I need to attach a CFW-9 v2 to an ST2000XM. I haven't The needed screws to attach the wheel to the camera body. According to manual these should be 4-40 3/16 screws, well ... I buyed them but are too short to even lean out from the wheel back. The manual is wrong at this point. What is the right length? I have the provided screws to attach the T thread D Block, can I use these or are they too long? There is a warning on CFW9 manual to use the right screws to not breaking through the blind taps.
Hmm... that's pretty old stuff. Looking at the drawings. The mounting holes on the camera are 4-40 UNC-2B, 0.125" deep. The thickness beneath the screws on the filter wheel is 0.060". So the correct screw length would be 3/16". They would need to be cap screws, not pan head. This would work: https://www.mcmaster.com/#92196A105
Only flat-head screws are measured by including the head. All other screws are measured from the base of the head. You cannot use flat-head screws here. It needs to be a socket head cap screw.
Those are Phillips flat-head screws. They are used to attach the T-thread block. The Allen (hex) key also in the bag would not fit them. It would fit the cap screws used to attach the filter wheel to the camera head. Those screws are not present in the photo. Please refer to the manual: http://diffractionlimited.com/wp-content/uploads/2016/03/CFW9_manual.pdf
The instructions on page 5 of the CFW manual describe the process for installing the filter wheel onto the front of the camera. The written instructions are pretty detailed, but the illustrations are not completely clear. The screws in the photograph are the ones that are used to attach the D-Block to the front of the camera (or in your case the front of the CFW9 Filter Wheel). Be careful when you take the front cover and filter cartridge off of the CFW9. It is a little bit tricky to get the filter magazine free of the rotating mechanism. Also, when reattaching the cover, gently tilt it back into the rotating mechanism. Then, when you are replacing the cover, make sure that the pin on the top of the filter magazine fits into the hole on the center of the cover. This keeps everything aligned. The 4-40 X 3/16" socket head cap screws should have been supplied with the filter wheel. The illustration below is a typical socket head cap screw. Yours will be much shorter.