Hello there!!
Here is my second lenco project:
this is a Lenco i bought years ago for 'spares' for my main turntable: long story short.. my old turntable is in perfect shape, it wil probably outlive me and i forgot my 'spares' deck.
Some weeks ago it resurfaced and i decided to restore it.
The table had no tonearm nor plinth and were in bad cosmetical conditions, so i restored the motor and the usual mechanical stuff, filled the holes i didn't need on the metal base, scraped the paint off, drilled a new tonearm hole (SME style), had it painted by a professional in white, made a new plinth in mdf a(nd sorbothane on the upper layer), venered it in black (ebony?) wood, added 3 adjustable foots (super high end M8 screws) applied my own logo i use on my diy projects and installed my main tonearm (esoter track fifty a jelco 250 OEM) because it turned out really cool.
Then the upgradite begun and i decided to build a tonearm.
I decided for a design by Carlo Morsiani: that tonearm is an unipivot design with an innovative magnetic antiskate: You can regulate a different antiskate force for the outer part of the disk and for the inner part of the disk using 4 magnets (2 fixed in the pivot assembly and 2 adjustables on the tonearm rest to change the antiskate force).
Morsiani built this tonearms commercialy in the past but he seems retired at the moment (his website morsiani.it explains the theory of his arm in a simple but exaustive manner).
He also released a series of papers and plans some years ago (1995) on the italian DIY hifi magazine Costruire HIFI (you can find the project on numbers 15 17 18 20 21).
He released the project in a proto 'non commercial open source kind of gentleman's agreement' basically you can make your own tonearm, have a machine shop make one for you but you can't use his pivot design and magnetic antiskate on a commercial design.
i recently got a copy of his articles and decided to build the tonearm: the original is built with classic machining materials and tecniques i decided to adapt the project for the tools i own (3d Printer) so i redesigned the tonearm and modified some parts to adapt them for 3d printing.
Here is the 3d model and some printed parts.
Those parts are going to be my new tonearm
I followed Morsiani's project pretty faithfully but i changed some parts: i changed some parts dimensions and the materials of the counterweights (he used a custom molded lead counterweight and i don't want to deal with that so i modified the counterweight material and dimensions,
he used an armonic steel pivot made from gramophone needles installed in the pivot carrier by drilling a m3 grubscrew and attaching the needle to the grubscrew, i decided to use a sewing machine needle installed in the pivot with hot temperature to melt the plastic to create a solid fit.
For the bearing cup i used a m3 hex screw and buy thet i mean the needle will stay and rotate on the hexagonal part of the screw.
The needle i used are SCHMETZ brand (if you plan to use sewing machine needle for an unipivot use no other brands, they are the best, have the best surface finish, the best geometry and the best steel, other brands are crap), the needle point is UNIVERSAL type (the most pointy point) ( do not use leather or denim needles because they have a non symmetric point geometry) and 120 size (that size is unobtanium at the moment, i think they are no longer produced, i have a large stock of them but that's another story, by the way you can use 100 size every reputable sewing shop should have them in stock).
I also made some other minor modifications like the headshell mounting, some minor tubing variations and decided to use glue insteaad of screw for some mountings.
I am finishing printing the last parts tonight and i will assemble the tonearm in the following days.
i plan to use this thread to post some photos of the work in progress, to share ideas and to share some sound impression when i finish the build.
I also have a linear tracking tonearm in the backburner that is basically an opus cantus clone but with an innovative kind of bearing but that is for another thread.
Last thing i want to say is a big thank you to the forum: my first 'serious' machanical project outside of my job was the restoration, replinth etc of my first lenco some years ago, since that i built some electreic bikes (some really high powered), some linear motion CNC type machines, 3d printers, electrostatic headphones and a pllethora of other smaller things but what started it was my lenco i couldn' have done it without the shared knowledge of this forum, thank you people!
