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Tak autoguiding not TOO bad...


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This was the guide trace for first light of Speed Machine One, a Tak FSQ/Altair 80 Triplet parallel imaging rig guided by Lodestar/ST80. When I first opened the guide window to check it I cursed because I thought it had stopped working. It hadn't!

Capture-X3.jpg

Our Tak EM200 mount gave us some grief early on but it has been doing nicely for a couple of years now and a recent adjustment to the Dec worm end float seems to have got it nailed down. (Thanks to Per for his input on this.) The trace above was recorded shooting just above the horizon using three second subs and ending with the counterweight in the air. I think it'll do for now! :)

SM1-NIGHT-L.jpg

Pity I made a small bungle on the capture in one of the scopes but we won't mention that...

Olly

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That looks really good, Olly! It is amazing how such small adjustments makes such a big difference. I bet that most mounts would perform a lot better if people dared to tighten or loosen the bearing pressure to make it just right. Sorry to say, most people are very,very,very,very,very,very,very,very scared of touching something that was "adjusted at the factory"...

My stuff is in the closet right now waiting for darkness... On the up side; plenty of daylight and the boat is in the water and ready to go!

/p

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Not only good guiding but extremely good seeing. Does the 0.02 related to pixels or arc seconds?

What is the Dec worm end float?

It's (binned) pixels, Martin. And, yes, the seeing must have been good. Bear in mind that this was a tree skimmer, Rho Ophiuchus, too. I used 3 second guide subs to let the seeing average out.

The dec worm end float is the play along the line of the worm itself. (ie can you pull the worm up or down along its axis?) It is easy to adjust, though count on dropping and then losing the screws which hold the encoders on!! You remove the encoders, which are keyed so as not to lose any information when fitted or removed. They just hang on their wires. This reveals the bronze bush which carries that end of the worm. It has a screwdriver slot in it of the kind that has the middle obscured by the shaft, so a pair of needle or maybe circlip pliers can go into each accessible side of the slot. Screwing in a tad reduces the end float. And that, plus a poor connection on the dec autoguide port, was my problem all along. Maddening but now resolved!

My earlier fudge was to pack a little nylon disc under the cover at the opposite end of the worm. This worked quite well, in fact, but adjusting the bush properly is the way.

Olly

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I wish I could get my eq6 to guide like that Olly!

You have just got to be pleased with that sort of graph.

In my opinion, the NEQ6 has very good potential. Mine guides almost like Olly's Temma, and I attribute that to:

Better bearings (Swedish SKF, of course)

Careful shimming

Just the right pressure on the main conical bearings

Correct worm gear pressure

Correct end float adjustment of the worms

When all this is done carefully, it will guide like a €5000 mount. And the funny part is that it was actually dirt simple to do! I think people are too afraid to dare go into their mounts... Just get the toolbox and do it slowly - there isn't much that can go wrong, and it certainly is correctable afterwards.

Take the example of my trip to Olly's. It didn't guide as good as I wanted it to, so I loosened up the RA conical bearing just a little and got really good guiding after that. The process takes less than five minutes and you do it on a hunch.

/p

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Per/Olly

I am not adverse to having a bash at it. I backed off my RA worm gear mesh a tad last night as it was over running after button released. I am waiting for the really short nights in a few weeks before I really give it a good going over. My DEC axis is very sticky despite adjusting the bearing collar thing?? So that will need further investigation. Read the strip down guide a few times so will order the bearings and shims. Will be all ready for the new season then,

Cheers

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