Posted by Wednesday, November 21st, 2012 @ 1:11 pm


Diamond handpads come in a variety of shapes, but the rectangular 2 1/4” x 4” format is by far the most popular version since it fits so easily in the palm of the hand. The handpad consists of a diamond section (small islands of diamonds on a flexible layer that permit a certain amount of flexibility) glued onto a foam support. The diamond islands are available in two basic forms:

  • Electroplated: grits range from coarse grit sizes such as #30 to fine sizes such as #1200. The most popular grit sizes for marble being #70, #220, and #400.
  • Resin bond: grit ranging in size from #600 through #3500.

Resin bond products have no scratching ability of their own other than the diamond itself. The resin base only holds the diamonds in place, making them ideal for polishing applications. The diamonds produce successively finer scratch patterns until the patterns become so small that to the human eye, the surface appears polished. As every fabricator knows, nothing is more frustrating than to finish a job and then notice scratches still present on the surface. Resin bonds are generally less “aggressive” than electroplated metal bonds. They are more forgiving and therefore do not leave large, undesirable scratches.

Sample Applications

For a typical job that calls for polishing a rough cut granite edge, try this procedure: in succession, use the electroplated #70, #120, #220, and #400 grits followed by the resin bond #600, #800, #1800, and #3500 sizes. This sequence will produce a glossy finish on almost any stone. Note that when working with marble or granite, an additional buffing sequence will bring out the full gloss of the stone.

For special applications, very fine grit diamond hand pads (8000 and smaller) or very coarse grit pads are available. For grits finer than #400, the most economical encapsulation method is resin bond because, as I mentioned above, they’re more forgiving than electroplated metal bond.

Important Considerations for Custom Handpads

Manufacturers can deliver a custom solution for every stone-cutting preference and need. When diamond handpads are tailored for each aspect of a job, manufacturers pay close attention to these important considerations:

  • Rigidity – important to maintain a flat, mirror like surface on products such as counter or table tops. Hand pads used for these surfaces are generally made with foam handles and offer the best characteristics of an all-around tool.
  • Flexibility – key to those who polish rounded surfaces such as bullnoses or ogee shapes. Diamond handpad material is available from manufacturers and can be cut into strips of any size. These strips can be fastened with hook-and-loop backing to specially shaped forms which mirror the shape of the finished edge.
  • Ruggedness – essential for heavy-material removal, such as tile edging and sizing, or even rough work on hard stones. Although still foam-mounted, custom handpads can be made on very rigid substrates with much larger diamond islands, allowing them to withstand the greater pressure.

Water is Essential to Diamond Hand Pads

For a better finish and to extend the life of the handpad, be sure to use water while polishing. Although some work can be done dry, water offers important benefits. For example, because resin bond diamond handpads are particularly intolerant of heat, water is an essential accompaniment. The water not only rinses away the cuttings (dirty water) from the stone’s surface, it also cools the diamonds and prevents the resin base from overheating.

The Power of Orbital Pads

Any time hand pads are the best tool for the job, orbital pads are the only power alternative to consider. Orbital pads are mechanically powered, and therefore offer relief from excessive arm muscle fatigue. The power tool to which they are attached should have a “jitterbug” or vibratory type of motion. This is important because if more work is done with one grit versus another (because the arm gets tired), the finished stone will not display an even degree of reflectivity and could translate to poor workmanship. Orbital pads are larger than hand pads and are available in the same grit sizes. They are also available in a wide variety of dimensions to match the power tools being used.

Don’t Work Too Hard

There’s no question a shop can experience solid benefits from the proper use of diamond hand pads. The fabricator should be able to profit by:

  • Saving time
  • Achieving consistent finishes
  • Increasing productivity
  • Reducing costs

The single most important thing to remember when using diamond hand pads – let the diamonds do the work.  In other words, don’t treat a diamond hand pad like one made of silicon carbide. Forcing the hand pad to work harder than necessary will only decrease its useful life.

Topics: , , , ,


Posted by Monday, October 8th, 2012 @ 10:10 am


Almost all diamond disks in use today for polishing stone consist of diamonds embedded in a resin (plastic) matrix. Diamonds are mixed with the resin to form blocks rather like the lug pattern on the soles of shoes. The diamonds are randomly scattered throughout the resin matrix to a specified depth. As the resin matrix is worn away, the diamonds are gradually exposed.

Disk Use

A wide variety of diamond disks is available today. Popular sizes for the fabrication shop are 3″, 4″, and 5″ diameters, where 4” is by far the most popular and larger and smaller sizes are typically reserved for specialty uses.

The most popular grit sizes for electroplated disks are #70, #120, #220, and #400. Beyond that, there is ample demand for both the coarser #30 and #50 grits and well as the much finer #600, especially for marble work.

Grit sizes for resin bonded disks commonly range from the coarsest #30 to a very fine #8000. Typically, #50, #120, #220, #400, #800, #1800, and #3000 are most commonly used in the shop for processing granite surfaces. Marble processing is less stringent and the combination of grits #50, #220, and #800 usually yields the desired finish.

A point has to be made on the abrasiveness of the stone itself. Marble is soft, but tends to yield a more abrasive slurry than granite, which is harder but less abrasive in slurry form. Some shops try to polish both types of stone with a single set of disks, and this is a mistake. Disks are recommended for specific materials based on grit size, plus the bond (electroplate, metal, or resin), the number of diamonds that are working at any given time, and the hardness and abrasiveness of the material. Some disks work well with marble and poorly with granite, just as a marble diamond saw works well on marble and inadequately on granite. There are no universal disks any more than there are universal saws.

Flexibility vs. Rigidity

There is a trade-off between the flexibility and the rigidity of diamond polishing disks. Flexibility is usually achieved with the use of a rubber universal joint mounted on the spindle of a right-angle grinder, or by using a flexible disk attached with a hook and-loop fastener.  Rigidity is the result of a rigid disk attached with a snail-lock fastener.  A good compromise consists of a rigid disk and a hook-and-loop fastener.

Flexible disks tend to conform to the surface of the material, polishing high and low areas with equal ease. In heavily veined marble or on extensive granite surfaces, the flexible disk will tend to ride over the hard areas and dig into the softer portions. The job may go quickly, but the finish will be wavy. Moreover, the flexible disk will not do a good job of levelling untrue surfaces.

Rigid disks, on the other hand, will do a better job of levelling and have less tendency to dig into soft areas. The rigid disks are also less forgiving; the slightest inconsistency in the polishing procedure will show up as a flaw when the work is completed. The novice can usually obtain better results with a flexible disk. The experienced craftsman will generally prefer the rigid setup. Rigidity prevents rounding of the edges and produces a flatter desirable surface. In all cases, a slight cushioning is necessary to prevent rapid wear of the diamonds due to vibrations generated during the rapidly rotating polishing sequence.


Water is a desirable component of diamond polishing, since it efficiently cools both the work and the disk. (Resin bonds especially are quite intolerant of heat build-up.) Beyond its cooling properties, water flowing over the work at a steady rate yields other advantages: the job will go faster with less effort because the slurry helps remove material, there won’t be any dust, and the finished surface will be superior to anything that can be done dry. This is just as true for hand-held grinders as it is for large production machines.

Rotation Speeds

For diamond abrasives, the best speeds are typically 3000-7000 RPM for a 4″ disk. Higher speeds allow the diamonds to do the work rather than relying on pressure. In fact, excessive pressure will noticeably shorten the life of a diamond disk.


All resin-bonded disks need to be broken-in, a process that exposes the diamonds enclosed in the plastic matrix on the surface of the disks. This is easily done for all grit sizes on the rough surface of the material being worked.  With the coarse grits, simply attach the disk and start grinding. For the finer grits, e.g., #3000, break-in is best done on a surface that would be produced by a coarse grit of #120 or so.

A #3500 disk can be broken-in during the normal polishing routine, i.e., on a surface produced by a #1800 disk, but it will take some time. A disk is broken-in when all the grinding surfaces have lost the gloss they had when they came out of the package.


On the basis of materials only, diamond polishing tools are significantly more expensive than silicon carbide tools. The overall advantages, however, clearly favor diamonds: less grinding time, improved production rates, better finished surfaces, and longer disk life.  These important benefits lead to improved profitability.

For disk polishing with hand-held grinders, the advantages of diamonds include:

• A 50% reduction in polishing time.

• A cleaner shop without the dry grinding dust.

• Reduced worker fatigue with lighter tools requiring less pressure.

• Increased production throughput.

For more information about grinding and/or polishing stone, visit our website or feel free to Ask an Engineer080 about your specific needs.

Topics: , , , ,