Electric Motor Secrets

[Jetijs]

I finally got all the parts assembled to see how small the gap is. I must say, that it is a pain in the ass to adjust everyhing, it takes a lot of time. But when I was done, the air gap on each side was about 0.3mm or so. I could probably get it smaller, but I made too many mistakes in the building process, to the gap is as wide as it is. But its good for a prototype. Tonight I will work on the plastic coil holders. I will make them out of plexiglass and glue them on the startor with epoxy. Then all whats left is to wind the coil, but that should be easy enough Here's a picture:


The gap on the farthest side looks kinda big, but that is only the shaddow, because the rotor is in a little bit lower position than the startor

Edit: Here's the coil holders:

[Peter Lindemann]

Awesome Work!!!

I finally got all the parts assembled to see how small the gap is. I must say, that it is a pain in the ass to adjust everyhing, it takes a lot of time. But when I was done, the air gap on each side was about 0.3mm or so. I could probably get it smaller, but I made too many mistakes in the building process, to the gap is as wide as it is. But its good for a prototype. Tonight I will work on the plastic coil holders. I will make them out of plexiglass and glue them on the startor with epoxy. Then all whats left is to wind the coil, but that should be easy enough Here's a picture:


The gap on the farthest side looks kinda big, but that is only the shaddow, because the rotor is in a little bit lower position than the startor

Jetijs,

Excellent work. Thanks for the picture. This machine will allow you to test a wide variety of the principles in my DVD. With the air-gap at 0.3mm per side (0.0118") your total air-gap will be 0.6mm (0.0236") or very similar to the little demo motor I have here, so you will not be able to see high torque production. No problem, just keep going and finish it. Its a great start for your research efforts and learning.



Peter

[Jetijs]

I made the comutator plate with magnets yesterday. The plate is made out od 3mm thick aluminum and the magnets are 1/4"x1/4"x1" neodymium type. They are spaced 90 degree apart of each other, the plate is bolted to a thread in the other end of the shaft, here's a picture:


My coil holder plates are also done and glued to the startor. I am almost done
BTW, we have our first snow today

[adam ant]

excellent quality work Jetijs. machining is definitely something that i wish i had studied. good work.

[Jetijs]

Thank's Bryan
I have not studied anything of this is some engineer school, I had to learn everything by myself. In fact I am just a computer technician and a system administrator. We just have many tools and machines where I am working, so I have a chance to learn how to use them. Also I have built my own cnc machine, this gives me the freedom to machine almost any part I need. Here's a link:
Ðtrums vol.2 - BOOT.lv
Thanks,
Jetijs

[Peter Lindemann]

Commutator magnets will fly.....

I made the comutator plate with magnets yesterday. The plate is made out od 3mm thick aluminum and the magnets are 1/4"x1/4"x1" neodymium type. They are spaced 90 degree apart of each other, the plate is bolted to a thread in the other end of the shaft, here's a picture:


My coil holder plates are also done and glued to the startor. I am almost done
BTW, we have our first snow today

Jetijs,

As usual, your workmanship is excellent. I will caution you, however, on the design of your commutator wheel. Your motor will be capable of very high speeds. I assume your little magnets are glued onto the aluminum wheel. At some speed, the glue WILL fail, and you will embed one or more magnets in a wall, ceiling, or your head! Please consider mechanical restraint.

Also, you will see very shortly that the little reed switched are very sensitive and the magnetic field around your magnets is very strong. You may not be able to get the timing you want with magnets that big. The best way to test the placement of the reeds is to connect them to a continuity meter that makes a sound and start moving the reed around the magnets. When you find a location that seems to be commutating properly, build a structure to hold the reed in that location.

Good luck,

Peter

[Jetijs]

Peter,
what if I make a second disc with grooves for magnets and glue it on the other side of the magnets? This way the magnets will be gluded between those two plates, and also pressed together with the screw. I used a strong epoxy designet to glue together metal. I think this should work. But I have also been thinking about the size of the magnets. These are the smallest ones I have. I will try to use them and see how it goes, If they are too strong, I will gave to get some smaller ones. Also for timing adjustment I was going to use a simple relay. I will attach the relay to the reedswitch so that it makes a clicking sound when a magnet passes by
Thanks.

[elias]

Excellent Job ...

Jetijs,


I am very eager to see your motor running, it looks pretty cool.

Keep up the good work ...

Kindest Regards
Elias

[Jan H]

about commutator

jetiis,

first i'd like to compliment you on the excellent work, you seem to be very patient and thorough while making something. I usually cut a lot more corners than you do

but anyway: the commutator is just bolted on there, don't you think it could slip a bit and lose its timing? It might be better to give it a little notch, so it stays where you want it.

and then about epoxying the magnets, i did the same thing with my sg. Have you got any experience doing that? Because im also afraid mine is going to fly apart.

[Jetijs]

Thank you all for the kind words and the encouragement
Jan H, I have not any experience with attaching magnets to anything that rotates at high speed, but I have used this kind of epoxy in various other applications, it has never let me down This is what I am gonna use:


I am sure, the magnets wont fly away in such configuration
Thanks

[lighty]

Simply add a thin layer of mylar or some similar non-magnetic, non-elastic, strong material. Glue it with epoxy adhesive along the circumference to cover the magnets and it will hold your magnets 100% no matter how fast you spin them (I tried that configuration long time ago and it works on high speed constructions).

Since the magnets are quite powerful you could also remake discs and leave a 1-2mm of material at the outer end of the groove to hold the magnets. That also works flawlessly.

The third option would be to use the optical switch as I suggested earlier since with it it would be much easier to have a lighter disc made out of some polymer and would be much more versatile in shortening or lengthening the switch-on and switch-off times.

BTW- that's a beautiful craftsmanship. Last year I made some working models of Tesla's devices (Tesla turbine, Tesla induction motor, big Tesla transformer and a huge model of Tesla's Egg of Columbus) for the Tesla's Memorial Center in Smiljan and I thought the technical problems would never end. Especially when all the parts should work as well as look good and antique. That thought me to appreciate this kind of stuff. Great work Jetijs!!! Great work indeed!


Oh, and am I mistaking or did you use the SW for the CAD modeling?

P.S.
Could you give me the rough estimate of the dimensions of your construction so that I can ask my supplier how much would silicone steel sheets cost (a rather minimal price I should say) and maybe arrange some kind of cheap transport to Latvia? Usually I wouldn't go to such length to help people I don't know well but you're one of the rare people that I see to do practical work and actually know what you're doing from the engineering point of view.

[Jetijs]

Thank's lighty
Yes, I use Solidworks for 3D modeling my parts. I must say that solidworks is far more easier to learn than AutoCAD. For the dimensions, the rotor is about 120mm in diameter that is about as big as a CD I would appreciate your help with material very much, since I searched for the silicon steel here in Latvia for a long time and did not find anything.
Thanks

[lighty]

Hm, you will have to give me the estimated size of sheet for one cut (I guess you used water, laser or plasma cutting) that includes both stator and rotor- in other words the worst case scenario for the sheet size for one layer. Also, what is the thickness of the complete set of sheets you used? If I know that data I can see how many sheets would you require (depending on the sheet thickness).

Now back to bed- I'm burning with high fever and my head is not working properly any more.

[Jetijs]

lighty,
I will finish this setup and do some tests to see how good does this work. Then, if everything works out good, I will design another - better model. Only then I will be able to calculate the necessary sheet size. For this model I used 1mm thick steel sheets. I know, that this is not the best choice, but that is all I had and it is still better than to use one big metal piece of both startor and rotor.
When I will be ready to make the other model, I will PM you.
Thank's and get well soon

[adam ant]

Jetijs, you can easily use liquid resin and dunk the whole thing into it. when it dries it is a very hard, very strong plastic that should hold up to any speeds you can throw at it. i have resin experience with making molds and such, and they also use them in off-roading ignitions. (water proof it) if it turns out too think, shaving it is very simple, and if it is too thin, multiple coats are also easy. you can get a quart for around $10 us.