Multipoint Cluster Tools:

Introduction

Hand-set multipoint diamond cluster tools are manufactured in many differing shapes and sizes to cater for a variety of applications ranging from general machine shop usage to precision grinding. The Hamilton Lichfield range is detailed in table 1, however this only represents a selection of the most commonly used types, any variation or special tool can be manufactured on request.

Dressing Concept

Unlike the conventional single point tool, multipoint dressers have several diamonds in contact with the wheel face at any one time, thereby utilising smaller, cheaper diamonds to share the thermal load. For this to be efficient it is necessary for the full dressing face of the tool to be in contact with the wheel at all times. Multipoint tools must therefore have the correct approach angles built into the shank design to ensure full face contact. Failure to achieve this will cause the full impact of the dressing operation to fall on only one or two diamond points, this will quickly cause overheating and premature failure.

Tool Shanks

Multipoint dressers may be supplied in any form of holder such as swivel headed and taper shanks, usually at no extra cost. It is however necessary, as stated above, to specify any drag (approach) angle and any left or right hand crank which may be required to profile a form wheel. See fig.1.

Figure 1

Tool Composition

The multipoint tools described in greater detail below, have been designed for specific dressing applications. To this end a wide range of selected natural and synthetic diamond is hand-set in bonds of differing hardnesses to achieve the desired result. For this reason it is not advisable to use these tools on applications for which they have not been recommended.

It may also be seen that there is some overlapping of the types within the Hamilton Lichfield range of cluster tools, for instance both 'Multiset' and 'Topdress' (see Impregnated Cluster Tools data sheet) may be used for straight pass grinding. The reasons for this are largely historical and tend to reflect operator preferences.

MULTISET TOOLS

This is a very traditional range of tools which still find favour with many users for straight pass grinding, due to their simplicity and adaptability. The tools may be produced in differing head sizes and diamond patterns to cope with both small and large grinding wheels.

It is important to note that the MTS6 tools are designed to work in the horizontal plane, that is with only 1 row of 4 diamonds in contact with the wheel at any time. In this manner, when the initial row of diamonds is exhausted the dressing operation is carried on by the row immediately above it and hence with progressive dressing, the tool has 4 effective 'lives'.


"MST1" STYLE TOOL

"MST3" STYLE TOOL



"MST6" STYLE TOOL

ROTARY TOOLS


RTY1-3

These circular tools are designed for plain or straight pass grinding applications, where they work on the magazine principle. Once the initial layer of diamonds has been dulled or used up, the wheel may be rotated presenting new, sharp stones to the wheel. In general terms these tools are used to achieve finer finishes than those obtainable with Multiset tooling.

RTY 1 STYLE TOOL

RTY4-6

Similar in concept to the round tools these square dressers present a larger dressing area to the wheel and may be used for heavier dressing applications. Again a new face is presented to the wheel, by rotating the nib, once the initial diamonds have been exhausted.

The RTY-4 has a very heavy diamond content and may be used for severe dressing and truing applications. RTY-5 has a reduced and finer diamond content for medium severity wheel dressing whilst the RTY-6 tool is particularly suitable for fine finishing.

RTY 5 STYLE TOOL

RTY 7 & 8

Both of these types are a variation of the rotary magazine tool for use specifically in profile grinding. RTY7 contains a single layer of high quality natural long diamonds making it suitable for profiling accurate forms. In the RTY8 tool the longs are replaced by more expensive, but harder wearing, triangular maccle diamonds. This tool is capable of profiling and pre-forming large diameter and coarser grit wheels.

RTY 7 STYLE TOOL

RTY9

The RTY9 tool is essentially a magazine style single point tool which is particularly suited to dressing smaller wheels where a very sharp point is essential, for example, dressing internal grinding wheels. Being composed of 8 small diamonds each with an excellent point, the tool is an inexpensive alternative to the single point which avoids the necessity for resetting.


RTY 9 STYLE TOOL

BLADE TOOLS

ANG1-2 Blade dressing tools contain triangular diamonds set across the blades nib thus presenting the extremely wear resistant rib of the stone to the grinding wheel. The orientation of the diamonds giving a natural 60 degree included angle is exploited in these tools for the profiling purposes although they will also perform well for plain dressing. This combination makes the tool particularly suitable for use on angle head grinders where they are frequently used for grinding a series of reducing diameters. The difference in the tools is merely the diamond weight ANG2 having the bigger stones for use on larger wheels.


ANG 1 STYLE TOOL

CROWN TOOLS

A well known approach to situations where both the side and face of the grinding wheel have to be dressed, by the same tool, is to adopt the use of the Crown tool SDG1. When set at right angles to the wheel, it may be seen that the front face of the nib will directly dress the wheel face. However, once past the wheel edge further infeed will bring the side of the crown nib to bear on the side of the wheel ensuring that the wheel is well prepared for corner grinding. Again the Crown nib may be rotated to bring fresh diamond points into use.

SDG 1 CROWN TOOL

BLOCK TOOLS

A simple but effective means of side dressing an abrasive wheel is by use of the hand held block dresser SDG2. The tool is intentionally robust as we have found that it tends to get utilised for a whole variety of other uses and being inexpensive, it suitable for use with semi-skilled labour. The same nib may be set 90 degrees to the shank (often a screwdriver handle), to form a 'T' style dresser for straight off hand grinding.


SDG 2 STYLE TOOL

Table 1

TYPE CODE NIB SECTION NIB SIZE DIAMOND TYPE PATTERN APPLICATION
Multiset MTS1 Round 1/2" (12.7) Natural longs 1 layer of 5 Straight Pass Grinding
Multiset MTS2 Round 5/8" (15.9) Natural longs 1 layer of 5 Straight Pass Grinding
Multiset MTS3 Round 5/8" (15.9) Natural longs 2 layers of 5 Straight Pass Grinding
Multiset MTS4 Round 7/8" (22.2) Natural longs 1 layer of 7 Straight Pass Grinding
Multiset MTS5 Round 7/8" (22.2) Natural longs 2 layers of 7 Straight Pass Grinding
Multiset MTS6 Rectangular 3/4" x 5/8" Natural longs 2 layers of 8 Straight Pass Grinding
Rotary RTY1 Round 3/4" (19.0) Needles 4 layers of 20 Straight Pass Grinding
Rotary RTY2 Round 3/4" (19.0) Needles 4 layers of 20 Straight Pass Grinding
Rotary RTY3 Round 5/8" (15.9) Needles 4 layers of 20 Straight Pass Grinding
Rotary RTY4 Square 1" (25.4) Needles 4 layers of 24 Straight Pass Grinding
Rotary RTY5 Square 3/4" (19.0) Needles 4 layers of 24 Straight Pass Grinding
Rotary RTY6 Square 3/4" (19.0) Needles 4 layers of 24 Straight Pass Grinding
Rotary RTY7 Round 7/8" (22.2) Needles 1 layer Profile Grinding
Rotary RTY8 Round 7/8" (22.2) Triangles 1 layer Profile Grinding
Rotary RTY9 Round 5/8" (15.9) Octahedrons 8 x 0.1 ct Straight Pass Grinding
Blade ANG1 Rectangular 1/2" x 1/4" Triangles 3 x 0.15 ct Angled Head Profile Grinding
Blade ANG2 Rectangular 5/8" x 1/4" Triangles 3 x 0.30 ct Angled Head Profile Grinding
Crown SDG1 Crown 5/16"x1"x1/2" Octahedrons 42 x 0.15 ct Side & Face Grinding
Block SDG2 Rectangular 3/8" x 1" Octahedrons 30 x 0.15 ct Side Grinding

Hamilton Multipoint Tools share the following advantages:-

  1. Cheaper than an equivalent Single Point Tool
  2. No resetting required, reducing stock levels and records
  3. Tools used to destruction, eliminating down time for tool changes
  4. Less vulnerable than conventional dressers if unintentionally abused by operators
  5. Specialised tools available to tackle difficult grinding problems