6 Collimating and locking knobs for Meade 12" Lightbridge Dobsonian primary mirror

A separate set of knobs (#BKLBS) is available to replace the Philips head screws used to collimate the secondary (or diagonal) mirror. Purchasing both sets of Bob's Knobs (separately or in money-saving package #BKLB12ST containing both) eliminates the need to carry two different screwdriver types out into the field. Installation of the knobs is a snap with the included instructions, and you can undo the modification at any time.

The screws used in these Bob's Knobs are made of stainless steel. The knobs on the collimating screws are five-point smooth fluted black plastic, 30 mm (1.25") in diameter. The knobs on the locking screws are knurled black plastic, 25mm (1") in diameter. The difference in size and shape assures that you won't confuse the function of the knobs in the dark. The telescope optical tube assembly will clear the rocker box with the collimation knobs installed.

One of the primary mirror knobs may interfere with the cooling fan connector. The cooling fan plug will fit properly between the knob flutes (as shown in the feature photo), so leave this one knob stationary and collimate the mirror using the remaining knobs. If desired, you can leave the factory collimation screw that is next to the fan connector in place, rather than replacing it with the Bob's Knob.

Bob's Knobs recommends that you remove one collimation screw at a time and replace it with a knob, then repeat the exchange one at a time with the remaining five screws. Check the thread size of each factory screw as you remove it and compare it to the replacement knob, as the collimation and locking screws use two different thread sizes.