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DRO - Digital ReadOuts on a Mini-lathe

What's the point?

DRO stands for Digital Read Out. In terms of mini-lathes and micro-mills, this means having a digital display of the displacement of one or more of the directional axis.

The usual cheap way of implementing DRO (digital read-outs) on a mini-lathe or micromill is to butcher a digital vernier caliper, and use the digital unit. This unit is then attached to the lathe so that the reading changes as you, for example, move the cross slide.

In my mind, DRO on a mini-lathe is about as useful as a digital RPM indicator on a mini-lathe. Utterly useless.

MY reasons behind this statement?

• Mini-lathes are not terribly stiff. Niether are there tools. There is a fair amount of accumlated slop that means that if I advance the cross slide by 1 mm according to the DRO, I will bet you any money the amount of metal subsquently removed does not turn out to be what you expected according to the DRO.
• It is possible, with professional machine tools, to calculate the correct rate of tool advance and RPM for making a given cut in a certain material. But this is not how we use a mini-lathe. A mini-lathe and a micro-mill are operated by feeling and touch. Not by wathcing numbers of digital readouts.
• To make a part of a particular size, I would never trust the DRO to tell me that I had advanced the tool the correct amount. I would measure the part, advance the tool slightly, measure again. MEasure Measure Measure. This is the key to success with a mini-lathe and a micro-mill.

In summary, if you want to fit DRO to you mini-lathe or micro-mill then go ahead, but I don't think you will find them very useful.

If you are debating whether you should pay extra for having digital RPM and DRO fitted to your new mini-lathe then DON'T BOTHER - waste of money. Spend the money on something more useful.