Bill Spurling mentioned that he has seen rollers that appear almost as if they have been sliced by the cams. The roller I was mostly concerned about wasn't that bad, but it was glazed quite a bit, and it did have some pretty good grooves worn into the surface.
As you can see from the photo below, oil also creeps in through the oil points at the ends of the frame. Good thing to remember to not over oil these.
Here you can see that the rubber has broken down and filled the space in between the teeth creating a smooth surface across the cam.
I've heard that replacing the rubber can be a bit of a challenge. It's pretty tricky to slide the thick walled rubber roll onto the steel core. Apparently there is a tool for this job, and apparently folks like Dave Seat make this process look as easy as the book describes. The book will describe the steps: “slide the rubber on while holding your thumb over the end. This will cause the air inside to be compressed and cause the roll to expand and slip easily upon the shaft.” Really? Sounds like a snap. But, honestly, I knew I was looking at a project. Brian Donnell had also told me that he had spent a lot of time fighting with the keyboard rubber years ago when it was necessary to replace his.
I tried to apply a bit of rubber rejuvenator, a product that we keep around the shop for use when the offset dampening rollers become glazed. It did seem to bring back a bit of life to the rubber. The surface of the rubber roll had a little less sheen. But after studying the caked cam teeth once more, and perhaps because I can be a bit of a glutton for punishment, I decided to replace the rubber.
No turning back now. Of course the books say: “slip the old rubber off” or something like that. There was no slipping. The rubber roll liked the steel core and wasn't planning on going anywhere. The book the mentions: “it may be necessary to slit the rubber length wise to remove it.” Yup.
My heart sunk a bit when I discovered this. What?!? The roll is too short? Crap! I didn't measure the roll before I spent the last hour and half fighting with it to go on. After a bit of kneading to rubber into place, the roll expanded. Of course! I just spent all of that time putting pressure on it, no wonder it would compress. Whew.
|Here it is, as it should look.|
Ready to be placed back into the key cam frame.
|Reassembling the frame.|
|Completed frame, and tired dude.|