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Old 28-09-2020, 05:14 PM
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LewisM
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Restoring a $150 Skywatcher ED80 refractor

Recently, an old gold-tube Skywatcher ED80 was offered here, advertised as "foggy optics" and scratched tube plus a few other quibbles for $150 posted with the rings and dovetail bar. It was worth taking the gamble to me so I struck the deal. See picture 1 and 2 for the seller's pictures through the scope. Not good.

Hoping it was just salt or condensation between the elements, I took off the dewshield cap upon arrival with trepidation. Optics looked ok, but the smell of old electrical tape (holding on the dewshield cap and the dewshield itself acting as a shim around the cell) had me suspecting off-gassing of the glue was vapor-depositing onto the objective. Time to disassemble that cell and clean the glass. Big inhale...and hold...


Got out the retainer ring spanner, but found I didn't even need to - the ring was on finger tight. OK, odd. What was even more odd was I was confronted by the weird sight of the element spacer foils on the OUTSIDE of the front element - a "HUH, WTF" moment. Curious indeed. Placed a thick wad of felt onto a cat-food can, and pushed up the objective, knowing in advance I should be REALLY leary about the front element.

Sure enough, as per my diagramme below, I was confronted by an objective arrangement that had been completely and utterly incorrectly reassembled by someone. Well, there you go, that accounts for the under-performing refractor. No wonder it wouldn't come to focus and look foggy.

I gave the glass a clean with Pursol anyway, and reassembled it the correct way. I then tested the optics on a garage near by. A little better I must say (pic. 4 - taken with my iPhone dangling unaligned over an eyepiece - very scientific)
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  #2  
Old 28-09-2020, 05:21 PM
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The tube as received, as well as the focuser and focuser wheels were in need of attention too. See the first 2 pictures.

I identified the scratches and gouges (some to the metal) and proceeded to fill them with automotive body filler. Next came a LOT of block flat sanding until I was happy with the result. More on the repaint in the next post.

The focuser wheels had the old rubber grips that are notorious to fail and fall off. I visited Bunnings and found a sheet of self-adhesive ribbed rubber non-slip matting (used on running boards etc). Carefully measured and cut and fitted them to the "mag wheels". Back to perfect.

Lastly, the focuser itself felt odd. Being a Crayford focuser, this was almost to be expected . I disassembled it, and found the teflon pad that rides in the pinion groove had fallen out, and that the rubber glue SW used to secure it was bundling up in a goopy ball of crud. Cleaned all that out, reaffixed the teflon pad with some special glue I have and reassembled. Not bad, not bad at all.
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Old 28-09-2020, 05:31 PM
croweater (Richard)
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Nice work Lewis. Looks like you have created a bargain there. I hope you're going to paint it a lovely white shade and not some horrible takky green colour? .
Cheers Richard
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Old 28-09-2020, 05:31 PM
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And lastly in this enjoyable saga, the repaint. I quickly came to the colour choice after Dulux brought out a range of new colours. I chose Capital Yellow - slightly reminiscent of the original SW Gold.

3 good primer coats rubbed back, then 4 good solid colour coats over 4 days. Satin always responds well to a hand-rubbed polish, so I brought it from satin lustre to more of a true semi-gloss (there is a difference ). I left it a few more days, then gave it 3 hard wax coats. That'll make the dew run

Lastly were some small personal touches - I reglued the original data decal onto the focuser in a quasi-Takahashi style. I replaced the focuser affixing screws with stainless domed head cap bolts (small head size), as well as the crayford bearing plate retainer screws with the same. The pinion cover screws got nickle plated as well. The interior of the dewshield received 2 coats of blackboard spray paint followed by a roller coat of Stuart Semple's Black 2.0 (still hasn't crumbled or deteriorated on my test piece from 2 years ago that's been out in the weather!)

The focuser was a little loose on the tube, so I shimmed it with thin velvet at 3 points around the circumference. The lens cell perimeter got a full band of the same velvet to retain the dewshield.

Lastly, I replaced the simple SW ring nuts with nice tall knobs, and refelted the rings themselves.

$150 spent on the scope, about $95 on paint, screws, tape, velvet/felt, $80 on a Losmandy plate, and $35 on a 2" to 1.25" adaptor as I only have a 1.25" Tak diagonal Time - a bit, but all after work so enjoyable.
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Old 28-09-2020, 05:32 PM
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Quote:
Originally Posted by croweater View Post
Nice work Lewis. Looks like you have created a bargain there. I hope you're going to paint it a lovely white shade and not some horrible takky green colour? .
Cheers Richard

- you may not like my canary.

I WAS inspired by a Tak though (Tak Epsilons are yellow)
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Old 28-09-2020, 05:41 PM
croweater (Richard)
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Haha. Looks (and no doubt is) better than new. Nickname "Tweety" ?
Cheers, Richard
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Old 28-09-2020, 06:19 PM
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Nickname "Tweety" ?
Cheers, Richard

Bingo
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Old 28-09-2020, 06:25 PM
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Now you can sell it back to the original owner for $700
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Old 28-09-2020, 06:27 PM
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Now you can sell it back to the original owner for $700

Ha ha...nope.


This is my visual grab n go. Performs really nicely with good EP's and a prism diagonal.
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Old 28-09-2020, 07:11 PM
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Another successful Lewiscization.
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Old 28-09-2020, 07:12 PM
jahnpahwa (JP)
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Nice job, Lewis! Looks really nice and nice to read about your work on it.
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Old 28-09-2020, 07:45 PM
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Ta.


Now thinking about the carry handle design. I have a plan...
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Old 28-09-2020, 07:46 PM
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Ta.


Now thinking about the carry handle design. I have a plan...
Does it come with magwheels?
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Old 28-09-2020, 08:16 PM
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Does it come with magwheels?

No, sewing machines.


Really.


All will be revealed.
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Old 28-09-2020, 08:19 PM
gaseous (Patrick)
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That's a cracking looking scope Lewis. For the focuser wheels, I've found the rubber rings on tennis racquet handles to be a great replacement - my 8" dob has two "Prince" rubber wheel grips.
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Old 29-09-2020, 06:41 AM
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Quote:
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That's a cracking looking scope Lewis. For the focuser wheels, I've found the rubber rings on tennis racquet handles to be a great replacement - my 8" dob has two "Prince" rubber wheel grips.

Thanks for the tip, though I found cutting the mat very simple, and I got spot on both times. I secured them further with permanent double sided tape, so there are 3 glue layers - double sided tape, and the glue already on the back of the rubber matting. You watch...the double sided "permanent" tape will fail first
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Old 29-09-2020, 06:51 AM
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Originally Posted by LewisM View Post
No, sewing machines.

Really.

All will be revealed.
Yep, if you’re the one doing the sewing....

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Old 29-09-2020, 06:59 AM
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Yep, if you’re the one doing the sewing....

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Old 29-09-2020, 07:00 AM
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Yep, if you’re the one doing the sewing....

make it sew!
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Old 29-09-2020, 07:01 AM
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