digital reader

[clive]

The DRO on my lathe is not reading correctly, out by about .002” in a infeed of .020”. I suspect it needs a good clean but I have no idea what is inside it.Turning it upside down there is a cover in two halves that the reader fits between but I am reluctant to take the ends off to completely dismantle it till I know what is there and what damage I can inflict if I do it wrong.
Anyone know what is in there?
Thanks in advance.

[GWIZ]

How far is it off in 12"?

I suspect you need to load whatever you are feeding to get a good measurement, snug up the locks and make your test, that is if you have locks.

[clive]

GWIZ, it only does about 6”, but I found this https://www.youtube.com/watch?v=_Rs7P1SHIyM which shows what is inside so I’ll give it a good clean and see if that improves it

[clive]

took it apart, cleaned every part of it and put it back together. Still out .001” in .010” so guess it’s new reader time.

[toprecycler]

Originally Posted by clive

took it apart, cleaned every part of it and put it back together. Still out .001” in .010” so guess it’s new reader time.

Is it always consistent .001” off? Depending on the model of the DRO brain unit it may be able to be programmed to the change you need. Try doing a search for calibration of your unit.


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[greywynd]

Some DRO’s will allow a correction factor to be programmed in for things like this. Some of the older ones it was hidden away in parameters, some of the newer ones are a little easier to find.


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[Shade Tree Welder]

My unit has internal calibration marks, you have to move the X and Y enough when powering up the machine before you start using it so it can calibrate, your might have a similar system.

[greywynd]

Originally Posted by Shade Tree Welder

My unit has internal calibration marks, you have to move the X and Y enough when powering up the machine before you start using it so it can calibrate, your might have a similar system.

Forgot that one, and some also have reference marks near the end.


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[clive]

Thanks for your help guys, I found the manual and it showed how to set the reference point, which I did. Then set up a dial gauge to zero, DRO to zero, then dialled on .010”. Surprise surprise, both the DRO and the dial gauge read .009”. I repeated this and got the same results each time.
Chinese lathe, about 8-9 years old so I doubt if it is leadscrew wear but could be, at least I know the DRO is functioning, I can live with that. Next I’ll check the complete length of the leadscrew. I’ll post the results.

[clive]

I just tested the thing (X axis) over the entire length of movement and it was the same. As this includes parts of the screw I have never had occasion to use I think it is shitty Chinese manufacturing techniques, maybe the one dial fits several machines and they accept this as a trade off.