An Undulator is a reciprocrator "on steroids". The key difference is that one of the cams is replaced with another which is not round. There are many shapes, many with shapes like a rosette.

These cams are similar to the oddly shaped cams or gears in a Spirograph, and similarly amazing shapes can be thusly produced.

Additional pictures of this device

Examples of work produced with this device

Examples of this device in use

Usage Notes

How it works

Notes on making one

More Information

Published Articles

  • Amplitude Adjusters by Al Collins. Al explains the history of amplitude adjusters and how they work, then surveys the current crop of these very useful rose engine accessories.
    Ornamental Turners International Newsletter, Volume 27, No. 1 - May, 2020, pg. 16
  • Amplitude Adjuster for an MDF Rose Engine by Rich Colvin.
    Ornamental Turners International Newsletter, Volume 26, No. 2 - Winter, 2019, pg. 23

Books and Papers

  • Hotzapffel, Volume VI by John Edwards. John compiled a great amount of information about this device, starting on pg. 521. The drawings of various cams and associated waves produced explain this topic far better than I could.

Web Sites


  • Scott Barrett gave a demonstration to the club about his undulator. The recording for this video is in the Ornamental Turners Int'l (OTI) member meeting videos, August 2023.


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Disclaimer: eMail comments to me at OTBookOfKnowledge @ Gmail.com. The process of woodturning involves the use of tools, machinery and materials which could cause injury or be a health hazard unless proper precautions are taken, including the wearing of appropriate protective equipment.