Buying a Digital Readout for a mill

[Daravon]

As an equipment manager I have been charged with purchasing an DRO for the school mill. I don't have any idea how to proceed. It says

Clausing
Div of Atlas Press Co.
Kalamazoo, MI
model 8530

And looks rather ancient. I'm supposed to buy a 3-axis DRO for it, with at least +-.001" (the mill is probably worn beyond that anyway). If anyone knows of any place to start looking for one, or if it's possible, advice would be appreciated.

[Griveton]

I might be able to give you a hand.

So, basically you want linear position encoders with a digital readout, or do you already have the signals? How long is the travel in each of the axes?

If you don't have the signals, you have two options:

The first is mounting linear encoders along the whole table. Depending on your size, this might be rather expensive.

The other option is mounting rotary encoders with absolute positioning in the
controls. This will most probably be cheaper, but you'll need to calculate the turn:travel ratio and make the adjustment in the DRO. This will also be a more robust solution, plus, if you insert a servomotor in there (instead of just the encoder), you'll be able to electronically control the machine.

As for the repetibility, 0.001" is not hard to get. I'll get back to you soon with some more specific info.

Do you have a set budget?


[EDIT]

Newall (www.newall.co.uk) might have what you need. I can't give you prices, since you'll have to get a direct quote from them. But their C80 DRO is a rather nifty piece that if I remember correctly, is relatively affordable. Plus, if you don't have the position encoders, Newall does make linear position encoders. I'd suggest you use absolute positioners, since you'll have to set a reference position and travel to it every time you power down the reader otherwise. These encoders have an accuracy of about 0.0004 inches, with a repetibility of 0.00005 inches, which is better than your requirements.

I could probably give you better info (or a better option) with more information, basically:

- Budget
- Travel distance of every axis
- Are there encoders or sensors already in the machine?
- Turn:travel ratio of the cranks used to move the table and spindle. These should be printed in the crank.



Oh, and if you're on a tight budget, you can always eBay for the pieces. You'd be surprised at the interesting stuff you can find in there.