Electric Motor Secrets

[Peter Lindemann]

Cleaning the Bearings

Peter,

I shaved my rotor as you suggested, and now I have four segments on each side, as seen in the picture. The only problem I have now is that one of the bearings has so much friction to it, and I suppose it might be better to change it. Since I have never done this before, I need some advice about doing so, without damaging my rotor, because it seems fixed so tightly to the shaft.

Thanks

Elias,

I agree with Mart. Just buy a can of Engine De-Greaser spray, pop off one of the side seals and spray out the bearing while turning it. The goal is not to remove all of the grease, but just to thin it out a bit. Then DON'T add anymore new grease. If there is no real damage to the bearings, then they should run smooth and easy after this operation. If there are no further friction points, then just pop the side seal back on and you're good to go! Try this first.

Rotor looks great!

Peter

[theremart]

RE: bearing

Peter,

I shaved my rotor as you suggested, and now I have four segments on each side, as seen in the picture. The only problem I have now is that one of the bearings has so much friction to it, and I suppose it might be better to change it. Since I have never done this before, I need some advice about doing so, without damaging my rotor, because it seems fixed so tightly to the shaft.

Thanks

I have found that that rubber center of the bearing comes out with a blade. You can then use carb cleaner or gasoline to get the gunk out of the bearing then... You can fill it about 2/3 full of good grease ( do not fill it all the way or you cause more friction and problems ) There is a youtube video for cleaning skateboard bearings.

Cleaning bearings
YouTube - How to clean bearings


Compare ceramic bearings to standard:
YouTube - Ceramic Bearings vs. ABEC 7's

[elias]

changing the bearings

Peter,

I shaved my rotor as you suggested, and now I have four segments on each side, as seen in the picture. The only problem I have now is that one of the bearings has so much friction to it, and I suppose it might be better to change it. Since I have never done this before, I need some advice about doing so, without damaging my rotor, because it seems fixed so tightly to the shaft.

Thanks

[elias]

You're work is done pretty good..
Do you have pics from the stator winding???
Actualy i'm working on that to and i have found an old motor with a 12 awg
gage,i think!!!! When it comes to put it inside the stator,i just can put 6
winding inside the slots.
If you have pics from the inside of you're motor i would appreciate!!!
And again NICE WORK
peper10

I have put some pictures on my previous posts, I'll give some pictures after I cut my rotor as Peter has mentioned. Thanks for your encouragement.

[elias]

Peter,

Thanks,
I placed my magnets on my commutator, because I am familiar with hall devices, and I got some in home. I ran it on 18 volts drawing 250mA, and it ran around 2000 RPM, with reasonable torque, although I could stop it by my hand. As I moved my hall sensor, I found the spot at which the maximum RPM was achieved, and I found out that the maximum RPM occurred at an unexpected spot, where the rotor tends to move backwards initially, so you are right I should have cut off two more segments to get better performance. I suppose the collapsed spike was causing the rotor decrease in speed as I moved the hall sensor to a position where the rotor starts moving in forward direction. So maybe the back spike needs more space to deliver forward action instead of backward.

The collapsed spike was rather noisy when it was disconnected from the charging battery and slowed the rotor down pretty much.

I'll cut off two more segments tomorrow, and keep you informed about my progress.

Best Regards
Elias

[Peter Lindemann]

Rotor Modification

Thank you very much Peter, I got it. Modifying the stators was risky, so I shaved my rotor.

I shaved my rotor like a butterfly for testing. What do you think about this. Also I want to place my timing magnets on the commutator wheel, is that Ok?

Regards

Elias,

Nice job on the rotor. But according to what I said in my last post, you have still not taken enough segments off the rotor. Currently, you have 6 segments on each side, but the width of the space between the stator poles looks like it is about 4 segments wide. You can try it like this, but you will find that cutting the rotor back to 4 segments will allow better performance.

You can try to place the magnets on the commutator wheel, but I don't think it will work, unless you are going to trigger the circuit with a Hall-Effect device. If you are planning on using a magnetic reed, like I do, you will need to get the reed switch away from the magnetic field of the stator coils. The magnetic reed has to disconnect for the fields of the stator to turn off. If the reed is IN or near the field of the stator, it may latch ON and not turn off when the little magnet goes away.

Plus, with the magnets outside of the motor, it is easier to find the best placement for the magnetic reed for proper sensitivity and ON time.

Keep up the great work.

Peter

[elias]

butterfly rotor

Thank you very much Peter, I got it. Modifying the stators was risky, so I shaved my rotor.

I shaved my rotor like a butterfly for testing. What do you think about this. Also I want to place my timing magnets on the commutator wheel, is that Ok?

Regards

[theremart]

RE: help about converting motor

Dear Peter,

THANK YOU

[Peter Lindemann]

Shaping the Rotor

Dear Peter

I recently found an old vacuum cleaner and took the motor out as you can see in the attachment. I was planning to see if I can turn it into an attraction motor. What do you suggest? The airgap of it is around 0.015" as I measured several times to get sure. Fortunately the number of segments are Even would make balancing it easier. But I don't know if the stators are fine for this. How much do you recommend me to cut and shape the rotor?

Thanks in advance

Elias,

Yes, the vacuum cleaner motor is an excellent place to start. The main drawback of these two-pole stators is that the outer edges of the pole faces get so close to each other. This limits the width of the rotor to the width of the space between the stator poles. The reason is that the rotor must be just at the beginning edge of one of the pole faces and be attracted into alignment during the power stroke. If the rotor is wider than the space between the stator poles, then when the fields come ON, the rotor is attracted forward, but is also attracted backward. This geometry partially negates the forward mechanical energy you are trying to produce.

You can see in the design that Jetijs is building right now, how this problem has been eliminated by selecting a better geometry for the stator that includes stator poles that are only 70 degrees of arc.

One thing you could do is TRY to cut some of the outer lips off the stator poles. This is very difficult because the silicon steel is murderously tough material and dulls saw blades easily. The other issue is to do all of this AND protect the coils that are currently in place. One little nick from an errant saw blade and the coils can be ruined.

So, it just depends on how much work you want to do. The simplest thing to do is to cut the rotor down to the width of the space between the stator poles (or a little bit wider) and leave it at that. Get your first model going, and do more extensive work on your second one.

Good luck,

Peter

[elias]

Dear Peter

I recently found an old vacuum cleaner and took the motor out as you can see in the attachment. I was planning to see if I can turn it into an attraction motor. What do you suggest? The airgap of it is around 0.015" as I measured several times to get sure. Fortunately the number of segments are Even would make balancing it easier. But I don't know if the stators are fine for this. How much do you recommend me to cut and shape the rotor?

Thanks in advance

[Peter Lindemann]

Abrasive Wheel

I am looking for suggestions for cutting the plates on the rotor of a DC motor so they are square like the motor Peter has demonstrated.

My first thought is to use a saber saw with several blades the coating on the plates does eat the blades...

Another thought I had is to use an abrasive wheel or a torch. The torch seems like a bad idea, but I am open to what methods other people have found to work.

From what I am seeing no modification is needed for the coils in the walls of the motor housing.


Thanks.

Dear Mart,

Yes, the silicon-steel laminations are pretty tough. You need a thin, high speed abrasive wheel in an electric drill to cut through them. There are a number of other considerations to keep in mind when modifying your series wound, universal motor. The first is whether the rotor has an EVEN number of segments or an ODD number of segments. I've seen them with either even or odd. Obviously, the ones with an EVEN number are going to be easier to BALANCE after the modification. Second, make sure you cut off and remove all of the copper windings on the rotor. Just disconnecting them from the commutator or removing the brushes is not enough. All of the copper windings are short circuited together and will cause back EMF drag on the rotor unless they are removed.

The size of the air-gap between the rotor and the stator will determine the total amount and efficiency of mechanical energy production. Although it is not exactly true, the rule of thumb is that if you cut the air-gap in half, the torque should double. When modifying an off-the-shelf motor, modifying the air-gap is impractical, unless you save the stator and make a whole new rotor piece. But that is a bigger project. The motor I show on the YouTube films has an air-gap of .021 (twenty-one thousandths of an inch). Just so there is no confusion, that is .0105" (ten and a half thousandths) per side. With this air-gap, I have measured the mechanical energy production at about 30%. So, choosing an off-the-shelf motor with the smallest air-gap helps a lot. Even so, at high speed, this motor will go OU as the total ON TIME of the commutator approaches the inductive current rise-time of the coils. As the motor speeds up, the total percentage of electrical energy recovered rises as well. At 2500 rpm the electrical recovery is about 25%. This suggests that the motor will go OU at about 7000 rpm, or at the speed where the electrical recovery exceeds 70%.

The plastic wheel the motor turns has the little magnets in it to operate the magnetic reed switch, but also doubles as a calibrated dynamometer that is exactly one foot in circumference. The motor is capable of very high speed, so I have embedded the magnets in the wheel so they don't go flying across the room. At the speeds this motor can turn, this danger is very real, as I actually threw the magnets off the wheel three times before finally embedding them this way!

What you are building is a simple demonstrator of the principles of the motor, where the stator acts as the inductor in a DC-to-DC forward converter, and the rotor responds passively to the changes in flux of the inductor.

Good luck with your experiments!

Peter

[theremart]

Making the no EMF motor

I am looking for suggestions for cutting the plates on the rotor of a DC motor so they are square like the motor Peter has demonstrated.

My first thought is to use a saber saw with several blades the coating on the plates does eat the blades...

Another thought I had is to use an abrasive wheel or a torch. The torch seems like a bad idea, but I am open to what methods other people have found to work.

From what I am seeing no modification is needed for the coils in the walls of the motor housing.


Thanks.

[theremart]

RE: Answers

Theremart,

Please read the entire thread. I have answered these questions at least twice before.

Thanks,

Peter

Wow, I did not realize the depth of what is on this forum. From the first message, i found that the link to where an off the shelf motor is modified by removing the windings, and cutting it square.

Thanks for pointing me where I can find this information. And sorry for not doing it sooner.

Mart

[Peter Lindemann]

Answered in an Earlier Post

Thanks.

Are there plans that you have of the motor in the video that I could take to a CNC shop and have them make one? Did you just take one of the patents and make the motor yourself?


There seems that there would be a market for these custom motors were they to be made, as the Amish who make their own power, and those people out in the middle of no where.

Also, I have purchased a 5HP Baldor motor, I am in process of making it a Roto Verter. I have seen others at otherpower.com put neos on the shaft inside the motor. Is there a conversion that you would recommend for changing this motor from a standard motor into one that harnesses the back EMF or helps efficiently?

Thanks

Theremart,

Please read the entire thread. I have answered these questions at least twice before.

Thanks,

Peter

[theremart]

RE: Iron cup

Thanks.

Are there plans that you have of the motor in the video that I could take to a CNC shop and have them make one? Did you just take one of the patents and make the motor yourself?


There seems that there would be a market for these custom motors were they to be made, as the Amish who make their own power, and those people out in the middle of no where.

Also, I have purchased a 5HP Baldor motor, I am in process of making it a Roto Verter. I have seen others at otherpower.com put neos on the shaft inside the motor. Is there a conversion that you would recommend for changing this motor from a standard motor into one that harnesses the back EMF or helps efficiently?

Thanks