Cutting hard tissue life science sample? Worried about hydroxy apatite crystals in bone or teeth or other hard tissue such as chitin containing samples?
When selecting the SPI Supplies Materials Science Diamond Knife, select diamond "MT" and the standard default angle of 45°. Depending on your samples, a 55° might give longer knife lifetime, but the knife will also be prone to produce compression effects. Papers have been published using 55°, angle knives, however we continue to be concerned about compression induced artifacts when using these higher angle knives.
Is there anything inherently wrong with a small angle on a materials science knife? No, and however well the knife cuts at 45°, it will cut even easier and faster at, for example, 40°. However the knife wear rate will be appreciably higher and the knife, literally will wear out much faster.