Ah, ok. I did come across that perforated hanger material when I was searching for that strapping but didn't know if the perforations would cause any problems. They also make that hanger material copper-plated - would this help generate more flux?

Or, would using an air-core make more flux since the magnetic field wouldn't be channeled into the center as much? If so, I could use something like this as the core.

 

Ah, ok. I did come across that perforated hanger material when I was searching for that strapping but didn't know if the perforations would cause any problems. They also make that hanger material copper-plated - would this help generate more flux?

Or, would using an air-core make more flux since the magnetic field wouldn't be channeled into the center as much? If so, I could use something like this as the core.

An air core doesn't concentrate the magnetic field, thats why a magnetic material is use in transformers and motors and certain inductors. Google 'electromagnetic field images' to see what I'm talking about.

Seriously the steel banding is the best and can be had from many places. When they uncrate things they just throw it away.
The holes in the plumber strap won't hurt a thing if you want to go that way. The copper plating will not help or hurt, the Home Depot stuff is just cheaper.

 

I'm thinking why not just get some threaded rod and make "U" bolts out of them, three different lengths for the "legs", wind on a bunch of turns of magnet wire in the curved area, and have each U-bolt turned 120 degrees. You won't need a very strong magnetic field to get an object like an egg spinning; it's just that the field needs to rotate.

 

I may try u-bolts in a 2 phase configuration if my toroids don't work - however I did make two toroids out of the 3/4" perforated steel banding; both are about 6" outer diameter, one is ~1" thick and the other is ~2" thick (not sure which of the two will work better).

So now that part is done, the driver is in the mail, I believe its time start determining what gauge of wiring to use, and how many wraps we'll need in the coil.

22 gauge = 5 amps

or

14 gauge = 5.87 amps
22 gauge = .918 amps

Not sure which chart is right, seems like each one I find has different numbers, though this chart seems inline with the second set of numbers. Anyway, the driver can support 35V and 6A through a separate power supply to the motor -- I think we should try to (safely) maximize the power to ensure the device works...unless you think the circuit rating of 12V and .1A is enough.

How do we determine the # of wraps in a coil?

 

It's not going to take much force to get a smooth egg-shaped object spinning if it's placed on a smooth surface.

 

Munk - the 1" one should work good. Have you wrapped the core with tape? If I was doing this for myself I would have taken the strapping and layed it out flat and put a layer of tape on one side of it. Transformers and motor s that have laminated cores are insulated between layers. That was the reason to push for the metal banding. The banding has a layer of varnish or lacquer on it from the factory and would insulate between layers of the coil. This is to prevent 'eddy currents' between layers, probably not a problem at current and frequency of this though.

To find the amount of wire this is how I would do it. Tape wrap the core, get it as smooth as you can, it will make winding the wire easier if its smooth. Then divide the core into four equal quarters, these will be your poles. take a piece of wire or sting and wrap it around the core(like the windings will go) and mark it where it meets. This will give you the length for one wrap. Measure the distance on the inside of the core, of one quarter of the inside. Divide this measurement by the diameter of the wire you choose to use. This will give you the number of wraps needed for one pole. Multiply that by the measurement of the cross section of the core that you did first. This number will be the length of wire needed for one pole, add a couple of feet for the leads to the controller.. And you have four poles.

As far as wire gage, use the largest (smaller number) that you think you can manipulate around the core when winding. I would wrap each pole with tape as I wound it to keep it in place. The windings will/should be closer together on the inside of the core than the outside. Do to the difference in diameter.

 

The outside of the core is wrapped with electrical tape, but not in between layers. The circumference of the core is 16.25", making each quadrant ~4". Using just my headphone wires, it's 3.25" to make one wrap, and the wire (with insulation) is 1/16" thick. That's 64 wraps per pole, or 256 wraps total. That comes out to about 70ft + 5ft for the leads = 75ft of wiring. I will need to go look at some other wiring to see what the largest gauge is that I can manage, and redo the calculations.

When I wrap this core, is there any direction I need to go if I am looking to get a clockwise rotation? Also, with 4 poles being on this core, does that mean i'll have 8 "loose" wires when all is said and done, two for each pole, or do I wrap this is such a way to where the north and south pairs are part of the same winding (ending up with only 4 loose wires)?

 

The outside of the core is wrapped with electrical tape, but not in between layers. The circumference of the core is 16.25", making each quadrant ~4". Using just my headphone wires, it's 3.25" to make one wrap, and the wire (with insulation) is 1/16" thick. That's 64 wraps per pole, or 256 wraps total. That comes out to about 70ft + 5ft for the leads = 75ft of wiring. I will need to go look at some other wiring to see what the largest gauge is that I can manage, and redo the calculations.

When I wrap this core, is there any direction I need to go if I am looking to get a clockwise rotation? Also, with 4 poles being on this core, does that mean i'll have 8 "loose" wires when all is said and done, two for each pole, or do I wrap this is such a way to where the north and south pairs are part of the same winding (ending up with only 4 loose wires)?

The wire you want to use is called 'magnet wire' here is a link to some;
http://www.allelectronics.com/index.php?page=search&search_query=magnet+wire&x=20&y=9 Wire like head phone wire isn't good for this, the insulation takes up space that can be used for more wire, and thats what you want. More actual wire(copper) means more magnetism.

Is your 16.25 circumference inside or outside? You want the inside circumference for your calculations.

You can use either direction to wrap your core, just do all of the poles the same way. Pick one side as the top and wrap in same direction for each pole.

You want to end up with eight leads coming out of your coil. Using "switch 1" on your driver board will allow you to make it run either direction.

 

The inner circumference is about 10.25", divided by 4 is about 2 9/16" (or 2.5"). Turns out the core is about 5" in diameter not 6" as I originally eye-balled it.

To connect these leads to the driver, will there be soldering involved or do the wires connect with a screw-clamp thing?

 

Yeah, your going to have to solder. The driver is a kit, it will have to be soldered together on the PCB. What ever you do don't use a soldering gun or plumbing solder. Plumbing solder is not made for electronics, it's too big in diameter and has an acid core.

 

Noted.

I received the kit in the mail, and it appears that the blocks where the motor wires would connect are indeed screw-tightened (the 3 blocks on the far left). Once I have the time, I will go get a soldering iron and some proper circuit solder, as well as the biggest gauge wire I think I can manage winding.

In the mean time, here are some pics of the core and the kit:

 

Wow! Great job on your core!

 

thank you

Ok, hopefully today I can get the soldering stuff and wire. Any soldering tips?

 

thank you

Ok, hopefully today I can get the soldering stuff and wire. Any soldering tips?

Watch This Video

Covers most mistakes and misconceptions about soldering.

 

I know you said to use magnet wire, but is there any drawbacks or incompatibilities with using stranded wire of the same AWG?

 

You won't be able to get nearly as many windings on the core, resulting in a weaker field. You'll also have a lot lower resistance, allowing a huge amount of current to flow unless you wind a thousand feet onto the coil somehow.

 

The core is wound with 18 awg (solid) wire. All I need to do with it now is tape it once more.

For the driver, is there any sequence in which I need to connect the various components, or can I just solder them on in any order? Also, how can I ensure I don't connect anything backwards?

 

The core is wound with 18 awg (solid) wire. All I need to do with it now is tape it once more.

For the driver, is there any sequence in which I need to connect the various components, or can I just solder them on in any order? Also, how can I ensure I don't connect anything backwards?

Is the wire magnet wire? The reason for magnet wire is because it has a lacquer coating on it for insulation. If not magnet wire it will short out where ever two wraps touch, not good.

Read and follow the instructions included with the kit. The PCB has the part locations printed on it. The components go on that side, solder on the copper side. Be careful not to make "solder bridges"(solder connecting two or more components or traces) Not good.

 

You know what, I don't think this wire is actual magnet wire. I got it from home depot when I picked up the soldering material, and didn't really give it a second thought. I think I will just go ahead and order some off the internet to be sure it's the right kind.

As far as the driver goes, I do see what side the components go on, and I do see the locations for each component, but I still have a dilemma. For example, take a component with two leads -- I could put it in one way, or spin the component 180 degrees and put it in a different way (all on the correct face of the PCB). The instructions don't really go into that amount of detail, so I do know if it matters or what. Does that make sense?

_____________

EDIT: Since I have to buy new wire anyway, I could go as large as 12 AWG for this core instead of the 18 AWG that I had before. Would this make the field stronger or weaker? I think I remember reading something saying that the more turns you have, the stronger the field (given equal voltages running through the wire). Then again, the more wire length you have, the more resistance you have. Just out of curiosity, what is the benefit of choosing the largest wire gauge for this project?

 

*bump*

I am still confused about that soldering question. Does it matter what orientation the components are so long as I soldering them on the correct side of the circuit board?

For example, if I have a resistor with writing on one side of it, does it matter if the writing is facing left or right?