Advise on TT Support Platform

Hello All, this is the OP-

  I'm a little surprised about so many replies suggesting the instability issue of the project. I'll try to further describe the build, I wish you could post pics/drawings here that would make my description easier to visualize, anyhow...

  Using the 3/4" dia. pipe, the base of it will be set within a 2' x 8" dia. hole filled with concrete, 5' below the hardwood floor surface into the dirt ground of the crawl space. Moving upward, & at the floor joist level (~8" below floor surface) 3 stainless cables (stays) will be attached to the pipe (at the same level) at 120 degree angles. Two of the cables will run "horizontally" and anchor into the house's poured foundation walls. The walls (5' in height) come to a corner ~2' from the pipe. One of these walls is an outside wall of house, the other wall supports a house beam under the floor (it does not have a wall above it within the home's listening room. These two cables (stays) are anchored & tightened using turnbuckles & will each be ~ 15 deg off of 90 degree angles to the walls.

  The 3rd stay, 120 deg from the other two, will have a "vertical incline (~30deg)" to its attachment to the pipe since it will be anchored into a post hole filled with cement (~10' from pipe) similar as the pipes hole & also tightened with a turnbuckle.

  From the stays point of attachment (to the pipe) to the top end of the pipe (this being the TT's platform attachment site) is about 42"(3'6"). So, I believe we're talking about the amount of sway that the earths rotation will impart on the effective length of 3'6" of 3/4 inch pipe with 44lbs at its apex. Please note, there are no winds/drafts inside the house, no little fingers to clench onto it and swing from it, it is not in an area of traffic or where objects could bump into it. Further, I will be the only one to touch the TT. My cartridge, a Sumiko Blackbird HOMC is very delicate as you know and for that reason alone only the utmost finesse will be used when using the TT.

  I just fail to understand where the "swaying like the Empire State Building in a storm" is coming from? With the mass on top of the effective 3'6" length I can understand if you pushed it, it would "give" some, but sway around, unstable? I also (although I'm not versed in this) think that a little "give" could be beneficial to absorb some man made shock introduced to the TT platform; being beneficial in absorbing impact and possibly saving the Blackbird stylus. There will be no contact what-so-ever with the floor or walls so no vibrations can be introduced that way. I really fail to see that acoustic sound waves are going to create such resonance forces as to start the platform structure to vibrate , sway, or in any way move somehow.

  One easy to do adjustment to the build would be to use 1" pipe rather then 3/4" pipe to add more rigidity and help alleviate any introduced shock to the turntable, how much effect that would have I don't know but easily done without any change to price.

  I have the time to do this. It will only cost 25-$30, a far cry from the simplest shelf or stand and feel it could be better. But I appreciate any further discussion on this project to my latest update here-

Thanks to all who have replied,
Robes-

  

@robes I think the source of some concern is regarding seismic vibration. Turntables are very sensitive to this sort of interference from construction, traffic or micro-quakes. The arrangement you are proposing risks exacerbating the effect of seismic activity. 

By the way you can post drawings and pictures as part of a virtual system, maybe you can try this so we can see what you have in mind?

Robes, do you know the difference between the conscious mind and the subconscious?  An example of possible mistakes made by just thinking would be:  You sit in your house, thinking of a car tune-up.  First, you think I will do an oil change, then change the spark plugs, then adjust the dwell, and on and on.  You then go outside, and you can't even get the nut off to change your oil-so, all that other thinking was a waste.  I think you have to test out all ideas, one at a time, rather than speculate on things(for instance, maybe coupling to something heavy doesn't work whatsoever, so that idea would be mistaken, and everything else based on that idea would also be a mistake.).  This is just an idea on the pitfalls of thinking consciously only.

Sometimes you have to take a step back and reconsider your
options.
I certainly give you credit for creative thinking but as a few already
pointed out stabilizing your floor structure is straight forward
and cost effective. My method also.
Proceed upwards from there.

Symposium ISO