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250PX Flextube


russ
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My latest scope and hopefully the last one for a few years. Wasn't my first choice, would much rather of had the solid tube but hey ho.

It certainly looks better than the solid tube. But i was a little disppointed when i first got it. It's not as well balanced and raising the truss was a lot harder than i expected. The thing wouldn't budge. If the collimation was okay, it certainly wasn't after i had jolted the truss into place. It matters not though as i don't intend to bolt the truss permanently in place. So collapsing the truss won't be used again, even for transport to the dark site.

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Started modifying already. Played around with the azimuth bearing, replaced the focuser, added another finder, secondary collimation thumb screws and counterweight system. Just leaves the shroud and side supports to go.

russ-albums-kit-picture11555-250px-counterweights.jpg

Optics are superb, couldn't happier with those. The primary mirror cell is top notch too. And with the mods so far i'm much happier overall.

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Nice clean job, looks the business.

BTW have you adjusted the tension of the truss tubes? On the side of each bottom part of the truss tubes (where the tube passes trhough the flange) there's a little spring loaded adjustment point. Sounds like the tension is set to high making it difficult to move the truss rods. I'm assuming the chrome headed truss locking knobs have been loosened.

John

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re: ease of erecting the top assembly; have you tried adjusting the tension screws for the struts? They're the black rounded nuts on the side of the strut slide assembly at the top of the lower tube.They controll the amount of pressure applied by the ball bearing to the strut. Lower tension = easier to move - you need to get the sweet spot where there's enough tension to hold the upper tube in the extended position until you have locked it off, but not so much its hard to move.

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Nice clean job, looks the business.

BTW have you adjusted the tension of the truss tubes? On the side of each bottom part of the truss tubes (where the tube passes trhough the flange) there's a little spring loaded adjustment point. Sounds like the tension is set to high making it difficult to move the truss rods. I'm assuming the chrome headed truss locking knobs have been loosened.

John

beat me to it!

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Thanks John and Gaz. I'll go and check the tension of the truss now. :)

John, you may have noticed i have raided the WDS parts bin. What a great site.

looking good russ :) have you ordered your shroud from astroboot :hello2:

Sadly it's nowhere near big enough, a few inches short of wrapping round. Wondering if i should have ordered the 12" version?

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Looks very good Russ. I have had problems with raising the upper section even though I adjusted the spring loaded points. Because it was a problem every time I used the scope I now leave it permanently in place.

I bought a Meade Lightbridge shroud from Astroboot last year but should have bought the 12" for my 10" scope. However, I cut the Shroud and it works ok and the bit that was left I use as a dew shield.

I like your Finder - what size and make Russ?

Mark

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Very nice mods.

I do miss the grab and go aspect of owning that dob :)

The truss will be tight as i did them up tight, I stored it all open and only collapsed it to take it to the shop for you to collect.

I think i will get another dob in the future after the obsy and ccd is all sorted.

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John, you may have noticed i have raided the WDS parts bin. What a great site.

QUOTE]

Yes WDS stock an amazing amount of Astro related bits and pieces. :) Great service as well and very, very helpful.

BTW like the finder :)

John

Edited by johninderby
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Very nice mods.

I do miss the grab and go aspect of owning that dob :hello2:

The truss will be tight as i did them up tight, I stored it all open and only collapsed it to take it to the shop for you to collect.

I think i will get another dob in the future after the obsy and ccd is all sorted.

All sorted Earl. Loosened off a bit and now perfect. Thanks Gaz/John for the tip.

And balance now perfect with the counterweights. Even with the heavier focuser and incredibly heavy finder it balances without the tension handles.

And have i mentioned how good the optics are? :)

Thanks Earl :)

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I bought a Meade Lightbridge shroud from Astroboot last year but should have bought the 12" for my 10" scope. However, I cut the Shroud and it works ok and the bit that was left I use as a dew shield.

I like your Finder - what size and make Russ?

Mark

Mark, do you mind me asking how you got the 10" Lightbridge shroud to fit? I quickly wrapped it round but it was a few inches short.

And the finder is courtesy of John and also Astroboot. It's a 20x65. I have one last improvement to make to the finder, hopefully this week.

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All sorted Earl. Loosened off a bit and now perfect. Thanks Gaz/John for the tip.

And balance now perfect with the counterweights. Even with the heavier focuser and incredibly heavy finder it balances without the tension handles.

And have i mentioned how good the optics are? :)

Thanks Earl :)

Good stuff - it's a stunning scope isn't it, I couldn't be happier with mine. Well, apart from the Az "bearing" if you can call it that. But then you have to have *something* to tinker with don't you?

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Good stuff - it's a stunning scope isn't it, I couldn't be happier with mine. Well, apart from the Az "bearing" if you can call it that. But then you have to have *something* to tinker with don't you?

Next phase is some Ebonystar or something similar for the Az. Got it working pretty good with some new Virgin teflon, milky bottle washers and Sailcote lubricant. But Ebonystar will be the finishing touch.

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Next phase is some Ebonystar or something similar for the Az. Got it working pretty good with some new Virgin teflon, milky bottle washers and Sailcote lubricant. But Ebonystar will be the finishing touch.

I'm in the same boat - new teflon and turtlewax, combined with loosening the central bolt, has helped a lot, but there's still some stiction. Let me know how you get on, I might be following in your footsteps.

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will do. would you be interested in some Ebonystar? It appears you can only buy it in 3m lengths.....that's a lot of dob mods. :)

I was, right up until the moment that John posted that teleskop service link! Cutting the stuff was the one thing putting me off. Think I might have to place an order...

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I was, right up until the moment that John posted that teleskop service link! Cutting the stuff was the one thing putting me off. Think I might have to place an order...

me too....will that ring fit between all the allen key bolts in the base?

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me too....will that ring fit between all the allen key bolts in the base?

I was thinking about that... but I'm planning to fit the teflon pads to the rocker box and make a new base with the ES glued on. That way you don't need to worry about the bolts...

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