Just wrapped up building 96 pairs of Wilton, Rock Island, and Reed 3C jaws. I am already low on 14 other pairs, but I wanted to fit a set of Parker jaws to my 956 vise. What I learned in this round of fitting is that the Parker company really did not have a sure fire setup for building these jaws.
Each vise is stamped with a number on both the Static and Dynamic jaws supports. Then each jaw has the same stamped number, so during heat treating the fitted jaws should end up back where they belong. The 3″ jaws shown have the number 96 stamped very closely to each other. The other set is stamped the same number 96 but with a large gap between the 9 and 6. Clearly the assembler would know where the jaws belong.
Another issue I found is that the face of the static and dynamic jaws are not parallel. This is why you see some Parker jaws with the faces hand serrated by a file. They filed the serrations because the jaw faces were resurfaced smooth for custom alignment and then the serrations were hand filed. The set of 4″ jaws I measured shows a .044 difference that has to be made up on the jaw faces, I believe this adjustment was made in the final fitting.
I cut the serrations on the jaw blocks when they are square, and I feel confident Parker did too on some of their jaws. Parker used a shaper, while I used a CNC with a double angled cutter. This is why I have to custom fit each jaw to each Parker vise. Next, I fit the jaws with my surface grinder. I dress an angle on the face of my wheel. The 6″ jaws take a 12.96 degree angle. Then I set the jaws in a Wilton 7″ sine vise and set it to 12.96 degrees. The wheel is relieved on the back side so I can use the back of the wheel to grind the jaw flat and square.
I found all of these numbers with the microscope and setting points on my cad program. Then, after I got close to the width of the slot, I started slowing down for the final fits.
Here is where I found trouble. The jaw inserts I used for gathering my numbers and creating the points only got me close. When I was at a point to check the squareness of the serrated faces I found my angles were off. And not by a little either. I was off by .09. This means I have to redress a new angle on the wheel and reset the sine vise, but at least I will know my final correct angles. The rest is easy, and by taking my time, making sure the static and dynamic jaws supports are filed and stoned flat, the finishing fit is just minutes away. Next is cutting the top radius and pinning the jaws to the Static and Dynamic jaw supports. I will cover this in the last blog on these Parker Jaws.