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Basic Machine

Bokö Model VH4/12, 6 axis universal vertical boring and milling machine in standard design equipped with a Fidia M2 control. Including one set of accessories to the machine, however without milling tools or tool holders. The machine is equipped for 460 volts, 3 phase, 60 hertz.


Six NC-controlled axes:

  • X = Longitudinal cross movement of table.
  • Y = Transverse in/out movement of table.
  • Z = Vertical movement of spindle head carrier at column.
  • B = Circular movement of the table.
  • A = Rotary vertical tilting motion of the spindle +/- 100 degrees from vertical.
  • C = Rotary horizontal motion of the spindle, 360 degree continuous.


Machine Accuracy

  • Machine accuracy to VDI/DGQ 3441: Direct Path Measurement, linear axes: X, Y and Z.
  • Position allowance: Tp = 0.02 mm/m or 0.0008/39.4" absolute
  • Position divergency: Ps = 0.01 mm or 0.0004" absolute



Machine is equipped with:

  • Heavily cross-ribbed, cast-iron machine construction.
  • Double walled, cast-iron column design.
  • Larger diameter precision ground ballscrews for linear slides.
  • Direct slide position feedback using precision glass scales.
  • Large working range of machine due to long X and Y Axes.
  • 20 Kw AC main spindle drive.
  • Fidia M2 control.
  • 6 axes under CNC (X, Y, Z, A, B, and C).
  • Automatic spindle speed change in 3 ranges.
  • Hydraulic counter balance of the headstock.
  • Backlash free feed drives.
  • Anti-friction coated slideways.
  • Anti-collision protection between column and table.
  • Pendant mounted operator's control station.
  • Oil chiller unit for spindle head lubrication system.
  • Digital display for all axes, pendant mounted.
  • Automatic central lubrication.
  • Hydraulic drawbar.
  • Machine light.

Noise level transmitted by air La max. = 75 dBA will not be exceeded.


Mechanical Design Data

Single column machine design has large longitudinal, transverse and vertical travels.

Cast-iron, bed-type design with ideal absorption of the cutting forces and workpiece weights by amply dimensioned structure of the individual part of the machine, such as base, column, cross-slide, etc. are important features of the machine.

Precision ground, hardened way bars in the slide movements of longitudinal (X axis), transverse (Y axis) and spindle head carrier travel (Z axis) guarantee a consistent high accuracy.

Anti-friction coated counterway surfaces of longitudinal, transverse and spindle head carrier slides. For their support, 4 symmetrically positioned roller elements on the X and Y axes are provided with variable hydrostatic preloading and are manually adjusted based on the workpiece weight. In some places, roller guiding elements are installed in preloaded narrow slideways.

Special advantages:

  • Reduction of static & dynamic friction
  • Higher accuracy
  • Balanced and adjustable static and dynamic friction resistance depending on workpiece weight
  • Faster rapid traverse rates.

NC-rotary table (C-axis) 1800 x 1200 mm (70.86" x 47.25"). Rotary work table from fine grained cast iron (Meehanite). Built-in rotary table worm wheel made from high alloy bronze serves also as a support slideway. In addition, depending on the workpiece weight, adjustable hydrostatic support for relief and improvement of friction conditions is performed. A radial prestressed combined ball bearing guarantees efficient dynamic running condition.

Individual AC servo feed drives are provided for all motions. Drive is effected via infinitely variable permanent magnet AC motors. Drives are maintenance free.

The feed drives of the axes X, Y, Z, A, C, B are made without backlash. This is accomplished by installation of preloaded precision ball and roller bearings, split and preloaded drive gears for the linear drives, and special toothed belts and split preloaded worm-drives for the rotary movements.

Softwired overtravel limit switches protect the machine from inadvertent overtravel. Hardwired switches prevent the servo drives from powering the drives beyond their position and finally rubber-bumper slide limit end stops for each individual slide positions (X, Y, Z axes) protect the machine elements in case of overtravel. The B & C rotary axes are 360 degree continuous axes without "wind-up" or overtravel.

All travel directions both linear and rotary, X, Y, Z, A, C, B are NC-controlled. This permits a highly universal application of the machine. With the workpiece clamped on the rotary table (C axis) on top of the cross slide (X & Y axis), the following machining operations can be performed:

  • Machining the workpiece in X and Y axes.
  • Circular milling or milling circular sectors of any angle.
  • Positioning of the 4 x 90 degrees angle positions.
  • Tangent milling and boring.
  • The workpiece can be machined on 5 sides in one setup.
  • Complete 5 axis contour machining.

The 2 axes, bi-rotary head permits both vertical and horizontal spindle machining on the full table surface. Because of the large throat of the milling head, the lengthy X axis movement of the table and by using the rotary table, both horizontal and vertical machining operations can be executed throughout the work envelope defined by the entire table area.

For 5 axes CAM generated programs using the 2 axes rotary head in combination with the rotary table, programming can place the tool for stock removal anywhere and at any angle in the work zone. Many parts can be completed in just one setup.


Metric Inch

Working Range

Work table length x width 1800 x 1200 mm 70.9 x 47.2"

"T" slots number x width 10 x 18 mm 10 x.7"


Maximum Feed Travels

Longitudinal movement of table (X) 2400 mm 94.5"

Transverse movement of table (Y):

(forward) +direction 1100 mm 43.3"

(backward) -direction 600 mm 23.6"

Total 1700 mm 66.9"

Vertical movement of spindle head carrier (Z) 1200 mm 47.2"

Tilting motion of the milling spindle (A):

+ direction 100 degrees - direction 100 degrees

Total 200 degrees

Rotation motion of the milling head

without limit to both sides (C) 360 degrees inf.

Circular movement of table, continuous

without limit to both sides (B) 360 degrees inf.

Throat of milling spindle 1230 mm 48.4"

Max. workpiece diameter on circular milling approx. 3200 mm 126.0"

Max. height of the workpiece:

Max. distance spindle nose to table 980 mm 38.6"

Max. distance bracket to table 1480 mm 58.3"

Max. table load 7500 kg 16,500 lb.


Feeds: Three Phase AC Motors (Infinitely Variable)

X, Y and Z axes feed 4-15000 mm/min. .16 - 590"/min.

Rapid traverse 15 m/min. 590"/min.

Slow feed 4 mm/min. .16"/min.

A, B and C axes feed 4-1440 deg. /min.

Rapid traverse 1440 deg./min.


Milling Spindle

Tool shank: steep taper (DIN 2079) ISO 50 Taper


DC Spindle Motor

Speeds infinitely variable within 3 steps 25 - 5600 rpm

Power (constant at 60% ED) 30 kW 39 HP

Total connected load, approx. 80 kVA 105 HP



Machine unpacked 22500 kg 49,500 lb.

Packed for rail transport (planks) 23000 kg 50,600 lb.

Packed for ocean transport (cases) 26000 kg 57,200 lb.


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Copyright © 1996 Bokö Services Group, Inc.
Last modified: January 10, 2002