Standard adjustable heads should be set in the following manner
- The turrets are rotated to bring the spindles to the required centre distance or pitch circle diameter.
- In cases where a particular spindle setting is frequently required, setting rings can be provided for quickly locating the spindle in their relative positions.
- When setting the spindle centre distance, the head can also be turned relative to the drill unit adaptor. This adjustment may be necessary in order to line up the spindles with the holes to be drilled or tapped.

Adjustable centre heads are suitable for drilling or tapping 2 holes, 3 holes equi-spaced in a straight line and 3 or 4 holes equi-spaced on a common PCD. When there are applications for heads where the hole pattern cannot be attained by means of the standard spindle adjustment, fixed centre multi-spindle heads can be provided. These heads are specifically made to suit any form of hole pattern.

When accurate hole positions are required, it is always necessary to support the drills in close proximity to the work by means of drill bushes. Under these conditions, it is therefore essential, that either bushed jigs or bush plates are used with both adjustable and fixed centre heads.


GY-ROLL Heads are lubricated with MultiGrade 10W-30 Oil as specified on the nameplate, it is important to ensure that grease is never used as this will clog up the lubricating system.

The oil in a GY-ROLL head is carried in a polyurethane felted foam block. It is fed by a capillary action to the gears and bearing extremities. The oil absorbed in the polyurethane block, adequate for lubricating the entire heads. There should be no free oil floating around in the head. Any indication of oil dripping from the spindles or any other part of the head means there is an excess of oil in the head.

Oil is pumped into the head by means of the nipple in the side of the body. 2 - 3 strokes of an oil gun should provide sufficient lubrication for approximately 500 running hours. If there is an excess of oil in the head it can be drained off by running the head with the lubricating nipple or oil plug removed.

It is important to appreciate that the GY-ROLL lubricating system is not based on an oil bath, as with this system the oil would settle in a different part of the head according to how the head was mounted. This could adversely affect lubrication to bearings at the extremities of the head while other bearings may be flooded causing unnecessary agitation of the oil and overheating of spindles if there were run at high speeds.

As it is most important to ensure that grease is never used, if there is any risk of someone pumping grease into the head it is safer to replace the lubricating nipple with an oil plug. The nipple can then be put back at the appropriate time interval when the head is due for a further injection of oil.