Phil


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## Kludge (Jan 9, 2009)

4156df  said:
			
		

> Then I moved to the wood lathe and shaped the curves using HSS wood turning tools. The lathe was run at slow speed (500 rpm in my case) and I made very light cuts. It worked pretty well and I wouldnt be afraid to try a more complex shape. The key is keeping a negative rake.



This was of particular interest since I have wood turning tools (I used to turn wooden pens.) and they're sitting idle at the moment. The idea of using them on metal never occured to me. I guess I should take another look at them for metal turning.

Thank you, Dennis. 

BEst regards,

Kludge


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## mklotz (Jan 9, 2009)

For those of you who wish to try hand turning (it's effective and fun) and don't have woodworking tools to hand, try making your own. Here's one I made...







The square (could be round) aluminum handle has a slot milled into it to accept a standard 1/8" HSS lathe toolbit. The standard 1/2" steel box section slides over it and the setscrews lock the toolbit in place. It's easy to change bits so you really need only the one handle.


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