How to Calculate CNC Router Feed Rates

The chip load is the measurement of the thickness of material removed by each cutting edge during a cut. This is a valuable piece of information that can then be used to calculate new set ups.

Chip loads are based on material thickness of average size for cutting edge length of the tool. The calculation below does not apply to thicker material or tools with a long cutting-edge length. These feed rates are only a recommended starting point and do not accommodate all circumstances. Therefore, tooling damage may still occur and use of the calculator does not provide any warranty for tool breakage.

The Calculation:
Spindle Speed x Number of Flutes x Chipload (High/Low) = Feed Rate


The Calculations are based on depth of cut being 1xD for a standard length tool. For 2xD reduce the chipload by 25% and for 3xD reduce the chipload by 50%.

RPM Selection

The general operating RPM for tooling contained on this site is between 10000 - 20000 revolutions per minute (RPM). These will differ dependent on tool selection due to us putting in some extensive research to see where the tooling best suits. For most materials a good starting point for RPM is between 16000 - 18000. There are a number of different scenarios where this will change (Composite Materials, Honeycomb, Soft Plastic to name a few). If you have any questions then please give us a call or drop us an email.

Frequently Asked Questions:

  1. What does RPM stand for? Revolutions per minute. This is how quickly the tool is spinning in the material (EG 18000 rpm)
  2. What does Feed Rate stand for? This is how quickly the tool moves through the material. Usually displayed in mm/min or m/min (EG. 3000mm/min or 3m/min).
  3. What does Plunge Rate stand for? This is how quickly the tool enters the material in a vertical motion. Plunge Rate is usually between 30% - 50% of the feed rate.
  4. What does Ramping stand for? The process of ramping means to enter the material on an angle with the tool running at its optimum spindle speed. Ramping is the best option in most cases as it reduces tool wear.
  5. What does step over mean? This is the distance a tool will move over before making the next pass.
  6. What does pass depth mean? This is how deep you are cutting down into the material. 
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Recommendations for machining of soft woods such as Cedar, Cottonwood, Pine, Redwood.

Hard Wood Data

Recommendations for machining of Ash, Beech, Birch, Cherry, Mahogany, Maple, Oak, Poplar, Teak, Walnut

MDF Cutting Data

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Soft Plywood Data

Recommendations for the machining of Soft Plywood

Hard Plywood Data

Recommendations for the machining of Hard Plywood

Laminated Wood Data

Recommendations for the machining of laminated chipboard.

Soft Plastic Data

Recommendations for the machining of Soft Plastic such as ABS, Polycarbonate, Polyethylene, PVC, Polypropylene, HDPE, Polystyrene, UHMW, Extruded Acrylic

Hard Plastic Data

Recommendations for the machining of Hard Plastic such as, Cast Acrylic, Melamine, Nylon, PVC, Vinyl

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Recommendations for the machining of Aluminium.

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Recommendations for the machining of solid surface materials such as Corian®, Formica®, Hi-Mac®

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Recommendations for LMT Onsrud Drills covering composites, plastic & wood.

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Recommendations for the machining of foam such as polyurethane foam and polyethylene foam.

Honeycomb Data

Recommendations for the machining of Honeycomb style materials.

Composite Data

Recommendations for the machining of composite materials. Includes detailed cutting data breakdown for 66-500 to 66-800 series for full slotting to finishing.

PCD Data

Recommendations for PCD Tooling from the LMT Onsrud Series.

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