What is a Cam Action Grinder Dog?
A Cam Action Grinder Dog is a device used to drive cylindrical workpieces that need a precision grinding operation (s) between centers.
How to Select a Cam Action Grinder Dog
To select a Cam Action Grinder Dog you have to consider the size of the diameter you are going to be clamping on; the material of the workpiece being ground; whether the workpiece clamping surface is finished or not; the size of the area to be ground and the workpiece wall thickness.
Size of the Diameter You are going to be clamping on
These grinder dogs’ clamping capacity depends on the model number you get. Here is a chart from the Ready Tool Company:
| Part Number | I.D. | O.D. | Work Pc Capacity |
| 109 | 0.562″ | 1.500″ | 1/8″ to 1/2″ |
| 110 | 0.812 | 2.062 | 1/4 to 3/4 |
| 111 | 1.187 | 2.435 | 1/2 to 11/8 |
| 112 | 1.625 | 2.875 | 7/8 to 11/2 |
| 113 | 2.125 | 3.375 | 13/8 to 2 |
| 114 | 2.562 | 3.875 | 17/8 to 21/2 |
| 115 | 3.062 | 4.375 | 23/8 to 3 |
| 116 | 3.562 | 4.875 | 27/8 to 31/2 |
| 117 | 4.062 | 5.375 | 33/8 to 4 |
| 118 | 4.562 | 6.000 | 4 to 41/2 |
| 119 | 5.062 | 6.500 | 41/2 to 5 |
| 120 | 5.562 | 7.000 | 5 to 51/2 |
| 121 | 6.062 | 7.500 | 51/2 to 6 |
The material of the Workpiece Being Ground
These type of grinder dogs work best when clamping on unfinished, hardened steel workpieces. If you have to grind parts made from aluminum, brass, bronze, etc.. You would need to use the version with the brass cam and make sure the set screws you are using are also brass. Be very carful dough. The brass cam and set screws wear very easily causing the workpiece to slip.
Not only sleeping will cause a scrap part, but it also can cause a crash. If the workpiece start to slip the grinding wheel will cause a flat on diameter being ground. If you are using an in-process gage, the machine will continue to grind trying to find the size. If the part is grabbed by the grinder dog, the force created by the wheel trying to remove some much material at once can cause the workpiece to fly out of the centers and the grinding wheel break creating a very dangerous scenario.
Whether the Workpiece Clamping Surface is Finished or Not
As mentioned above, these grinder dogs work best on unfinished, hardened steel parts. If you want to drive the workpiece clamping on a finished diameter, you would have to use the brass cam and set screws. You would also have to decrease the speeds and feeds of the grinding operation. Always make sure you have enough clamping pressure to prevent slippage.
Workpiece Wall Thickness
The wall thickness of the workpiece will be a critical consideration on whether you can use one of these cam action grinder dogs. These dogs are not recommended for parts with a thin wall. Here is an example:
