jasonharris
sage
Reged: 09/16/06
Posts: 305
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Hi All, I am just starting my observatory. I have dug out a 1m3 hole and will fill t this coming weekend.
I am thinking about the pier I will build. I see some designs have no way of leveling after bolted to concrete and others have a extra plate at either the top or the bottom.
This is in the form of an additional plate seperated by threaded rod which the adjustments are made.
It seems to me that this is best done at the top of the pier where the moments are less. Pier tech have it at the bottom, some others at the top.
Has there been debate about which is best? I plan to have a paramount and up to 16" sct on top so I am a little concerned about this 'weak' part of the design.
Thanks,
Jason
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Chris Schroeder
Postmaster
Reged: 12/11/04
Posts: 8515
Loc: N.E. WI Sky Glow
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Hi Jason, are you talking about a concrete footer with a steel pier on top? If that is the case you want the pier level and plumb, so you’ll probably want the leveling plate on the bottom of the pier.
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Chris
Mallincam Color Hyper Plus
10" DSH with SC DSC, CPC 800 XLT
AT 111EDT, AT 102Achro, ZS80FD 10th Anniv, AT 72ED, ZS66SD, PST
CG5-AGT, EZ-Touch, Voyager
POD XL3
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jasonharris
sage
Reged: 09/16/06
Posts: 305
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Yes Chris, I was planning the big concrete footing and a steel plate in the concrete at the bottom with bolts coming through.
The steel plate in the concrete is to give me a totally flat surface for the pier to mate to. I have a engineers level that will allow me to get the plate level on the concrete while it sets. I wouldn't need any additional leveling if the pier was perfect, but will it be...
I was a little concerned having not done this before that using bolts to level at the bottom would cause more wobble as it is dealing with the weight of all the gear as well as the heavy steel pier. The moment arm is also very long. Doing it at the top seems like it should be better but I have no 'practical' experience.
Thanks,
Jason
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JAT Observatory
NOT a Wimp
Reged: 02/20/05
Posts: 8893
Loc: In the Primordial Soup
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My pier is leveled from the bottom. The mounting plate for the scope has adjustments at the top. I try to get the peir as level as humanly possible. Bit I have made final adjustments using the top plate. The fact that I have an adjustable height pier it is important that it be leveled at the bottom. But as long as your pier is fixed in height and isn't canted at some extreme angle there is no reason the leveling can't be done from the top.
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-Marcus
Hey what did you expect? After all, I am just a pig with a nice smile!
www.jatobservatory.org
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jasonharris
sage
Reged: 09/16/06
Posts: 305
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Thanks Marcus, I have been to your site a lot and didn't seem to notice that.
PS, your site is one reason why I just ordered a 3.5m sirius dome 
Thanks,
Jason
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jasonharris
sage
Reged: 09/16/06
Posts: 305
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Marcus, I am curious how you leveled the paramount on the top, does the PT2 have the ability to level its top plate ?
I have been using the paramount on a portable pier I made so I level it there, I never noticed another way on the paramount?
Thanks,
Jason
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mikey cee
Postmaster
Reged: 01/18/07
Posts: 6993
Loc: bellevue ne.
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Jason.....Do it at the bottom you definitely want a nice plumb looking pier. With 4 sets of nuts and washers(8) this can easily be accomplished. Then if you feel it is absolutely necessary you can provide adjustments at the top. At 900 lbs. my set up is only at the bottom no flex problems at all!  Mike
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7x35 and 10x50 sears tower binocs, 3" f/10 edmunds reflector, 2.4" f/11.7 manon refractor, 6" f/8 jaegers refractor, 10" f/11 R30 Istar refractor, 3" f/15.8 sans&streiffe refractor, 3.1" f/15 selsi refractor(towa 339), 2.4" f/15 sears refractor, selsi 30x30mm spyglass, criterion 5-draw 25x45x75x spyglass(1957), 4.25" f/14.8 tasco 20te.
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jasonharris
sage
Reged: 09/16/06
Posts: 305
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Thanks Mikey, I was assuming it was going to be reasonably plumb without bolts but I haven't heard anything against bolts at the bottom, I have 3/4" stainless threaded rod so I think I will use that as my anchors and keep the pier very close to the ground so only 1/2" if possible of threaded rod between bottom of pier and concrete.
Thanks,
Jason
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mikey cee
Postmaster
Reged: 01/18/07
Posts: 6993
Loc: bellevue ne.
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Jason...Give yourself at least an inch of threaded rod under your plate....the nut and washer will take up at least 5/8". Mike
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7x35 and 10x50 sears tower binocs, 3" f/10 edmunds reflector, 2.4" f/11.7 manon refractor, 6" f/8 jaegers refractor, 10" f/11 R30 Istar refractor, 3" f/15.8 sans&streiffe refractor, 3.1" f/15 selsi refractor(towa 339), 2.4" f/15 sears refractor, selsi 30x30mm spyglass, criterion 5-draw 25x45x75x spyglass(1957), 4.25" f/14.8 tasco 20te.
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JAT Observatory
NOT a Wimp
Reged: 02/20/05
Posts: 8893
Loc: In the Primordial Soup
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Quote:
Marcus, I am curious how you leveled the paramount on the top, does the PT2 have the ability to level its top plate ?
I have been using the paramount on a portable pier I made so I level it there, I never noticed another way on the paramount?
Thanks,
Jason
Jason,
I have the base plate adapter on to the bottom of my ME. There are two piece thumb screws on each of the four corners of the ME base plate adapter. The lower set of thumb screws are used the level the base plate. The upper thumb screws are used to attach the base to the pier’s top plate (the upper screws need to be loosened in order to adjust the leveling screws). So in my case the course leveling is done at the base of my pier using the nuts on the threaded J-bolts. I then do the fine adjustment using the base plate adapter screws.
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-Marcus
Hey what did you expect? After all, I am just a pig with a nice smile!
www.jatobservatory.org
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jasonharris
sage
Reged: 09/16/06
Posts: 305
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Thanks Marcus, I have the heavy duty baseplate as well, unused so far - not for long 
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jasonharris
sage
Reged: 09/16/06
Posts: 305
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Thanks again all of you that replied.
FYI, here is a pier that I made for a different project. Its 10" RHS. It's a bit short for this one but I am going to see what I can do t reuse it for this project.
First thing is to get it a hot dip galvanise.
I will also start a new thread to show my project. I will also start to put it on my site (just started) www.mydiversions.com.
Thanks,
Jason
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