11-11-2012, 09:05 AM
DaveH's method works well, and like he says there are other methods. I saw a
method demonstrated on you tube ( can't find it now but I'll keep looking) that
works really well for me. And like lemelman said having two chuck keys really helps.
First like DaveH says, eyeball it as close as you can. Try to get it within .050" or less if you can.
This method will still work even if you're at .100 or more but you really should be able to eyeball it closer than that.
And Like DaveH said it makes it difficult to move if you're much more than .050" out.
Anyway after you've got the piece held gently in the jaws indicate it with your Dial. Make sure you've got some load on the indicator all the way around. Rotate the piece until you find the lowest reading. Lowest in this case meaning where the piece is the furthest away from the indicator.
With the piece at it's lowest reading, set the Dial bezel to zero. Now rotate the piece and see what the highest reading is. For example say the highest reading (meaning the piece is as close to the dial as possible) is 47 divs. Half of 47 is 23.5. Rotate the piece until the dial reads between the 23 and 24 marks. Now without moving the piece reset the dial bezel to zero again.Your dial is now set where Zero IS your target. Rotate the piece so the nearest cross pair jaws, 1 and 3 or 2 and 4 are horizontal. Push-pull the piece with your chuck keys until you read zero. Rotate to the other cross pair and push-pull with the keys again until zero. Check the first pair again, adjust as necessary. Now start tightening down. I always tighten towards zero if that makes sense. In other words if it's reading zero all around but I'm still just lightly holding the piece, I 'll tighten just one side 3 thou pushing past zero. Then swing around the opposite side. Now it will indicate 3 thou under zero, so 'tighten to zero'. Same thing with the opposite pair. When I come back to the first pair, if everything is still reading zero all around, I'll tighten/push 2 thou past zero then again on the opposite side 'tighten to zero'. Rinse and repeat until it's tightened as desired and you still read zero on your indicator all around. Sometimes you'll find you keeping indicating 1 thou off no matter what. In this case your indicator is 1/2 thou or so off of where it needs to be, adjust the dial bezel accordingly. This of course works just as well with metric indicators.
The beauty of this method is that assuming you are anywhere kinda close to centered, there is one and only one point on the piece that is exactly at the correct distance from the centerline of the lathe and you've now put your indicator's zero point precisely on it.
method demonstrated on you tube ( can't find it now but I'll keep looking) that
works really well for me. And like lemelman said having two chuck keys really helps.
First like DaveH says, eyeball it as close as you can. Try to get it within .050" or less if you can.
This method will still work even if you're at .100 or more but you really should be able to eyeball it closer than that.
And Like DaveH said it makes it difficult to move if you're much more than .050" out.
Anyway after you've got the piece held gently in the jaws indicate it with your Dial. Make sure you've got some load on the indicator all the way around. Rotate the piece until you find the lowest reading. Lowest in this case meaning where the piece is the furthest away from the indicator.
With the piece at it's lowest reading, set the Dial bezel to zero. Now rotate the piece and see what the highest reading is. For example say the highest reading (meaning the piece is as close to the dial as possible) is 47 divs. Half of 47 is 23.5. Rotate the piece until the dial reads between the 23 and 24 marks. Now without moving the piece reset the dial bezel to zero again.Your dial is now set where Zero IS your target. Rotate the piece so the nearest cross pair jaws, 1 and 3 or 2 and 4 are horizontal. Push-pull the piece with your chuck keys until you read zero. Rotate to the other cross pair and push-pull with the keys again until zero. Check the first pair again, adjust as necessary. Now start tightening down. I always tighten towards zero if that makes sense. In other words if it's reading zero all around but I'm still just lightly holding the piece, I 'll tighten just one side 3 thou pushing past zero. Then swing around the opposite side. Now it will indicate 3 thou under zero, so 'tighten to zero'. Same thing with the opposite pair. When I come back to the first pair, if everything is still reading zero all around, I'll tighten/push 2 thou past zero then again on the opposite side 'tighten to zero'. Rinse and repeat until it's tightened as desired and you still read zero on your indicator all around. Sometimes you'll find you keeping indicating 1 thou off no matter what. In this case your indicator is 1/2 thou or so off of where it needs to be, adjust the dial bezel accordingly. This of course works just as well with metric indicators.
The beauty of this method is that assuming you are anywhere kinda close to centered, there is one and only one point on the piece that is exactly at the correct distance from the centerline of the lathe and you've now put your indicator's zero point precisely on it.
If it's crazy but it works, it's not crazy.