The DRO we've fitted to the M300 Lathe is a basic chinese import unit with 2 scales, one for the main slide and one for the cross slide. Both scales have a resolution of 0.005mm (5μm) The DRO does have a tool memory and some advanced functions but right now we're not using those so you'll have to re-zero the scales each time you start work, move your workpiece, or change tools. It is vitally important that tool heights are correctly set to the lathe centre-line, otherwise diameter readings will be inaccurate.
Using the Digital Read Out (DRO)
The DRO has two axis’ X & Y; the X is linked to the Cross-slide and Y to the movement of the Saddle on the axis inline with the bed and Chuck.
Setting and using the diameter scale
Turning a diameter turn just enough to clean up a diameter so as to have a completely round diameter with no low-spots (due to any irregularity in the stock material). Once a section has been successfully "cleaned up", bring the tool away on the Y axis only (without changing the cross-slide setting) and measure the diameter with a Micrometre or Vernier Calliper.
When you have established the diameter press the X button (shown right), enter the value and press the ‘ENT’ key to store the value. From now on the DRO will automatically convert radial movement to display anew the diameter on successive cuts. It is advisable to leave a small amount extra on the diameter and re-measure before going for your finishing cut and final diameter for the sake of accuracy.
Setting and using the length scale
Face off the front of your Stock and without moving your Saddle Traverse Wheel the use the Y0 button to the right of the Y-scale to zero it. It's normal convention to regard movement towards the chuck as being in the negative Y direction so your zero point goes on the end of the stock and negative measurements towards the chuck. Then use the method discussed in Turning a Diameter to set the X value.
Turning to a shoulder
Feed just short of the desired length on successive cuts leaving material for your final shoulder face. Check the diameter when you are close to your finished size. Make your final pass and go to your finished Y dimension to then create your finished shoulder then draw the tool out using the cross slide in order to clean up the shoulder.
Find an accurately ground piece of material such a square tool stock or a rule as an edge-finder aid; place this against the face of the work-piece. Bring the Parting tool alongside the edge-finder and rotate up and down whilst maintaining full contact with the end of the stock and using the compound slide to bring the right hand side of cutting edge of the Parting tool so that the edge-finder just rubs against it without being deflected. (This may need to be repeated a few times before you master it). When satisfied, set your Y readout to zero. Move the carriage to the desired length and part off. If you intend to reverse the work-piece in the chuck you could allow a small amount extra so you can then face off a portion to get to your finished length.