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Calculating your cutter diameter (using your Depth of Cut)

I was recently training an employee on how to determine the appropriate slitting saw diameter after our customer gave her the desired depth of cut. Although it is a simple calculation it is not as straight forward as you might think. In order to calculate the diameter, you need to know what the arbor hole of the slitting saw/milling cutter will be. Once you have the arbor hole size, you need to look up what the arbor spacer diameter is for that arbor hole. Below is a table that shows standard arbor hole diameters along with the standard arbor spacer diameter for that arbor hole.

Standard Arbor Hole Diameter

Standard Arbor Spacer Diameter











Once you have the arbor hole spacer diameter you can calculate the cutter diameter if you know the desired depth of cut. The formula is:

[(Depth of Cut) x 2]+(Arbor Spacer Diameter)=Minimum Cutter Diameter

Let’s say you have a 1.6” depth of cut and want a slitting saw with a 1” arbor hole. Form the chart above we know the arbor spacer for a 1” arbor hole is 1-1/2” in diameter.
(1.6×2) + 1.5 = 4.7

So, for this example the minimum cutter diameter to achieve a 1.6” depth of cut is 4.7”.
Although 4.7” is the minimum diameter I would recommend using a cutter that is a bit larger if your application allows it because the spacer will most likely rub on the part you are machining. In this case 4.75 or 5” would be better.

The above example is assuming a few things:
The first is that the arbor spacer you are using is a standard spacer. If you are using a custom made spacer or the standard spacer has been altered plug the diameter of your spacer into the (Arbor Spacer Diameter) in the formula above.

The second assumption is that the hub width of the cutter is less than the cutting width. If the hub width is greater than the cutting width AND the hub diameter is greater than the spacer diameter then the hub diameter is the important number. In this scenario the depth of cut will be:

(Cutter Diameter)-(Hub Diameter)   =  Depth of Cut
If you have any questions about calculating the appropriate cutter diameter (or any other cutting tool questions) feel free to leave us a comment here on our blog or fill out the form on Super Tool’s Contact Us Page.

Bryan Enander
Super Tool, Inc