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Pier and mount question

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#1 CounterWeight

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Posted 05 August 2009 - 08:46 PM

OK,
I am looking into making a pier and was looking at the pier plates here...

http://www.pierplates.com/index.html

my thinking is to go with a 10" pier and an 8" pier plate and my TEC will be fine to the meridian (an 1" past) as there is 4" clearance between the OTA tube and 'electronics pier' portion of my CGE, and the SSP v2 CCD cooling housing is abt same width as the scopes OTA.

Thes pier plates come only in 8" and 12" sizes and I am thinking to go with the 8" if practical.

Anyone else done this with the 8" pier plate on a 160 mm or so f8 or longer refractor? I'd like to hear any input if this was adequate and satisfactory, thanks :)

#2 Dan G

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Posted 05 August 2009 - 08:56 PM

Jim -

Will this be a cement or steel pier?

Dan in NY

#3 CounterWeight

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Posted 05 August 2009 - 09:36 PM

Thanks Dan,

My current thoughts are to go the Sonotube/cement route, a friend indicated that the cement route would be more practical and inexpensive? Also have a friend to do the rebar bend & tie for it.

My initial impulse was to look at the steel pipe/tube offerings and they are more expensive.

The concrete area where I want to do this was poured back in 1930 and not to current codes(it varies in depth from ~4" to ~8") so I'll be doing some re-slabbing also...

I like the idea of a steel tube as could weld thick plate over end and just bolt that to the 'crete, and removal if I ever move would be relatively just as simple. But $$ for the project is unfortunately a bigger concern over the short/med term, am looking to replace frankenmount eventually.

#4 CounterWeight

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Posted 06 August 2009 - 12:11 AM

Thanks to CN'er David Pavlich I'll be using the 12" pier plate, thanks for the great deal on the plate(s) David! :)

Still all original questions apply...

#5 CounterWeight

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Posted 15 August 2009 - 11:42 AM

Hoping someone else who has made a concrete pier will notice and respond. Unusual to get zero responses here... is this wrong forum for this topic?

I am now in process of making the pier and etc. Noticed that the 12" 3/4 10 SS J bolts spec'd by the pier plates manufacturer are not really availble outside McMaster-Carr at $$ wow are they expensive! (reason for this is our local building construction codes only require 5/8 for what they do) I did find - at one of our many local 'threaded products' places - 3/4" 10 18-8 SS allthread at only $5.00 / foot. :)

So I can make my own J or L bolts for far less than the M/C... but, what if I just put a slight bend in a 24" length and tied it to the rebar before pouring top of pier? (using pier-plate as a guide for proper placement) This would still be only about 40% cost of other bolts... what have other folks done here?

Thanks for any answers. :question:

#6 HunterofPhotons

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Posted 15 August 2009 - 12:24 PM

There's no need to tie it to the rebar.
Making the bends can be a pain. Get the all thread and sandwich a large washer between two nuts at the bottom. It works just as well as a J-bolt.
Keep the bolts away from the edge of the concrete and work the mix well to eliminate any trapped air.

dan

#7 CounterWeight

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Posted 15 August 2009 - 02:50 PM

Thank you Dan!

Great suggestion and very easy to do :) (and easy on wallet). The fellow helping with the rebar and cement work suggested always try to keep 2" distance minimum for metal to cement outer dimension. He also has a very large vibration tool that is touched on rebar or casement after pouring cement to help clear any voids. Top plate arrived today and so can continue - hoping cure will be good (72 hrs) to try and check it out during new moon. Keep forgetting to take pictures of process.

#8 CounterWeight

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Posted 17 August 2009 - 12:51 PM

Well we ended up using his rebar bender to just bend the ends of the allthread to make 'L' bolts. I didn't get any shots of the rebar assembly before we got in in the hole and poured the footing. The footing is 24" cube below grade with about a 3" flare at the very bottom. The rebar reinforcement looked almost to the structure used for the Eiffel tower! With the addition of a few square hoops at the base. I took a few images two days ago when we poured the 12" column. So far 18 60lb bages used and still have not completely poured the footing. There are 9 bags for the sub-footing and another 9 bags for the pier section (it is shy of 6' tall) Tried to get a sot showing some of the rebar work.

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#9 CounterWeight

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Posted 17 August 2009 - 12:55 PM

And here is how it has been sitting since Saturday afternoon...

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#10 Tom and Beth

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Posted 17 August 2009 - 06:06 PM

Just saw your post....

I have a TEC 140 mounted on an AP600 on a ~10 inch Concrete pier. I haven't hit the pier yet :p

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#11 David Pavlich

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Posted 17 August 2009 - 08:59 PM

And here is how it has been sitting since Saturday afternoon...


Hey....looks terrific!!

Daivd

#12 CounterWeight

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Posted 18 August 2009 - 02:25 PM

Thank you David,

Poured rebar reinforced slab yesterday. Protruding near base of pier is conduit with romex for AC, romex for DC, and some cat5 cabling. Here is a shot of the completed job - with any luck it'll cure in time to use during this new moon phase :) Now I need to start thinking of the structure to go around it...

Tom and Beth - well I went to 12" pier to keep a good buffer of concrete for the pier plate bolts - I am going to need to be very careful near meridian (if near overhead) with the SSP v2... maybe should put a rubber baby buggy bumper around it?

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#13 Dan G

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Posted 18 August 2009 - 03:14 PM

Jim -

This looks like a great pier. Question for you though. Is the slab tight up against the pier or did you leave a gap so vibrations are not transmitted to the pier?

Dan in NY

#14 gavinm

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Posted 18 August 2009 - 03:29 PM

Was going to ask the same question re: vibrations.

#15 CounterWeight

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Posted 18 August 2009 - 03:53 PM

Hi Dan,
There is no gap at the contact of slab/pier. We decided just to not rebar them together. I'm actually more worried about cars and trucks passing on the street 20 feet away - all of it is clay down below. If my walking on it is a big problem, I'll put in a small raised deck. We also discussed possible need for short triangular bracing, or a doughnut type riser or both if needs be. I'll know pretty soon what if anything will be necessary?

#16 CounterWeight

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Posted 22 August 2009 - 02:40 PM

Amazingly stable - vibration absolutely no problem at all. I could not be happier with the results. Pelican shot taken in my photo gallery in process in this image :) :) :) Last night got some 10 minute galaxy images and again - pier just does the job! :jump: :) :yay: :whee:

Oh, almost forgot, Pelican was almost zenith - CGE switches kept SSP v2 / OTA from hitting pier... didn't measure exact distance, maybe next time if I can remember.

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