Re: [CAD_CAM_EDM_DRO] Dynamics research DRO

LEW BEST wrote:

> Thanks Jon
>
> I did open up the one that doesn't work; found a bunch of swarf in it.
> Plan to do some "real cleaning" on it but haven't yet. Reason for
> questions now is I wanted to start looking for more scales anyway as
> would like to have at least 3; just have 2 now.
>
> On the scale (glass I think) itself there's the number 500 stamped
> (which I assume means 500 lines per inch; also from the model number).
> It has an led plus what appears to be a photo cell. At a glance there
> are no other noticeable electronics.
>
> The display has a mfg date of (I think if I recall right) 1976. This
> came off an old non-working huge non-working horizontal mill talked to
> the scrap buyer at the sale; told him I'd try to buy it and give it to
> him if he wouldn't bid against me as I had no way to move it if he'd let
> me remove the DRO & mist coolant system and he said OK. Gave $37.50 for
> it. Guess I'm lucky anything works! Only controls are on/off and reset
> (or zero; don't recall terminology). If you slide the working scale
> back & forth the reading just keeps adding.

Well, then, the "working" scale isn't actually working right, either. Either
the quadrature decoder in the readout box has gone bad, or the scale is producing
incorrect signals. The reading should go back down when you reverse the
direction of the scale.

You may just want to get rid of all that stuff and start over! (Sorry to have to say
that, but trying to ressurect at 31 year old DRO could be a very difficult project!)

Your 500 = 500 lines/inch may be right, 1976 was before all the DRO makers
went metric. 500 L/I would give .0005" resolution if counting all transitions.

Jon