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TW Raven Owners: Set Up Questions

Through the magic of sweet talk, I turned my Orbe into a Raven and mounted my Graham 2.2/Benz LP.
I am looking for a isolation base for the Raven. I have a 1 3/8" piece of granite coming soon so I can ditch the MDF I use now (a temp. meas.!) Symposium, SRA, HRS, etc., can anyone share their experiences with isolation bases? I saw the thread about loosening the Stillpoints.
Initially I had an issue with using the rough side of belt. The belt shimmied up/down on the pulley at a specific spot on belt. Also, the speed fluctuated and I could never get it dialed in with the PSU. So, I went to the smooth side of the belt and then raising the back side of the motor (unscrewing one of the isolation feet) slightly moving the belt down from "center" on the pulley. This moved me from 33.2 to 33.3 and I have no more belt shimmying and the speed is rock solid.
I'd appreciate any tips/tricks etc.
gerardff
peterayer
1,382 posts
 
Ebm, it's engineering and Halcro sounds like an architect. I understand about these prestressed concrete slabs. They are thin, and do flex, but they don't break under the design load. Think of a very hard, yet bouncy web. I imagine that they could even ring under certain loads.

Suteetat's apartment floor slab does not at all behave like a thick concrete slab on the ground. Whether or not a wall shelf would be better in his situation, I can not say.
suteetat
435 posts
 
I don't know anything about concrete floor, bounce and such. The concrete floor is 30cm thick, is that thick or thin I have no idea though. Since it can support 400 kg/m2, how much weight or force do you need to make it bounce?
peterayer
1,382 posts
 
Suteetat, I can't answer that. And I'm not sure you will ever get your floor to flex. I'm just saying that Halcro is describing a type of pre-stressed concrete slab and it will not behave like a standard concrete slab located on the ground. You may not have any issues at all.

However, if you can borrow a Vibraplane or other serious isolation platform for you unsuspended turntable, you should hear quite an improvement in information retrieval or resolution.
suteetat
435 posts
 
I agree that something like vibraplane is something that I would like to try. Unfortunately there is nothing locally similar available so I think I will have to wait until I know for sure what I will do with my tw regarding motor option before I will invest in vibraplane or minus k. In the meantime I probably will try symposium since I can use it with other equipments later and thy are not so expensive.
halcro's avatar
halcro
2,664 posts
 
30cm is quite thick for a concrete slab.....especially a prestressed one. How do you know this fact?
The load carrying capacity of any floor has little to do with with it's BEHAVIOR under dead loads, live loads and impact loads. 400 Kg/m2 is not so great considering that 4 hefty men each weighing 100Kg can stand on a floor area not much more than this?
A trampoline can certainly support this load also but I would be loathe to locate my turntable on one?
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