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tonearm

Posted by herve robert 
tonearm
May 27, 2019 01:53AM
this tonearm is made with the same kind idea of the ball bearing describe in this topic:

https://reprap.org/forum/read.php?152,839120


when you use a unipivot tonearm, all the weight of the arm is on needle use to made the pivot:




for the up and down tonearm movement, it is easy to rotate the edge of a knife (as in a mechanical balance)



for arm movement from left to right, use magnets to hold the pivot upside down. it can only move around the vertical axis.







the scad and stl files of the tonearm:

https://www.dropbox.com/s/up9wnkhewp1qwne/tonearm.tar.gz?dl=0

videoA

https://www.dropbox.com/s/rp0t3cofz0d8klp/tonearmC.mp4?dl=0

videoB

https://www.dropbox.com/s/jd2kf5lxeion3eh/tonearmD.mp4?dl=0

Edited 1 time(s). Last edit at 05/27/2019 02:00AM by herve robert.
a design improvement...
May 30, 2019 09:01AM
...is to fix the knife edge and the pivot on the same line (see schematic).



Edited 1 time(s). Last edit at 05/30/2019 09:01AM by herve robert.
Re: tonearm
June 12, 2019 02:25PM
why invert it? to save weight? do the magnets impart any force or alter force as it rotates?

Edited 1 time(s). Last edit at 06/12/2019 02:26PM by MechaBits.


[mechabits.co.uk]
Re: tonearm
June 17, 2019 02:26PM
unipivot case:

-all the gravity force is put on the tiny needle and made a heavy pressure on it.

upside down pivot case:

-magnetic force cancel the gravity force and is set only to put a slightly force on the needle (no more no less).
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