Customers ask how to cut serrations in the jaw faces. Here’s how I do it.
There are a couple ways of doing it. One is using a metal shaper, which pushes an angle cutter through the steel. Or maybe with a Bridgeport type machine you could tilt the head and use the corner of a carbide end-mill to cut the grooves.
I decided to build a fixture. It holds carbide tipped slitting saws or carbide tipped side mill cutters with a 1″ ID 4″ OD, and range from 1/2″ thick to 3/16.
I also built a fixture to sharpen the cutters on my surface grinder. I can get about a dozen jaws cut before re-sharpening.
The holder is custom made and I made it long enough to serrate a set of 9″ wide jaws. I can cut 7″ deep with this holder.
Next I needed an angle fixture to hold all the different fixture plates. I made the angle plate from 1-1/4 thick aluminum, and it is solid. The fixture plates are designed to hold the jaws at 30 degrees and made so when you are through the first cut then you rotate the jaws to the other side of the fixture plate to finish the diamond serrations.
Jaw sizes require different pitches and depth of cuts. The pitch is the difference between cuts. The baby 2″ jaws have a pitch of .050 between cuts where the 8″ jaws have .125 between cuts and are much deeper of a cut. I like about .04 square diamond on the bigger jaws where the 2″ jaws have a .020 diamond flat.
Fixturing for the straight serrations used on Yost and Starrett jaws should be a little more accurate. Cutting a 6″ jaw and having the jaws just a little cocked will show a crooked serration. I use pins that the jaws rest on to keep the cuts straight. The Starrett jaws are shaped like an L, and after cutting the serrations, I remove the material on the back side before heat treating.
The Wilton 6 inch and the 8 x 1-1/2 x 1 inch jaws like the Parker jaws have to be held by a special fixture that I hold the blocks by the back side.
These 8″ Parker jaws first need the serrations cut before carving out the back side for final fitting.
The serrations are obviously an important part of the grip of jaws. Cut serrations like these are old school and well worth the effort. The newer style jaws made after the late 1970’s are from powdered metal injected into molds, so the serrations do not have to be cut. This easier and faster method results in a brittle jaw that chips. The quality of the newer style will never compare to the jaws built from tool steel by the vise companies of the past.
You can see the difference in a molded set and cut serrations. I do not have to mention which is which because it is so obvious.