Question for RobC

[Warrior]

Hello Rob,

I was going through some diaries and noticed your 5.5 HP motor conversion. It made 1000 watts @ 800 rpm. You didn't mention at what voltage and if it was into a battery bank or heating elements.

Unfortunately all the pics you posted are gone

I would really like know a bit more about it since it's what I'm looking at building.

I'm interested in your output @ 2 or 3 different rpm ratings.

I have an old large 3 HP, three phase 220 volt motor that I'd like to convert using ceramic magnets. I can't afford neos at this momment so it has to be cheap.

The output I need is 200-300 watts @ 400 rpm at about 18 mph. 24 volts system. Prop will be about 7-9 foot diam.

If you have a few minutes I would really appreciate if can you repost more details about your conversion and maybe a few pics.

Thanks,

Warrior

[RobC]

Let me get back to you in a day or so. I will try to put additional info in this diary entry. RobC  

[Warrior]

Thanks Rob, I really appreciate it.

I will keep an eye open to your comments.

Kind regards,

Warrior

[RobC]

Hi Warrior I'm back. I've looked everywhere for the info I had on that motor without success.    

 I can tell this you don't want to go to the trouble to grind ferrite magnets like I did it's a major pain in the neck. Another problem I had was when I turned  the armature down enough to have room for the 1 inch thick magnets it tried to fall apart and I had  to put bolts through it to hold it together. The motor is a slow speed 6 pole industrial grade 1 phase unit. I think if I ever try this again I will use 2 layers of the radioshack style magnets the ones that are I think 1 by 2 by 3/8 thick. I think these will make a decent curve surface. After the magnets are glued in place I personally would find some heavy kevlar thread or maybe some non magnetic stainless steel mechanics wire and put on a layer and then coat it in epoxy. I think this is cheap insurance against magnets coming loose. I know what you mean about the cost of magnets it can get expensive for neo's although I plan to try that next time. You might try  asking the guys if they know who is selling  curved ferrite's  those would be great if you can find them. One thing that impressed me about this motor was that at 800 rpm it would run my big worm drive Milwaukee saw pretty well. If I get a chance this week I may hook a drive motor to this conversion and try to get some volt/amp readings so check back later in the week. Wish I could tell you more but thats all I have for now. If I can be of further help let let me know. One more thing a tile saw with a diamond blade and water will cut ferrite's very well. RobC

[Warrior]

Hello again Rob,

Thanks for your comments. Any info you can get me will be greatly appreciated. I just want to compare your conversion to my "to be" conversion. I plan to use the lowes 3/8" x 7/8" x 1 7/8 magnets, this should match the stator curve much better. The rotor will be solid steel and I plan to mill some flats on it with my lathe. I might also strap a bronze or stainless sheet around them for containment and protection.

I took this motor apart and wrote down the dimension, but last night I was looking for the piece of paper were I wrote it down and guess what...I couldn't find it LOL.

I do remember that the armature diameter was about 4.5" and the stator stack length was also around 4.5", maybe a little longer; 36 slots.

The motor frame is about 9-10" in diameter as well. Unfortunately it doesn't have a nameplate but due to the size a wild guesstimation is that it's probably 2-3 HP, 3PH, 220/380 volts.

I know most will tell me it's a waste of time to use ceramic magnets, but believe me; I really can't spend on neos, maybe sometime in the future I can upgrade.

I just bought a new house and still have to spend more cash on furniture (but that won't stop me!!!)

Ceramics shouldn't be underestimated; they have a much lower gauss rating but with a large surface area you still get a good amount of total magnetic flux which is what really matters.

I'm not after huge amounts of power and I don't mind the weight of the motor for the low output I will get.

Considering your motor ran the worm drive Milwaukee saw, (I have a similar Skill Pro), it must have made some decent power cause those saws are massive.

Anyway, I don't want to bore you any longer. If you've still got those pics somewhere please post them. I'll check the board during the week for any updates.

Thanks,

Warrior

[etownlax]

Question for ya...

If it is a 5.5Hp Engine then... 1 horsepower is equal to 745 watts. Which at 5.5Hp it would be 4097.5 watts. If you only got 1000 watts then thats only about 1/4 of the power. Or is this at a lower RPM for this engine and therefor lower Hp? But if its not then that would mean you have about 25% efficient generator. Shouldn't they be a bit more effiecent?

Thanks,

-Randy

[RobC]

I was only able to run it to about 800 rpm. Full speed for this motor would be about 1150 rpm at which there would be an additional increase in power, how much I don't know. This motor was also built with relatively inexpensive ferrite magnets. If it had been built with neos  the power output would have been much higher. Still in the long run a 1000 watts out of a free motor and some cheap magnets isn't all bad. Now the problem is finding time to finish the tower and the 3 to 1 serpentine belt speed increaser.