3HP motor conversion Update

[andyman5002]

Hi all, been a while since I've posted because I've not done a lot. I recently got the rotor back from my dad with the alu cage pressed on with the holes in it, 60 in total. Thought I'd post a few pictures of it here:

There is the cage with holes and what I hope is the correct skew angle, I did what dinges suggested and drew a 10 degree angle and then drew a line across to a straight line on the other side, it follows the magnets so all looks good. I will only find out if it cogs and how badly when I get it back together.

Ive started putting the magnets in, quite a tight fit, I'm using loctite to bond them in. The mags need to be pressed into the holes so I doubt they will come out.

Hopefully should have it finished by the end of the weekend and assembled ready for a test. Not sure of the outputs im going to get but hopefully should be better than my last attempt, not even sure how im going to test it. I dont think ive got anything big enough to drive it. Im wondering what its going to be like sliding the finished rotor back in, whether its just going to fly in.

Once all this is done need, to think about blades

Andy

[Ungrounded Lightning Rod]

I trust you're being VERY careful to get the magnets right-pole up.  B-)

[dinges]

Ehm Andyman...

I did NOT say you should use a 10 deg. angle; at least, not in THAT plane. In fact, I think this is incorrect if you have a 36 slot stator...

It's all a matter of projection, but an important detail nevertheless. In my 3hp case, a 10 deg skew means a line of about 4 deg angle to the longitudinal axis of the rotor. Just to be very clear about it all.

Others say you should simply use the same angle as the original rotor had; if that's 10deg, I doubt you would go very far wrong. The downside is a slight imbalance that must be corrected for.

The only conversion I've finished so far uses the Jacques-M method of offsetting. It works excellent, absolutely no cog is present.

It looks very nice, btw. Professional job. For Loctite, the positive play should be as small as possible. Loctite application-engineers recommended me to use Loctite 327 (from memory) to bond nickel-coated magnets. I will be using epoxy though.

BTW, I hope that the magnets in the picture that are inside the pockets are glued in. I doubt you could get them out again if they're not (well, at least, I can't, with my flat-bottomed pockets. First try of inserting them & glueing MUST be right; no 2nd chances...).

ULR is right. Triple check your magnet polarity before glueing & inserting. I've been known on occasion only on the 3rd check to find a polarity error...

Also: be carefull when inserting the rotor into the stator. Do not manually insert it, it will simply be ripped out of your hands. Use something to gently & controllably insert it into the stator.

Following your story with interest!

[willib]

from the looks of it it looks great,

all the best , getting the rotor in

would some aluminum cans , with the top and bottom cut off , used as shims help?

just a thought

[dinges]

Correction:

------------

Others say you should simply use the same angle as the original rotor had; if that's 10deg, I doubt you would go very far wrong.

The only conversion I've finished so far uses the Jacques-M method of offsetting. It works excellent, absolutely no cog is present. The downside is a slight imbalance that must be corrected for.

----------

The downside of the Jacques-M method is an imbalance; it's NO downside of a 10 deg skew. <sigh>

[vawtman]

That is awesome work Andy.

 

[andyman5002]

Thanks everyone for your comments. In regards to the skew, it is a 10 degree angle on a flat plane, but a 5 degree skew on the rotor, and it follows the existing angle on the rotor near enough which was 5 degree.

I checked the polarity three times on each mag there all the same on that pole so far, yes there is no way they are coming out so I put in the loctite first should be bonded now, the next pole will be opposite polarity and so on. Not sure about the alu cans, I need something to control the movement so i can gradually lower it in.

I will keep you posted over the weekend.

Andy

[andyman5002]

Ok guys, ive finished it, its finally done. All 60 mags went in without a hitch all the correct polarity. We assembled it tonight as well. I was surprised at the speed at which the rotor flew in. I thought I had it covered but was wrong. Anyway no damage was done.

Ive been messing around with it seeing what it can power, so far things seem good. Much better than my last attempt, i need to find something that can drive it now. I shorted out 1 phase and it becomes very hard to turn. I tired hooking up the car bulb that i used before on my last gen, it glows very brightly at only a few rpm. I think if i pushed it anymore it would blow. That was connected to 1 phase, raw AC. Im looking forward to getting all 3 phases rectified and trying it out on a battery. Open volts ive seen 80 with my cordless drill, seems to reach open 14v fairly quickly. I also measured shorted current on 1 phase and saw around 5 amps, that was with really thin wire and a cordless drill that couldn't really handle it, very uneven rotation due to shorting just one phase.

In terms of cogging, it is a little more noticeable than my last attempt, I think this is due to the sheer power of this one and the size of the mags compared to the last one. I don't think it will affect the startup.

During the week im going to pick up another bridge rectifier and see how things go then. I would like to get some proper testing with rpm ratings but that might be hard. Its going to have to come apart again so I can seal it up, I just wanted to try it out and so far very pleased.

Anyway so far so good. I will keep you posted as things progress.

Andy

[SparWeb]

Have you seen my diary?  I hung the rotor from above and lowered it with a come-along.  Maybe a bit over-kill.  I cut up a plastic container as a buffer when the rotor and stator came into contact.