Adjustment #3: Grip Cam Limit Switch (w/video)

Grip Cam Limit Switch Adjustment

At the risk of being overly simplistic, the Grip Cam Limit Switch (shown below) controls the amount of travel of the Gripper Arm (along with several other things that I wouldn't go into here). In other words, it controls the amount that the Gripper Arm opens, both in the "Home" position (my term) as well as in the Play position. It is a snap-acting switch controlled by two cams: the Grip Cam Outer, and Grip Cam Inner.

The "Outer" cam controls the amount of stroke in the Play position, and the adjustment screw is seen here (circled in orange):

The "Inner" cam controls the amount of stroke in the Home position, and the adjustment screw is located almost 180 degrees opposite (circled in yellow):

For adjusting purposes there are two of these "Stop Pins" provided, one located on the Gripper Housing, the other located on the rear flange of the Gripper Drive Shaft.

Here is a picture of the two pins when the Gripper Arm is located over the Record Magazine (Home position):
 

Inner Position

And here is a shot of the same two pins after the Gripper Arm has rotated over into the Play position:

Outer Position

Note there is a difference in the gap between the pins in the the two positions. More on this in a minute.

With regards to adjustments, the IOM states, "When the gripper arm is in the rest position over the record magazine, the cam shaft should be stopped so that there is approximately 1/4" opening between the two stop pins....". Now this is all Fine and Good, but what it doesn't say is that the Gripper Arm will continue to rotate a little when the motor shuts off, so be aware that adjusting the Inner Cam based on manually rotating the Gripper Shaft will result in a misadjusted switch! You may have to revisit this cam a couple times in order to get it to switch right where you want it.

Looking up to my "Inner Position" picture, one may see this as a 1/4" gap, based on this angle, but in reality it is larger than that.

The IOM also states, "When the gripper arm is in the turntable position, the cam shaft should be stopped so that there is approximately a 1/4" opening between the two stop pins". Now on this one I will take an extreme exception to, as there's no way you can adjust the Outer cam to get this gap once you've properly set the Inner gap! Why? It's easier to show this in the video, but the reason that this is impossible to achieve is that the two cams "push" against each other. To help explain, look at this picture, particularly what I have circled:

Setting aside which cam is which right now, let's say in the picture above that you need to adjust the "upper" cam in a CCW direction a little. Well, you can't, as the "lower" cam is blocking it from rotating any further (it is "pushing" it). Likewise, if you needed to adjust the "lower" cam in a CW direction just a little, you wouldn't be able to, as the "upper" cam is in the way.

Bringing this back to the Real World, adjusting the Inner Stop Pin gap to 1/4" means that the Outer gap is going to be wider (the Inner cam will "push" the Outer). And adjusting the Outer Stop Pin gap to 1/4" means that the Inner gap will be wider. This is why the IOM is a little, "optimistic", when it comes to adjusting both cams to a 1/4" gap, as there's simply no way to do it!

But thankfully you don't really need to set them this way. Why?

Recall that the purpose of the Grip Cam Limit Switch is to set the amount of travel (or "inner width", if you will) of the Gripper Arm in both the Play, and Home, positions. In other words, this switch shuts-off the Gripper Arm actuator when the proper amount of opening has been achieved in either/both positions.

Thankfully there is some "play" in the system, and by that I mean that near the end of it's travel, additional rotation of the Gripper Arm Shaft doesn't equate to more opening (width) of the Gripper Arm. (Go ahead and read that again, as it may be one of the more important parts of this Post.) You should be able to adjust both cams so that the Grip Cam Limit Switch changes over at the exact point that is best for your particular set-up.

Don't worry about where the Stop Pins are "supposed to" end-up according to Rockola, but rather, pay more attention to where the Gripper Arm needs to be at it's widest- during the Home position, or during the Play position. On this particular unit, I found it best to "advance" the cams a little so that the Gripper Arm is at maximum width when it is in the Home position.

Don't get me wrong here. I haven't sacrificed the action of the Gripper Arm during the Play position, as it definitely opens wide enough, but rather I found that due to my use of the non-original Gripper Housing (see my "Setback" post), I preferred to "cheat" the cams just a bit and prioritize things so that I got the maximum opening possible when the Gripper is over the Record Magazine. 
 
This all may be easier to understand in the video:

Link to video: https://youtu.be/BnEbcBs6NLc