Hall effect magnet
 

Recently my Hall effect magnet in my MVVS 58 quit working.When I pass another magnet under the pickup sensor i get spark.Does anyone know how to remove the old magnet to install a new one?Could I find one locally at a electronics shop or do I have to send away for one..Thanks for any info..Steve

RE: Hall effect magnet
 

Steve, getting the magnet out is pretty easy. Most are glued in place with epoxy or JB Weld. Just heat the hub a little with a heat gun or torch. Try the heat gun first. I JB Weld mine in and it takes a torch to free it. Be careful as the magnet will sometimes ooze up and others have popped off. Clean the hole and install a new one. You can get them from CH Ignitions. I order them in bulk from Adams Magnet Products. They are Alnico 5. You need to measure the hole or call MVVS for the size of the magnet.

RE: Hall effect magnet
 

Best magnets I have found come from allelectronics.com
100 for $18..
about .1809 square and .080 thick...I put a .234 hole .085 deep in the hub and press in with some 5 minute epoxy...Never go bad, never come out...:D

How's this for keeping information "close to the vest" ;)

RE: Hall effect magnet
 

Hmm id love to know where to get a .234 drill, I guess 6mm would do eh?

RE: Hall effect magnet
 

5.95 would be closer, You could probably order one from a machine tool supplier.[:-]

RE: Hall effect magnet
 

Thanks for the tips guys

RE: Hall effect magnet
 

Let's not get silly with drill sizes, in reality drills are not that precise, and to measure a drill to two decimal places (metric) is a bit much, after all, 0.05 mm is approx only .002" .
It all depends on the operator's skill, material, how it's been sharpened etc. etc. as to what size hole you actually end up with! :)
You can sharpen drills to cut different sizes - probably up to .005" bigger if you want. Holes in aluminium will vary enormously at different temperatures, and if the hole is too small you can warm it up and the magnet will probably drop in. ( epoxy to make sure).
In short, technique will be more important than the nominal drill size, - save your money I reckon! ;)

RE: Hall effect magnet
 

Rcign is putting a square magnet in a round hole so i am sure you are right about the .05mm not matterring much. when i work it out that magnet would need a 6.5mm hole to slip in(correct me if I am wrong) so a 6mm would probably still be a tight fit.

The reason I answered crustys question like that is cos thats what he asked (well half of it anyway).

RE: Hall effect magnet
 

Yup, the square corners of the magnet make it a press fit, and the 5 minute epoxy ensures it will never come out....Also, mine are not on the outside diameter of the hub, they're on the bottom where centrifugal force has no effect...:D

RE: Hall effect magnet
 

Thanks guys, that all makes sense! ;)

RE: Hall effect magnet
 

Rupurt, I was taking the piss, I think ralph was too, when he gave that silly hole size:D

RE: Hall effect magnet
 

Nope, the hole size is .2337....I get end mills from a tool grinder when they get ground too small for the CNC machines...The .234 was measured with a caliper, the .2337 is exact, measured with a Swiss Etalon 0-1 carbide face micrometer...:D

RE: Hall effect magnet
 

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RE: Hall effect magnet
 

Just FYI, a .234 drill is a common drill size. It is a "A" size drill. It will come in any drill set that includes letter sizes.

RE: Hall effect magnet
 

I reckon the main thing is whether it works or not,- once you get a drill (or cutter) making the right size hole, then lock it away in a safe and only use it only for that purpose, saves endless hassles! :)

RE: Hall effect magnet
 

two sides of the magnets are not the same, take care about negative pole face to the sensor