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My 3D printed tonearm - MK4

TankPopper

TankPopper

Well-Known Member
Hey everyone! its been a while since I posted something.

Finally, after years of R&D, I found the time to create my latest version of my 3D printed tonearm, based on the famous Frank Schröder. The arrival of my brand new 3D printed provided some more incentive because now I will be able to create much more precise parts.

Another personal goal that was thrown into the mix - print as many parts as possible, with minimal use of ready-made \ off the shelf parts.

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The Pivot housing, Arm and headshell,

My first challenge was structural integrity. The arm dangles on a cord and two strong magnets aligned to stabilize everything. To deal with the pressure from the magnets, I had to use a frame to house the pivot, giving it as much strength as possible.

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To keep things simple I chose on arm geometry that im familiar with, which is the REGA geometry. Due to print size limitation and concerns regarding structural integrity, I decided to print the pivot, headshell, and counterweight but use a ready-made tube to connect them. So far I tried 8mm Carbon fiber tubing, which worked great, and im now experimenting with Aluminum.

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Recently, my first set of white hairs appeared, and my insistence on having a removable headshell play a critical role in their existence. It seems that nobody actually sells the needed parts (for a reasonable price that is), so I had to improvise with a lockable 4-pin aviation plug. It… ahh… works.

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Earlier versions had a very small magnet, and the arm was less than stable. So this time I decided to use much BIGGER magnets, which brought me to the next challenge... Securing the cord, and that's the subject of my next chapter.

Hope you like it so far.
Tank out.
 
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What about the effects of a magnetic field near the very small electric current in the tonearm wires?

Seems that it might have some affect to the signal? Just curious.

Nashou
 
Nashou66 said:
What about the effects of a magnetic field near the very small electric current in the tonearm wires?

Seems that it might have some affect to the signal? Just curious.

Nashou
Click to expand...

To be honest, im not sure. I did have concerns about it in the beginning, but further reading revealed only that a few tonearms on the market have strong magnets near the cables. I couldn't find anything but the actual effect. Personally, I've never noticed anything wierd about the sound, and I've don't quite a few comparisons. Maybe someone who is more knowledgeable on the subject could shed some light?

polypetalous said:
Awesome! Nice work.

What printer are you using?

Ben
Click to expand...

Prusa I3 Mk3, which is outstanding.

thank you all! ill post the next part in a few hours.
Tank out.
 
TankPopper said:
Prusa I3 Mk3, which is outstanding.

thank you all! ill post the next part in a few hours.
Tank out.
Click to expand...

Your prints look really clean!
At home I use an Anet A8, love the more robust frame (among other things) of that prusa.

Out of curiousity can I be super annoying and ask:
Filament? Slice height? Infill?

Subbed for sure, please keep the updates a’comin’

Merry Christmas
Ben
 
polypetalous said:
Your prints look really clean!
At home I use an Anet A8, love the more robust frame (among other things) of that prusa.

Out of curiousity can I be super annoying and ask:
Filament? Slice height? Infill?

Subbed for sure, please keep the updates a’comin’

Merry Christmas
Ben
Click to expand...

Not annoying at all!
The filament is actually some cheap grey PLA. Layer height changes from part to part, some are 0.15mm and some are 0.05mm. infill changes also, and ranges from 20% to 60%. The Prusa has really proven itself and in my opinion it's the best deal out there of a home FDM printer.
 
OK, time for our next chapter - Securing the cord.

Another substantial challenge was securing the cord that holds the arm above the magnet proved quite the challenge. Earlier editions of my tonearm saw the string go up through the housing, take a turn and loop around a screw. The idea was that the pressure around the screw would be enough to prevent it from spinning and dropping the arm, but that didn't work with the much bigger magnets I was using now.

The old design looked like this:
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And its cross section:
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So here came the biggest challenge of them all… 3D printing a screw and nut that will sit on the same axis as the cord, eliminating the chance that the downforce will cause it to turn and drop the arm. Designing a screw to be 3D printed is quite the challenge, and it took me some research to figure out, but surprisingly enough - it worked from the very first print.

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That's it for now.
Tank out!
 
Really like what you have going here. So I have it right. The two magnets serve as the pivot point and oppose each other to somewhat levitate the arm bolstered by a cord that I assume fit's into the open hole of the frame? The bottom will sit in the plinth and be securely mounted there?
 
MRL_Audio said:
Really like what you have going here. So I have it right. The two magnets serve as the pivot point and oppose each other to somewhat levitate the arm bolstered by a cord that I assume fit's into the open hole of the frame? The bottom will sit in the plinth and be securely mounted there?
Click to expand...

Actually, its the other way around :)

The magnets actually pull each other, and the cord is the only thing that stops them. By pulling each other, the magnets stabilize the arm that would otherwise just dangle on the end of the cord.
The axis is the point where the cord meets the arm. Maybe this image will explain it better:

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TankPopper said:
Actually, its the other way around :)

The magnets actually pull each other, and the cord is the only thing that stops them. By pulling each other, the magnets stabilize the arm that would otherwise just dangle on the end of the cord.
The axis is the point where the cord meets the arm. Maybe this image will explain it better:

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Click to expand...
Very fascinating idea. Is there any plan to incorporate any viscous damping or bias (anti-skate) adjustment?
 
That is a very well thought out design. I would try fine wire instead of string to eliminate and stretch. Nice job! Be interesting to hear how it sounds :thumbsup:
 
TankPopper said:
Hey everyone! its been a while since I posted something.

Finally, after years of R&D, I found the time to create my latest version of my 3D printed tonearm, based on the famous Frank Schröder. The arrival of my brand new 3D printed provided some more incentive because now I will be able to create much more precise parts.

Another personal goal that was thrown into the mix - print as many parts as possible, with minimal use of ready-made \ off the shelf parts.

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The Pivot housing, Arm and headshell,

My first challenge was structural integrity. The arm dangles on a cord and two strong magnets aligned to stabilize everything. To deal with the pressure from the magnets, I had to use a frame to house the pivot, giving it as much strength as possible.

v4tEqTRbBmz-_dwYYUsYdRyz5ckWY2pATjC8h0UlSAbaghvpL9Tv5C3QTgdXImuy_c6jQB9tJ5XxOSuPej9Q8oDTWuMUUdxK-zE2I04WJRU71QXFQB_6OYENhE5eKx6ptkM4ffQxFGkVM_04AnCiq91HivbRiRTXpRa2JHwRYaH8FgRy7tR3dGbvqMzE4fx4EgwU7U7HrZG6E1i63p7vaYuynSC3nIlF8PX2o5m7uhbiEen80b9U2zGeQYJtzw2u6yARGev9PW9L4c74QGEEdjxjypn3tJexVgJLOsh8t--uiNlYgf8wkdWgbM_r93ZjPJxyAT6617nSQS8RGMYiH-PushGVFw7cIKUrhJcuOFkKSILwFSUBxhSWTht-KNXQfTuAzsevMXwyoS-QpE8afdYgKAgswLkpQojogg-ZcSDiktlgJxDMSZYUpUAzD1cMGHCFYJzWW5L_Eq3vNYGSoilJuN_EDvqOis1UyNGzNworwOIyvS2DFRIjVA3PW8dbfp8HxuyFWQZgxpkdTpIP-4QDzxxJebX3YmC0TtjUkhuKAf3jaIt_5bA__skUlg-nIH4HmdpLypYpJR_Tpp9aNq0PU5wsaiDgw2JmYjnCnlzyYg78m7cZQWDypRe-qLlSffJ2ikFCX8jPPDceFq_B3etv39ZjB9kPB1_y0Xr_BNYAiCW1rlLBENSAFMZde2ADuZmNqZFOC5uKIbjbNQ=w679-h904-no


To keep things simple I chose on arm geometry that im familiar with, which is the REGA geometry. Due to print size limitation and concerns regarding structural integrity, I decided to print the pivot, headshell, and counterweight but use a ready-made tube to connect them. So far I tried 8mm Carbon fiber tubing, which worked great, and im now experimenting with Aluminum.

k0VrOxC7LIT6gIy9NoDk-YK_CTq2c1wfNbpOzaPvLC837AjRczWvTjSBtg-jgu-poMck3-6R68dFWwgkVbInyyYeUQs4zE3I1NaqBqr4lERxJqdGmYNZSfQcrJV_wYaNJstRQSbqFWK9QriX0kPdm4NnwrKU4pz5mpcTagIyuauF6aIYsB4nH0t6pnyqCBaP2QZtamZ5s01D0GCXd3xPqkiOVCfbB_0xi3KQ92BT42MLxmovGsUFjeIKN3vYIcZIkMGLjklQx3KadKg_kQPGz_8hYYxHf-3yvwTA0_WRw89ncZVWLfPWhxvb3N3zhZSB84EIv30mwThvkY73Wm-xp6sc1NRU0fhmxbSgfnR1ud-5FSUssqlUG4dycP8k5umiHKg48RocSCJp_sDK43cB5kfttEbmzd68kcd1zjrUXwKwGeJpW5aGphoDBL06EuzmMJwlTZXBnXLe0gb3UdZ3SOLiXRIOf7DUVYWmhwU4Ot6jQb6irSOqISjBajSZRq8FpRNfJ-62xkFukt7XhYskyknh-AJ2MUEt4Hf5ej7aG1k5FmLsIfm1kv0qOgaJ4_eTn4M5e53h2wspzTxlSyWt6596TheEcnGdMZss2smIvFOpIV9hZ1TUF37gVuuPDn2-Vo_eNMLtofMAHq-ZLAgLecLm9mr1e31VLDO7E60TGMzTZXkbxcrSA9M_Zj2PDcdjN4mdPtBBiregv8elbA=w679-h904-no


Recently, my first set of white hairs appeared, and my insistence on having a removable headshell play a critical role in their existence. It seems that nobody actually sells the needed parts (for a reasonable price that is), so I had to improvise with a lockable 4-pin aviation plug. It… ahh… works.

LeoSPXprPrhEdupDounfdHcMVGNDLeU5mTksq8SgNUxxm-XfXe5MFkVb-9Qi1OKs4EdxZCi2evIqEoA5ax9QPbCr33XDa_OE3s9f6YvStFa-7_junVN-BmhyUpeXM-dfcaBISwW2dqa3kClgUBXpHzTtpgYSsL5XEzlAg0ktkan1d3_fAlz7qr0l_MWrNxTiXtC5EPHHxeAC72e7_IE5aHoohzXjWU8AlrvJEy85YyNih9_j0FdXXyiR-yyj9hDPBBg7JFggEpoy7S60aoozVroCFDLzhsXKCf2Vp7rbtbY55w1k8OfwuWfmUOnI8pQl_2sbUMdIkvkWJPIrCiQDWXG1fe113NNsezSExDBociU5ArQkczl4jBgJtCv2s5YmwKHx2hHZW_sBVMeAWwGwVs2NfkECDpAPKgYVYH4uP2xjF0P_--gax9Y2ZlW3gWDM8VxiT7c_YXwHy8uGOD8mDTPReLPwwMjy-c8xve_702-L3JdqXBTgUvByEo4XF5wDDPNzc93IehIx019G6UsYZ4WkhIZRqT6N4hD8ihfED3q5Yhls7S_MrQ-PoL9bnm5GUrs0xNxpa1Q3JWfXy1XxZ62Q3c7Id62qILnrsTtGO1FpDVoWnX2xgtQki9vd6-BIMNGlfrAyl52fFz9ZhJKfWUSOLpN9LCDOnhVH0ZCvcOs69mGaIkNPLfAaMgb8GjDPZ7LB1RxnNqQrnI32VQ=w679-h904-no


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Earlier versions had a very small magnet, and the arm was less than stable. So this time I decided to use much BIGGER magnets, which brought me to the next challenge... Securing the cord, and that's the subject of my next chapter.

Hope you like it so far.
Tank out.
Click to expand...

Good on you for diving into this... I’ve so daydreamed about doing something similar. We have multiple printers at work and I’ve been keeping notes...
 
Ah... I see that now with the actual photo and the drawing. Using a string or cord would seem to add some variability over time, cord stretch, shrink etc. whereas a wire should hold the position more readily. Just a thought. Fantastic work.
 
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