Making a C120-110
- Thread starter h0tr0d
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Idontwanttopedal
1 kW
Bruno got a 12095 for sale
Thud
1 MW
Just fab a new flux can in a size that works. You could buy new-corrected length magnets for it also.
Either way, it would be simple lathe work to modify the existing flux cans & tig weld them together.
Either way, it would be simple lathe work to modify the existing flux cans & tig weld them together.
h0tr0d
1 kW
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I thought of welding but my fear is heat distorting the very thin cans. Apart from the heat possibly affecting the magnet strength...
A new can is a good idea but how do I unglue the Magnets?
What about a aluminium can over the 2 iron cans? Glued or screwed...
A new can is a good idea but how do I unglue the Magnets?
What about a aluminium can over the 2 iron cans? Glued or screwed...
Thud
1 MW
You won't be getting the magnets out of the can unless there is a solvent that will work on the epoxy.
The only thing that works reliably in my experience is heat....& that is death to the neo-mags.
If you turned the cans to get the magnets close enough to work...you could turn a well fitting external ring to align them..it could be a press fit, or bonded with high temp epoxy.
Let your imagination run
The only thing that works reliably in my experience is heat....& that is death to the neo-mags.
If you turned the cans to get the magnets close enough to work...you could turn a well fitting external ring to align them..it could be a press fit, or bonded with high temp epoxy.
Let your imagination run
salty9
1 kW
Thermal shock was mentioned in a googled article for destroying epoxy bonds. Made me think of using dry ice. Perhaps dry ice inside the can and a heating pad wrapped around the outside for maximum safe (for the Magnets) delta T. I have no idea if this will work.
Found ths later:
"EMBRITTLEMENT OF ADHESIVE BONDS WITH COLD
Hard, rigid adhesives are often easier to shatter upon exposure to very cold temperatures than are more flexible
ones. Dipping the part in liquid nitrogen, wrapping it in dry ice, or otherwise bringing its temperature below -60oC
may embrittle an adhesive. Tapping of the cold part may shatter the bond and allow the parts to separate. Once
separated, a solvent soak may still be necessary to remove residual material."
Found ths later:
"EMBRITTLEMENT OF ADHESIVE BONDS WITH COLD
Hard, rigid adhesives are often easier to shatter upon exposure to very cold temperatures than are more flexible
ones. Dipping the part in liquid nitrogen, wrapping it in dry ice, or otherwise bringing its temperature below -60oC
may embrittle an adhesive. Tapping of the cold part may shatter the bond and allow the parts to separate. Once
separated, a solvent soak may still be necessary to remove residual material."
Don't weld. It is be hard to balance and will break eventually. You'll need a whole new can.
You can remove old magnets by destroying the can: cut it through, all the way from front to back (one side only), spread and unfold. Magnets should fall off.
Haven't tried it, but seems doable.
You can remove old magnets by destroying the can: cut it through, all the way from front to back (one side only), spread and unfold. Magnets should fall off.
Haven't tried it, but seems doable.
h0tr0d
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.
What do you guys think about some pieces of metal glued between the magnets? Since the stator applies the forces to the magnets
I have 2 options:
1- Aluminium rods and epoxy; lightweight solution?
2- Mild steel rods and steel filled epoxy; more weight but better magnetic path between magnets?
What do you guys think about some pieces of metal glued between the magnets? Since the stator applies the forces to the magnets
I have 2 options:
1- Aluminium rods and epoxy; lightweight solution?
2- Mild steel rods and steel filled epoxy; more weight but better magnetic path between magnets?
The last thing that you want is a magnetic path between the magnets at the gap level. Magnetic spacers, less than 1/2 the magnet height might give a slight advantage as back iron. I think I would use something non-magnetic though and, if not electrically non-conductive, at least insulated. You need to break all possible paths for eddy currents.h0tr0d said:
h0tr0d
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Miles said:
Thanks Miles.
I looking at Lebowski's rotors and thought there wouldn't be a problem with something conductive between the magnets...
Can I ask (pretty, pretty please
) if you can simulate that on FEMM?Any advice on plastics for this application?
EDIT:
http://www.hobbyking.com/hobbyking/store/__15386__Carbon_Strip_1x3x750mm_5pcs_set_.html?strSearch=carbon%20strip
Would this Carbon Strips be good? I imagine the fibers being parallel to the magnets...
There are two issues:h0tr0d said:
The reason for spacing the magnets apart is that, if the magnets are touching or close, the flux from the edges short circuits and doesn't enter the stator. Using magnetic material to completely fill these gaps is the worst of all cases.
Whilst the fundamental frequency won't generate eddy currents in the rotor, they are generated by the harmonics. This is the reason for the use of segmented poles and insulation between the magnets and back-iron.
h0tr0d
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Miles said:
In other words: All motors that have 100% magnet coverage of the back iron (like a hubmotor) could be better if the magnets were a bit apart?
In your inrunner you have the back iron slightly elevated between the magnets for easy mounting and better back iron "efficiency", right?
I don't need magnet spacers per se, I need something to connect the 2 rotors. Those carbon strips looked nice for that purpose...
What about putting magnets (halbach'ish array) to unite the 2 rotors? Little gains, big bucks...?
Farfle
100 kW
I would take a mild steel sleeve whose ID is the OD of the existing cans that is the length of the entire twin cans, and use the existing can bolts (obviously longer ones would be needed) to go through both cans
Farfle
100 kW
Take a look at my double wide fat arse outrunner if you want some ideas.
endless-sphere.com/forums/viewtopic.php?f=30&t=41576&start=75
endless-sphere.com/forums/viewtopic.php?f=30&t=41576&start=75
Farfle
100 kW
I would love to see more people try building double wide motors, as it really is not that hard, and the results can be impressive.
Thud
1 MW
send me all your burned out hub motors.......in two's please.
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