Mill DRO Errors?

[qualitymachinetools]

Be sure to click the CC option at the bottom of the player to see the captions. (Video sucks yes new videos for everything are in the works, but it will give you an idea if you pause it step by step) Set all scales to 5.0 res and you will be set. The math is working out with the .2 setting and then Metric on the display. 5.0 in the parameters, and Inch on the display should get you there.

 

[RJSakowski]

Head alignment will not impact the measurement process. I think that you have shown that the error is in the scale calibration. Dial errors occur if metric lead screws are used and the dial reading is an approximate inch value. A ".100"/turn" dial on a 2.5mm lead screw would move 25 mm or .984" in ten turns. Curiously, this is a .016"/1" error but it is in the wrong direction based on what you have experienced.

As far as I know, DRO scales are inherently metric, either 1micron, 5 micron, or 10 micron; and inch readout is done by a conversion factor. I would try using the metric readout. For 1 inch of travel, you should be reading 25.400 mm. If you are reading correctly, the conversion factor is wrong. If you are reading 25.806 or thereabout, I would suspect the scale calibration.

 

[mksj]

See below, do a reset of the DRO, make sure the shrinkage is off and redo the scale resolution.

 

[hwelecrepair]

One thing to look at, is that you have multiple places where this accuracy can be lost. Rock in the table/saddle, head movement, and actual knee movement/rock could also be causing this.

Was the DRO installed at the factory or by you? An improperly mounted scale can also cause accuracy issues.

Jon

 

[BobRock]

@qualitymachinetools figured it out. My DRO setup was for .2um scales (instead of 5um scales) and in metric (not imperial) mode. The wild thing is that with that combination of incorrect parameters, the display and the increment in movement was at least plausible for inches!

 

[BobRock]

Also, kudos to @qualitymachinetools for very fast and accurate technical support. If you are thinking about a mill or a lathe, don't forget the importance of good US-based help.

 

[hwelecrepair]

@BobRock To clarify, did you mean 2um or .2um? Never heard of .2um.

Jon

 

[BobRock]

@BobRock To clarify, did you mean 2um or .2um? Never heard of .2um.

The "resolution for encode" DRO parameter was set at 0.2um. Mine has a large number of possibilities including .2, 2, and 5um.

 

[hwelecrepair]

@BobRock Dang, never heard of a .2um. I mean, it is just resolution, but its just not one I have seen.

Thanks

Jon