Need Your Advice
Posted 31 January 2013 - 09:54 PM
Posted 01 February 2013 - 12:29 AM
In the "old days", I had an orange-tube Celestron 11. Any time I wanted to use it, I had to assemble it by mounting the tube in the fork.
The older C11 and C14's saddles were designed to be taken apart so they could be transported more easily. There were studs attached to the rear cell that fit into slots in the saddles to facilitate assembly/disassembly.
The NexStar and CPC scopes aren't designed this way, but can the tube can still be 'deforked' by removing the screws holding it to the saddles. The process is not difficult, but will be a lot easier if you have an 'extra pair of hands' nearby.
To avoid damaging the tube, before you remove it loosen the screws holding either or both fork arms. That way, when you remove the screws from the saddles, you can spread the fork slightly to keep it clear of the tube. You can also wrap the tube with a towel for even more protection.
The C11 tube weighs around 27 pounds or so. Not heavy, but awkward to try to move by yourself in tight quarters so I'll reiterate the benefit of having a helper.
Posted 01 February 2013 - 09:41 AM
Mainly visual? The 14 is sweet, but will be perfectly happy on a less expensive mount like the Losmandy Titan.
The 900 is a fine mount for folks who need the payload and for whom imaging is _all_.
Posted 01 February 2013 - 10:28 AM
What Dan said about de forking ...
I'll add that the NexStar GPS mounting point also has a pin (1/8" x about 1/2") in each side in addition to the bolts holding the bracket to the ota. The pins seems to provide a very precise position and attachment between the bracket and the ota (no movement like what can occur with just bolts).
The pins are not difficult to deal with during the de forking (but as Dan has mentioned you need to be careful not to scratch the side of the ota and the extra pair of hands really helps). The pins I have removed (on two scopes) were very snug on one side (usually on the bracket) and required some work a pair of needle nose pliers to remove them completely.
If I was re forking an NS GPS scope (which I haven't done) I would dry fit the pins to ensure they won't stick too much during hand assembly, and then tap one side in with a small hammer. Not a difficult procedure but something you should be aware of during the de and re forking procedures (where you don't want any "surprises").
Posted 01 February 2013 - 07:59 PM
Uncle Rod, as always you provide very practical advice. I know the AP 900 is an extravagance, but I'm not getting any younger, and this will probably be my last big astronomy related purchase. For the past several years I've been going more and more toward video astronomy and CCD imaging, because my eyes are not as good as they once were, and I don't tolerate the hot and cold weather as well either. Am I trying to justify the expense--you bet!! I'm sure the Titan is a very good mount, but I'd like to experience that "new AP smell" just once in my life!!
Mark, thanks for the hint about the pins. I don't recall reading about those pins before, so I will be particularly watchful for them. Thanks so much.
If anyone has ever reforked a NS11, I would really like to hear your experience with the process. Thanks to everyone for your helpful advice!!
Posted 02 February 2013 - 09:18 AM
I will again say, though, that for your purposes, I think a nice C11 will make you happier. Especially with video field is important. A C11 on an AP900 is one heck of a nice rig.
Posted 02 February 2013 - 10:34 AM
Posted 02 February 2013 - 12:12 PM
Posted 08 February 2013 - 09:15 PM
Posted 08 February 2013 - 10:20 PM
The bolts you need to loosen are in the base of the arm. You can get away with only loosening one side. To get at them you'll need to remove the plastic covers on the fork arms, this requires an allen head wrench and it's a size that isn't really popular and may not be included in some allen wrench sets. (7/32" I think) You might also need to take a few bolts out of the base cover but I don't think you have to completely remove that cover.
For the bolts in the base of the fork arm all you'll need is a big phillips head screw driver. If you loosen the bolts you'll be able to tip the arm away from the ota enough to get those little pins I mentioned earlier to release. Those phillips head bolts are big and require a bit of torque to break them loose (two hands on the big screw driver is fine). Don't remove these big bolts completely otherwise the fork arm can rotate forward or backwards when you release the ota and that will pull the wires tight and that will unplug them within the base (or worse break the connectors).
This is also where the extra pair of hands really comes in handy (one pair to hold the ota, one pair to work on the fork arm). Even once the fork arm is loose the extra pair of hands helps to keep the ota stable so you don't scratch the sides (which would be a real shame with that nice carbon fibre).
Posted 09 February 2013 - 01:11 PM