- Joined
- Apr 21, 2015
- Messages
- 665
Your welcome. Glad you figured it out!
It’s worth checking your indicators for repeatability, but they are probably good enough at measuring distance. They use gears internally, not screw threads (unlike most table and quill travel dials) so they won’t have the metric/inch issue.
To check repeatability, put something with a known dimension on top of your mill vice. The shank of an end mill works well if you don’t have gage pins, 1-2-3 blocks, etc. Roll the shank under the indicator until you find the point of maximum deflection, then raise or lower the quill to zero the indicator and lock it at that point. Then repeatedly roll the shaft under the indicator point, ensuring it returns to zero each time.
If you do check the calibration for distance measurement you’ll need a small set of gage pins or gage blocks. Zero at the top of the reference and read the value when removed. Then do the opposite, zeroing on the table or vise top.
Beware of cosine error (if the shaft of the DI isn’t perfectly vertical). Also, always roll the pin from the same direction — it’s usually best to come from behind, especially with an angled DTI lever arm.
Lastly, if your dials consistently read 0.015748 less than expected per inch of travel, then they are mislabeled metric screws. (25.4 x 0.984252 = 25)
It’s worth checking your indicators for repeatability, but they are probably good enough at measuring distance. They use gears internally, not screw threads (unlike most table and quill travel dials) so they won’t have the metric/inch issue.
To check repeatability, put something with a known dimension on top of your mill vice. The shank of an end mill works well if you don’t have gage pins, 1-2-3 blocks, etc. Roll the shank under the indicator until you find the point of maximum deflection, then raise or lower the quill to zero the indicator and lock it at that point. Then repeatedly roll the shaft under the indicator point, ensuring it returns to zero each time.
If you do check the calibration for distance measurement you’ll need a small set of gage pins or gage blocks. Zero at the top of the reference and read the value when removed. Then do the opposite, zeroing on the table or vise top.
Beware of cosine error (if the shaft of the DI isn’t perfectly vertical). Also, always roll the pin from the same direction — it’s usually best to come from behind, especially with an angled DTI lever arm.
Lastly, if your dials consistently read 0.015748 less than expected per inch of travel, then they are mislabeled metric screws. (25.4 x 0.984252 = 25)
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