While collecting SPT samples through 2.25-inch hollow stem augers in Triassic silt stone, JD Barker, owner of Quantex in North Carolina, started seeing cutting shoe failures when sampling 50 blow count intervals. -Conversations with tools engineer Quinton Bogner prompted potential solutions.
“As you can see the spoon actually caused the shoe to break outwardly because I believe the end of the spoon relied on the threads to stop the downward blow force and thus caused it to fail,” Barker shared when sending a photo to Bogner.
Based on Barker’s feedback, the tools engineering team came up with multiple test configurations by optimizing material properties and part geometry.
These subtle material and geometry changes increased the strength of the standard cutting shoe by more than 20 percent and made a difference for Barker in the field.
Customer feedback from the field not only strengthened the standard cutting shoe (225524), but also resulted in a NEW blunt nose cutting shoe option (236717) better suited for high blow count situations. The geometry of this shoe does not meet the geometry outlined in ASTM D1586.
“While ASTM D1586 recognizes that blunt shoes are used in coarse grain or dense soils for durability, the blunt nose geometry does not conform to the standard. No research has been done to quantify the effect of the blunt shoe on N values. Use of a blunt shoe should be noted in the test report.” Kyle Riedel, tools group manager, said.
These customer conversations also prompted development of a NEW basket bypass ring (239568), which will work with either shoe.
“It is intended to be used in formations that do not require a core basket, and is good for high blow count formations,” Riedel said
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Failed cutting shoe.
Standard split spoon cutting shoe 225524 now more than 20 percent stronger thanks to subtle material and geometry changes.