Re: [CAD_CAM_EDM_DRO] Cnc PCB drilling machines z axis linear pot

This is somewhat surprising as potentiometers are:
1. Prone to go noisey
2. Diffiuclt to seal against dust etc
3. Are contact devices and thus liable to wear
4. Are analogue devices and thus less accurate
5. The signal requires conversion to a digital signal before it can be used
(unless the system is fully analogue).

The only advantage would be cost

Regards Peter

----- Original Message -----
From: <byron@...>
To: <CAD_CAM_EDM_DRO@yahoogroups.com>
Sent: Monday, December 10, 2001 3:59 AM
Subject: [CAD_CAM_EDM_DRO] Cnc PCB drilling machines z axis linear pot


>
> On studying many CNC PCB drilling machines I find that most professional
high speed drills with hit rates above 100 drills per minute use a linear
potentiometer on the Z axis [drill depth] instead of a encoder/linear scale.
>
> The X & Y axes could have a linear scale or rotary encoder depending on
accuracy required and end price.
>
> Is there any advantage of using this potentiometer. The Z axis has to do
the most hard work and may retract at speeds of approximatly 10 to 25
metre/minute. Average depth accuracy approximatly 20 to 50 microns.
>
> Look forward to the groups views on this
>
> Byron Damania
>
>
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> [Non-text portions of this message have been removed]
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