Re: [CAD_CAM_EDM_DRO] Machine mounted Tachometer with Surface Meter Per minuteThis

Oh yeah there's also gonna be a limit to a Hall/gear tooth sensor
response time. A decade counter to lower the pulse count won't fix
this. If it's too fast, the sensor won't have time to fall after one
tooth leaves before the next tooth rises and it can't find a pulse out
of that. 30K RPM * 6 teeth in a collet= 180KHz. Pretty fast to ask
for. Especially since the collet "teeth" aren't very deep so its signal
level might not drop that far between peaks to begin with even when
going slow.

Danny

On 9/11/2010 2:55 AM, Michael Fagan wrote:
> In order for this to work, you need a gear tooth sensor, which is a hall
> effect sensor with a built in biasing magnet. It will read High when there
> is ferrous metal 0.5-2mm from the sensor
>
> On Sat, Sep 11, 2010 at 03:05, Tony Smith<ajsmith@...> wrote:
>
>>
>>>> Most routers have a nut at the collet. If using non-ferrous metals
>>> (or
>>>> wood or plastic), a hall effect sensor can pick up the points or cuts
>>>> (for ER type collets.)
>>> Can you elaborate a little on how this would work since Hall effect
>>> sensors
>>> are only sensitive to change in magnetic field.
>>> Gaston
>> Google 'gear tooth sensor'. The datasheet for the hall effect sensors
>> usually have this as well.
>>
>> The sensor can pick up the difference between air& steel, if you're got a
>> gear with big enough teeth, it can pick when it's moving. Not sure it'd
>> work with the nut though.
>>
>> Tony
>>
>>
>>
>
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