Project: Cam-Action Quick-Change Tool Post

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One of the greatest accessories you can add to your lathe is a quick change tool post (QCTP). The most important benefit is convenience and time savings, but precise control of the tool height is another major advantage.  Each cutting tool has its own dedicated holder and height setting and can be swapped in or out of the tool holder in seconds. Since the tool height has already been set in advance, you don't waste time fooling around with shims. Because the tool is at exactly the right height the quality of your work is improved.

Very nice commercially-made QCTPs are now available from Phase II and TS Engineering and are an excellent choice if you don't want to invest the time and effort of making your own. For some of us though, there is real satisfaction in making something ourselves - after all, that's why we have machine tools, right?

Besides the enjoyment I get from designing and making my own tools, I like the fact that I can make extra holders when I need them and can make holders for special purposes. For example, I prefer to use 3/16" tool blanks for most of my work and the commercial QCTPs are not designed to handle such small tools. I have also designed the tool holder to be able to cut very close to the face of the chuck which comes in handy when parting and threading small parts.

Over the last two years or so, I have played around with a number of QCTPs of my own design. Most of them worked pretty well but each had one or more shortcomings that made me continue to strive for a better design. Presented here is an original design that I'm very pleased with. A rear-mounted cam lever actuates a piston that locks the toolholder with light fingertip pressure. The action is silky-smooth and very pleasant to use, yet holds the tool very tightly.

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Each tool holder has its own height adjustment with a self-locking feature. Tool height can be adjusted to within .001 in seconds and, once set, will retain the proper setting indefinitely. For boring operations, the toolpost can be swung around 90 degrees so that the dovetail is parallel with the ways.

While not simple to make, I think you will find it to be a very interesting project and will be very pleased with the end result. As always, dozens of close-up color photos, dimensioned drawings and helpful tips will guide you to a successful result.  Among the skills that you will learn is how to cut precisely mating dovetails.

Skill Level: Intermediate / Advanced

Topic Length: Approximately 50 pages when printed

Tools and Materials Needed

Materials Needed:

  • 1/16" drill rod, 1" length (for camshaft cross-pin; wire brad could substitute)
  • 1/8" drill rod, 3" length (for camshaft handle)
  • 3/8" drill rod, 3" length (for camshaft)
  • 3/8" dia. brass round, 2" length (for cam; or turn down 1/2" stock to 3/8")
  • 1/2" dia. brass round, 3" length (for camshaft bushing and toolholder height collars)
  • 3/4" dia. aluminum round, 3" length (for piston)
  • Aluminum block 1 1/2 x 2 x 5/8"  (one for each toolholder; thickness depends on tool bit size, see Part 3 for details)
  • Aluminum block approximately 2 x 2 x 1 1/2 (for toolpost block)
  • 1/8" dia. Teflon rod; 2" length (for setscrew locking plugs)
  • 4-40 x 1/8 set screw (1 for each toolholder you plan to make)
  • 8x32 x 3/4" socket head cap screw (1 for each toolholder you plan to make)
  • 6-32 x 1" socket head cap screws (2 ea. for 3/16" tool bit holders)
  • 8-32 x 1" socket head cap screws (2 ea. for 1/4" tool bit holders)
  • 10-32 x 1" socket head cap screws (2 ea. for 5/16" tool bit holders)

Note: as always, it is a good idea to have extra materials on hand in case you make a mistake during any of the operations.

Tools and Supplies Needed: