Dual contact spindles offer many advantages when high performance machining is required!

Existing machines and toolholders can be used in BIG-PLUS Spindle System machines and toolholders.  When a new machine with BIG-PLUS Spindle System is introduced, existing toolholders can be used.  It is not necessary to purchase all new toolholders.  Therefore, it is possible to save cost to introduce simultaneous fit toolholders.

Although other simultaneous fit systems requires exclusive new accessories, BIG-PLUS Spindle System uses existing accessories such as a presetter and a toolholder fixture as it is based on a conventional steep taper shank.  Therefore, no extra cost is needed.

Simultaneous fit of taper and face prevents vibration from heavy or high speed cutting and discoloration on taper (called fretting corrosion).

At high speed rotation, a machine spindle expands due to centrifugal force and heat.  Then, a toolholder is pulled into the machine spindle.
On the contrary, BIG-PLUS toolholder is not pulled in even at high speed rotation as the flange face fits the machine spindle nose.  Then, variation of projection length in Z axis is minimized. (variation due to heat exists.)

Rigidity is enhanced by simultaneous fit of taper and face.  There are excellent effects on heavy or high speed cutting, deep or large dia. boring and especially using a cutting tool with long projection length.

Since BIG-PLUS toolholder is rigidly supported on taper and face, higher repeatability at ATC can be achieved.  This brings about many good effects such as higher T.I.R and stable precision of finish boring.

BIG-PLUS Spindle System is strictly controlled in dimensions of a machine spindle as well as a toolholder in order to guarantee simultaneous fit between taper and face, the dimensions are measured by a exclusive high tolerance gage and measuring devices.  Full interchangeability exists between all BIG-PLUS machine spindles and BIG-PLUS toolholders.