An original solution to the problem. I intend to insert my magnets manually (2"x1"x.5" ones), but the rotor will have small grooves (about 2-3 mm deep) milled in it to keep them properly located as the epoxy sets. I'd only have to make sure they don't move parallel to the shaft, which shouldn't be too hard.
You have relatively high magnets, so you obviously had to remove a lot of material from the rotor. You were right, those holes are by now pretty close to the magnets.
I'm not sure if you already have locked the nuts on those bolts but if not, I'd certainly do. Using locktite, a tiny weld or whatever. A turning, vibrating rotor is a harsh environment and things are bound to vibrate themselves loose over time.
I don't see how you are skewing the rotor to prevent cogging, so I assume you will be skewing the stator. That would mean a rewind too. Impressive project for a first conversion :)
Peter.
Those magnets look about 3-5 degrees off the centerline. Is'nt that skewed enough? I don't mean this to be critical...only for my reference if I ever get around to making one myself. Skewing to reduce cogging is relative to the diameter & spacing, so is there any ROT (rule of thumb)? ie.: 1.5 x the width if the magnet or coil??
I love seeing people using their head to come up with different ways to do things! Great job!Rural McG[ Parent ]
As far as any rule of thumb goes; Zubbly in one of his 3 .pdf files explained how to skew (http://www.otherpower.com/images/scimages/4/zubbly2.pdf and http://www.otherpower.com/images/scimages/4/z_conversion_all.pdf). Basically he said 'skew by one slot'. I've slightly modified that rule (it goes wrong when you use relatively little magnets per row, i.e. 2 or 3) and let a bit of math loose upon it. See this .pdf file:
http://www.otherpower.com/images/scimages/3538/decogging_tutorial_V1.pdf
Peter. [ Parent ]
As I mentioned in another post here, I believe the amount of skew you want, over the full length of the rotor lams is equal to one stator tooth width (including the space between the teeth). Laurie Forbes Calgary, Canada [ Parent ]
Yes, the grooves would be a nice addition. Doing it manually though, would you have to slide the neos in (if so, I'm thinking that may scrape off the expoxy which is one reason I decided to lower them in directly)?
I have used locktite on the all-thread - probably a good thing too as we were getting quite a bit of chatter when turning the rotor.
BTW, we starting turning w/o the all-thread and added it after an outer lam came loose. One result seems to be that the lams now extend about 1/2" further along the shaft. I'm guessing that the machining heat melted the glue (or whatever) between the lams and allowed them to spread out somewhat. So, all the more reason to add bolts or all-thread....
It's not all that obvious from the pics but the neos are skewed (one tooth width). It's most evident on the close-up pic where the black layout lines can be seen. Laurie Forbes Calgary, Canada [ Parent ]
