Cutting Tool Tolerance

[Brian B 74]

I just want to make sure I am understanding this correctly.  If a cutting tool catalog calls out a H10 tolerance on the cutting diameter, the chart says 10mm-18mm is +0/-.07.

 

If I am reading this correctly - the diameter is then +0/-.0027"? 

[mikenaturalice]

That sounds right to me. I use some inexpensive endmills and find some of them are +0 -.002", (cutting diameter) and then the really cheap ones are +0 -.005"! That is on 1/4, 3/8, and 1/2 too! Now I have found even on these two different tolerances that most of my tooling comes in about -.001 -.002". Maybe the .005" is 'just in case' 

[gaijin_2007]

I am wary of tooling suppliers showing +0 -(something) tolerances for their cutting tools.

The reason being that ground carbide rod is typically supplied to h6 tolerance which is +0 -(something) tolerance.

In my opinion that means that to ensure that the edge is correctly ground (and is not left as the same diameter as the shank and potentially not sharp) then the maximum cutting diameter needs to be less than the minimum shank diameter.

So realistically the tool should have a -/- tolerance.

 

For example a 1/2" tool will have a tolerance (h6) on the shank of 0.5-0.4996 (if my math is correct to 4 decimal places).

 

So the cutting portion needs to have maximum diameter of less than 0.4996.

 

Seco, among others, list the diameter tolerance of their tools as e8 which is -/- tolerance.

A bit more realistic as far as I'm concerned.

[Brian B 74]

This conversation stems from the Guhring catalog I received.  It says the cutting tool diameters are H10 tolerance.  I also received a Fraisa catalog.  In that catalog it calls out an E8 tolerance on their cutting diameters.

 

I just wanted to make sure I was understanding those tolerances.  Thanks for all the responses.

[rob@fain]

an H7 tolerance on 10MM should be +8 to +15 Microns. (15microns is .00060