Zhumell 12 inch dob...primary mirror question

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Cosmos63
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Zhumell 12 inch dob...primary mirror question

#1

Post by Cosmos63 »


Haven't had it long and yet to use it due to needing a base, which I'm building. I got it for a bargain-cannot-refuse price, new in the box. I now have it out inspecting everything closely, snugging up loose screws and such. While doing so, I noticed what appears to be a small piece of packing styrofoam down in the mirror cell and suspect there may be more.

It appears like the only way to get it out is remove the cell which looks easy enough. Six tube screws and the whole thing should lift right out. While doing that, having read about pinched optics due to the rubber mirror clamps being snugged down a little too much from the manufacturer, I'm going to check that while I have it out, using the business card gauge method I've heard about. Can anyone confirm that's the correct tension on those? Out of curiosity also, does anyone know if the Zhumell mirrors are glued/silconed in and not simply held in place by the 3 mirror clamps?
Way too many telescopes for an ordinary mortal

Orion ST80/SLT mount, Meade ETX80, Celestron Omni XLT 150/Orion EQ3 mount, Celestron 6SE, Skywatcher 8" Collapsible dob, Zhumell 12" dob. Boxes and boxes of misc parts, gadgets, and eyepieces....probably a bunch of stuff I forgot I have.
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MistrBadgr United States of America
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Re: Zhumell 12 inch dob...primary mirror question

#2

Post by MistrBadgr »


I do not own a Zhumell, but I cannot imagine them doing a glue job on a 12 inch mirror. I know someone who owns or has owned both a Z10 and a Z12 that they used for sidewalk astronomy. I don't think they would have been a repeat customer with a glued-in mirror.
Bill Steen
Many small scopes, plus a Lightbridge 12, LX 70-8R,6R,6M
Many eyepieces, just not really expensive ones.
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Re: Zhumell 12 inch dob...primary mirror question

#3

Post by Lady Fraktor »


If you can slip a business card between the mirror and holding clip the mirror will have enough room to prevent pinching and expansion.

I do not recall anyone mentioning the mirror being siliconed in place.
See Far Sticks: Antares Elita 103/1575, AOM FLT 105/1000, Bresser BV 127/1200, Nočný stopár 152/1200, Vyrobené doma 70/700, Stellarvue NHNG DX 80/552, TAL RS100/1000, Vixen SD115s/885
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Re: Zhumell 12 inch dob...primary mirror question

#4

Post by notFritzArgelander »


My z12 is glue free and optics were never pinched.
Scopes: Refs: Orion ST80, SV 80EDA f7, TS 102ED f11 Newts: AWB 130mm, f5, Z12 f5; Cats: VMC110L, Intes MK66,VMC200L f9.75 EPs: KK Fujiyama Orthoscopics, 2x Vixen NPLs (40-6mm) and BCOs, Baader Mark IV zooms, TV Panoptics, Delos, Plossl 32-8mm. Mixed brand Masuyama/Astroplans Binoculars: Nikon Aculon 10x50, Celestron 15x70, Baader Maxbright. Mounts: Star Seeker IV, Vixen Porta II, Celestron CG5
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Re: Zhumell 12 inch dob...primary mirror question

#5

Post by helicon »


I have removed the mirror cell twice since 2012 to clean the mirror. (Last time was October 2020 as I recall). Its easy to take out the six screws, pull the cell out with the mirror attached, and also easy to re-insert and screw the cell back in. I did use a piece of blue painter's tape to mark one of the screw holes on the tube, and a small piece on the cell, so I would insert it back in exactly the same sequence as it came from the factory. I did not notice the mirror being glued to the cell. (Z10)
-Michael
Refractors: ES AR152 f/6.5 Achromat on Twilight II, Celestron 102mm XLT f/9.8 on Celestron Heavy Duty Alt Az mount, KOWA 90mm spotting scope
Binoculars: Celestron SkyMaster 15x70, Bushnell 10x50
Eyepieces: Various, GSO Superview, 9mm Plossl, Celestron 25mm Plossl
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Re: Zhumell 12 inch dob...primary mirror question

#6

Post by omeek »


As with nFA and Helicon, no glue and no pinches. :)

Years ago I even attached a dew heater to the back of my primary and reisntalled it into the base/holder.
-Oliver
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Telescopes: Orion XT8i, Zhumell Z12
EP's: Baader Ortho 6mm, Orion Expanse 9mm, Tele Vue 10mm Delos, ES 68° 16mm, ES 68° 24mm, 2" Q70 32mm, 2x Orion Shorty Barlow (and various Plossls)
Bino's: 12x42, 12x60
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