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Probing Without Locking the Spindle


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Is it possible to run a Renishaw probing macro without locking the spindle? What type of errors would be potentially introduced. Some machines do not have an M19 command, or have it disabled for various reasons.

In this situation, some people use hacky workarounds to lock the spindle for probing, such as an adapter plate that gets attached to the spindle, and a custom collar with a dowel pin on the probe. The probe (with its collar) gets inserted into the adapter plate on the spindle - locked into place by the pin - an accident waiting to happen. You have to remove the pin or collar if your tool change laser/macro spins the spindle.

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41 minutes ago, mayu said:

Is it possible to run a Renishaw probing macro without locking the spindle? What type of errors would be potentially introduced. Some machines do not have an M19 command, or have it disabled for various reasons.

In this situation, some people use hacky workarounds to lock the spindle for probing, such as an adapter plate that gets attached to the spindle, and a custom collar with a dowel pin on the probe. The probe (with its collar) gets inserted into the adapter plate on the spindle - locked into place by the pin - an accident waiting to happen. You have to remove the pin or collar if your tool change laser/macro spins the spindle.

In short: No.

You typically need Spindle Orientation and Macro Variables to be installed on any machine which would be doing Spindle Probing.

I've seen people try and do all kinds of strange hacks over the years, and it usually ends up with a mistake being made, or inaccurate Probing results.

Many machine tool builders will implement some kind of "Uni-directional measuring option", for obtaining the highest accuracy. In these cycles, the Probe will not just "lock into a single position". With uni-directional measuring, the M19 is commanded with some type of "position command" (Could be "S"), but rather than "decimal degrees" for the position, (EX: S0. or S180.), the position is output in "encoder counts", where 90.=S1024., 180.=S2048., 270.=3072. and 360.=S4096. Using the M19 Sxxxx command, the machine's spindle is positioned every surface being measured is approached with the same tangent point on the ruby ball. This can cut your measurement error fairly significantly in some cases.

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If your machine does not have spindle lock (M19 usually), any spindle rotation whatsoever during the probing process will result in an inaccurate measurement/calibration. Should this be the case in your machine the only real option you have is to get the values in #502 and #503 to 0. Sometimes this means dialing in your stylus run out to 0 (or less than 1µm), sometimes it means creating run out. #503 and #503 are where the trigger points are.

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16 minutes ago, Colin Gilchrist said:

Many machine tool builders will implement some kind of "Uni-directional measuring option", for obtaining the highest accuracy.

Our new Mori has a double bump option, rotating 180 degrees between each bump.

This definitely seems to help on 2d offset pickups.

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My take on this subject is to do some testing and find out.  You won't be able to do anything super tight, but chances are you can manually align your probe such that you get somewhat acceptable results.  Z will calibrate fine.  XY will basically have the error of the combined stylus/trigger point runout.  In theory you should be able to adjust it to near zero error, but in practicality it will be a very tough process to achieve.  Will you be able to get it to a sub .001" level.  I think without a doubt yes, and likely pretty easily/quickly.  Sub .0001", maybe not, unless you have a strain gage type probe, then I don't see why not.

What will happen is you will end up with an center offset of 0,0, and all you will end up calibrating is the probe radius, and and offset length

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