How to Achieve Accurate Depth of Cut on a Manual Lathe

Manual machines can be tricky to achieve an accurate depth of cut.

Often, we move the slide the correct amount according to the dials but find ourselves taking not enough material off, or even worse, too much. In this video, Marc from G Code Tutor shows us some tips and tricks to eliminate this inaccuracy when turning both lengths and diameters.

One of the tips is to use gauge blocks (often called slip gauges) between the saddle and the end stop.

This enables us to turn very accurate lengths on a machine without a digital readout. Care must be taken to protect the expensive gauge blocks when used in this way so that they are not damaged.

When we need high accuracy, we can also place a Dial Test Indicator on any moving surface to measure how much we are moving the slides by. This is a technique that is often used when thread turning to achieve the tight tolerances that are required for this operation.

Marc takes that technique one step further and suggests using a D.T.I. during the finish turn procedure so we know exactly how far our slides are moving.

We still have to allow for slight errors due to bar deflection, but by using this technique we can achieve very accurate work on any manual lathe.