Re: Steel Pier recommendations


Hey Joe- There's all kinds of sandblasting media from frozen carbon dioxide to Silicon Carbide (with SiC the ruby nozzles wear out every three or four days if the grit blaster is in constant use).
Chert is plentiful out here in northern CA due to pressure from the Pacific plate sliding under the Coast plate creating great pressure in which all kinds of cherts, jaspers and some agates form. I usually walk a levee in the marshlands looking for some keepers and find the occasional finger size bit of jade which is a near cousin to chert.
I'm certain your use of "mixed media" is a good resonance dampener. I wonder if filling a tube with insulation pressured spray foam might be efficient too. The ideal test comparison might be to compare a tube of equal diameter but with smaller wall thickness empty against your baffled tube. I'm thinking thinner wall thickness = less resonance.

On 05/27/2021 1:43 PM Joe Mize <jmize@...> wrote:
No Robert, it doesn’t ring.  Thumping my OTA shows only a thump without afterwards ringing.
Before installing the Pier I filled it with Sandblasting Sand, and mixed in a bag of Kitty Litter to absorb Florida’s moisture.  
Sandblasting Sand, resembling flint, is crushed Chert, a fine-grained sedimentary rock composed of microcrystalline crystals of quartz, the mineral form of silicon dioxide (SiO 2).  Crushed Chert’s sharp edges absorbs vibrations well.
Sand on the otherhand is rounded, compacts more and doesn’t absorb vibrations nearly as well.  If you use beach sand be sure to wash out the salt, or your Pier will rust from inside out.
Overall my Pier alone weighs nearly 210lbs...joe

"May He Go Among the Imperishable Stars"
Joe Mize, StarFields Observatory,
Chiefland Astronomy Village
Sent: Thursday, May 27, 2021 1:33 PM
Subject: Re: [ap-ug] Steel Pier recommendations
Wouldn't thicker walls especially fabricated from steel or cast iron be more prone to vibration/harmonic vibration. Thought that was the basis for bell geometry - thicker wall - louder ring? -Best, Robert
On 05/27/2021 8:24 AM Joe Mize <jmize@...> wrote:
Robert, Dean has a good DYI alternative for Piers. 
I went to a metals salvage yard and found a 8”x52” Steam Pipe with a 2” thick flange already attached, $35.
I had a 1/2” flat plate attached to the top for mounting my AP1200 and 14.5” RCOS, another $35. 
I’ve used my pier for the last 15yrs without a hint of vibrations thanks to the 3/8” walls.
Call ahead, check for availability of steam pipes.

"May He Go Among the Imperishable Stars"
Joe Mize, StarFields Observatory,
Chiefland Astronomy Village
From: Dean S
Sent: Wednesday, May 26, 2021 4:38 PM
Subject: Re: [ap-ug] Steel Pier recommendations
I found an old street light pole and made several piers from it. 
From: Brian Valente
Sent: Wednesday, May 26, 2021 3:44 PM
Subject: [ap-ug] Steel Pier recommendations
Hi folks
I'm looking for any recommendations on a steel pier for a permanent observatory mount
fabricator? product? other??
we are installing a couple piers in our new observatory and did not want to build up the cement all the way.  This would be for Mach 2 maybe AP1100  type mount
Thanks for any tips or suggestions
Brian Valente

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