Also true to start tooling up after the money comes in and not before hand

]]>They are unique because a replaceable hex bit is inserted at the end and locked in place with a set screw. This virtually eliminates the issue of smaller bits twisting and breaking. They do occasionally have clearance issues from having wider shafts. Also at 140-160 dollars for a set of 7, they come at a premium. ]]>

In the last expression the ‘N’ should have been ‘N1’ the integer value.

We can not drill a non-integer number of holes. ]]>

In the last expression N should be replaced with N1, the integer value.

We can not drill a non-integer number of holes. ]]>

If L is the inset length

D is the tool diam.

S is the fractional step over (e.g. 40% is 0.4)

N is number of holes

then

L = (N-1) * S * D + D

with a little rearrangement we get

N= (L-D)/(S*D) +1

in general (unless the stepover is correct first time) the value of N will not be an integer. We can correct that by rounding N upwards for a smaller stepover or round down for a greater stepover.

If N1 is the adjusted integer value then we can further rearrange the initial expression to calculate the correct fractional step over as follows

S = (L-D)/((N-1)*D) or the actual dimensional step over = (L-D)/(N-1)

Just as with the trial and error method you need to repeat this calculation for both axis and the different areas of the pocket if it is not a simple rectangle.

]]>Catia also have 3D plunge operation as a Roughing strategi, but was not mentioned in your list. ]]>

Personally I will get a set of each, but 95% of the time I’ll be using the fixed end one’s. ]]>