How to read the numbers to the left of zero on a rotary table vernier in secounds?

[ome]

On my Yuasa rotary table there is o-60-o, in single secounds up to 60. Why are there numbers to the left of 60, are they negative numbers. How do you read such a number that falls to the left of the 60 mark.

Thanks,
Jon

 

[Tony Wells]

That's to give you something to use when you are dialing back the other way. All backlash is negated that way. You can't use the vernier on one side while moving one direction, then switch to the other set coming back in the opposite direction. That is, if I am understanding your question correctly.

 

[ome]

That's to give you something to use when you are dialing back the other way. All backlash is negated that way. You can't use the vernier on one side while moving one direction, then switch to the other set coming back in the opposite direction. That is, if I am understanding your question correctly.

Thank you , so to be clear, you Are saying that those that fall on the left are the backlashl
Thanks,
Jon

 

[Tony Wells]

No, not really. I don't think I am explaining this very well. You can actually use both sides, and they should agree. But one shows the amount below the nearest number on the dial and one shows the amount above the next lower number. If you went to a number like 10°30', then it should vernier out the same on both sides, but other than that, they will read in a complimentary fashion. Maybe that is easier to see.

 

[ome]

No, not really. I don't think I am explaining this very well. You can actually use both sides, and they should agree. But one shows the amount below the nearest number on the dial and one shows the amount above the next lower number. If you went to a number like 10°30', then it should vernier out the same on both sides, but other than that, they will read in a complimentary fashion. Maybe that is easier to see.

Yes, that makes more sense.Thank You
Regards,
jon