A Copernican View of the Turntable System


Once again this site rejects my long posting so I need to post it via this link to my 'Systems' page
HERE
128x128halcro
Nandic, the thought behind the design in something like Halcro and Corby's pod is 80-90% of the work. Even if there is no desire to own a CNC and that is outsourced it is still your mental labor that made it come together.

You are lucky to have a machinist as a friend.

Brad
Brad,
There are unfortunately no free lunches?
A truly "universal arm-pod" like Corby's, requires many 'connections' and 'cantilevers' all held by grub-screws or something similar.
The vertical micrometer is in itself a cantilever from the fixed base and then the arm 'platform' is cantilevered from this shaft.
In any cantilever, the bending moment increases as the square of the cantilever. The deflections involved in such solutions render the stability of the arm-pod questionable.
I find with my DaVinci Grandezza 12" Ref tonearm, that even extending the shaft to its maximum for VTA adjustment, affects the sound rather badly :^(
Cheers
Henry
Dear Brad, The machinist in casu is alas not my friend, so
even just one lunch , not to mention the plural, is out of question. My 'luck' is that this guy is also interested in tonearms. However my armpod is made by my
real friend Vidmantas by the Reed company. I am also lucky
I should think that I am able to pay for the 'lunches' in plural. BTW there are 'many' other things involved by the tonearms so to 'have' a machinist is as important as to have an 'beautiful lady' ( not from Italy of course).

Regards,
brad, you are correct in the 3" dia and 3" height. it's solid stainless and it is heavy. you're also correct in the amount of thought required with the design. i spent lots of time at that stage before the machining started. all of my plans were on scraps of paper and napkins! the emachine drawing is a definite asset.
henry, your observation about the cantilevering is a correct one. the only issue that i have with that is my armboard. the vertical shaft is solid 1" stainless. i can understand the extension within the arm itself making a sonic difference, since it's really only a relatively thin-walled tube supporting the whole arm. mine is set down, bottoming out and i let the 1" shaft provide the height adjustments. the reason that my armboard is so long is that i wasn't sure how much clearance that i would need for the grandezza as it swings past the micrometer. it turns out that i have a good 1" plus clearance, so i will make a new armboard, shorter and thicker at the shaft end for more contact area. i am happy with it now and don't want to break the set-up, but i will in the very near future.
thanks for the comments. it's still a learning experience.
don
Don,
It seems as if you know well the pitfalls of 'structural gymnastics' and are learning more 'on the job'...so to speak :^)
I'm impressed and looking forward to further evolutions of your ingenious arm-pod.
Cheers
Henry