- Joined
- Oct 31, 2020
- Messages
- 19
I was thinking about a DRO for my mill, but have been holding back because I like the simplicity of the dials, and now that I have converted the fixed dials to being re-settable (zero-able) the appeal of DROs has faded even more.
The only thing that would have sent me down the DRO path would have been a vast improvement in accuracy, as measure against the dials, so I set about testing that very thing.
The first step was to determine the accuracy of my dial indicator against my Mitutoyo vernier, and the D.I. came up being as accurate as the vernier, so the testing began.
The results were as follows:
"X" axis over 9mm of travel came up minus 0.05mm
"Y" axis over 9mm came up as spot on
"Z" axis over 9mm came up minus 0.5mm
I would like to measure the "X" axis over a longer distance to see if it gets worse, and I will do that with a calliper soon.
The "Z" axis was a real surprise. I never expected it to be so bad, but thinking about it, unlike the threads on the feed screws of the X & Y axis, the Z is a rack & pinion, which may well explain the poor accuracy, although you would think that the dial could have been marked to suit. That of course would make for a quite confusing scale.
The answer to the "Z" axis problem was to go the "Poor mans DRO" route and use a vernier as a DRO, which has proved to be an excellent fix. I used a carbon fibre ebay cheapie which runs to only one decimal place, but the dial is accurate enough to adjust to the second decimal place if needed.
If the "X" axis error proves to be greater over longer travel distance, then the 2-axis DRO route might have to be revisited.
The only thing that would have sent me down the DRO path would have been a vast improvement in accuracy, as measure against the dials, so I set about testing that very thing.
The first step was to determine the accuracy of my dial indicator against my Mitutoyo vernier, and the D.I. came up being as accurate as the vernier, so the testing began.
The results were as follows:
"X" axis over 9mm of travel came up minus 0.05mm
"Y" axis over 9mm came up as spot on
"Z" axis over 9mm came up minus 0.5mm
I would like to measure the "X" axis over a longer distance to see if it gets worse, and I will do that with a calliper soon.
The "Z" axis was a real surprise. I never expected it to be so bad, but thinking about it, unlike the threads on the feed screws of the X & Y axis, the Z is a rack & pinion, which may well explain the poor accuracy, although you would think that the dial could have been marked to suit. That of course would make for a quite confusing scale.
The answer to the "Z" axis problem was to go the "Poor mans DRO" route and use a vernier as a DRO, which has proved to be an excellent fix. I used a carbon fibre ebay cheapie which runs to only one decimal place, but the dial is accurate enough to adjust to the second decimal place if needed.
If the "X" axis error proves to be greater over longer travel distance, then the 2-axis DRO route might have to be revisited.