Milling my 180W conversion rotor

[Bobbyb]

hi all

I'm working on a 180 watt motor conversion.

The original winding still work so I'm not planning to rewind.

I'm using 48 12mm x 6mm magnets, they make 6 poles of 2 by 4 rows.

The original motor specs were:

-380/220V,

-0.18Kw

-0.8/1.4A

-50hz

-910RPM

-36 slot's 3 coil per faze

- cost 5 euro (that's probably the best spec )

I did all the metal work at my school; witch was great since they have all the right tools for the job.





First I turned the rotor down 6mm.

this took way longer than expected since the turning went with .5mm at a time

and took 15 minutes x 12 = a long time.





Lots of standing around looking at the machine doing all the work



Like I said they have all the right tools at my school.









Half way there



Here is a close up of the "plates" were the magnets go.  They aren't as deep as I wanted, but du to a mistake in my drawing I turned the rotor to small. Luckily it all turned out well in the end.





And the end result!!

Milling the flats for the magnets toke no time at all.

I ended up doing all this in one day and there was even time to completely clean the mill making the Teachers s really happy.

They were also amazed by the strength of the magnets....hahahaha

Well that's it for now, I can't weight to glue the magnets and se some watts.

[ghurd]

Looks Great Bobby!

As long as the magnet sits on flat ground, I think thats good.  Mine do not.

It meets my specs... "5 Euros".  Whatever a euro may be.  :-)

G-

[dinges]

Hey Bobby,

You sure work a lot quicker than I do. My conversions take a lot longer...

Just a few remarks:

1. when handling magnets cleanliness is important. Make sure all loose chips are wiped off the rotor before letting a magnet come near it. I see your magnets are already covered in metal particles. Getting it off the magnet is not a fun thing to do, and you won't be able to get everything off.
   
2. Hard to say for sure, but I think the bearing is not sealed/closed. The chips flying into it will not do it much good. Make sure you clean/flush it out thoroughly and re-grease. I'd have either removed the bearing, or packed it in ducttape to keep dirt and chips out.
   
3. you've learned that turning down the rotor is not fun. Another reason why I remove the entire old rotor and just put on a new steel core. Less resistance to magnetic flux, better, magnets hold more strongly, etc.
   
4. A tiny detail, but it looks like you haven't properly aligned the rotor on the mill; your bottoms are not equal. Won't matter for the end result though.
   
   

Next comes the fun part; wrestling the magnets in place. What type of glue do you intend to use, and will you cast the rotor in epoxy after glueing?

Teachers can get picky about cleaning the machines. Also, they don't like it when you want to 'clean' the lathe or mill with compressed air...

Looking forward to read about the further progress of the conversion

And Ghurd, a Euro is just like a dollar but has more value...

[jimjjnn]

Cleaning metal chips off can be done with those Sticky lint rollers for removing lint and all sorts of other stuff off of clothing.

[hiker]

nice...

whats the name of that flat bottem end drill bit--=been looking for one cant seem to find one.

you probley could have gotten away with using smaller mags on that conversion..

[Countryboy]

That is not a flat bottom drill bit.  A drill bit ONLY cuts metal with the end.

That is a 2 flute end mill.  The sides of the end mill are the cutting edges, but you can make a flat spot with the end of an end mill.  Do not attempt to 'drill' with an end mill farther than just making a flat spot.  (Trying to drill a hole with an end mill is a good way to break the mill bit.)  

If you know how to sharpen drill bits by hand, you can grind a regular drill bit into a flat bottom drill bit.  However, you should NEVER attempt to drill a hole with a flat bottom drill bit.  Its ONLY use is to flatten the bottom of a blind hole after it has been drilled with a regular point drill bit of the same diameter.

[Countryboy]

Good eye Dinges.

Depending on the intended airgap, having the flats misaligned can cause problems down the road if the intended airgap is very tight.  Misaligning the magnets will result in one edge of the magnet being slightly higher than it should be.

The easiest way I've found to remove tiny metal particles from a neo magnet is with duct tape.  Stick the tape on the magnet - when you remove the tape, it will also remove most (if not all) the metal particles.

I've used both compressed air to clean up metal shavings (followed by a broom on the floor), and used a shop vacuum at other times.  Both methods work well.

[Flux]

Nice work, it should be a good machine.

I tend to agree with Peter that making a new rotor core is better, turning packs of laminations is a pain to put it mildly. Having parts of the cage bars reducing the volume of iron is not ideal but will not really cause you any problem. Having to do it at school with limited time probably means that you were right to use the original core.

Yes the perfectionists will worry about your lack of exact centring of the cutter but as long as it doesn't affect your clearance it will make no difference. I tend not to be a perfectionist, get it done, have fun and as long as it works all is well.

Probably the cutter that someone asked about has different names in different parts of the world. To me it is a slot drill, I would recognise it as a 2 flute end mill, but I suspect there are versions of 2 flute end mills that will not plunge cut, the slot drill has a long and a short flute designed for feeding in endwise. Modified drills are not rigid enough to use on a miller but would be good enough to flatten the bottom of a hole drilled with a conical point drill.

Being brought up in an era before safety and common sense I still find fingers to be the only effective things to remove swarf from magnets but I didn't mention that here!

Flux

[hiker]

thanks for the info  countryboy.............

[ghurd]

Yes! Check the fit before the epoxy goes on. Not easy to do the way I do it.

But it's harder getting things seperated to move a magnet just a hair.

G-

[Ungrounded Lightning Rod]

Cleaning metal chips off can be done with those Sticky lint rollers for removing lint and all sorts of other stuff off of clothing.

Which are basically just wide masking tape on a roller.  I don't THINK they're any stronger than the regular stuff - otherwise they'd tear the clothes apart.

So try some masking tape before making a special purchase of the more expensive lint rollers.

[Bobbyb]

Wow lots of reply's .

1 euro = 0.80 us dollar

Next time I will leave the magnets far away from the rotor until its properly cleaned, but since this is my first conversion I was to curious to se how it would all look and fit.

I'll try the tape since I already learned that it is impossible to get is all off by hand.

Dinges: My bearings ware sealed so no worry's tear.

As for the uneven milling, the depth of the "hole's" is only .4mm so the magnets will maybe only rise .02 (ore something) more on one side than on the other (really not a problem).

I don't know witch type of glue I'll use maybe epoxy? Don't know so any advice is welcome.

Hiker: How it's called I don't know but is not a drill bit

Using a new aluminum rotor seems wrong to me, don't u need magnetic "conduction" at the bottom parts of the magnet? I don't se any aluminum rotors on a dual rotor system??

I also believe that the most part of the magnets need to be in a none electrically conductive material.

I think that there are changing amounts of flux in the outer shell of the rotor at it turns. And we all know that that creates currents = loss in the rotor.

It's hard to explain but if someone is interested ill draw a picture.

Greetings

Bobby

[vawtman]

Bobby if you plan on leaving the mags on permanetly go to a golf shop and get whats called shafting epoxy.If you tried to heat this epoxy to free the mags the mags would so called lose it.(magnetism)

If you want to remove them at some point use a little jbweld.

The rotor shoud be solid steel not solid aluminum but your okay just has you are.

 Dont worry be happy

 Mark

[Flux]

The magnet core should indeed be steel not aluminium. I am not sure anyone implied that it should be aluminium.

You are also right that there is potential for eddies to be induced in a conductive material surrounding the magnets. This doesn't in fact prove to be a problem and the aluminium cage suggested by Zubbly and others is perfectly satisfactory.

With a 3 phase winding there is little flux pulsation through the magnets. With single phase there will be quite a lot, but despite this, single phase alternators have always performed better with damping windings to prevent this pulsation affecting the whole rotor magnetic circuit.

There may be some argument for not taking the cage to the full height of the magnets as there will be some slot ripple flux change near the stator teeth and the presence of a solid conductor there may cause extra loss.

Flux

[vawtman]

Oh and make sure you get the polarity right on each mag.You seem new to this just want to make sure you understand that.Especially if you choose the first option.

[Ungrounded Lightning Rod]

Only place I saw a new rotor suggested it was explicitly a new steel rotor.

[RodN]

BTW

1. Euro = 1.32US$
   
1. US$ = 0.757€