Lathe Thread Gauges

I've read a lot of metalworking books that recommend setting your top-slide to an angle of 30° or 29.5° (relative to the cross-slide feed direction). The mini-lathe has angles scribed on a little protractor; these are relative to the saddle feed direction. I've never checked, but I'd be surprised if these are particularly accurate. In the past, whenever I wanted to set an angle accurately, I get the protractor out and try (often in vain) to get it into a position where it will measure the top slide angle.

Around this time, my work had decided it would be a good idea to get a 3D printer. It would seem a shame not to try it out! This seemed like a good project - design a little alignment gauge for threading. In the photo below, you can see the fruits of my efforts - one gauge for external threading and one for internal threading. They're extremely easy to use: hold them up to the top-slide and tighten the two M6 screws holding it in place.

The Gauges:

The holes in the corner are simply there to make it easy to hang them on a nail on the wall.

Using the External Thread Gauge:

The gauges were modelled using the (frankly amazing) 3D CAD library OpenJSCAD.org. If you're using a modern browser (I've only tested this with Chrome and Firefox; it almost certainly won't work in Microsoft Internet Explorer), you will hopefully see a 3D model of one of the gauges below.

You can drag it around (left mouse button to rotate, middle mouse button to move) to view it from different angles. You can also adjust many of the parameters that make it (the option to make a gauge for internal threading is probably the most interesting) and press update to get a new 3D model! If everything works, you can then generate an STL file that can be used with a 3D printer.

If the model below isn't working for you (it may take a few seconds to appear as your browser creates the model dynamically), send me a message with the contact form and I can email you an STL file for printing.