dunc.ellliott
sage
Reged: 10/06/06
Posts: 202
Loc: Syston, Leicester,UK
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Only just noticed these two threaded hole on the underside of the scope.
Any idea why or what they are for.
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Meade 8" LX200R + Dell Inspiron 1501 + DSI ii color
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Rainbow
professor emeritus
Reged: 08/27/04
Posts: 662
Loc: Norfolk, UK
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For a photo style tripod - OTA only, without the etx fork mount
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Meade ETX 90 UHTC, 497 Autostar, 884 tripod, right angle finder.
CALIBRATE MOTORS and TRAIN DRIVES!
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dunc.ellliott
sage
Reged: 10/06/06
Posts: 202
Loc: Syston, Leicester,UK
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Thanks Rainbow.
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Meade 8" LX200R + Dell Inspiron 1501 + DSI ii color
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Rainbow
professor emeritus
Reged: 08/27/04
Posts: 662
Loc: Norfolk, UK
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Close them off with tape to prevent dust getting into the scope
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Meade ETX 90 UHTC, 497 Autostar, 884 tripod, right angle finder.
CALIBRATE MOTORS and TRAIN DRIVES!
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seadaddy
member
Reged: 11/23/05
Posts: 28
Loc: Orlando, FL
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You can tape them up if you want but if you notice they don't penetrate the tube so I wouldn't be too worried about dust. The holes can be used for other purposes. If you remove the OTA from the fork you can attach a dovetail to mount your ETX OTA on an standard equatorial. Scopestuff has a rather neat rail which attaches to these two holes for mounting sliding weights for balancing the scope and I am sure that a little ingenuity will come up with other uses.
Clear skies,
Julius
--------------------
Orion Starblast 4.5
Meade ETX-125AT UHTC
Meade ETX-105AT UHTC
Meade ETX-80AT-BB
Meade ETX-60AT-BB
Astro-Tech AT66ED
Many eyepieces (the Meade kit offer)
Televue Radian 10mm, 8mm, 6mm, 4mm
Televue 5X powermate (great!)
UO Klee 2.8X Barlow
Toucam Pro
DSI
DSI Pro
LPI
Orion StarShoot DSI
Orion StarShoot SSI
Canon Digital Rebel XTi
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Rainbow
professor emeritus
Reged: 08/27/04
Posts: 662
Loc: Norfolk, UK
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The holes on my etx 90 go all the way through into the area occupied by the flip mirror.
Here is a typical picture:
http://www.mapug-astronomy.net/ragreiner/etxguider.html#Flip%20Mirror
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Meade ETX 90 UHTC, 497 Autostar, 884 tripod, right angle finder.
CALIBRATE MOTORS and TRAIN DRIVES!
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Astroboy86
sage
Reged: 01/28/07
Posts: 444
Loc: Southeastern Virginia
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Jordan Blessing's ETX Tune-Up doc recommends stuffing a section of foam into the gap to block both light and dust from entering the OTA through this opening. See:
http://24.237.160.4/files/astronomy/Autostar/etx%20tuneup.PDF
-Harry
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Our ever-growing equipment collection:
Celestron CPC 925 GPS XLT (The Precious)
EarthWin PFS-D binoviewer w/dielectric coatings
Meade ETX-125AT (Shadow Lass)
Meade DS-2130ATS-LNT (Mr. Magoo)
Meade 114NT/500 (Foggy Bottom)
StellarVue M4-style EQ mount
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seadaddy
member
Reged: 11/23/05
Posts: 28
Loc: Orlando, FL
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I just re-examined my 105 and 125 and I can assure you that the threaded holes in the tripod mounting plate do not repeat do not penetrate the blue OTA. On earlier units that might have been so (I cannot say) but on the ones I have the OTA is solid and there are no openings in that area. When I take pictures to post my ETX collection I will also take some of that area and see if I can show you what I am talking about. Dr. Clay Sherrod also said the same about blocking the gap and holes on Weasner's site. I don't understand but I am looking at my 125 right now and the holes do not penetrate the OTA.
Clear skies,
Julius
--------------------
Orion Starblast 4.5
Meade ETX-125AT UHTC
Meade ETX-105AT UHTC
Meade ETX-80AT-BB
Meade ETX-60AT-BB
Astro-Tech AT66ED
Many eyepieces (the Meade kit offer)
Televue Radian 10mm, 8mm, 6mm, 4mm
Televue 5X powermate (great!)
UO Klee 2.8X Barlow
Toucam Pro
DSI
DSI Pro
LPI
Orion StarShoot DSI
Orion StarShoot SSI
Canon Digital Rebel XTi
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Astroboy86
sage
Reged: 01/28/07
Posts: 444
Loc: Southeastern Virginia
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Seadaddy, it's not those 1/4-20 screw holes that need to be blocked, rather there is a gap that you cannot see between the plastic housing and the bottom-rear edge of the OTA. In other words, if you pointed your OTA straight up and dropped a tiny ball bearing into that open slot under the UHTC sticker, or through either screw hole, that ball bearing would drop down and roll into the back of the metal OTA cylinder.
Even if you thread a couple of short 1/4-20 bolts into those two holes, there is still an opportunity for light & dust infiltration through the slot at the front of that plastic housing.
-Harry
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Our ever-growing equipment collection:
Celestron CPC 925 GPS XLT (The Precious)
EarthWin PFS-D binoviewer w/dielectric coatings
Meade ETX-125AT (Shadow Lass)
Meade DS-2130ATS-LNT (Mr. Magoo)
Meade 114NT/500 (Foggy Bottom)
StellarVue M4-style EQ mount
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Rainbow
professor emeritus
Reged: 08/27/04
Posts: 662
Loc: Norfolk, UK
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It seems we are all learning new things
You have to trust Clay though, he has fully dismantled an incredible number of these scopes.
--------------------
Meade ETX 90 UHTC, 497 Autostar, 884 tripod, right angle finder.
CALIBRATE MOTORS and TRAIN DRIVES!
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dunc.ellliott
sage
Reged: 10/06/06
Posts: 202
Loc: Syston, Leicester,UK
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Glad i asked this question, my holes are now taped up.
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Meade 8" LX200R + Dell Inspiron 1501 + DSI ii color
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Rainbow
professor emeritus
Reged: 08/27/04
Posts: 662
Loc: Norfolk, UK
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Easy fix - cost zero
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Meade ETX 90 UHTC, 497 Autostar, 884 tripod, right angle finder.
CALIBRATE MOTORS and TRAIN DRIVES!
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dunc.ellliott
sage
Reged: 10/06/06
Posts: 202
Loc: Syston, Leicester,UK
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Rainbow when you said tape them up my first thought was he's mad but hat off to you, thanks.
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Meade 8" LX200R + Dell Inspiron 1501 + DSI ii color
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Rainbow
professor emeritus
Reged: 08/27/04
Posts: 662
Loc: Norfolk, UK
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Ha,ha, well I just try my my best
Maybe we will meet sometime at a starparty.
BTW that is the best way to explore things that you might want to buy
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Meade ETX 90 UHTC, 497 Autostar, 884 tripod, right angle finder.
CALIBRATE MOTORS and TRAIN DRIVES!
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radsdad
super member
Reged: 11/05/06
Posts: 116
Loc: Southern California
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I guess I'd better tape mine up as well, thanks for the heads up!
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Meade ETX-125AT UHTC and ETX-60AT
Zhumell 20x80 Supergiant Binoculars
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seadaddy
member
Reged: 11/23/05
Posts: 28
Loc: Orlando, FL
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Got it. I still don't see how it can (on my scopes it is pretty darn small ball bearing (.003" approx)), but why take a chance. I have filled the gap with high density foam padding and the screw holes are filled by the balance bar. Will post photos when I stop procrastinating....Right! Thanks again guys...never too old to learn....
Clear skies,
Julius
--------------------
Orion Starblast 4.5
Meade ETX-125AT UHTC
Meade ETX-105AT UHTC
Meade ETX-80AT-BB
Meade ETX-60AT-BB
Astro-Tech AT66ED
Many eyepieces (the Meade kit offer)
Televue Radian 10mm, 8mm, 6mm, 4mm
Televue 5X powermate (great!)
UO Klee 2.8X Barlow
Toucam Pro
DSI
DSI Pro
LPI
Orion StarShoot DSI
Orion StarShoot SSI
Canon Digital Rebel XTi
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Astroboy86
sage
Reged: 01/28/07
Posts: 444
Loc: Southeastern Virginia
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Quote:
I still don't see how it can (on my scopes it is pretty darn small ball bearing (.003" approx))
Julius,
I just arbitrarily picked "tiny ball bearing" as an illustrative example; I have no idea what the actual size of the gap is, only that there is one. In retrospect, I should have said, "If you dropped a photon into the slot..." 
-Harry
--------------------
Our ever-growing equipment collection:
Celestron CPC 925 GPS XLT (The Precious)
EarthWin PFS-D binoviewer w/dielectric coatings
Meade ETX-125AT (Shadow Lass)
Meade DS-2130ATS-LNT (Mr. Magoo)
Meade 114NT/500 (Foggy Bottom)
StellarVue M4-style EQ mount
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Astroboy86
sage
Reged: 01/28/07
Posts: 444
Loc: Southeastern Virginia
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Incidentally, here's what those threaded holes are for on my scope. Since these shots were taken, I've replaced all the washers with bigger ones. The ETX is still a bit nose-heavy, but not nearly as much as it was before.
-Harry
--------------------
Our ever-growing equipment collection:
Celestron CPC 925 GPS XLT (The Precious)
EarthWin PFS-D binoviewer w/dielectric coatings
Meade ETX-125AT (Shadow Lass)
Meade DS-2130ATS-LNT (Mr. Magoo)
Meade 114NT/500 (Foggy Bottom)
StellarVue M4-style EQ mount
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Ron in Michigan
member
Reged: 02/20/08
Posts: 41
Loc: W. Michigan
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Maybe the holes are desired? designed in?) for venting so as to aid in no moisture in the tube? better - er maybe not... air gets in the eye piece opening right? ok my bad.
Still condensation/mousture drain? since it's back of the bottom of the tube which wil be the lowest point almost always?
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Rainbow
professor emeritus
Reged: 08/27/04
Posts: 662
Loc: Norfolk, UK
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If you've got that much moisture inside your scope get a wetsuit!
--------------------
Meade ETX 90 UHTC, 497 Autostar, 884 tripod, right angle finder.
CALIBRATE MOTORS and TRAIN DRIVES!
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Bilbobaker
member
Reged: 02/23/08
Posts: 15
Loc: Cottage Grove OR
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When using a piggyback camera mount I've seen counterbalance weights attach with those screw holes.
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