Single-Line and Large Round Creasers
Single line creasers are used to make a single crease line parallel with an edge. They have one side longer than the other to ride over the edge of the leather. The other leg makes the crease line. The smaller the size number the closer the line is to the edge. They come in two size ranges. The regular single line creasers are narrower overall. Gomph made a larger size range they called "round edge creasers" and the Osbornes made a wider range they called "layer creasers". The tips on adjustable screw creasers can be opened or closed to set the width of the line. The larger sizes are called screw layer creasers or large screw creasers. Smaller ones are called loop checkering screw creasers or checkering creasers.
Adjustable Single Line Creasers
Adjustable creasers are called screw adjust or screw creasers. They can be set to variable widths by a thumbscrew that spreads the tips. Some creasers are designed to make more than one size edge creaser are listed here as well.
Regular Single Line Creasers
There are some individual size differences but as a general rule. here are the average sizes of the distance between the crease lines of the regular single line creasers. The sizes are based on handling quite a few of each size and getting an average.
#1 = 1/32 inch
#2 - 1/16 inch
#3 - 3/32 inch
#4 - 1/8 inch
#5 - 5/32 inch
Gomph Single Line Creasers
HF Osborne Single Line Creasers
CS Osborne Single Line Creasers
Single Line Layer and Large Round Creasers
There are some slight differences between individual tools, but sizes on the Gomph round creasers and Osborne layer creasers average out to be as follows.
#1 - 3/16 inch
#2 - 7/32 inch
#3 - 1/4 inch
#4 - 9/32 inch
#5 - 5/16 inch