Boring head graduations

I have a boring head from Arc Euro. The graduated dial to increase the radius of the tool only has graduations and no indication of how much each graduation represents. Any idea ?

Which one is it, they do several. EDIT, all the graduation sizes are given on ARC's site for each boring head

Ones that take metric tools will likely be callibrated for metric 0.02mm per div or 1mm per full turn off diameter, ones that take imperial tools will be in imperial 0.001" per dive or 0.050" per full turn off dia

Easy way to check is put a dti against the moving part of the head and measure how much it moves for one full turn.

Edited By JasonB on 22/05/2021 10:22:06

Hi Eric,

The graduations may relate to an amount taken off the Diameter of the hole.

I know mine does, though mines in thousandths of an inch, very accurate too, but can't remember from where I purchased it.

So really you will need to take a cut at one division, and measure the difference from the original hole size.

Bernard.

From Sunny Scunny...

Take apart, and get the thread gauges in use? That will determine the movement per rev. Divide that by the number of divisions will be your answer.

Why take it apart? Stick it in the mill, bore a shallow hole, wind it out 10 divisions and measure again.

Easy.

For very fine tolerance holes the Erikson Tenthset head has 0.002mm per division adjustment.

Emgee

Armchair job. Presumably Arc sold imperial versions a long time ago (nearly all metric items these days). Neither are they difficult to disassemble. It was only a suggestion. I would likely have experimented myself.

If new, ring Ian on Monday?

Whether graduations are in tens per rev or, say, eight might even give a clue as to metric or imperial if the tool was really old....?

As a quick check, I just picked up my 2” boring head, removed the Morse taper and proceeded to measure exactly ten turns of adjustment with my digi-calipers - quite easy to do. Also, the adjusting screw thread is sufficiently visible to measure the pitch (had my thread gauges happened to be in the house🙂 ).

Rather than making it as complicated as possible, simply do what JasonB suggested. Unless of course you really need unnecessary complexity in your life!!

cheers

Bill

I can assure you that simply taking a measurement with a thread gauge, or two with a caliper is even more simple than fitting the holder to the machine, setting up a dti (a dial gauge would be better) and taking measurements.

The whole problem is not exactly rocket science (no disrespect intended to the OP). I try to offer ideas of how to do it, not necessarily just the answer - which basically teaches nobody anything. Since when has anyone learned how to do long multiplication by using a calculator? Being given the answer does nothing towards learning a skill.

If you are not sure what the graduations mean set up a dial indicator and see how far the slide moves with respect to the number of graduations you dial in.