While some safety razor parameters have been generally illustrated before, here at B&B and elsewhere, a more comprehensive picture has now been created.
The general illustration above shows the blade and shave planes and the parameters that follow around the blade cutting edge for a blade loaded in a safety razor: blade angle, handle angle, blade exposure, guard span, cap span, blade gap, free-end distance, clamp distance. Free-end and clamp distances were measured for the first time with my photo analysis of the Edwin Jagger (EJ) DE89 head (B&B URL). Important details that could not be simply illustrated are included at the bottom of the picture. For example, I rigorously define blade gap based on personal experience in measuring the quantity with my accurate set of micrometer-measured feeler gauge blade combinations (B&B URL).
Blade gap is commonly associated with razor aggressiveness, but, at best, blade gap only loosely relates to razor performance. Blade exposure, guard span, and blade angle, on the other hand, are very important performance parameters with respect to aggressiveness and efficiency. Unfortunately, these three parameters are not easily measured. Photo analysis is the primary method for measuring the illustrated parameters, but physical measurements, such as for blade gap, should be used when appropriate to complement or supersede digital measurements. The illustrated parameters around the cutting edge apply both to double-edge (DE) and single-edge (SE) safety razors. The first note in the picture about using a blade with a nominal width for analytical purposes therefore applies similarly for DE and SE razor blades.
The illustration included here might be updated in the future, and if that happens, I will update this thread accordingly. Regardless, it is hoped that this picture or an updated version will become the premiere reference illustration for safety razor parameters around the blade cutting edge.
The general illustration above shows the blade and shave planes and the parameters that follow around the blade cutting edge for a blade loaded in a safety razor: blade angle, handle angle, blade exposure, guard span, cap span, blade gap, free-end distance, clamp distance. Free-end and clamp distances were measured for the first time with my photo analysis of the Edwin Jagger (EJ) DE89 head (B&B URL). Important details that could not be simply illustrated are included at the bottom of the picture. For example, I rigorously define blade gap based on personal experience in measuring the quantity with my accurate set of micrometer-measured feeler gauge blade combinations (B&B URL).
Blade gap is commonly associated with razor aggressiveness, but, at best, blade gap only loosely relates to razor performance. Blade exposure, guard span, and blade angle, on the other hand, are very important performance parameters with respect to aggressiveness and efficiency. Unfortunately, these three parameters are not easily measured. Photo analysis is the primary method for measuring the illustrated parameters, but physical measurements, such as for blade gap, should be used when appropriate to complement or supersede digital measurements. The illustrated parameters around the cutting edge apply both to double-edge (DE) and single-edge (SE) safety razors. The first note in the picture about using a blade with a nominal width for analytical purposes therefore applies similarly for DE and SE razor blades.
The illustration included here might be updated in the future, and if that happens, I will update this thread accordingly. Regardless, it is hoped that this picture or an updated version will become the premiere reference illustration for safety razor parameters around the blade cutting edge.