Howdy,
I believe what you are referencing is the old scratcher type chains. They have a left and a right hand slitter, and often three raking elements, a center raker, and then left and right rakers. The slitters are supposed to be higher than the rakers (Jointing). The "set" is built into the offset of the slitters, to establish the kerf width. (They do open up, but not aggressively).
These chains were standard, until the hooded cutter type chains were invented, and these became the chipper type chains that then led to our modern sawchain cutter designs.
The chain on the outside of the bar is what is called a staddle chain. Several different designs of these were tried in past history.
360,
You are correct. A properly sharpened scratcher chain will out cut a chisel chain! And leave a cut kerf endwall so smooth you can write on it with a pencil, and so straight you can neatly cut to a carpenter's line. Scratcher's were made in all pitches and gauges of the day, the last and smallest being 3/8 pitch, OREGON 12S. It's counterpart in chipper was 12C, which was the last of the true equal pitch 3/8 hooded cutter chains. It remained popular for years as the prefered chain for electric saws.
Today, scratcher chains are mainly historical pieces, but they are handy to belie the claims usually heard for chisel chains! Especially the nonsense about the advantages of chisel only cutting the end grain once. The filing was incredibly difficult and time consuming, as each element had to be filed with a flat file separately. The elements had no chrome plate due to the design, and that ment very poor staysharp. Someone who can file (including set and joint) on a crosscut, can file scratcher quite naturally, although it is all free hand. The number of different elements in the scratcher made it an expensive chain to manufacture, especially the hand assembly.
The last attempt at a modern scratcher known to me was some test chain in 3/4 pitch, with only a single raking element, that we built and field tested at Windsor in the early 1980's. Very fast, and with some chrome plate. Stayed sharp longer than other pond and deck chains, and was much smoother and faster. The mills loved it on deck saws, but it died for lack of enough market to justify the manufacturing investment. One has to wonder if it might be a better idea for the harvester machines these days!
Regards,
Walt Galer
Regards,
Walt Galer
