One of the most dangerous mistakes you can make on a jobsite is assuming that a machine rated for 40mm (approx. 1.5 inches) can cut any 40mm bar. In my years running crews, I’ve seen guys destroy expensive gear because they didn't understand the difference in steel grades.
Rebar is graded by its yield strength. Older or lower-grade steel, like Grade 40 (approx. 40,000 psi or 280 MPa yield strength), is relatively soft. A heavy-duty cutter might breeze through a massive piece of Grade 40. However, modern commercial construction heavily utilizes high-tensile steel, such as Grade 60 (420 MPa) or even Grade 75 (520 MPa). This high-strength steel is significantly harder and more brittle.
If your machine's manual states a maximum capacity of 32mm (approx. 1.25 inches), read the fine print. That rating is almost always based on standard Grade 40 steel. If you try to feed a 32mm piece of Grade 75 bar into that same machine, the resistance will exceed the structural limits of the shear block. You will likely snap the eccentric shaft, shatter the blades, or burn up the motor. Always know your steel grade, and if you are working with high-tensile bar, safely derate your machine's maximum capacity by at least 20% to 30%.
