What is the magnet in a 970 affecting?

[Rancanfish]

I'm playing with a couple of Mag 970's and just realized I have no idea how the magnet in the side plate affects the casting.

The spool is aluminum, so what is affected? The shaft maybe?

[Marcq]

I'm playing with a couple of Mag 970's and just realized I have no idea how the magnet in the side plate affects the casting.

The spool is aluminum, so what is affected? The shaft maybe?

Do a search on Lenz's Law

Marc..

[Rancanfish]

Ah, very good! Never too old to learn something new. Now remembering might be another issue, lol.

[Marcq]

Ah, very good! Never too old to learn something new. Now remembering might be another issue, lol.

Honestly I had to look for it, I couldn't remember 

Marc..

[VW]

Simple explanation as it applies to fishing reels.

The spool does not need to be magnetic, but does need to be conductive. Aluminum is great, very conductive and low mass.

When a spool is placed in the field of the magnet and moved/rotated, flux or eddy currents are created which counter the magnetic field. Or, more pertinent, the magnetic field counteracts the eddy currents from the spool, slowing the movement of the spool.

The stronger the magnet, the stronger the effect.

The larger the spool, the stronger the effect.  The greater mass of the larger spool requires more effect.

The physically closer the magnet and spool, the stronger the effect.  The adjustment on the reel is moving the magnet closer to, or away from, the spool.

The faster the spool is moving, the stronger the effect.

Basically, the effect counteracts momentum so that the only reason the spool continues to rotate is because it is being pulled by the line.

Here is a video demonstrating the effect.   

[Bryan Young]

This is one of the best videos that explain what happens without words in a 2 plane point of view

[jaypeegee]

What do you know of the effect of polarity in this VW?

That is if 5 magents are used in +++++ with distance, Spool weight, magnetic strength being static

the net effect compared to the same magnets used in a +-+-+ or -+-+- arrangement is weaker

I have read that having two magnets stacked together doesn't increase the strength.
But the cartoon horseshoe magnet shape uses a + and - magnet which does aggregate strength.

The reason being that I have seen a mag array that uses reversed polarity in lieu of springs to assist it when adjusting it closer to and further away from the spool
The TronixPro envoy mag

https://www.youtube.com/watch?feature=player_detailpage&v=-kAtTHyjMgg#t=313


What I wondered is not whether this is inherently good for the adjustment purpose but what effect it has on the spool re the eddies or rather, the distance and type or shape of the magnetic field it creates.

[VW]

Stacking magnets does create a larger/stronger magnet. That is one way people "adjust" the effect in non-adjustable set ups.

If you have a multiple position magnet set up, alternating polarity increases the effect.  If the magnets are stacked, each stack would have to be same polarity, but adjacent magnets, or stack, could be opposite polarity.

[Alto Mare]

That 970 has been working great for me, I never had much luck casting with a conventional, I now cast like a pro .
My magged reels are helping with backlash, but also feel much smoother overall.
Here is another interesting illustration on magnets:

[Rancanfish]

Ok theorists, my next question is this;  does the type of magnet actually make a difference? 

The Penn description mentions 'rare earth' magnets for example.

Careful here, we are not talking about strength of the magnet but type. Neodymiums magnets I have seem stronger. But are they, or could they be wrong for this application for the fact they put out too strong a magnetic field?

I'm obviously not checking google (because I'm off to work now but...) this has been on my mind while I perused the photo of the month thread this morning.

Hasta la bye-bye.

[Tiddlerbasher]

Neodymium magnets are fine for reels. I have converted most of my conventionals with these. They really do help to control backlashes and overuns (especially at night when you can't see where your bait is ) Most of mine are simple single fixed magnets. I try to get approx. 5-10 secs freespool with the magnet in-place. Try to get some thin stainless sheet that is magnetisable (not all are). Epoxy the small plate into the left side plate. Now try various size magnets to achieve the desired results. Glue the plate such that the magnet is very close to the spools outer edge for the most effective result.

[Rancanfish]

But now T-basher you are going back to my original question.

As I now understand it, as long as you have a conductive metal spool you shouldn't need to glue anything to the spool. The one magnet is on a threaded post in the sideplate of a 900 series Mag Poeer reel already.

All this makes me wonder why some of the upgraded reels I've seen done here have so many magnets? And on both the sideplate and the spool...

I have to get back to work, I have to pump out three proposals before lunchtime.

[Tiddlerbasher]

You don't need anything attached to the spool
Just have a magnet on a plate glued to the sideplate it works - trust in the magnetic force Luke Play with different strength magnets you'll get there

[VW]

I have not seen magnets attached to the spool.  Do not know how, or even if, that would work.  It would present a problem with keeping the spool balanced.  Someone on this forum did glue metal washers to the end of a plastic spool, and reported it worked OK.

Why so many magnets in some modified set ups?  Most of the OEM magged reels have been Ambassadeur/Millionaire or smaller reels.  The spools are smaller and they do not hold much line.  A single magnet like on the 970, or a plate with a few very small magnets, is enough to get the job done. Now consider one of the most popular reels to modify, the Penn 500.  It is considerably larger. The spool is larger in diameter, has a lot more mass, and it holds several times more line which has mass and contributes to the momentum of the spool.  The fisherman will probably be casting a few ounces of weight, and probably be trying to throw it as far as they can.  That produces some serious r.p.m.'s, and momentum, in the spool.  Most people find it takes 3 or 4 (or more) strong magnets to keep it under control.  

[Tiddlerbasher]

The last Penn 500 I modded used one 20x5 mm neodymium mag. It was a ring mag with a counter sunk hole in the middle (very easy to attach a machine screw to make the whole thing adjustable  )