TinMan Generator Research Moderated Topic

[picowatt]

You will find(or should) that if you reverse the polarity of the battery feeding the stator coil,the motor should spin backwards.You can achieve the same effect by using a PM embedded in the stator core.

Tinman,

If someone wanted to try embedding a PM in the stator, what would you suggest as the best method to do so?

PW

[Vortex1]

Attached are pictures of my breadboard lashup. Thus far I have tried many combinations of wiring. I used Faston connectors which made switching polarity fairly easy. I tried the original circuit as well as my modified circuit. Nothing to report yet, only a dimly lit #1819 bulb with about 36 watts into the rotor. Data to come when I get to where I can see a significant reduction of input current as Brad did. Further testing later in the day. I intend to add some type of timing device to sync the scope so that one complete revolution equals one sweep of the scope. I might use Hall effect, optical disc or just a simple magnet and pickup coil. The optical approach would be the easiest to balance.

Yes I do have high quality Fluke DMM's and scopes not shown in the pictures. This was done a few weeks ago, I am further along in my understanding to date.

Regards, Vortex1

[tinman]

Tinman,

If someone wanted to try embedding a PM in the stator, what would you suggest as the best method to do so?

PW

I use either thread lock mill bit's,or mill drill bits for the larger holes,as normal drill bits drill triangle shaped holes,and there not very good when drilling laminated cores.Dont drill all the way through,stop a couple of mm before you go through the core. Your magnet will then slide in neatly,and will retain it self. Do not glue in,as you may have it around the wrong way

[picowatt]

I use either thread lock mill bit's,or mill drill bits for the larger holes,as normal drill bits drill triangle shaped holes,and there not very good when drilling laminated cores.Dont drill all the way through,stop a couple of mm before you go through the core. Your magnet will then slide in neatly,and will retain it self. Do not glue in,as you may have it around the wrong way

Tinman,

So, basically, you would suggest something along the lines of the images Grum posted? 

Would you suggest a fairly loose or tight fit of the PM within the bored hole (particularly with consideration of PM's flux path)?

Would you suggest using something on the backside of the PM to close the path to the frame?

As I stated in response to Grum's post, I would think that the bulk of the magnet's flux path would be more so "kept" within the material surrounding the bored hole. 

I see you also have those screw shank end mills...

PW     

[gotoluc]

LUC
Those are very good points about cutting the laminations and the possibility for eddy current shorts. After the coarse cut, If you use a fine file or belt sander lightly along the length of the cut area to clean up the shorts and varnish the cut areas, you may be able to eliminate most of the shorts.
I agree trying it as is would be a good first step.

I wonder why you are using such a large motor for your initial tests, and your motor does not have the spiral rotor laminations. Any reason? Brad's motor was supposedly from an import buffer, and they can be had for less than $20 US. Also vacuum cleaners are along many trash pickup sites on the right days, but even those may be too large, not to say that the effect is not scalable.

Regards
Vortex1

Hi Vortex1,

thanks for posting your comments.  I agree with you in the finer finishing of the cut laminations. I do that also and mostly with parts I want to marry together. I place a fine sand paper on a flat surface and use a perfect 90 degree block to keep the end of what I'm sanding leveled.

As for the large motor. I don't think it matters it the motor rotor has spiral sections or strait. I chose this one because the small one I was experimenting with I accidentally dropped the rotor (just after I finished cleaning it) and the commutator hit another sharp metal piece and cut the copper wires and is unrepairable. Previously I had it working once I got the timing of the brushes right. So I decided to get something more robust. If I do get it working it can only be better as there is less resistance in the winding and mostly because it's a 120vac compared to the 220vac motors.

Nice build, did you adjust the brush timing?

Thanks for sharing

Luc