Drilling Resistance Measurement

 IML Sales Offices





IML North America

IML North America, LLC
15 Glidden Rd.
Moultonborough, NH 03254

E-Mail:   info(at)iml-na.com
Phone:   603-253-4600




IML Florida


P.A.1635 Eagle Harbor Parkway, Suite 4
Fleming Island, FL  32003

E-Mail:    info(at)imlusa.com
Phone:   603-253-4600

Measurement of the Drilling Resistance with the IML Resistograph Systems

Approved procedure, Quick results

The IML Resistograph System is based on the principle of measuring the drilling resistance. A drilling needle is inserted into the wood under constant drive. While drilling, the needed energy is measured depending on the drilling depth of the needle.

That way, anywhere and with little effort it is possible to get information about structures, inner defects or residual walls of trees and wooden constructions. Depending on the instrument series, the obtained data can be recorded electronically and then transmitted, evaluated and processed on your PC with specific software. This is a precision instrument that delivers significant results.    

The result:

Depending on which instrument you use, the measurement data is printed simultaneously on a (wax) paper strip on a scale of
1:1. The measurement profile delivers information about the internal condition of the wood. It shows annual rings and density behavior, as well as decayed zones in the wood.

Measuring curve (electronic recording)
To enlarge - click on the measuring curve!

Measuring curve

The y-axis describes the drilling resistance in % (Amplitude height).
The x-axis describes the drilled way in cm.


The drilling needle:

  • 100-150 drillings/needle (depending on the operation)
  • Diameter needle shaft: 1.5 mm
    Diameter needle tip: 3.0 mm
  • Sturdy special alloy & coated surfaces
  • Reinforced needle tip
  • Ground brad point

Application fields:

  • Care and inspection of trees along streets, in parks and forests
  • Tree inspection in the context of traffic safety
  • Evaluation of damages on forest trees
  • Research and development
  • Inspection of construction wood:
    - Utility pole testing
    - Playground inspection
    - Termite control
    - House inspection
    - Bridge inspection
    - Inspection of buildings

 to the IML Resistograph Systems


”Resistograph” products or services described on this Website are offered to buyers in all jurisdictions except, for trademark reasons, in Australia, Belgium, Bulgaria, China, Cyprus, Czech republic, Denmark, Germany, Estonia, Finland, France, Greece, Great Britain, Hungary, Ireland, Italy, Japan, South-Korea, Croatia, Latvija, Lithuania, Luxemburg, Malta, Netherlands, Austria, Poland, Portugal, Romania, Russia, Sweden, Switzerland, Slovakia, Slovenia, Spain.