Threading on Mini Lathe - illustrated guide 2

Page 1

Three - Make Start and end channels

Next I use my parting tool to make a channel at each end of the section to wish to thread. These channels give me somewhere for the tool to start and end on each thread cutting pass. Using the parting tool is the easiest way to make these channels. Its probably not the best way - the parting tool flexes and therefore the walls of the channels may not be perpendicular. However, it is good enough for our purpose.

This image shows the completed channels. As this picture came out very well, you can see the nice smooth surface ready to be threaded. Now we are ready to mount our threading tool.

The threading tool is a pointed tool with 60 degree sides. Its important to make sure the tool is very firmly mounted in the tool post. If it moves you are buggered. The tools should be mounted nice and perpendicular to the job. You can see that my threading tool is slightly chipped at the tip. Its fine for this example, but I ought to visit the tool shop again soon.
Set the correct threading tool advance angle.

Now that the tool is mounted we are ready to thread. From now on the tool must not be adjusted in its holder, and the job must not be moved in the chuck. Wind the tool in towards the job until it just touches the job, and look at the scale and note the reading. On the picture to the left we see its just to the left of the 28 mark. You will notice that there is always some small amount of backlash in the adjustment. Because thread cutting requires us to repeat the position of the tool, we must always finish moving the tool by winding IN. If you go to far, wind out a lot, and then wind back IN until you get to the required point.

Page 3

Mini-Lathe Beginners

Threading on Mini Lathe - illustrated guide 2

Three - Make Start and end channels