I am trying to get some technical information for the D-Block on my ST2000-XM camera. Specifically, the locking screw thread specifications for the dovetail insert. Would you happen to have anything like a dimensional drawing for the D-Block ? I don't see anything in the archives. Thanks Mike
It would take me an hour to pull up the drawing. I'd have to set up an old computer to run the old software. Pretty sure it's 4-40.
Thanks Doug. The thread size is what I needed right now. I keep thinking that I have a paper copy of the D-Block drawing somewhere in my files. I will look when I get home. Mike
If you mean the screw that goes into the side to hold the dovetail, some of them were quite tiny - #2-56.
Thanks all I have a follow-up question, probably for Bill: Is there a chance that you have an old D-Block from a ST2000-XM laying around that you would be willing to sell ? Mike
Mike, I have a D block with the T ring. Send me an email, bill@ sbig.com, if you're interested. -Bill
I have measured the T-adapter threads in the D-Block that is attached to the front of my ST2000-XM / CFW9 to be M42 X 0.75 ? I want to get a custom adapter made that will thread into this M42 X 0.75 T-Thread. Precise Parts has a SBIG T-Ring in their menu options, but it is described as a M49 thread. They also have a menu option for a Mandel Muscle Plate for a CFW8, 8A or CFW9, but they do not say what thread size this is. Can you tell me what a Mandel Muscle Plate is, and if the thread size is M42 X 0.75 ? Any help here would be appreciated. Mike
There are 2 usual ways to attach a midsized SBIG camera: a) T-thread. SBIG T-threads are camera industry standard T2 threads which are M42 x 0.75 mm. b) Machine screw bolt pattern. Four threaded holes, 1.6 inch on a side, female threaded to receive a 4-40 machine screw. Option b) is the way the D-block attaches to the camera or filter wheel. Correct. T2 is the standard connection to most telescope hardware. The D-Block normally retains either a 2-inch nosepiece or a male-threaded T-ring, using 3 small #4-40 socket cap screws. The diameter of the hole where the nosepiece sits is just under 2-inches, eg 1.95 inch or about 49.5mm. So I would guess PreciseParts has come up with Option c). The famous Mandel Muscle Plate was a third-party replacement cover for the front of the filter wheel. It was quite thick (about 0.25 inch thicker than the standard cover), designed to prevent flexing, particularly when used with an AO-7. Normally the 4 threaded holes for machine screws were used instead of the T-thread to attach the AO-7 bracket. Or you could move the D-block off the front of the camera t0 the front of the filter wheel or front of the Muscle Plate. And yes, the big threaded hole is again a T-thread, M42x0.75mm.
Thanks Colin I have an old ST2000-XM Camera with a CFW9 Filter Wheel. As you mentioned, I have the D-Block attached to the front of the filter wheel. Until now, I have been attaching the camera to my scope using the AP16T 2-inch nose piece that threads into the M42 X 0.75 threads of the D-Block (see sketch below), but I am looking for an adapter to connect to the 92FF on an Astro-Physics Stowaway. If I understand your answer correctly, I should be OK to build a Precise Parts adapter that connects to the Mandel Muscle Plate because it has the M42 X 0.75 threads as the T-2. Mike
At Precise Parts, why don't you pick one of these: (Top pick listed first): a) SBIG D-Block - this gives something that will insert into the D-Block and then you use the D-Block's three #4-40 screws to tighten it down. Plus you can adjust the orientation. b) SBIG CFW9 Filter Wheel - this gives a thread on both sides. c) SBIG ST7/8/9/10/2000/4000 (bolted) - bolts on the front. Not sure on this one.
Thanks Colin Option a) is definitely a good choice. I think I will go with that one. One of the issues that I need to address regardless is that the flat head screws that attach the D-Block to the filter wheel / camera protrude slightly above the face of the D-Block, making it questionable whether the adapter will be in good alignment with the face of the D-Block. The screws in question are hex head. I recently bought a spare D-Block from Bill Lynch, and I noticed that the screws are Phillips head, and they do not protrude above the face of the D-Block. I will probably just switch the screws. Otherwise, if I keep the original screws, I am going to have to either file down the tops of the screws or drill the countersink holes on the D-Block a little deeper. Mike
Adapter will go INTO the round part of the D-BLOCK, so a collision is fairly unlikely. Bill sent you the correct screws. I'd just use them. My photo above has the correct screws - they are flush. If you have flat head socket caps screws (the Allen head ones), it is very likely they are not original and someone replaced them.
Now that I think about it, I might have been the one who replaced those original screws. If so, I have the old ones sitting around somewhere, and if not, I will just use the ones that Bill sent to me. The protruding tops of the screws have never been an issue before now because the 2-inch nose piece that screwed into the T-2 threads has a shoulder on it that smaller in diameter than the bolt circle of the D-Block. In case you are wondering, I am getting the old ST2000-XM camera set up to use with my newest scope to use for the solar eclipse. The ST2000 can take 0.001 second exposures. Mike
