Mill Boring Head

[aliva]

I just purchased a 3 inch boring head for my mill /drill.
I wanted to check the accuracy to determine if I advance the dial to say .0010, what amount of stock am I actually removing. Well it turns out
that the graduations indicate the exact amount of stock being removed. So advance .0010, the head moves .005.
In checking this I noticed that in order to set the head for zero stock removal, the dial indicated .050, and not zero. I checked the run out with a dial gauge,
and adjusted the dial till zero deflection. The dial lined up with witness mark at the .050 line.
Now this is an offshore manufactured head, so I expected it would not have a very high accuracy, but .050 off is a lot. I can compensate for the discrepancy, but
I'd like to have the dial set at zero and get zero.
Is this normal for a boring head? Has anyone run into this, and how did you correct it?
I do understand that in boring a hole you'd probably scratch the id of the hole first then advance the required amount, so maybe this isn't an issue.
I have a couple of ideas to remake the dial so it can be adjusted to zero, but is there an easier way?
Any suggestions would be appreciated.

Thanks

 

[kd4gij]

The dial seting is going to depend on the size of the hole you start with and the boring bar that you are using. So the ods of it starting at zero is slim to none.

 

[GK1918]

The only suggestion I can think especially if you got CRS like me is to write it down-the start scratch
numbers. I just wonder why they dont have a movable ring with a witness mark to -0- the thing.
Supose some day they will be digital.

 

[Philco]

The only suggestion I can think especially if you got CRS like me is to write it down-the start scratch
numbers. I just wonder why they dont have a movable ring with a witness mark to -0- the thing.
Supose some day they will be digital.

Gk1918,That day is already here. Do a goggle search on ( The Big Kaiser digital boring head)