Not to insult your intelligence, but in case you didn't know, hardwoods are measured in quarter inches. 4/4 (pronounced "four quarter") is equal to 1" but can be as thick as 1 3/16". (If you are selling to a broker, 4/4 lumber must be 1 1/16" to 1 1/8" thick.) 5/4 (five quarter) equals 1 1/4", 6/4 (six quarter) equals 1 1/2" and so on.
The term you are asking about means the company will furnish a scale that will allow you to cut 2", 1" and 3/4" material by aligning some sort of marker on the saw head to a scale attached to the carriage frame. These "set points" have already included the saw blade kerf (the amount of wood the blade takes out) in their measurement so you don't have to do any math. The standard scale they refer too is just that, a standard yardstick if you will. It usually measures the distance up from the log bed in inches. You would use that if you were making non-standard lumber, like 1/2" or 8"x8", etc. When using the standard measure scale, you have to remember to take into account the saw kerf when doing your calculations. For most band mills, that means adding 1/8" to the amount of distance you drop for your next cut.
Clear as mud?
No offense, Sawmill, but that is not what 9/4 and 5/4 are for. They are simply units of measurement. Often, someone (i.e. brokers) will ask for "heavy 5/4" (for example) which means they want their lumber 1 1/4 thick plus some extra to allow for processing. In that case you would give them lumber that would be from 1 5/16" to 1 7/16" inches (in other words, an extra 1/16" to 3/16" over the actual size).
