Once I see by the customers pictures and sketches and feel pretty good about building their jaws. I need to correct the miss alignment in the jaw faces by adjusting the angle on the sine vise and re dressing the angle on the wheel to finish grind the jaws. One angle must be dressed on the bottom of the grinding wheel and the angle on the back side is set by the sine vise. I relieve the wheel for side wheel grinding to finish both angles.
Next is cutting the top radius. I create a surface model of the top arc in my software so my Cutting software will follow the surface. It cuts the arc by stepping over .05 and down .025 for roughing and a step over of .007 for the finish cut. The small step over along with a large ball end mill like a 3/8 diameter gives you a small peak to peak point that is easy to smooth down.
Next is adding the pin holes, if possible do it on a milling machine, even using a good drill press if the vise is a small one. Or using a hand drill also works. I drill and ream the hole for my customers and this allows the customer to use the same drill size to spot the center of the hole, then drill 1/64 under the finished hole size before using a reamer to finish the hole.
I have a Bridgeport 12 inch sine plate that I used for my #956 (6″ jaws) vise. The angle came out to 6 degrees so I could drive the 5/16 pins out from the bottom. It takes longer to get set up then it is to drill and ream the holes. I also include soft pins that are knurled at one end to provide a good press fit and making sure the pins do not work loose.
Now you are ready for cleaning up the radius cut and smoothing out the rest of the jaws, I mark the jaws underneath for assembling after heat treating. Now the jaws are ready for Heat Treating.
They come back at 54 to 56 Rockwell hard. A lot harder then the original jaws from Chas Parker. A hand file cuts the original jaws and just slides over the new set. Back from heat treating your choice is to mount them to your finished restored vise or do more hand polishing to remove the colorful design you get from heat treating. Final assembly by driving the knurled pins in.
Here is a finished # 978 Parker from Chuck in Tucson. These jaws are 8″ wide. Really nice job of restoring this old Chas Parker vise. Yes these jaws are expensive to build, but having one of these old Parker vises with ruined jaws makes the vise below par. The old USA iron should if possible be brought back to working condition. If you are interested in having a set of Chas Parker jaws built then please visit my site Here.