Re: [CAD_CAM_EDM_DRO] Capabilities of SPC (digital output) from indicators?

Its measuring repeatability. It is commonly measured and can be achieved by a dial indicatior mounted in the spindle touching off on a vise or any vertical surface at right angle to the table. Touch off and zero indicator and machine control, move away then return to zero then indicator and machine control should be at zero once again. Any discrepancy is the value of "repeatability". Another test is one for backlash. Touch off again with dial indicator and jog control in .001 increments, the number of inputs that fail to read on dial indicator is the amount of backlash present. Many softwares allow the user to compensate for this. Another test requires a precision ground standard that involves touching with the indicator to zero then traveling a known distance to another portion of the standard, and zero on the indicator to test the accuracy of the pitchlead of the leadscrew, handwheels and control over a distance. A 1-2-3 block mounted to the table with a gage-block clamped to one
end would work also. A good test in looking for a used mill is simply grabbing the end of the table and see how much it will shake in and out at right angle to the "Y" dovetail. Quickly tells how much use its had. If adjusting this out of the table with the wedge in the dovetail results in the table locking up towards the end of its travel, the machine is shot.

Ron

softtechinit <JFlanigan@...> wrote:


Other than 'downloading' the current reading from a digital
indicator to a PC, do SPC indicators offer any other capabilities?
For example, can I remotely (i.e. from the PC) re-zero the indicator?

Here is the background for my question: I would like to understand
what accuracies my mill is capable of. I am thinking of writing a
program (script) that will move the table from a known position
(where the indicator has been zeroed) out a known distance, return
it to the starting position and then read the indicator. This cycle
would then be repeated for various travel distances (along the same
axis), re-zeroing the indicator between cycles.

Is an SPC-capable indicator capable of this functionality? Is there
a particular brand of indicator that I should be looking at for this
functionality? Does this test sound reasonable to you?

Thank you for your considerations.

Regards,
John






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