Post by Owen Y on Mar 31, 2017 17:43:04 GMT 12
As mentioned in the Terminator Tonearm thread, the standard arm-mount consists of round Delrin pillar.  I've been thinking that this could be improved structurally at least - whether or not it changes or even improves the sound, remains to be seen.
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Post by Owen Y on Mar 31, 2017 19:44:15 GMT 12
The tonearm base looks like this....  You can see the air holes in the manifold (slider removed), the cueing lever & the VTA adjuster.
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Post by Owen Y on Apr 1, 2017 19:24:47 GMT 12
First cut at a redesigned arm-base to replace the Delrin pillar.... 
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Post by Owen Y on Apr 1, 2017 19:36:29 GMT 12
But my 'engineer' didn't like the ugly 'steps', he reckoned that he could smooth 'contour' it... (Model shown upside down bolted to a 'fixture' block for CNC milling.) 
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Post by Owen Y on Apr 1, 2017 19:53:20 GMT 12
Because the design has no parallel edges (the TT plinth is curved, as is the terminator arm-base), the block of material cannot be clamped in a vice for machining. So a 'fixture' block needed to be made first, onto which the arm-base block can be bolted. Although some reservations (about sonics) on my part, we agreed to use aluminium for starters, as offcut material was available.... The LH pc for the fixture block, the RH pc for the new arm-base part. 
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Post by Owen Y on Apr 1, 2017 19:56:10 GMT 12
(Warning, engineering porn ahead  ......) Initial 'facing' operation.... 
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Post by Owen Y on Apr 1, 2017 20:00:43 GMT 12
Fixture machined complete with locating bolt-holes... The large hole in the corner is a datum hole (as the arm-base part is an irregular shape). 
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Post by Owen Y on Apr 1, 2017 20:10:48 GMT 12
The arm-base stock was bolted to the fixture base in the vise, then machined & bolt holes drilled & tapped for M6 tonearm bolts.... The big hole is a counter-bored recess for the long M8 fixing bolt that goes through the TT plinth. 
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Post by Owen Y on Apr 1, 2017 20:14:37 GMT 12
A Ruby probe is used to reference the part/fixture position. 
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Post by Owen Y on Apr 1, 2017 20:17:55 GMT 12
Another facing operation and machining of the contoured surface done....  A close-up view of the finished part....  And a well-earned cuppa for the engineer
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Post by michaelw on Apr 1, 2017 20:50:17 GMT 12
milled aluminium is just so beautiful to behold... 
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Post by jon on Apr 2, 2017 16:33:02 GMT 12
Can i have one
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Post by Owen Y on Apr 2, 2017 20:57:29 GMT 12
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Post by Owen Y on Apr 2, 2017 21:03:40 GMT 12
Here it is at home....  
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Post by Owen Y on Apr 2, 2017 21:16:40 GMT 12
We decided to bead-blast the aluminium.....  
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Post by Owen Y on Apr 3, 2017 18:22:42 GMT 12
Bead-blasting looks great but does tend to pick up blemishes due to handling and/or surface contamination 
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Post by Citroen on Apr 3, 2017 18:50:11 GMT 12
Beaded looks nice and organic, stone like from the pics. But I do like a bit of unblasted shiny bling. 
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Post by michaelw on Apr 3, 2017 19:24:05 GMT 12
i prefer shiny
maybe some fancy tricks like jeff rowland ?
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Post by Owen Y on Apr 3, 2017 21:01:17 GMT 12
OK....consensus then, for the 'raw' look. Meanwhile....I became concerned about the added weight (430gm) of the new mounting block on the asymmetrically shaped slate plinth (below) of the Salvation, which sits on 3 x 'mag-lev' feet.... 
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Post by Owen Y on Apr 3, 2017 21:11:12 GMT 12
So we decided to take it back to the 'shop' to be 'pocketed' out, to remove a heap of metal. (Before....)  (After....) 
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Post by Owen Y on Apr 3, 2017 21:13:55 GMT 12
The finished piece.... (350gms) 
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Post by Owen Y on Apr 3, 2017 21:23:59 GMT 12
Would this affect the sound of the tonearm, compared to the original Delrin round pillar? (Despite the air-bearing tonearm's air-film horizontal slider, twin vertical pivots pins, etc.) 
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Post by Owen Y on Apr 3, 2017 21:41:32 GMT 12
Terminator tonearm re-installed onto the new aluminium arm base....  
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Post by Owen Y on Apr 3, 2017 21:42:42 GMT 12
Compared to the original set-up.... 
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Post by Owen Y on Apr 10, 2017 21:00:43 GMT 12
I should report on the sound.... I was initially shocked. My immediate reaction was to reverse things or at least ameliorate the effects (wood instead of aluminium maybe?) - sound seemed to jump out & was more 'forward'. On horn speakers this is confronting. I immediately tape-marked the floor & moved the listening chair backwards. Then I noticed stronger deep bass, punchier drum & bass, fatter tone to instruments & voice. Voice & upper registers also, have more energy & power. Much more 'attack'. Wider freq/tonal range. Orchestral power & dynamic range is at a different level. The next session & after, I am now liking it, a lot. The listening chair is back where it was. More long-term listening required...
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Post by Owen Y on Nov 9, 2017 20:22:30 GMT 12
Finally.... a batch of arm mounts has been machined & finished:  
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Post by Owen Y on Nov 9, 2017 20:24:57 GMT 12
Off to their owners this week, in USA, UK, HK, NZ. Complete with TT mounting & tonearm fixing hardware.... 
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Post by jon on Nov 10, 2017 10:34:28 GMT 12
Can I have one...
When you run again, that is.
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Post by Owen Y on Nov 10, 2017 12:22:55 GMT 12
Hi jon - of course. All of this initial batch (8 pcs) have been allocated, although 2 are still here awaiting final confirmation. I was planning to have some spares but the word has spread We will probably do some more, if you are not in a hurry - let me know. I will also await feedback from the Terminator owners, including from TransFi (Vic). I will PM you to discuss your TT dimensions & current costs. With the numbers, we've been able to keep costs down, although we've had to source more billet material.
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Post by jon on Nov 10, 2017 12:36:46 GMT 12
It's for the Breve turntable. I'm always in a hurry, however I've been waiting 5 years for this, so more time is definitely an option. Looking forward to the PM
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......)
