Hall Effect Tachometer Magnet Inbalance?

Squiddy202

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I want to make a small Arduino based tach/speedometer for my kart. If I just put one light neodymium magnet on the driveshaft/output shaft would that screw up my kart? It would theoretically, but mine already shakes like crazy because I go off-road with it. Any thoughts?
 

Kartorbust

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You might have better luck getting a wheel tone ring from say a Miata and trying to adapt it to the live axle and use a wheel speed sensor through Arduino. Then far as a tach, get one that reads off the spark plug.
 

Squiddy202

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What if I got one with a hole through the middle that can be bolted on? Would that then make the imbalance worse? I would need to put a hole in stuff. Then I couldn’t do a tach either. Optical would get covered in dirt I think. What would you do?
 

Squiddy202

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You might have better luck getting a wheel tone ring from say a Miata and trying to adapt it to the live axle and use a wheel speed sensor through Arduino. Then far as a tach, get one that reads off the spark plug.
What if I measured to ratios from the output shaft to the wheels and used the tach reading to calculate speed? It would vary based on small things like wheel PSI. The Miata tone ring sounds good, but a little out of my field. The tach speedo would be inaccurate at low speed from centrifugal clutch. Would it work at high speed?
 

Kartorbust

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You might be able to do that, but I haven't seen anyone do it that way. Most get a GPS speedometer app for their phones and use that.
 

Edwin Spangler

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What if I get one that can be bolted on?
If it can be bolted through, while also through the crankshaft, while also through a non-magnetized counter weight, then it would work.

The SLIGHTEST imbalance is asking for bearing failure.
 

Squiddy202

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If it can be bolted through, while also through the crankshaft, while also through a non-magnetized counter weight, then it would work.

The SLIGHTEST imbalance is asking for bearing failure.
In that case I will just add a weight or make it have dual magnets. I am just gonna use the spark to do tach so this would be for speeds. I am somewhat confused by your wording, as magnets come in packs I would bolt two through holes on the drive sprocket at either end of the sprocket. If I get nuts & bolts the same size it should be pretty much perfectly balanced right?
 

Edwin Spangler

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In that case I will just add a weight or make it have dual magnets. I am just gonna use the spark to do tach so this would be for speeds. I am somewhat confused by your wording, as magnets come in packs I would bolt two through holes on the drive sprocket at either end of the sprocket. If I get nuts & bolts the same size it should be pretty much perfectly balanced right?
I misunderstood. I thought you were drilling through the crankshaft. Disregard that then. Yes it would be balanced the way you describe.
 
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