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Can Repelling Magnets Replace the Spring in a Pogo Stick?

kjmagnetics.com

11–20 of 149 posts

Re: Can Repelling Magnets Replace the Spring in a Pogo Stick?

#11
post #6

Seems like electromagnets could help compensate for distance by drawing more current when far apart, and less when close together. A microcontroller could essentially make the force linear like a spring. Of course, then you need wires hooked up to your pogo, and that might be scary if the microcontroller has a bug (or somehow fails) since you are now essentially hopping onto a railgun.

[deleted]

Re: Can Repelling Magnets Replace the Spring in a Pogo Stick?

#12
post #2

Fully compressed I believe the opposite poles fields begin to attract each other, counteracting the matching poles repelling one another, and explaining the alternating pull force.

This is easily solved by including a minimal height spacer between the two magnets to prevent them from getting too close.

Re: Can Repelling Magnets Replace the Spring in a Pogo Stick?

#13
post #9

TL;DR Yes but not very well. A spring made from magnets doesn't have a close to linear spring rate like a traditional coil spring does.

Coil spring + magnets = success?

You're fundamentally going to be limited by the fact that magnetic force is roughly exponential with regard to distance whereas coil springs are roughly linear. By stacking a bunch of magnets in the article they reduce the travel of any one magnet pair so it's closer to linear. If you look at short enough segment of a graph of an exponential equation it will look linear, this is basically what they're doing.

Re: Can Repelling Magnets Replace the Spring in a Pogo Stick?

#15
post #6

Seems like electromagnets could help compensate for distance by drawing more current when far apart, and less when close together. A microcontroller could essentially make the force linear like a spring. Of course, then you need wires hooked up to your pogo, and that might be scary if the microcontroller has a bug (or somehow fails) since you are now essentially hopping onto a railgun.

[deleted]

Re: Can Repelling Magnets Replace the Spring in a Pogo Stick?

#17

TL;DR Yes but not very well. A spring made from magnets doesn't have a close to linear spring rate like a traditional coil spring does.

But is it linear, from the data? They had two datapoints and projected from that sparse data a regression line.

Re: Can Repelling Magnets Replace the Spring in a Pogo Stick?

#18
post #2

Fully compressed I believe the opposite poles fields begin to attract each other, counteracting the matching poles repelling one another, and explaining the alternating pull force.

This is easily solved by including a minimal height spacer between the two magnets to prevent them from getting too close.

They spacer could even be a spring to add a bit of springiness.. Oh, wait.

Re: Can Repelling Magnets Replace the Spring in a Pogo Stick?

#19
post #6

Seems like electromagnets could help compensate for distance by drawing more current when far apart, and less when close together. A microcontroller could essentially make the force linear like a spring. Of course, then you need wires hooked up to your pogo, and that might be scary if the microcontroller has a bug (or somehow fails) since you are now essentially hopping onto a railgun.

About as scary as my Tesla on autopilot going around a curve at 75mph. Every time I ask myself, what if there is a bug or if it turns off...

Re: Can Repelling Magnets Replace the Spring in a Pogo Stick?

#20

TL;DR Yes but not very well. A spring made from magnets doesn't have a close to linear spring rate like a traditional coil spring does.

But is it linear, from the data? They had two datapoints and projected from that sparse data a regression line.

There are far more than two data points on all of the charts in the article. What chart are you looking at?
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