Chas Parker Collars

Parker Collars like their jaws have to be custom fit.  Parker did not make their parts simple. The jaws were all hand fit and stamped with ID numbers to keep them with the right vise where the Collars were just bolted on to rough casting in many of their models.  This gives a un even wear or rub of the Spindle when opening the vise.  Not really a big deal unless you like little backlash.   I am sure you have seen some with a stack of shims to eliminate some of the backlash. Here is how I fit the Collars I make and sell on my website HERE.

To find which collar to purchase first you need to take a few measurements. I ask that you measure the large diameter of your vise casting since this is a good start and weeds out many sizes.

Parker 204 Collar Fitting 1-2018 (17)

On each Collar listing I add a machinist drawing and on the listing description I list this dimension as the width.  On the drawing I list the width of the top part of the Collar where it bolts up to the vise.

Parker 204 Collar Fitting 1-2018 (16)

The next dimension that is important is from the shoulder to the center of the mounting threads. This dimension is listed in the description as center of hole to shoulder and the dimension I list is the maximum your vise can be. This means if your vise measures less then no problem if it measures more then I need to alter the collar for you. To find this dimension first I measure the thread hole diameter.

Parker 204 Collar Fitting 1-2018 (21)

I divide this number by two and add it to this measurementParker 204 Collar Fitting 1-2018 (20)This example says the shoulder to the hole center is .210.

Next the collar needs to be fit in the depth area. The collar has two radial bosses that form the major diameter of the collar and rest and wrap around the Spindle lip.  There is three surfaces that need to all touch evenly for a proper fit. I have machines that cut the two steps evenly but if you do not have access to a milling machine then it has to be done with angle grinders and files. Look at this picture of a 954 Parker collar area that is raw casting on both levels. Also show a broken screw but hat was fairly easy to pull out.

Parker954 collar casting

Here is how I cut my two levels on the Parker Dynamic Jaw Support.

Parker 204 Collar Fitting 1-2018 (9)I then cut the next level so I can match the collar level;s

Parker 204 Collar Fitting 1-2018 (11)Again this will have to be done with a file to do it the right way.  I did the math with this collar steps and it should fit like this.

Parker 204 Collar Fitting 1-2018 (13)If you want to eliminate backlash then you will either shorten the two ears and adjust the casting for a close gap between the collar and spindle lip or add Stainless Steel shims or a rather thick one like this one below.

995 collar (3)

I wish there was a easier way to fit these collars.  i am showing the best way but these Parker collars will work just bolting them on since most were never fit properly.


Swivel Jaw Taper Pins: Removal, Sizing and Fabrication

If you are thinking about buying a swivel jaw vise without the pin, or one that is damaged beyond repair, it really shouldn’t be a deal killer. Swivel jaw vises use a pin that is tapered, and the pin should fit tightly and not wiggle or rock.  If the pin is kept clean, oiled and taken out every now and then,  you will never have a problem.  That said, removing these pins after years of not being used is some times difficult!

See the swivel pin all smashed in this 7" Prentiss

Hard to see the swivel pin all smashed in this 7″ Prentiss Vise.


I have had several that were really stuck, and making a Jack Screw is a great starting point. I use a coupling nut with two bolts which is as good as a simple compact jack screw.

Pushing a Swivel Pin (4)



Next, be sure to have a steel plate underneath the jack screw so you will not damage the cast dovetail that locates the nut.  The tapered pin hole in the swivel jaw and the static support has a through hole so you can get to it underneath inside the square slide area.

The 7 inch Prentiss I show in my top picture will most likely have to be drilled out and removed with a slide hammer.  I just know it.  I’ll add a picture when I get to this repair. I will be using plenty of heat from my oxygen and acetylene torch.  When using heat, be sure to heat around the pin.  I like having the flame pointing away from the stuck pin, and on the mass around the pin.  If you heat the actual pin, it will expand the same as the casting.   You want the steel around the pin to expand and break the rust seal holding the pin.  keep pressure underneath with the jack screw and eventually she will pop.  You don’t have much time heating though, because the pin will inevitably warm up too. Doing this a couple of times will work. This way works too if you are replacing the pin with a new one. I tapped the pin with the largest thread I could get away with and built a puller setup like in the picture. Using the square slider as a support for the setup is a safe idea. I kept heat on the pin area and eventually it popped.

Prentiss 21 swivel jaw Repair (12)


The Prentiss pins are made to 3 degrees per side, 6 degrees for the included angle.Prentiss # 20 pin You might need to measure a old pin or vise to figure what angle the pin is that they used.  Some have suggested cutting a thin shim and hand file the angle till there is no gap.  Then use it to set the angle on your lathe or angle grinder.  I prefer to measure the major diameter then the minor diameter subtract the two and divide the sum for the triangle end. Then measure the length of jaw support for the other leg of the triangle.  Use simple trig (TOA) Tangent = opposite over adjacent then atan the sum for your angle.  Some just duplicate the geometry on a CAD system to figure the angle like what I do. Prentiss-swivel-jaw

This drawing is a cut away view of a Prentiss 19-1/2 Swivel jaw. I added the triangle for this example.


Making the pins can be done in a couple ways.  I like spinning the pin in a surface grinder on a sine plate with a spin fixture. The ground surface is a clean way to make angle pins. If you have a lathe, then it is an easy angle adjustment on your compound.  You can be creative on the knob end.  Make it a full ball, or what ever shape you want.  I like adding a 3/16 hole through the side in case it ever gets stuck. Prentiss #20 pin

I also like to build the pin out of 303 SS so it will not rust. Stainless Steel is a soft metal but will hold up fine under clamp pressure.