You can see the inside of the cuff in the lower left of this photo. I am going to engineer some hardware that will attach to the center hole of this piece without modifying it any further. First, I'm going to countersink another T-Nut to be glued in, a little later, to the elbow chassis. The red arrow indicates the location of this piece.

A little brainstorming, and a little shopping around,... a whole lot of funny and confused looks from sales clerks at several stores, and this is what I came up with. WIPER MOTOR BUSHINGS, found at most Autozones in the 'HELP!' section.

I pulled out the metal grommet, and screwed in a 3/8" threaded rod. This serves as an excellent handle as you grind away a little of the lower diameter so it fits snug inside the center hole of the cuff. This material is like car tire rubber compound, so I used my disc sander to do this.

Here, I've taken that 3/8" threaded rod and threaded on the T-Nut that will be glued on to the elbow. Also, I've threaded on what's left of the wiper motor bushing so that it is flush with the end of the threaded rod. The red arrow indicates where I've put a mark on the threaded rod. This is where it will have to be cut.

In this case, it's just a little over one inch.

Here, I've epoxied in both the threaded rod and the T-Nut, in the same manner as one of the elbow hubs, to the top of the elbow. I've left 1/2" threaded rod protruding for the cuff.

This area will need to be cleaned up a bit but I will deal with that later.

This picture simply shows the concept of this new hardware. Here, I've taken my modified wiper motor bushing and jammed in another T-Nut. This piece, once installed inside the center of the cuff, will allow it to thread on nicely without the use of any tools.

As it gets tighter, it squishes the rubber outward making a very solid bond to the cuff. This is similar to the way a sanding cylinder attaches to a rotary shaft.

NOTE :: Space is not very forgiving inside the cuff. If you do these steps, you will have to modify at least one of the arm pistons. This is covered in Stage VIII.