Quote:
Originally Posted by Al Skierkiewicz
Eli,
I seriously doubt that a CIM driven CNC would give you the accuracy needed or do a better job than stepper motors. The brush spacing won't give you the accuracy needed for precision machining.
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I will see you in 80 days from my trip around the world
Considering that you will gear down the CIMs significantly to achieve the target IPM feeds the brushes are not nearly as significant an issue as they would first appear.
I do not disagree that steppers driving directly into an axis are far more likely to produce the fine control easily that someone would desire for this application.
However even my Mitsubishi HC-KFS43K servo motor with encoders and controller are geared down on my machine.
These are no toy servos.
Especially if the axis in question is a lead screw you immediately gain gear ratio.
Besides I can easily demonstrate my point right now.
Find a really high precision X/Y table in a machine shop and turn the cranks.
Many of them require multiple complete revolutions to travel extremely tiny distances.
You don't even need nearly that level of gearing.
Plus you will be magnifying the trust of the axis by gearing down the CIM.
Put the encoders at the output side of the axis and they will move slower and you can measure where the output is.