Lathe DRO Accuracy

[ddickey]

What is a good way to check a lathe dro for accuracy?

 

[mksj]

On overall accuracy, I clock mine to the machine dials over several inches to see if the scales track with the dials with each revolution, if looking at shorter accuracy I use wither 123 or 246 blocks with a 0.0001" indicator. My magnetic scale on the tailstock was spot on after 4+" of travel on the "0".

 

[MrWhoopee]

1-2-3 blocks are good or a mic standard (the longer the better).

 

[ddickey]

What should I be looking at here, the dial or the indicator?
Please explain how to set up the 1-2-3 blocks.

 

[MrWhoopee]

For the cross-feed, the dial should tell you what you need to know. For checking the carriage travel, zero the indicator against the face of the chuck and zero the DRO. Then move the carriage back and place the 1-2-3 block with the 2 in. face against the chuck and bring the carriage up until the the indicator reads zero against the 1-2-3. The DRO should read 3.000.

 

[ddickey]

Okay thanks.
In the above pic the indicator and DRO agree but not the dial. Okay I'll just go off of the dial then.

 

[MrWhoopee]

Okay thanks.
In the above pic the indicator and DRO agree but not the dial. Okay I'll just go off of the dial then.

I'm a little puzzled by this, is that a 2 in. indicator? How much disagreement are you seeing?

 

[ddickey]

Yes it is.
With -150ppm I'm getting .001" over 7"
.0005" over 2". DRO reading higher than dial.

 

[MrWhoopee]

Yes it is.
With -150ppm I'm getting .001" over 7"
.0005" over 2". DRO reading higher than dial.

I have noticed, repeatedly, that hobbyists tend to get unnecessarily worked up about precision that is only required for aerospace and electronics.

Your DRO is fine, go back to work.

 

[ddickey]

Not worked up, just asking about the proper methods.
Easy on the mill but a little more difficult to check on the lathe.