Author Topic: machining the flats on the rotor, terrible goof  (Read 1100 times)

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jacquesm

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machining the flats on the rotor, terrible goof
« on: December 25, 2004, 03:44:25 AM »
So, today I machined the flats on the rotor.



First I drilled four 3/8 holes in the rotor to be able to mount it on the indexing table. I don't have 3/8 clamping stuff, so I made 4 ground down nuts and put them on pieces of threaded rod. Centering was done using a led based center help, then I started on the flats.



This is where I messed up terribly, I started working right away in the morning, and by the time I looked at fieldlines it was too late to take Victors error correction in stride... TomW indicated Victor had posted feedback to tell me I was on the wrong track. The rotor I made had 12 1/2 flats, I don't know what I was smoking, but as Victor pointed out that should have been 12 1/3rd (one slot + associated 'finger' on the stator).



I managed to correct it somewhat after remounting the rotor on the indexing table, it cost me about 30 thou of airgap.



The other half of the rotor will be machined to the right dimensions, this will at least allow us a slight benefit from messing up, we can compare two rotors that are identical but for the airgap.



If the difference is too big then I'll make a third one, but for now we'll be using this one for testing purposes.



According to Victor I won't need to offset the rotors, and it makes sense that way, we'll see how it all works out in practice.



tomorrow I'll try to rework the motor housing and machine the shaft so we can fit this rotor in place and try it.



DanB has bet me $5.00 that we won't be able to get this kind of power (2400 Watts) out of the frame I'm using. Anybody else want to take us up on that ?



Yesterdays cad file has been corrected to incorporate the changes, I also added a side view.



pictures:



Drilling the mounting holes (I'm drilling on the mill here because it has a DRO, which lets you place holes very precisely without marking them):







Done with that chore:







Mounted on the indexing table:







Milling the flats: (the little bits at the top are 'trials', to see if I have everything set up right (and of course I didn't which is why they're offset...):







The finished rotor, this is after correcting it, so between this picture and the previous one the rotor has been unmounted, fit, and remounted and reworked (I hate rework :) ):





« Last Edit: December 25, 2004, 03:44:25 AM by (unknown) »

Victor

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Re: machining the flats on the rotor, terrible goo
« Reply #1 on: December 25, 2004, 09:19:53 PM »
 Now I'm thinking that the two rotors in different orientations may be a good idea.


 If they are 180 degrees apart you may have no ballance problems.


 I'm thinking that my previous statement about less power is probably  wrong.


Victor

« Last Edit: December 25, 2004, 09:19:53 PM by Victor »

Jerry

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Re: machining the flats on the rotor, terrible goo
« Reply #2 on: December 25, 2004, 10:17:47 PM »
I just offset the 2 rows of magnets by 1 slot. works great. No cogging and no loss.


                                 JK TAS Jerry

« Last Edit: December 25, 2004, 10:17:47 PM by Jerry »