I recently purchased a co-axial indicator, a Blake clone, that I am pleased with. For those who aren't up on these, this is a live center finding tool, similar to a edge finder, except it can also be used to find center on a centerpunch mark. It is used to find center on a bore or to read the outside to center on a shaft or cylinder held in the milling vise. There is nothing, well…almost, that this tool can't do, that can't be done with an Indicol in one fashion or another. The co-axial indicator is much faster to set up and the reading under power is a real bonus, instead of hand turning a spindle. Reading is easy as the dial always faces you.

To use it, you install a anti-rotation bar that you hold to keep the dial facing you and put the correct straight or curved feeler into the mounting hole. Adjust the mount til the feeler touches the bore. The mount is a friction adjusted part. Turn the machine once to insure the the feeler is sweeping the hole or cylinder completely. (in other words, eyeball it in to less than.25") Then turn on the mill as its lowest rpm. Then adjust the X and Y on the table to reduce the needle movement to as close to zero as you can.

I bought it from Fleabay and I was pleasantly surprised at the quality and finish. As I don't suffer from "buy American" principals, and the cost of a Blake is over $300, I expected to have a lower quality product for under $50, but I don't believe that is the case at all. There is almost no visible movement of the needle when rotating, which means no built in errors.

As Blake says on their site:

"The Blake Co-Ax indicator is a centering device. It requires a reading of both sides of the bore (or boss), in each axis, to arrive at center. Its sole function is to find center. It is never to be used as a measuring instrument.

You can not certify the Co-Ax on a surface plate. It must be put in the spindle of the machine in which it would normally be used and indicate a precision ring or plug. Then remove it and use a .0001" indicator to check that you are on center.

The Co-Ax indicator is made to be used under power. When checking the Co-Ax position with a test indicator the spindle should be rotated manually for both indicators due to the fact that spindle torque under power on some machines will give a different reading for center." -

In other words – The dial could be blank or have a picture of Bugs Bunny on it. You just want the needle to stop wiggling so much.

Starting with the wooden case, it's a keeper. Usually the wood cases of Chinese tools made in the Wun Rong Turn factory are falling apart, and the latches don't work…I wonder why they even bother. This case is very nice, it will last for years.

It has a complete set of feelers for inside and outside centering. The finish on the critical area that rotates against the non-rotating housing is mirror smooth. There was no excess lubrication or cosmoline  present, and I believe lubricating this tool with a very light oil is all that is needed. Anything that collects dust could affect the reading

The indicator is held in the spindle with a 3/8" collet chuck. This size is even acceptable in a small table top machine. Here's what you get in the kit.

This is the co-ax unit ready to work.

Here the Co-ax indicator has indicated center on a 1/2" drilled hole at 250 rpm