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
How it works
Notes on making one
- 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
- 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.
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.