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Mounting Triplanar Tonearm to SME 20/2 Turntable

I just got a Triplanar U2 SE tonearm and am wondering how to mount it to my 20/2.  
The arm board I have is for an SME tonearm.  Until now I've had a SME IV mk vi mounted.  
After removing the SME arm I used the TP jig to see approximate location of the three holes.
Two of the holes land on the aluminum of the board and the third one is in the open hole in the center.  
It does not seem likely that I will be able to use the SME arm board for the TP arm.  Unless using only two holes to mount it will be enough???
I've also wondered about using 3M high bond tape to fix the arm to the board.  I use this tape in my profession and find it to be of excellent strength and longevity.  This doesn't mean that it's an acceptable application.  Just curious.    
In searching these forums and internet searches I have not been able to find a TP compatible arm board for use on an SME TT.  
Please share any info you might have.  Thanks!
128x128snackeyp
snackeyp's avatar
snackeyp OP
455 posts
 
A friend of mine owns a machine shop and has agreed to make one for me.  BTW, I think the material for the SME original is brass.  I took it off the plinth and noticed it feels much heavier than what aluminum would weigh.  
I'm going to see if I can get the new one made from brass as well.  
Also, a guy in the U.K. offered to make a custom board for 670 UK Pounds.  I think that's more than $800!  Crazy.

snackeyp's avatar
snackeyp OP
455 posts
 
I made a temporary arm board last night from aluminum disk material I found online, and mounted the new tonearm.  It's not real pretty but it works great.  It only cost me about $30 for the materials.  At least I can listen to records while a nicer version is being machined locally.  

The Tri-Planar arm is an amazing work of engineering.  I'm already blown away by it.  I've only played one record and still need to tweak some things, but it's immediately evident that it's a wonderful tracking tonearm.  
mijostyn's avatar
mijostyn
8,570 posts
 
snack, the SME plinth is aluminum.
Atmasphere, I absolutely agree that the tonearm has to be rigidly connected to the main bearing but I'm not sure the arm board has to be exactly the same material. It certainly has to be rigid. Plain wood of any species is not a good choice because it is not dimensionally stable. However MDF Laminated with aluminum or a heavy plastic or solid surface material should be fine. You can even make the MDF harder by soaking it in Watco overnight. 
snackeyp's avatar
snackeyp OP
455 posts
 
Today my machinist friend confirmed that the SME arm board material is brass.  He's going to make the blank version for me out of brass as well.  I'm surprised to hear the plinth is aluminum.  It's such a heavy turntable, and besides that I would think aluminum would not isolate vibration as well as some combination of materials.  If it is aluminum they did a great job making the thing rock solid.  Thanks
mijostyn's avatar
mijostyn
8,570 posts
 
I have a 30/12 and rock solid is an understatement. Aluminum may be lighter than other metals but it is still pretty heavy. It is used in this application because aluminum does not ring. It is self damping and in the thicknesses used by SME real stiff. I own one so you could say I am biased and there may be cooler looking tables out there but IMHO none that sound better. Maybe as good but not better.
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