[mactec54]

Well, I tried to search this forum for the term "JERK FACTOR" and the only thing that came up was your posts. SO........

It does help if you know what you are looking for

Not sure why you replied if you don't know what the problem is when using low count Encoders, ask in the real world you may get the answer if you know what to look for, some high end controls are now including Jerk control in there software to help over come this problem also, even with using high PPR Encoders this is the next step for software developers, here is a snip related to using a control that has advanced jerk control

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Digital signal processing with computer circuits and software has encouraged control engineers to realize more capable control algorithms that today include jerk control. Today, "servos" can be defined as the use of negative feedback for the position, velocity, acceleration and jerk of inertial loads.

"Jerk" is the time rate of change of acceleration. It is the acceleration of the acceleration.
Jerk ramps the acceleration to smooth the velocity. Steps—sharp edges in command values—tend to excite mechanical systems to oscillate at their natural (resonant) frequencies. The bigger the step, the greater this tendency. If a system is not rigid relative to the performance that is expected of it, control over jerk can round the velocity corners. This reduces the amplitudes of the frequencies that excite resonance oscillation. As a result, acceleration factors can be set higher.

With higher acceleration factors, a tool can transition corners and traverse contours of constantly changing curvature at a faster rate, and do so more smoothly when the corners of both the longitudinal and lateral acceleration are ramped.

There are ( 2 ) things that can help to control machine "jerk" Encoder PPR and enhanced software, the control software is out of the range of most Hobby user but High PPR Encoders are not, any good AC servos have a minimum of a 16Bit Encoder, which is available and most Hobby user's can afford, this will help to smooth out a not so rigid machine and add a much better cut performance

The Performance difference between a 1000 PPR Encoder and a 65,536 PPR ( 16Bit ) Encoder you can see it, feel it, and enjoy the end results