A request for information on your mill or lathe

[rgsparber]

I would like to learn the electrical resistance between the spindle and the machine's body of people's mills and lathes using a common ohmmeter. Take a reading, turn the spindle by hand a few degrees, and take a second reading.

If you could supply the make, model, and resistance readings, I would be much obliged.

Thanks,

Rick

[nova_robotics]

Here you go good buddy. Measured with a cheapo low ohm meter and verified against a semi-okay multimeter/oscilloscope.

Standard Modern 11" (Manual Lathe)
0.66 - 1.31 ohms from chuck to ways

Hardinge VMC600ii (CNC 3 axis mill)
Strange readings, assuming it's due to lubrication floating the spindle when it's turned
Let it settle for a minute: 0.97 ohms
Spin it slowly and let it settle over a few seconds 80 ohms
Moving slowly by hand >1k

Chiron FZ 08 KS Magnum (CNC 5/7 axis VMC)
Spindle on XYZB head: OPEN (meter goes >1M, tried lots of things, couldn't get any reading)
Lathe spindle 10k to over 300k. It looks like this is actually open, but there's some capacitance coupling the spindle to ground which changes as the spindle rotates.

Craftex CX600 (Small Manual Mill)
0.09 - 1.2 ohms from spindle to table

Shark HD520 (CNC Router Table)
Spindle is OPEN to table
Spindle is 29 - 77 ohms to Z axis rails

[rgsparber]

Thank you so much for the invaluable information!

Rick

[nova_robotics]

Thank you so much for the invaluable information!

Rick

Whatcha doin'? Making a touch probe?

[rgsparber]

Whatcha doin'? Making a touch probe?

I’m assessing how many people could use my least sensitive version. I’d say all of them which is a big surprise.

Rick

[nova_robotics]

I’m assessing how many people could use my least sensitive version. I’d say all of them which is a big surprise.

Rick

How are you handling the spindles that are isolated?

[rgsparber]

How are you handling the spindles that are isolated?

Resistances greater than 1 ohm aren’t a problem. When we get below 0.2 ohms, my edge finders can’t reliably detect touchdown.

Rick

[Toolmaker51]

I’m assessing how many people could use my least sensitive version. I’d say all of them which is a big surprise.

Rick

We like the legacy version Rick, just the way you are.

Some had our fill of sensitivity several months ago, many even longer; much longer. IYKWIM, LOL.


It interests me still, but have to postpone collecting readings. There are a couple with serious mass between spindle and table.

[rgsparber]

Whatcha doin'? Making a touch probe?

I've already developed a family of Electronic Edge Finders that cover a wide range of spindle resistances. They all compare the spindle to machine body resistance before and after touchdown. My simplest one works down to a spindle resistance of 1 ohm. My most complex ones go down to 0.1 ohms.

Rick

[odd one]

Atlas 12" late 60's to early 70's WELL WORN had been in a production facility.
Spindle to ways .4 - 7.7 ohms High and low readings were repeatable at the same places on the chuck after several revolutions.

Smithy Midas 1220XL probably less that 2 hrs. on machine
.4 - .7 ohms Lathe chuck to ways