Probably best not to attach the bracket via the gib screws – honestly it will be a PITA, there are times when you will surely need to ‘snug them up a bit’ in the middle of some critical or unwieldy job, and the other issue will be that securing the bracket will probably upset the gib setting as you do it.

It is absolutely ‘allowed’ to drill and tap a couple of small holes to allow fixing of measuring devices to a machine.

If fixing into a casting (which is unlikely to be flat) you can use ali. washers filed to a wedge shape or stand-offs to keep things square.

If freehand drilling, a steel block accurately drilled-through with the same bit and used as a guide will help keep holes perpendicular.

DRO on a milling machine is a no-brainer because there are 3 axes, all working from different reference points over longish distances.   Human error is much reduced, including backlash compensation.

I haven’t bothered to fit a DRO on my lathe because the way of working is different.

• I measure distance along the bed and hold it by setting a stop, or by working to a line reference. The dial is mostly for rough positioning, though it’s not the law!    I often go slightly over, make that the reference, and trim accurately to size from the other end – whatever works best.   When accuracy really matters, better than about ±0.025, I use a caliper, template or micrometer rather than the dials.
• Likewise, turning to a diameter isn’t done relative to the axis.  Instead I skim round work to ensure it’s true, then measure from the cleaned up surface as a reference.  To get to 20.00mm, I might rough to about 20.2, then come down to target via 20.1, 20.05, 20.02 etc.   I don’t measure 20.1 accurately, I take much more care at 20.02.   I prefer to compare and fit rather than to  measure absolutely, but needs must – caliper or micrometer when the dial isn’t good enough accurate.   Whilst a DRO on my lathe would undoubtedly be convenient, it’s far from essential.

Ten years ago I fitted a really basic DRO to my mill just to get a feel for it.   Cheap and cheerful, and if it worked out, I intended to upgrade.   Pesky thing refuses to die,  so I’m stuck with it!

Dave

I converted my Sherline mill about a year ago using scales and displays from Arc but found batt consumption troublesome so fitted dummy wired 2032s and plugged into a wall wart with 4 usb outlets and so far so good.

On 12 August 2025 at 07:46 Steve355 Said:

I have a question about lathe DROs, having never used one before.

I get the longwise axis, that makes sense.

On the crosswise axis, one obviously needs to zero the tool at the centre of the lathe axis – not particularly easy to do with significant accuracy, but a careful facing operation might do it, or using a dead centre in the tailstock.

But that’s obviously only relevant to the tool that is being centred. As soon as the tool post is adjusted in any way, the centering is invalidated.

I can also imagine skimming the workpiece, taking a micrometer reading, and then using that. But again it suffers from the fact that any adjustment invalidates the zeroing.

The DRO has a feature that can double the reading, obviously intended to convert a radius into a diameter. But I’m struggling to see the great usefulness of a DRO on the cross-axis of a lathe, given the amount of re-zeroing required.

Hopefully I can be educated.

You zero the x axis by taking a skim, measure the diameter with a mic and set to that value. You can have several different tools set up in memory, so switching between tools it adjusts itself. Doing this using the Chinglish instructions is ‘interesting’, a good subject for a MEW article. DRO is more useful on mill, but I wouldn’t be without mine on the lathe.

I find the DRO really useful on the lathe crosslide. Set it to read diameter, do a skim to get the workpiece round, then measure the diameter with calipers or micrometer. Enter that value into the DRO and then turn the workpiece very accurately to the required size.  I don’t generally need to change tooling because a CCGT insert does facing and turning. But if I did need to use another tool – let’s say I wanted to machine a 1mm deep groove using a form tool – I would just touch off on the diameter, zero the DRO, then machine to -2mm diameter.