Re: [CAD_CAM_EDM_DRO] rotary hand encoder wheels with detent

Even better is you can use these steppers to generate the encoder
signals.. No need for the encoders...

Garry

To: CAD_CAM_EDM_DRO@yahoogroups.com
Organization: Pentam Aerospace
From: Doug Fortune <pentam@...>
Date sent: Wed, 13 Feb 2002 19:48:58 -0700
Subject: [CAD_CAM_EDM_DRO] rotary hand encoder wheels with detent
Send reply to: CAD_CAM_EDM_DRO@yahoogroups.com

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Alan Marconett KM6VV wrote:

> Are you saying that the pulse generating hand wheels
> actually have some force feedback, or that you can
> feel the steps (detents?) of the encoder? So once
> zeroed, their scales remain accurate to position,
> just like a manual mill?

How about just using a big knob connected to a small
dual shaft NEMA 17 or NEMA 23 stepper motor (to give
the quality 'feel' of detents), and add an encoder to
the back of the stepper for feedback to the computer.

The stepper motor is not connected up, its just there
to add the 'feel'.....

If the encoder has the same resolution as the steps
of the motor, so much the better.

Here is an improvement: I just grabbed a slo-syn NEMA23
200 step stepper off the the shelf (this one is dual stack)
to 'feel' it, and it does feel nice.. those little
detents just whip off...

However, shorting some of the leads causes the motor to
be difficult to turn (this is no surprise), so much so
that individual steps can be felt and almost counted! ..
it is hard to turn it more than 10 or 15 steps/second....
so that it would be easy to rotate into a given particular
spot without overshooting it. Thus maybe a pushbutton
should be placed on the panel somewhere to put the
'encoder wheel' into this mode for
'sneaking up' to a precise position.

Everybody try this at home with your spare steppers!

Also note that the real cheap 7.5 degree or 15 degree
steppers could also be used, if you wanted 'big hops'
between steps, instead of little mini ones.

Doug Fortune
http://www.cncKITS.com


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