De-forked 12" LX200GPS OTA on Losmandy G-11?

[Omaroo]

Has anyone done this successfully?

The G-11's advertised capacity is 27kg.

If I were to de-fork my 12" LX200GPS (16.6kg~ish), add a dovetail (2.5kg), FS60-C guidescope (2kg), guide rings (1kg), Electronic MicroFocuser (1kg) and a DSLR (1.0kg) (Total approx. weight: 24.1kg) and then put it on a G-11 would it cope well? Given that the G-11 was originally developed for the Celestron C-11 it can't be far off.

After unsuccessfully trying to sell, so far, the LX200 to buy a Tak 130 I'll probably end up just keeping the LX. It's a great scope, but with the forks is way too heavy for my back - which suffers from a burst L5 disk. The reason I wanted to go with the Tak was it gives a great photographic performance without the weight. However, if I were to de-fork the OTA, its reduced weight is more in line with my current strength. With a f/6.3 focal reducer it'll be great for photography.

I know people will try to advise me to just buy an OTA from scratch and sell the current one, that's what I've tried to do without success so far. I'm not going to give it away, so I may as well use the thing. I believe that the 12" can be de-forked without having to disassemble the arms, which is what screws up the smaller OTAs after putting them though the process. The forks, GPS, and all the other guff can sit in a cupboard until one day when I mount it permanently in an observatory.

Any advice from anyone at all? I've heard stories about de-forked OTAs are VERY difficult to re-fork, but I'm not sure that I can find enough reliable evidence of this.

Thanks in advance

[Zuts]

It's not much but I asked Bintel about unforking my C11 and they said basically dont do it as you will never get it back again without sending it to the factory.

As far as a LX200 on a G11, I saw one at bintel and it looked very big on the G11. A C11 is a fair few kg lighter than a LX200 12 inch so maybe that would make all the difference.

I dont blame you for not wanting to 'give away' your scope. I am planning on selling my C11 and would be happy enough to at least get enough to get a new C11 OTA or maybe a new LX200 R 10 inch OTA. Maybe the pain of selling your scope at a bit less than what it is worth would be offset by a nice shiny new LX200 R 10 or C11 on your G11.

Just my 2 bits worth
Paul

[madtuna]

"...... I've heard stories about de-forked OTAs are VERY difficult to re-fork, but I'm not sure that I can find enough reliable evidence of this."


I heard that rumour too Chris, while it's no LX200, I've deforked and reforked a C8 a zillion times with no probs at all

[Omaroo]

Thanks Steve. The LX200GPS OTA relies on (supposedly) PERFECT re-alignment with the fork saddles so that the Level-North system reference is re-established.....or something along those lines.

Maybe I'll just do it and stuff the consequences... :shrug:

[Omaroo]

Thanks Paul - much appreciated. I tend to agree that the LX is a bit heavier than the C-11 - by about 3kg I believe. I'm of the opinion that the advertised 27kg capacity of the G-11 would be conservative, as they'd be silly not to say that.

I'd LOVE to go to a Titan, but at an additional $7k my wife tells me, very positively, that I'm dreaming.

Cheers
Chris

[h0ughy]

it was a struggle on the eq6, but i suspect the losmandy will handle it

[Omaroo]

Thanks David

Yep, the EQ6 is only rated to 20kg, and I'd suspect that rather than a conservative figure it's pretty accurate from what I've heard.

I know you had the 12" on the EQ6 - and then you sold it re-forked. Was it the GPS and did it still work as advertised?

[h0ughy]

bugger lightnig everywhere - yes it worked - just on the eq6, but with adding everything else it was far too much in weight. the losmandy g11 however should be able to handleit . man i have never seen so much lighting .

back on the forks it needed to be re aligned properly but performed well. It was the classic

[netwolf]

I looked at doing this wihth my LX90 and based on what i found decided against it. It seems it is possible but not an easy task to refork the Meade LX series. However i have read that the Celestrons are easier to do as they provide some sort of marking so your OTA will be orthogonal when you refork it.

[Omaroo]

Thanks Fahim, but at the end of the day I'm really not sure I care if it will re-fork well or not. With my back I can't use it in its current configuration, so to me it's nothing more than a bloody expensive boat anchor. LOL!

I own it, so don't have to pay any more to get myself a damn good OTA. I'd rather someone bought it so that I could do what I want - but no-one seems interested, which is a great pity. The price is right.

[astronut]

Chris,
Have you tried one of the LX-200 Yahoo groups.
I'm sure your answer would be in there.:thumbsup:

[AndrewJ]

Gday Chris

Bassnut who posts here had a 12" on a G11 and did some good stuff
so perhaps he may comment on that side
but re



Totally wrong
The level north is done by a board bolted to the DEC axle
It uses a rolling ball sensor to detect level
When it does this, it measures at three points, hence any misalignment of the sensor is self excluded. The sensor could be 5deg off level, and the process will still work.
There is no problem deforking the OTA. If the arms are a bit tight, just spring them and the OTA will slide out.
The only problem on reassy is realigning the OTA orthogonal to the RA axis
This is simple but can be time consuming. Meade do provide jacking bolt holes, so if you preset them before removing the OTA, they will give you a good datum for later reassy.
One more thing. If you have a bad back, make sure everything is well supported ( lay scope on floor ), as it is light, but very awkward to disassemble whilst avoiding scratches.

Andrew

[Omaroo]

Fantastic Andrew! Thanks for clearing the L/N question up! :)

There ARE fine-threaded "jacking" holes that are drilled-in from the edge of the cell assembly that do look like adjustment devices. There are no grub screws inside (I've just checked by inserting an small allen wrench inside and can see the end pop out the other side) so I'll need to find something to fit. I'll take a few points of reference with them and see if I can also take measurements between various surfaces with a micrometer.

[acropolite]

Don't believe that to be so, the LNT module on my LX is not preciesly mounted and has calibration routines and to determine where level actually is relative to the sensor. I suspect that any error in the level position is calculated when you point the OTA at sigma octans during the calibration routine.

IMO re-alignment of the optical axis of the OTA with the forks would be the main problem after removal.

[netwolf]

In a similar thread by me.
http://www.iceinspace.com.au/forum/showthread.php?t=24307&highlight=ota

Jase provided a very good link on the re-alignment procedure.
http://www.mapug-astronomy.net/AstroDesigns/Mapug/OTA_Alignment/OTA-1.html

[Omaroo]

Thanks for that Fahim - a very comprehensive guide indeed :thumbsup:

I guess that if I remove the OTA it may never re-join the forks anyway - so it's OK by me. Pity - I'd still rather someone buys it complete so that I don't have to dismantle it.

[Satchmo]

Chris , I'm getting the photo bug a little and share a problem with my L5 also !

You might find you can sell your outfit with a little more drop in price. Why not advertise in the local mags. Despite its large membership I suspect that the market of active purchasers of pricier gear is still very small on IIS, and probably biased towards smaller refracters.

I'm hoping that the Orion ED102 F7 proves good for photography so the combination with an HEQ5 Skyscan will prove fairly lightweight and cost effective combo at around $2500 all up. Otherwise a well baffled 6" F6 Newt would probably be superior, not needing a coma correcter /field flattener.

[Bassnut]

Chris, I dont know about de-forking an LX200, but I have a 12" LX200R tube on a G11 and its OK, marginal, but with care you can do great pics with it. My ED80 guide scope tipped the weight over the limit, but with an ST80 guide scope it was fine. I see your FS60 guide scope is only 2Kg, so itll be OK. I also had a heavy ST8XME camera and autofocuser, a DSLR would be much lighter. The light guidescope also had much less flexure. You can see pics of this rig, and astro pics from it on my site.

[Omaroo]

Thanks Fred

The little Tak actually weigh 1.3kg, so lighter still.

I'll certainly have a look at your site. Good to know it's kind-of OK. Last thing I want to do is to have to go a Titan.

[Omaroo]

OK Fred - I've had a look at your site.

I wish I hadn't. Please tell me that from M16-down on that page you used the LX.

:jawdrop:

I take it that the RCOS/Paramount set-up has superseded the LX200/G-11 setup.

[AndrewJ]

Gday Chris

Just reading that fork alignment link, it doesn't really apply to you
Orthogonality setting is a two stage process
1) You get the DEC axle orthogonal to the RA axle
( if you dont touch the bolts holding the forkarms to the base hub
this is not going to affect you )
2) You get the OTA set up orthogonal to the DEC axle
( or more precisely, colinear to the RA axle when the scope is set at DEC = -90 )
The simplest way to do this is point at the pole and spin the OTA
if you cant keep the stars rotating within the EP, you are off.

As to micrometers etc, not reqd.
Just get four bolts to go in the jacking holes ( in the back of the saddles ) and screw in till they hit the screws holding the saddles to the OTA. Loctite/locknut em
Loosen the 6 OTA screws and remove OTA, spring the forks if necessary.

On resetting ( if you ever do ), just fit the OTA and snugly fit the 6 holding screws. Swing the OTA up and jiggle until the 4 rear screws in the saddle plate rest evenly on the jacking screws.
Do up the 6 screws in the OTA and yr 95% there.
To make this process easier, I actually replaced the 6 socket head capscrews with hex head bolts so i could get to them when the OTA was pointing up.

Andrew

[Bassnut]

All the pics were from the LX200 except the few at the top labeled from the RCOS. Both M16s were from the LX200.

The RCOS/PME is now GRAS G15 in SA, but I still have the LX/G15 here at my place, all it needs now is another camera (its cam went to SA).

[Omaroo]

Thanks Andrew :) I was thinking just that. Use them as reference - as long as they're locked in place and don't move.

I believe that they are 4/40's? They're pretty thin and long!

Thanks a lot for your help!