Model Forum / General / Models / August 2010

Haven't a clue.  I know you should spin a two flute cutter twice as fast as
a four flute cutter.  I also know that a two flute cutter isn't necessarily
a slot drill unless it can drill - ie it's centre cutting.

I guess you get more flutes as the cutter diameter increases.   If you had a
twelve inch end mill,  it would look a bit sad with just four flutes.

Hello Peter,
My understanding it that there are two main issues. More flutes means
a higher feed rate is possible because the limit is roughly a
feed/flute hence more flutes means more feed.

Secondly, if you mill a slot with an end mill, the front cutting flute
gives rise to a side force on the cutter. This both deflects the
cutter by bending it a little and also takes up any bearing clearances
and any other play in the system all of which presses the flute at the
side of the cutter into the side of the slot. Hence a 4-flute end mill
will generally mill an oversize slot.

I have also never heard of a 1 flute cutter, 3 flutes are a relatively
recent development I think and I assume get more feed without
suffering the oversize slot problem. Obviously once you get to big eg
4" diameter shell mills the story is more a matter of making best use
of the large chunk of costly material and getting a smooth cutting
action rather than a fly cutter type effect.

Richard

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A lot of it is down to the compromise between finish and speed. Less
flutes means more space for swarf hence higher removal rate but poorer
finish.

Quality, price and speed, which two would you like?

AWEM

A single flute "endmill" is very probably really a wood working
mortice cutter, I have several. They do look exactly like endmills

Rigidity I assume.

Cliff Coggin.

Was that on the J B Cutting Tools stand? I was allowed to choose one for
free as I bought 4 very long carbide slot drills from them. It intrigued
me and assumed it was a one flute slot drill rather than an end mill as it
can be plunged in as it cuts across the centre unlike an endmill which
cannot. It has the designation JT0005 5x12x60/8 (ie 5mm diameter, 12mm
maximium depth of cut, 60mm total length with 8mm diameter shank).

The long reach 2-flute carbide slot drills were unusual. 3 had straight
flutes and were 6x40x100/8, 5x50x100x8 and 7.5x20x60/6 and the other
8x30x75/8 had slow spiral flutes. What attracted me to them was the
extremely long reach and very deep depth of cut (40, 50, 20, 30 mm
respectively) and cheap price.

Alan

Traditional cutter grinders could not sharpen a centre-cutting tool
with more than two flutes, so slot drills were limited to two.  But
modern machines can make fancier shapes, so the limitation no longer
applies.  Replaceable-tip tools have only one insert in the smallest
sizes, then two, three and so on as the diameter increases.