A guide to choosing CNC tools for stone working

guide to choosing cnc tools

In a CNC machine for stone working it’s possible to use a huge quantity of tools, every of them designed specifically for performing a special work.
In every of them it’s possible to get the best result for feed, speed and finish quality choosing the right tool to use.

WHAT MATERIAL TO WORK WITH THE CNC MACHINE? 

Obviously the first criterion to consider when choosing diamond tools to buy is the type of material you want to work.
For the stone industry we have 2 main categories:

  • Soft material – Marble & Travertine
  • Hard material – Granite, Quartz, Engineered stone

WHAT WORK TO PERFORM ?

With a CNC machining center it’s possible to perform many types of tasks to produce your  stone products as kitchen countertops, sinks, stone steps, artistic reliefs, stone writings or any other stone fabrication applications.
Some common tasks done with a stone working CNC machine  are as follows:

  • Engraving (letters, numbers, reliefs finishing)
  • Light roughing (roughing  and semi-finishing for reliefs; incremental cuts)
  • Heavy roughing (large and deep recess drain for sinks, kitchen countertops, shower trays)
  • Holing ( through hole, blind  hole)
  • Cutting and drilling
  • Profiling shaped edges
  • Polishing and finishing

Let’s write in a table  works to perform and diamond tools types to use.


SOFT MATERIAL

MARBLE, TRAVERTINE, SOFT LIMESTONE

HARD MATERIAL

GRANITE, QUARTZ, LAVA STONE

ENGRAVING
(letters, numbers, reliefs finishing)
RELIEFS FINISHING
LIGHT ROUGHING
(roughing, reliefs semi-finishing,
incremental cuts)
HEAVY ROUGHING
(large and deep recess drain for
sinks, kitchen countertops)
HOLE MAKING
(through and blind holes)
CUTTING – DRILLING
with side entrance on the material
EDGE PROFILING
Widia V-bit router for marble

Widia V-bit router for marble

Widia Router Bits are ideal for simple engravings on marble and soft stones.
They are also called as V-bits because their Conical V-Shaped tip. It possible to choose them with different angles, 30°, 60° or 90°.
Bits 30° can be flat and radiused (from 0,55 mm to 3mm radius).
For all widia V-bits it’s suggested to go inside the material with an inclination angle of 30°.


Polycrystalline Diamond (PCD) Router Bits

Polycrystalline (PCD) Router Bits

Polycrystalline Router Bits are suitable for engrave granite, quartz and engineered stone.

These tools are harder than widia ones, allow to work with a higher speed, have a life 10 times more and the quality of the finishing is really high.
As the widia tools the  polycrystalline tools are available with different angle but they don’t have flat and radiused model.
Polycrystalline router bits can be used also for finishing step in bas-high reliefs.
Also for this kind of tools is suggested to go inside the material with an inclination of 30°


Drainboard Wheels are used to remove big quantity of material in a very fast way and they are used during cnc machining of sinks, kitchen countertops and shower trays.

electroplated and sintered drainboard wheels

Electroplated and sintered drainboard wheels

Electroplated drainboard wheels  for marble working are available with a diameter of 87 mm while for granite and quartz the right tool to use is  the Sintered model that can have diameter of  50mm, 87mm or 91mm.
Also for this kind of tools is suggested to go inside the material with an inclination of 30°.


Sintered core drill bits - granite

Sintered core drill bits – granite

Electroplated core drill bit - marble

Electroplated core drill bit – marble

For the execution of holes with a CNC machine there is a tool specifically designed for this purpose: Core Drill Bit available in different sizes for different holes in diameter.

These tools can be with Segmented diamond bits or Continuous for smoother drilling.
As other diamond tools also the core drill bits can be electroplated, for hole marble and soft stone, and sintered to make hole on granite, quartz and engineered stone. 

 

 


Electroplated finger bit - marble

Electroplated finger bit – marble

Sintered finger bit - granite

Sintered finger bit – granite

One of the most used tool is the Diamond CNC Finger Bit used to cutout and other purposes on the material.
These tools, in the most common versions, can not enter the material from the top because they have no cutting segment  in the bottom for drilling so they can only cut from the side.
To make a cut at the center of a slab the most common technique is to perform a pre-drilled hole and then enter with the Finger Bit tool exactly inside the hole.


 

 

For machining shaped edges for example in kitchen tops and sinks   there are specific shaped wheel tools known as  Diamond Profile Wheels.

Diamond profile set

Diamond profile set

There are wheels to profile different shapes and every shape is identified by a letter.  In the next image we have a list of the standard edge profiles often used in stone working:

Edge working Standard Profiles

Edge working Standard Profiles

The making process of the edge includes a series of steps done with different tools, from the roughing of the material, up to a perfect polishing.  Every step is done a tool included in the edge profile tool kit.
The tools in a kit are identified by their position, the order that should be used. In  a 7 pieces tool kit we have tools from Position 0 to Position 6.
Position 0 is the roughing tool and  position 6 is the last tool for final polishing.


Frangistone wheel

Frangistone wheel

It’s possible to add also another tool that extends the kit, the position 00. For example Marmoelettromeccanica has a patented wheel called FRANGISTONE. The FRANGISTONE grinding wheel is a special tool composed of a series of disks, with different diameter, which together form the desired profile.  This  diamond wheel has a strong power for material removal and thus dramatically reduces the wear of the positions that follow it.

 


Razorstone wheel

Razorstone wheel

Also in position 0 it’s possible to use a special tool designed to improve performance and quality. In this case Marmoelettromeccanica supplies the Razorstone wheel.
The Razorstone wheel has now completely replaced the old grinding wheel sectors for four main reasons :
– 5 times faster than the old grinding wheel sectors
– 24 hours for delivery , thanks to the modular system
– 24 hours for the realization of any design in profile
– 50 % less costs because it has a longer life than the grinding wheel in sectors


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