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CarolG
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Reged: 10/16/06

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Need Your Advice
      #5655153 - 01/31/13 09:54 PM

I have a Nexstar 11 fork mount scope in my observatory. I have been saving my money to get my dream mount, an AstroPhysics 900. I have almost enough saved for the mount but not for the Celestron 14" Edge that I would like to eventually get. That leaves me with two options. Wait until I have enough money saved to get both at the same time, which would take a few more years, or get the AP 900 now and defork my N11. I've read that deforking the scope is not too difficult, but how difficult is it to put the scope back on the fork arms? As soon as I have the money saved, I would get the 14" and remove the 11" from the AP mount and use the 11" as a fork mounted scope again. What would you all advise I do? Anyone re-fork a SCT, and, if so, how hard is it? Thanks for any advice, tips you can give!!

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Digital Don
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Re: Need Your Advice new [Re: CarolG]
      #5655390 - 02/01/13 12:29 AM

Hi Carol,

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.

Good luck!

Don


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rmollise
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Re: Need Your Advice new [Re: Digital Don]
      #5655932 - 02/01/13 09:41 AM

What do you do with the scope? If its imaging, the main "benefit" of the 14 is _less_ field. Also, if you stick with the 11 you won't need to go to an AP900.

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_.


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mclewis1
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Reged: 02/25/06

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Re: Need Your Advice new [Re: CarolG]
      #5656049 - 02/01/13 10:28 AM

Carol,

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").


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CarolG
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Re: Need Your Advice new [Re: mclewis1]
      #5657052 - 02/01/13 07:59 PM

Thanks, Don, for the helpful hints. It doesn't sound like it is very difficult to defork the OTA, and having another pair of hands is a very good idea. I'm guessing that reforking the tube is just doing all that in reverse.

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!!


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rmollise
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Re: Need Your Advice new [Re: CarolG]
      #5657746 - 02/02/13 09:18 AM

Carol, if you want an AP900, you should get it. Treat yourself!

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.



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CarolG
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Re: Need Your Advice new [Re: rmollise]
      #5657874 - 02/02/13 10:34 AM

I think you may be right about the C11. Even if I had the money, I believe I would not get the 14" right away. I have the top dovetail plate on my 11", the Microtouch autofocuser installed, and the Hyperstar ready to use, so switching to a 14" would be a big expense.

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rmollise
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Re: Need Your Advice new [Re: CarolG]
      #5658026 - 02/02/13 12:12 PM

Slap an f/3.3 reducer and a Mallincam on a C11, and there is very little that will escape you.

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mclewis1
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Re: Need Your Advice new [Re: rmollise]
      #5658352 - 02/02/13 03:25 PM

+1 to what Rod said ... very very little.

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CarolG
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Reged: 10/16/06

Loc: Oklahoma
Re: Need Your Advice new [Re: mclewis1]
      #5669784 - 02/08/13 09:15 PM

I have one more question about deforking the C11. I know I need to loosen the screws holding the fork arms, but which screws are they? Do you take off the base plate to get to them or what? I want to be fully prepared before I start so I don't have any surprises. Thanks again for all the help!!

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mclewis1
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Re: Need Your Advice new [Re: CarolG]
      #5669888 - 02/08/13 10:20 PM

Carol,

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).


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CarolG
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Reged: 10/16/06

Loc: Oklahoma
Re: Need Your Advice new [Re: mclewis1]
      #5670725 - 02/09/13 01:11 PM

Thanks, Mark. I'm thinking that for a little extra security, I might just lie the whole scope with forks down on our pool table with the OTA resting on some towels. I plan to remove the NS11 from my observatory pier and not try to defork it there. Also, once I get it deforked, that might be a good time to really clean the corrector plate and inspect everything.

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