Hi
I want to make a breuer type tonearm ,has anyone experience of using oscillating weight ball bearings from an automatic self winding watch?. I am thinking of using them for the vertical pivots and computer hard drive bearings for the horizontal at least the bottom one. Absolute novice on a mini lathe but intending 10.5" either aluminium or magnesium rod .Would be nice if someone had done this already and ironed out the issues.
I want to make a breuer type tonearm ,has anyone experience of using oscillating weight ball bearings from an automatic self winding watch?. I am thinking of using them for the vertical pivots and computer hard drive bearings for the horizontal at least the bottom one. Absolute novice on a mini lathe but intending 10.5" either aluminium or magnesium rod .Would be nice if someone had done this already and ironed out the issues.
I built a tonearm and originally used commercial carbide/sapphire pivots ($700 worth), which was a failure as the pivots could not take the mass of the arm. After testing a lot of different options I ended up using carbide scribe/M4 set screws. The scribe points were radiused and the M4 setscrews had a radius forged into the bottom. They were then highly polished. These pivots are very good with extremely low starting torque about 4mg.
https://www.diyaudio.com/community/threads/diy-4-point-pivoting-arm.375071/post-6808955
https://www.diyaudio.com/community/threads/diy-4-point-pivoting-arm.375071/post-6808955
Hi Warrjon
Thanks for your quick reply. Your thread is one I have already followed and am really impressed with the outcome, congrats.
I have thought of pivot types, years ago I bought an old Helius tonearm only to find the pivot points broken, after talking to Helius who explained how to regrind them simply with a drill and grinding paste to re-polish the ends I also replaced the steel balls with ceramic and it has worked well up to now.
I thought Mr Breuer having been a watchmaker probably used what he knew best and the most robust watch bearings seem to be the oscillating weight ones, although he may have used ruby bearing which the high cost watches seem to use. I like the idea of a solid path for energy transfer and rubies may not be suitable.
If I go down the road of pivots how do you go about forging and polishing the grub screws?
regards
Thanks for your quick reply. Your thread is one I have already followed and am really impressed with the outcome, congrats.
I have thought of pivot types, years ago I bought an old Helius tonearm only to find the pivot points broken, after talking to Helius who explained how to regrind them simply with a drill and grinding paste to re-polish the ends I also replaced the steel balls with ceramic and it has worked well up to now.
I thought Mr Breuer having been a watchmaker probably used what he knew best and the most robust watch bearings seem to be the oscillating weight ones, although he may have used ruby bearing which the high cost watches seem to use. I like the idea of a solid path for energy transfer and rubies may not be suitable.
If I go down the road of pivots how do you go about forging and polishing the grub screws?
regards
There are many benefits to the pin pivots, starting torque is very low, they are much more silent than ball race bearings, do not lift with stylus drag force, provide a better path for acoustic energy out of the arm. And if done correctly no chatter. The vertical pivot (horizontal pins) need to have a very small amount of end shake. My arm wand very heavy over the pivots which prevents the arm lifting just like a unipivot.
The pivots are a bit fiddly to setup correctly because the grub screws I used are regular not fine thread so dialing in the correct load took a bit of trial and error. These pivots are so good that this massive arm will track a very high compliance Stanton 881s with no mistracking.
Mr Breuer may have used jewel watch pivots, I have never seen this arm but is a good bet as these pivots have been used in watches for a long time.
One thing Mr Breuer didn't get right was the stylus is offset to the arm wand. Lining the stylus up so it's coincident down the center of the arm wand with the pivot is the only way to go. Lining the stylus up reduces to almost nil the rotational torque trying to twist the arm.
M4 grub screws are very hard and can't be drilled. I made a forge from a bit of 12mm round steel that has a 2.5mm hole all the way through and has an M4 thread in the bottom. I use an old needle roller which has the radius on one end. My needle roller is 2.5mm OD and is a loose slip fit in the 12mm round steel. Insert the grub screw into the bottom needle roller into the top and hit it with a hammer. I originally used an old drill bit to do this but the screw is harder than the drill and the drill molded to the grub screw radius. If you do decide to go this way let me know and I can take photos of my forge.
Next step is to burnish the grub screw, I use the needle roller in a hand drill to burnish the screw. Next is the polishing I use the drill with a toothpick broken is 2 and use the broken end to polish the screw. I use diamond past in varying grades to 0.5microns for the polishing.
Making the pivots is time consuming but the result IMO are the best tonearm pivots available. I have had 1 broken carbide pivot (the top pivot pin) but the scribes and M4 screws are cheap. The broken pivot was caused by the radius on the pin being a bit too small. I have rectified this and my pins use a 0.1mm radius and M4 screws 0.4mm.
The pivots are a bit fiddly to setup correctly because the grub screws I used are regular not fine thread so dialing in the correct load took a bit of trial and error. These pivots are so good that this massive arm will track a very high compliance Stanton 881s with no mistracking.
Mr Breuer may have used jewel watch pivots, I have never seen this arm but is a good bet as these pivots have been used in watches for a long time.
One thing Mr Breuer didn't get right was the stylus is offset to the arm wand. Lining the stylus up so it's coincident down the center of the arm wand with the pivot is the only way to go. Lining the stylus up reduces to almost nil the rotational torque trying to twist the arm.
M4 grub screws are very hard and can't be drilled. I made a forge from a bit of 12mm round steel that has a 2.5mm hole all the way through and has an M4 thread in the bottom. I use an old needle roller which has the radius on one end. My needle roller is 2.5mm OD and is a loose slip fit in the 12mm round steel. Insert the grub screw into the bottom needle roller into the top and hit it with a hammer. I originally used an old drill bit to do this but the screw is harder than the drill and the drill molded to the grub screw radius. If you do decide to go this way let me know and I can take photos of my forge.
Next step is to burnish the grub screw, I use the needle roller in a hand drill to burnish the screw. Next is the polishing I use the drill with a toothpick broken is 2 and use the broken end to polish the screw. I use diamond past in varying grades to 0.5microns for the polishing.
Making the pivots is time consuming but the result IMO are the best tonearm pivots available. I have had 1 broken carbide pivot (the top pivot pin) but the scribes and M4 screws are cheap. The broken pivot was caused by the radius on the pin being a bit too small. I have rectified this and my pins use a 0.1mm radius and M4 screws 0.4mm.
Hi via-venti,
I can't answer your question about oscillating weight ball bearings, but I have successfully used flexural pivots from C-Flex in all my tone arms since the 1980s. I'll have to do some research to find out what oscillating weight ball bearings are.
Sincerely,
Ralf
I started off attempting to build a unipivot (based on J. Bickerstaffe's "Torsional Stability and the Unipivot" in Wireless World) but was defeated by the amount of machining involved, when all I had were hand drills and a vise. So... I went with a simple gimbal bearing. Radio Shack 4-40 screws for the "sockets". HSS drill bits with the twisty part snapped off and ground the ends to points. To make the divots, I used a larger diameter drill bit ground to a wider-angle point as a punch. Crude unheated-shed machining, but the bearings worked. I couldn't feel any play, and when balanced the arm would move with a breath. And the arm was light enough to match the high compliance of the Ortofon cartridge I designed it for.
The arm lift was an Audio-Technica accessory found at a local radio/TV parts dealer.
The arm lift was an Audio-Technica accessory found at a local radio/TV parts dealer.
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Thanks for all input so far. I think some progress has been made in that I have just ordered some bits off ebay . 4No. dial indicator tips used for surface measurement they are screw in types, tungsten carbide with ruby ball ends . 2 will be for vertical pivots they have 1mm dia balls, 1No 8mm ball for bottom bearing and another 1mm for top bearing. Have also ordered some press in bronze bearings by Bergeon for the ruby balls to run on. Will see how they look when they arrive may need to polish them in?
Am I mad
Am I mad
As a Hatter.........
1mm is quite big for the pivots, you'll need to test arm sensitivity to ensure it's not too high, but the theory is sound, let us know how it goes. Here is my TA testing vertical sensitivity. A 1cm^2 piece of 80gsm paper is 8mg.
Dangrus, I have built seral arms now. I to do not have many machining tools at home. but I joined two local hobby clubs, One did wood turning where I made the Temaad arm Main body from wood. The other had a metal work shop. where I made the Temaad arm Main body etc. from Aluminum. Also maybe the most important thing is they had experienced retired guy's who were more than willing to impart their knowledge and I also found Derek from Temaad most helpful & friendly, answering all of my many questions very quickly.
Cheers
Cheers
I used 0.7 mm uniball jetstrem ball pens with 3 mm stainless steel set screws for bearings. It worked very well. I did a similar test as warrjon did. Please see the video.