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Re: Grinding flats into motor to make syncronous help!

Original poster: "Barton B. Anderson" <bartb@xxxxxxxxxxxxxxxx>

Hi Nick,

The motor looks small. Likely, it just doesn't have the torque at sync to keep in sync. You probably need a little more HP.

Take care,

Tesla list wrote:

Original poster: "seanick" <edgarsbat@xxxxxxxxxxx>

I actually am having trouble making my motor synch right now... when I first made it I had a lot lighter rotor on it, and it would sync only after the second time my friend made larger flats on it. but it is 3600 RPM. so that is a little more difficult than 1800 rpm I think in that the flats have to be bigger. After the second time he machined the flats they were more like an inch and a half wide, and it would sync at that point. Since then I got a larger rotor and larger electrodes, and put the rotor in a separate box with its own bearings and coupled them with a hose (because the motor's shaft was too short and caused too many problems trying to make the phase adjust work) and now it won't synch at all unless I really adjust it to be perfectly in line and even then it only synched once or twice and now it won't synch at all. I might need even bigger flats, or I might have just bruised the windings to the point where I need an entire new motor... but it is still sort of working so until it fully dies I am just going to use it asynch...

I have a picture from when I was using a universal joint .. http://www.themotocam.com/gallery2/main.php?g2_itemId=3921&g2_imageViewsIndex=3 but the universal joint was replaced with a short length of air hose and two hose clamps. that actually got it to synch twice... but since then hasn't synched since. Not sure what the problem is now. so like I said I think it might just be that the motor is dying.


----- Original Message ----- From: "Tesla list" <tesla@xxxxxxxxxx>
To: <tesla@xxxxxxxxxx>
Cc: <striker754@xxxxxxxxxxxxx>
Sent: Sunday, May 28, 2006 4:18 PM
Subject: Re: Grinding flats into motor to make syncronous help!

Original poster: Vardan <vardan01@xxxxxxxxxxxxxxxxxxxxxxx>

Hi Aaron,

There are three options (I did not make the ZIP file...) It was the guy in CA but his name escapes me at the moment... He has been on Ripley's a few times with Danielle Stampe... Blame him :o)))

1. Cut them like picture motors_2.gif.


2. Cut them like picture salnt_3t.jpg.


3. Or, just cut them 0.75 inches wide ;-)

The first two do not match, and they should.... But if salnt_3t.jpg had followed the directions in motors_2.gif they would have been way too small....

I think John Freau has shown it is just not real critical... The more you cut the higher the torque but the hotter the motor gets...

"I think" 0.75 inches would be fine. However, many on this list like Dr. R, Bill Wysock, John Freau... Would know far more than me... All my gaps are electronic now ;-)) If you mess up, you can use one of my old sync gaps ;-))) But I think 0.75 wide to like an inch wide would work fine. You can always cut more but it is hard to put metal back on... The more you cut the hotter they get and the more current they draw which can be a pain...

Your dimension "d" in the picture is probably just fine too... I don't think anyone has ever made a sync motor, no matter how much they cut, that did "not" work... I like less, to cut down on motor heating, work, and lower current draw... It does on take much to spin a rotor...



At 03:07 PM 5/28/2006, you wrote:


I did some measurements, using the rotor diameter to flat size. Your ratio is about 3.8 with a 3.22 diameter rotor, and .85 flat size. My rotor is about 3.5 inch diameter. With a 3.8 ratio, that works out to 0.92 inch wide flat.

0.944" is the distance from outside to outside on those poles where the blue d is marked. http://theflyingbullet.com/motor/IMG_1769.JPG Basically the outside to outside distance of 3 of those poles.

Center to center distance over 3 of those poles is about 0.7" or so.

Should I do the 0.92" flats?

Original poster: Vardan <vardan01@xxxxxxxxxxxxxxxxxxxxxxx>

Hi Aron,

See the notes here too:




At 12:55 PM 5/28/2006, you wrote:
>I'm trying to convert this motor to syncronous operation. I am not
>sure how big to cut the flats. Picture 3 in terrys zip file shows
>the flat going to the edge of the next pole. Yet the motors 2
>picture in the same zip file says measure to the middle of the next
>pole. What should I do?
>Here is a picture of the motor:
>Is the black area the dead pole? The red ones dont have direct run
>windings around them, but they are totally encased in the windings,
>which is what I think matters correct? The black one is inbetween
>the 2 loops of windings which is what I think I want...
>Is that the correct distance for the flat to be cut? Half way
>between the next active pole? The armature is ~ 3.5 in diameter.
>Thanks guys
>PS: Terry, can you email me your phone number, maybe we can get
>together sometime again.