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kayaker
09-27-2012, 09:50 AM
A stupid question from a complete beginner. That said, here it is. . .

I am putting a magnetic scale style DRO on my milling machine. Will the magnetic scales or reading heads be damaged or generate measurement errors if I use strong magnets to attach items to the mill. Example, magnetic base that hold DTI's, or magnets to hold plastic chip guards covering ways of z-axis column and back of y-axis, etc?

Thanks in advance.

MaxHeadRoom
09-27-2012, 10:18 AM
It shouldn't have any effect, the inductive pick up on the scale usually has a two secondaries that are excited from a high frequency primary.
http://www.meas-spec.com/downloads/Principles_of_the_LVDT.pdf
The stationary field from a magnet does not normally affect them.
Max.

kayaker
09-27-2012, 02:57 PM
It shouldn't have any effect, the inductive pick up on the scale usually has a two secondaries that are excited from a high frequency primary.
http://www.meas-spec.com/downloads/Principles_of_the_LVDT.pdf
The stationary field from a magnet does not normally affect them.
Max.

Thanks Max.

ikdor
09-28-2012, 03:10 AM
Well, I think that depends a bit on the type of magnetic scale. If it's indeed using a transformer principle you're fine, however if you're using a magnetic tape I wouldn't touch the tape with the magnet. A magnetic chuck a few inches away I wouldn't be too worried about though.

Igor

kayaker
09-28-2012, 07:50 AM
Well, I think that depends a bit on the type of magnetic scale. If it's indeed using a transformer principle you're fine, however if you're using a magnetic tape I wouldn't touch the tape with the magnet. A magnetic chuck a few inches away I wouldn't be too worried about though.

Igor

I bought the Electronica magnetic scale kit sold by DRO PRO in the U.S. I'm not sure how that kit factors into the type of scale you describe, but the magnets I use to on the mill are definitely within 2" - 3" from where the scales will be mounted.

MaxHeadRoom
09-28-2012, 10:19 AM
The 'Magnetic Tape' or the Ferrand Inductosyn principle is also pretty immune to any outside interference.
http://www.ruhle.com/rotary%20transducers.htm
Shows rotary type, but linear is the same principle.
Max.