I have pm'd Jason Khadder over at CloudyNights to get his permission to reproduce his posts there on making the milk jug washers for your secondary hold/collimation screws/Bob's Knobs. All credit for this goes to Jason Khadder known as Jason D over at CloudyNights. This mod made using and collimating my XX14i much easier using the Bob's Dobs. So enough from me, here are the images and his thoughts. You can download the picture/image to make a pattern and cut it out.
"As the person who came up with the idea of using 2 milk-jug washers as opposed to the more common metallic washer solution, let me explain:
1- The two washers make it easier to rotate the mirror when the set screws are slightly loosened
2- The washers hold the mirror stalk in place better when the set screws are tightened
3- The washers protect the mirror stalk from dents – just like the metallic washer
4- The most important advantage of the two washers by far is the ability to make fine adjustments by tightening one set screw without the need to loosening the other two. Because of the elasticity of the two washers, they behave like micro-springs."
Also from Jason in reply to someone not comfortable (I believe) in removing the secondary to put on the milk jug washers.
"You do not have to wait. You can add the milk-jug washer and experiment with it without the need to remove your secondary -- see attachment. Just make a radial cut and slide it in. If yyou like it, then you can add an uncut one later.
I found two milk-jug washers to work better than one. Give it a shot."
Above and below are the milk jug washers I made for my XT10. I made a more permanent set for the XX14i.