Re: [CAD_CAM_EDM_DRO] Simple Linear Encoder?

edfasula wrote:

>I'm building a hydraulic press for hot metal work. It will be
>outfitted with a 12 V solenoid valve to allow an automatic mode
>where the ram repeatedly engages the metal and returns.
>
>Since the ram speed is fixed, I plan to set the speed of the
>repetition by adjusting the length of the return stroke. I'd like
>to be as accurate as I can in setting the depth that the ram
>advances into the hot metal before it returns.
>
>Others have done this with a set of limit switches, but before I did
>that I thought I'd have a look for alternate options. One thought I
>had was a small (cheap) surplus servo motor with an encoder, fitted
>with a spur gear that would run on a rack. I don't know what would
>be required for reading the location and turning it into a signal,
>though.
>
>

You can probably buy commercial counter units that will count encoder
pulses and close
a contact when a preset number of pulses happen. If a switch starts the
counting at some
reference position, then the counter's switch closure can flip the
hydraulic valve to reverse
the ram. If you will always be moving the same distance, then this
should do it. If you
need to automatically increase the depth of stroke each cycle, then it
gets a bit more
complicated. Red Lion Controls, I think, make some devices like this.
They are in the
relay and industrial controls section of catalogs like Newark and Digi-Key.

Jon