Roll your own Magneto (stator)
- Thread starter impression
- Start date
No biggie on the rewind, I have lotsa wire left. Question, Rohmell. How should I test the output of my magneto to compare it to the OEM's output? I mean, what type of testing unit needs to be used? I figure if anyone would be able to answer this it will be you or maybe someone else reading this. Any help is appreciated.
You could wind another coil with a steel core and place it where the magnet goes. Energize that coil with a signal at a specific level and read the outputs of a stock magneto and compare it to the ROLL-YOUR-OWN magneto:
EDIT: You might not have to wind a coil, maybe you have a solenoid or an old relay that you could salvage from it a ready-made coil.
Essentially you are trying to create a transformer, and use an external coil as your primary, and the magneto's coils as the secondary.
EDIT: You might not have to wind a coil, maybe you have a solenoid or an old relay that you could salvage from it a ready-made coil.
Essentially you are trying to create a transformer, and use an external coil as your primary, and the magneto's coils as the secondary.
Last edited:
Awesome idea,
Simple yet effective. Of course I am very limited to my testing equipment, boiling down to a DVOM and a clamp on amp meter. I do think the clamp on reads small dc amps fairly well, so I may be able to compare that as well as the voltage output. I like the iron core with magnet wire wound on it, then hook up a 5 VDC power plug. A place to start, anyway. Thank you very much for the information.
Simple yet effective. Of course I am very limited to my testing equipment, boiling down to a DVOM and a clamp on amp meter. I do think the clamp on reads small dc amps fairly well, so I may be able to compare that as well as the voltage output. I like the iron core with magnet wire wound on it, then hook up a 5 VDC power plug. A place to start, anyway. Thank you very much for the information.
Yes, exactly like you taught me on the test circuit ! And the wallwart is exactly what I was thinking.
Edit: or use the ac power supply I made for the CDI test rig. 6.3 VAC.
Edit: or use the ac power supply I made for the CDI test rig. 6.3 VAC.
Last edited:
Rewind photo. As of today I rewound the Magneto and made it through without a wire break. The silly counter failed on me, though. I feel I may have gotten too many turns on which is easiest to fix. I tested the ohms but don't trust my meter. I need to dig out my other unit. This meter read 525 ohms. And that spindle is fully wound ! Almost overfloweth. I just didn't want to stop. Also made my electro-magnet today for testing the magneto. Photos prly tomorrow.
Attachments
Nice work.
I'm shelving the modification stuff for the time being. I may come back to it. But let us know how it all goes ?
I'm shelving the modification stuff for the time being. I may come back to it. But let us know how it all goes ?
Okay, I used the other meter and got 527 ohms, so it was close. I hooked 6 VAC to the electromagnet and suspended it in the magneto. Output on the mag was 6.5 volts AC. Now all I have to do Is remove my OEM mag and test it for a comparison. Don't stay gone too long Impression, I like your input on this project.
Today I tested the OEM mag coil. Used the same magnet and power supply as yesterday. 6 VAC input, 10.2 VAC output. Now I need help figuring out what this means? I was assuming the higher voltage would be what I was trying to acheive? I did forget to mention the OEM mags' ohm reading. 330 Ohms. My rewound unit was 525 Ohm. Okay, maybe the higher ohms means lower volts out but may also mean more punch in the amps department? I think I need to go find ohms law and do some math.
Edit: Looks correct. My hand wound unit puts out about 2.5 times more umph than the OEM unit.
Edit: Looks correct. My hand wound unit puts out about 2.5 times more umph than the OEM unit.
Last edited:
Am I missing something?
You wrote that your magneto measures 527 ohms and puts out 6.5 VAC, and the OEM magneto measures 330 ohms and puts out 10.2 VAC.
Using (E^2)/R your magneto's power is .08W and the OEM's power is .315W.
Even accounting for wire resistance losses, I would think that your magneto with more windings would be more powerful than the OEM magneto.
You wrote that your magneto measures 527 ohms and puts out 6.5 VAC, and the OEM magneto measures 330 ohms and puts out 10.2 VAC.
Using (E^2)/R your magneto's power is .08W and the OEM's power is .315W.
Even accounting for wire resistance losses, I would think that your magneto with more windings would be more powerful than the OEM magneto.
Yes, you have the numbers correct. At this point I am dumb-struck as to what I did wrong. I will do a re-test within the next few days and will try to borrow a much better meter than my own. Thank you for your help.
I think you should try your measurements again.
The external coil's core should be in contact with both of the magneto's arms, rather than thru an air gap.
Use steel nuts, washers, whatever so that the external coil makes good contact on both arms, so that the magnetic flux energy can be easily transferred.
The external coil's core should be in contact with both of the magneto's arms, rather than thru an air gap.
Use steel nuts, washers, whatever so that the external coil makes good contact on both arms, so that the magnetic flux energy can be easily transferred.
Last edited:
Funny you should mention these dimensions. Here is a pic of everything in question. The electro-magnet is a steel cored barbell design that was easy to chisel out on the lathe. Common sense has taught me that magnets work best when in contact, so I decided to use an interference fit. The barbell is 1.311" long. Opening on OEM mag is 1.308" and rewound mag measures 1.303". Yes a tight fit on the rewind but certainly not over-done. If I were to take the fit down to same dimensions all around I felt that minor flexing could occure causing the magnet to oscillate or vibrate when energized.
Attachments
I didn't know that you still had the lathe 'winding rod' attached to the core.
This would increase eddy currents and losses in the core due to the welding of the rod shorting out the laminations, which are insulated from one another.
This might be clutching at straws, but maybe remove that winding rod, and clean away any weld material from the core, maybe even grinding, to try to restore to insulation between the leaves of the laminated core, and give it a whirl again.
This would increase eddy currents and losses in the core due to the welding of the rod shorting out the laminations, which are insulated from one another.
This might be clutching at straws, but maybe remove that winding rod, and clean away any weld material from the core, maybe even grinding, to try to restore to insulation between the leaves of the laminated core, and give it a whirl again.
Well, removed the stud and all the weld, ground everything flat and smooth. I can see every single leaf and see that there is no contact. Randomly checking for continuity I find it everywhere, drat. Some places more than others. Get a wild idea and check out the OEM mag. Guess what? Random continuity in that one as well. And the OEM unit has not been touched at all. Makes me think a bit different about this magneto gig. Maybe I need to make the entire unit myself and do it the way it would be if it was made in the USA.
That would be a lot of work, but then you would have an ultimate and correctly assembled magneto.
The problems that you are finding with the laminations is probably why one kit's magneto will be powerful and reliable, and work for years and another one will be weak and maybe fail in a short period of time.
It is amazing the variation in quality of assembly between one piece and the next.
EDIT: Now that I am thinking about it, perhaps I have seen magnetos with a bead of solder running across the laminations to connect them electrically?
The problems that you are finding with the laminations is probably why one kit's magneto will be powerful and reliable, and work for years and another one will be weak and maybe fail in a short period of time.
It is amazing the variation in quality of assembly between one piece and the next.
EDIT: Now that I am thinking about it, perhaps I have seen magnetos with a bead of solder running across the laminations to connect them electrically?
Last edited:
It won't be too hard, just need to make a cad drawing of the leaves and then send to a sheet metal fab shop that has a turret punch and does prototyping. It just may cost a bit, but I could probably get like 500 for the same price as is required to do one. Laminating them is easy if to have a hydraulic press. Choosing the insulating paper for between the leaves will take a little research. If money is no object, anything can be had. Sadly, money is always and object
I believe that these magnetos simply use a shellac or lacquer coating as insulation between the laminations. Maybe the existing magneto core can be immersed in a solvent to remove all traces of the insulating coatings, disassembled,and then the individual leaves of the laminate can be recoated properly and reassembled?
Has anyone rolled their own magneto without the infamous "White Wire"? It seems to me that without the secondary winding, you could add additional turns to the spark coil, resulting in extra spark.
Any ideas on this?
Any ideas on this?