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### Author Topic: Probing speed  (Read 650 times)

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#### joeaverage

• 6,219
##### Re: Probing speed
« Reply #10 on: November 15, 2018, 03:46:59 PM »
Hi,
just to show how the calculation works I will demonstrate using the parameter of my mill, namely acceleration of 375mm/s2.

At 50mm/min approach:
V=50/60
=0.8333 mm/s
ts=V/a
=0.8333/375
=2.22ms
d=0.5 * 375 * (0.002222)
=0.925um
ie the overrun is les than 1 um, plenty good enough accuracy.

At 100 mm/min:
V=100/60
=1.666mm/s
ts=1.6666 / 375
=4.444ms
d=0.5 * 375* (0.004442)
=3.7 um

ie at 100mm/min the overrun is about the same as the accuracy of my machine, ie its acceptable.

At 200mm/min:
V=200/60
=3.33mm/s
ts=3.333/375
=8.88 ms
d=0.5 * 375* (0.008332)
=14.8 um

ie at 200 mm/min approach the overrun is nearly 15um and about three times the accuracy of my machine. If I am probing normal 1 oz board,
35um copper, then the probing overrun amounts to 43% of the thickness of the copper layer which is unacceptable.

Craig
My wife left with my best friend...
and I miss him!

#### RICH

• 7,412
##### Re: Probing speed
« Reply #11 on: November 15, 2018, 10:21:37 PM »
See attached FWIW.
RICH