CNC Marble Machining

Kitchen Countertop CNC Production from A to Z — The Complete Process Guide

✍️ USEL Engineering📅 01 May 20269 min read

The kitchen countertop is the product CNC marble workshops make most often. The process looks simple (cut, finish, fit) but it consists of 12 separate stages, and a mistake can be made at each one. This guide sets out the standard process flow used by professional workshops.

The Overall Process Flow (12 Stages)

  1. Taking the customer survey + analysing requirements
  2. Slab selection (type, colour, pattern, thickness)
  3. CAD drawing — the countertop dimension file
  4. CAM program — the cutting path + edge profile
  5. Placing the slab on the table + securing it
  6. Straight contour cutting
  7. Sink cut-out + hob cut-out
  8. Machining the edge profile (ogee, bullnose, V-cut and so on)
  9. Polishing + buffing (manual or semi-automatic)
  10. Quality control (dimensions + surface)
  11. Packing + loading
  12. Delivery to site + installation

1. Taking the Customer Survey

Wrong dimensions = a wasted countertop = a lost customer. Professional standards for taking the survey:

  • A laser distance meter (accuracy of at least ±2 mm)
  • Corner angles — walls are rarely a true 90° (a 3-5° deviation is common)
  • Making a template — mandatory on a complex countertop (aluminium profile or foam)
  • Sink + hob position — the cut-out dimensions differ by brand (check the installation guide)
  • Additional connection points — the line of the wall cabinets, any clash with a drawer
  • The datum level (height reference) — any slope in the floor must be noted
  • Photographs + video — a reference for any doubt back in the workshop
The Classic Mistake
The customer says "the sink cut-out in the middle" but which point is "the middle" was never settled in the CAD — a 5-10 mm offset often results. Always confirm with a template or a photograph.

2. Slab Selection

  • Type: marble, granite, travertine, onyx, engineered stone (Silestone, Caesarstone, Quartz)
  • Thickness: 20 mm (standard), 30 mm (premium), 40 mm (luxury / island)
  • Colour + pattern: chosen with the customer item by item (at the workshop or the marble yard)
  • Slab size: on average 3000 × 2000 mm (marble), 3200 × 1600 mm (engineered stone)
  • Colour matching: selecting from the same block is essential (the difference in tone between blocks is marked)
  • Defect check: cracks, porosity, tone distribution — a buyer's signature is advisable

3. CAD Drawing

The CAD file is the source of the cutting instruction. Common software: AutoCAD, Rhino, SolidWorks, sector-specific CAD (StoneCAD, MarbleCAD).

  • The main contour — the outer boundary of the countertop
  • The sink cut-out — offset to the brand's cut-out dimensions
  • The hob cut-out — to the size of the gas or electric hob
  • Edge profile drawing — which profile on which edge (by symbol or hatching)
  • V-cut lines, decorative patterning — where present
  • DXF or DWG output — for CAM

4. The CAM Program

The CAD file is transferred into the CAM software, where the cutting path + tool selection + parameters are set. Common CAM packages for CNC bridge machines: TEX Computer (the USEL standard), Fagor, Alphacam and the CNC versions of MasterCAM.

  • Cutting order — from small detail to large (for accuracy)
  • The pierce (entry) point — place it where it will not be seen
  • Blade selection — mesh, diameter, segments
  • Cutting speed — from the table, by material + thickness
  • Cooling water — flow rate + nozzle direction
  • Multiple passes — for thick work (30-50 mm of depth per pass)
  • Optimisation — idle travel is minimised
  • Simulation — collision checking in the CAM (critical on 5 axis)

5. Securing the Slab

  • Vacuum table — fast and suited to large slabs (the modern standard)
  • Mechanical clamps — for small pieces or where vacuum will not hold
  • Template logic — for repeat production on the same slab type
  • Support under the slab — extra bearing for thick work + heavy slabs (40 mm+)
  • Checking the hold — every point is tested before cutting
A Workholding Failure
Inadequate workholding = the slab being thrown clear during cutting = damage to the machine and the operator. Workholding is NEVER skipped.

6. Contour Cutting

Standard cutting parameters (30 mm marble):

  • Blade: 400 mm diameter, #50-60 mesh, medium bond, 24 segments
  • Speed: 2,500-3,000 rpm
  • Feed: 1,500-2,500 mm/min
  • Cutting depth: a single pass (30 mm)
  • Cooling: 25 L/min flow
  • Standard time: a 2.5 m contour takes ~3-5 minutes

7. The Sink and Hob Cut-Outs

The sink cut-out requires an internal edge profile — it takes time after the cutting:

  1. The pierce point — in a corner of the cut-out that will not be seen (beneath the slope)
  2. Internal contour cutting — at slow speed (risk of kick-back)
  3. Corner radius — mind the blade radius (at least 12 mm)
  4. The internal edge profile (5 axis) — softened with a milling tool
  5. The edge under the countertop (which will not be seen) can be left plain

8. Machining the Edge Profile

4 Axis — Manual Polishing

  • It comes off the cut rough
  • Manual transfer to the polishing machine
  • The operator works it on the profiling machine
  • Time: 15-25 min per countertop
  • Accuracy: depends on operator skill
  • Hard to standardise

5 Axis — A Single Setup

  • Cutting + profiling on the same machine
  • The profile is machined with a milling tool (ogee, bullnose, V-cut)
  • Time: 5-10 min per countertop
  • Accuracy: a consistent ±0.1 mm
  • Easy to standardise (the same program)
  • Final manual polishing: the last buffing only

9. Polishing + Buffing

  • Stage 1: 60 grit (coarse)
  • Stage 2: 100 grit
  • Stage 3: 200 grit
  • Stage 4: 400 grit
  • Stage 5: 800 grit
  • Stage 6: 1500 grit
  • Stage 7: polishing powder (the final buffing)
  • 6-7 stages are enough for marble, 8-10 stages for granite
  • A semi-automatic polishing machine — 3-5 times faster than manual work

10. Quality Control

  • Dimensional check — with the template or a laser distance meter (±1 mm tolerance)
  • Corner angles — with a square or an angle gauge
  • Surface check — inspecting for cracks and porosity with a magnifier
  • Polish quality — a reflection test (even under a light)
  • Sink cut-out fit — confirmed with the template before installation
  • Certification and labelling (for premium work)

11. Packing + Loading

  • EVA foam covering (protects the polished faces)
  • Corner protectors (foam or card)
  • Stretch film (dust + moisture)
  • A timber pallet or an A-frame (for transport)
  • Loading: forklift or crane + safety strap
  • Driver briefing: secured in the vehicle, gentle braking

12. Delivery to Site + Installation

  • A delivery appointment with the customer
  • Site check — cabinet alignment, wall flatness
  • Setting the countertop onto the cabinet — with timber battens or silicone
  • Fitting the sink + hob
  • The joint line — keeping the whole consistent (marble mastic or an invisible adhesive)
  • Care instructions for the customer — daily cleaning, annual buffing
  • Getting the acceptance document signed

Typical Timings

Stage4 Axis Workshop5 Axis Workshop
Customer survey + CAD40-60 min40-60 min
Cutting + sink15 min15 min
Edge profile20-25 min (manual)5-10 min (CNC)
Polishing15-20 min8-12 min
Quality + packing10 min10 min
WORKSHOP TOTAL~95-110 min~75-95 min
Site delivery + installation60-90 min60-90 min
The Productivity Difference
A 5 axis workshop gains around 20 min per countertop. 60 countertops a month × 20 min = 20 hours of additional production capacity.
Frequently Asked Questions

COMMON
QUESTIONS

4 axis is enough for straight cutting plus manual polishing. If the edge profile is to be machined automatically on the same machine, 5 axis is essential. There is a detailed comparison in the /en/academy/4-axis-vs-5-axis-bridge-saw article.