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How Do You Remagnitize A Switchable Mag Base?
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4GSR
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It died..... Would you like to have a formal burial for it here on H-M?
Seriously, I'm not aware of any process, electrical or otherwise, that will restore the magnetic flux in a magnetic core such as in a magnetic base.
You could wrap the core with a heavy insulated wire from end to end, say a 6 ga. Attach the ends to your welding leads, set at a low setting. Turn on and off a few times. It may restore some of the magnetic flux and may not. Find someone with a Magnaflux machine. They might be able to zap it and regain some of the flux. Bottom line, I don't think there is any way to completely restore the flux. I could be wrong....
Seriously, I'm not aware of any process, electrical or otherwise, that will restore the magnetic flux in a magnetic core such as in a magnetic base.
You could wrap the core with a heavy insulated wire from end to end, say a 6 ga. Attach the ends to your welding leads, set at a low setting. Turn on and off a few times. It may restore some of the magnetic flux and may not. Find someone with a Magnaflux machine. They might be able to zap it and regain some of the flux. Bottom line, I don't think there is any way to completely restore the flux. I could be wrong....
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I do not know who does this professionally, except maybe certain audiophiles working on very expensive speakers. The question in your title is interesting. There was not a lot of info on re-magnetization but i found a readable PDF.
How do you remagnetize switchable mag base?
How do you remagnetize switchable mag base?
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- Jan 18, 2016
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- 398
I have lost the location but i had copied the information.
The question was about losing magnetic power after dismantling a mag base assembly and what could be done about it: The name at the bottom is from whom the information is derived.
Sorry for the double post. I thought this may be helpful after i noticed that 4gsr/ken had replied.
Lken
1. What is the the composition of the material which rotates inside the assembly?
This material is typically Alnico magnet material. It is an older magnet material type. it doesn't have particularly good resistance to demagnetization, which can occur if you do not remove such a magnet from its ferromagnetic surroundings in an "optimum" manner. For this reason, many assemblies containing Alnico magnets are magnetized AFTER assembly.
2. How do the constituent parts of the magnet operate to create a magnetic field that can esentially be turned "on" and "off"?
The "secret" here is that the bottom surface of the device is typically designed to concentrate the magnetic flux density generated by the magnet, into a small area of contact. It does this when the magnet is in the "on" position - the flux flows from one pole to the other, through the steel part it is resting on. The unit is designed so that when the magnet is in the "off position", when the magnet is physically rotated to a particular position, the flux prefers to loop inside the device from one pole to the other, rather than going externally through your piece.
3. This is the crux of why I am writing -ahem- Once disassembled why is the previously strong magnetism totaly lost?
This is a combination, perhaps, of the disassembly "knocking down" the magnet, and of the fact that the magnet, even in the fully magnetized condition, will not generate as strong a pull force as you would by concentrating the flux it generates through narrow pole pieces.
4. I know the assemblies can be re-magnetized; can this easily be done? What can be experimented with to do this on a small scale?
Typically you would need to re-magnetize such a magnet in a solenoid - on an industrial scale magnets are generally magnetized using such solenoids that are hooked up to capacitance-discharge machines, which pump a lot of current through the coil for a split second. You have to watch when doing this for Alnico magnets, as you can sometimes get a "back pulse" at the end of the pulsing cycle that will slightly demagnetize the magnet. So, you need specific equipment for Alnico. You could try using other stronger permanent magnets to re-mag it, but that would be difficult - and you still have the problem of re-assembling it properly.
Also remember that the magnet is probably not as strong as you think it would be, even when fully magged, for the reasons given above.
Hope that helps!
One other point - there is a rule of thumb that the pull force a magnet or magnetic device exerts, is proportional to the area, multiplied by the square of the flux density at the pole faces. So although a reduced area would tend to lower this value, increasing the flux density by making pole pieces narrower [thus "squishing" more flux into a given area] more than compensates because of the squared effect.
Gareth Hatch
Director of Technology
Dexter Magnetic Technologies Inc.
The question was about losing magnetic power after dismantling a mag base assembly and what could be done about it: The name at the bottom is from whom the information is derived.
Sorry for the double post. I thought this may be helpful after i noticed that 4gsr/ken had replied.
Lken
1. What is the the composition of the material which rotates inside the assembly?
This material is typically Alnico magnet material. It is an older magnet material type. it doesn't have particularly good resistance to demagnetization, which can occur if you do not remove such a magnet from its ferromagnetic surroundings in an "optimum" manner. For this reason, many assemblies containing Alnico magnets are magnetized AFTER assembly.
2. How do the constituent parts of the magnet operate to create a magnetic field that can esentially be turned "on" and "off"?
The "secret" here is that the bottom surface of the device is typically designed to concentrate the magnetic flux density generated by the magnet, into a small area of contact. It does this when the magnet is in the "on" position - the flux flows from one pole to the other, through the steel part it is resting on. The unit is designed so that when the magnet is in the "off position", when the magnet is physically rotated to a particular position, the flux prefers to loop inside the device from one pole to the other, rather than going externally through your piece.
3. This is the crux of why I am writing -ahem- Once disassembled why is the previously strong magnetism totaly lost?
This is a combination, perhaps, of the disassembly "knocking down" the magnet, and of the fact that the magnet, even in the fully magnetized condition, will not generate as strong a pull force as you would by concentrating the flux it generates through narrow pole pieces.
4. I know the assemblies can be re-magnetized; can this easily be done? What can be experimented with to do this on a small scale?
Typically you would need to re-magnetize such a magnet in a solenoid - on an industrial scale magnets are generally magnetized using such solenoids that are hooked up to capacitance-discharge machines, which pump a lot of current through the coil for a split second. You have to watch when doing this for Alnico magnets, as you can sometimes get a "back pulse" at the end of the pulsing cycle that will slightly demagnetize the magnet. So, you need specific equipment for Alnico. You could try using other stronger permanent magnets to re-mag it, but that would be difficult - and you still have the problem of re-assembling it properly.
Also remember that the magnet is probably not as strong as you think it would be, even when fully magged, for the reasons given above.
Hope that helps!
One other point - there is a rule of thumb that the pull force a magnet or magnetic device exerts, is proportional to the area, multiplied by the square of the flux density at the pole faces. So although a reduced area would tend to lower this value, increasing the flux density by making pole pieces narrower [thus "squishing" more flux into a given area] more than compensates because of the squared effect.
Gareth Hatch
Director of Technology
Dexter Magnetic Technologies Inc.
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- Mar 14, 2014
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They recharge the magnets in magnetos with a magnet charger, im not sure if it would work on a mag base, try some of the local Hit and Miss engine collectors in your area, they may be able to help. If i was closer, We could have at least tried.
Tom
Tom
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Inserting new magnets would be interesting to see. If the base is one of the generic cube type, the polarity is likely along the long axis of the cylinder and not across the cylinder like we are most familiar with. Not impossible to find, but certainly not as run of the mill as the standard button magnets we all have kicking around. That is only one style of base though, others might be easier.
-frank
-frank
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You don't, you buy a new one for less then $40.00
I just dug out an old brown and sharpe that I found in the garbage years ago and the magnet has always been able to be pulled out. I tried to find the poles with another magnet and I couldn't even tell where it changed. So while it may be possible to insert new magnets I think it would be more work then its worth.