Quick n' Easy : DIY Bias Weight.

Hiten

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Hello friends,
At first I hesitated to start a thread about measly DIY Bias weight. But then I thought someone who wants to make temporary but right looking bias weight for their tonearm might benefit from this. Atleast they will get approximate weight of various parts and process to work. So here is my second DIY attempt. (After LM317 regulator flea watt amp :lol:).



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You all know mixer grinder has some brass and steel part. I salvaged the spindle and hexagonal nut from old mixer. Somehow by looking at the shape I thought these would make good bias weight. Mind you these nut and spindle has reverse thread. Means when you try to turn clockwise it comes out.



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The Brass nut's hexagonal side were filed to make rough round shape. Then in the mixers steel spindle it was tightened. I fitted it in my electric drill and with varying grit paper made almost perfect (The center hole and drill chuck are not perfect center) round shape. One good thing is with a pointed punch I was able to make a hole on top. If I had to do a proper bias weight I would take steel object and make circle perfect through hole with laser cutter and finish it. But this brass nut being hollow and as I wanted to make it quick this came in handy. The weight of only brass nut was 1.89 gms.




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I cut the threaded part of steel spindle to use it to fill the brass hollow part. I though this would be handy in adjusting -/+ weight which was required. I think somewhere in the forum it is posted that these particular bias weight is 2.85 gms. Though logic tells since counter weight has dial upto 3 gms. it should be 3 gms.



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I tried to make the weight look as original as possible So I gave these two parts (Brass nut and threaded steel screw) to a guy who used to silver plate ornaments. The cost was 40 Rs. So This is silver plated Audiophile bias weight :D. The Weight some how was reduced to 2.56. Which I guess was due to acid wash prior to plating. I didn't had a chance to see plating process. Just like original a nylon thread was tied with a tiny spring wire so as it does not come out. I had to put extra tiny nut to increase the weight. I also put in 2 drops of Fevicol inside to securely keep thread and nut in place. If need arises the weight can be kept in water to loosen the fevicol. The final weight came to about 2.89 gms. Which I guess is ok middle value.


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Thanks and regards.
 
Superb engineering. I really admire any work which takes extra trouble to get good finish. I've tried; it's not easy. :D

Which turntable and tonearm is this?
 
Thanks tcpip.
To be honest I was not totally satisfied with it. I wanted perfect cylinder with 90 degree edges. But if I had filed any more, the side wall would have become very thin with the risk of cutting through to threads and top would also become thin. But time was short and resources were few. This is Jelco SA-50 arm used to come with Cosmic 4000 MK II and in the west it came with Ariston RD-11 turntable.
Regards.
 
Here are the complete arm pictures LINK. Good tonearm with well made bearings.
Regards.
 
Thanks tcpip.
To be honest I was not totally satisfied with it. I wanted perfect cylinder with 90 degree edges. But if I had filed any more, the side wall would have become very thin with the risk of cutting through to threads and top would also become thin. But time was short and resources were few. This is Jelco SA-50 arm used to come with Cosmic 4000 MK II and in the west it came with Ariston RD-11 turntable.
Regards.
Ah. Cosmic 4000. Brings back memories. :)
 
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