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Old 20th February 2019, 02:57 PM   #2761
hottattoo is offline hottattoo  United States
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nocdplz,

Bird Precision

Very good company with a large variety of of screw mounted jewel bearings. This is where I bought my bearings. The bearing are very light in weight so shipping should be fairly cheap.

Niffy,

I wound up buying about 100 jewel bearings (unmounted) on ebay. These bearings were used to repair Russian ship clocks !!!! They are about .111" OD small hole through center---If anybody needs, I will give some.
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Old 20th February 2019, 03:22 PM   #2762
nocdplz is offline nocdplz
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Thank you too, Hottattoo. I hope to solve with the repairer nearby, but just to begin that link has a lot of valuable information, provided I could ever think in inches and fractions of ....
carlo
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Old 20th February 2019, 04:59 PM   #2763
niffy is offline niffy  England
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Quote:
Originally Posted by hottattoo View Post
Niffy,

If possible and get some time, could you post some pictures of the bearings you are trying to improve ? I have a hard time picturing your turntable drive system. good luck with your research.

Hi Joe,

I hope these clarify my description.

IMG_20190220_162950-1280x960.jpg

IMG_20190220_163120-1280x960.jpg

IMG_20190220_163211-1280x960.jpg

The belt takes a 90 turn around the motor pulley and each idler wheel, touching the subplatter for 30 in between each. The photos are of the new idlers. The bearings are mounted in M4 grub screws. Any new bearings will need to also need to be M4 based which give a maximum diameter of about 2.5mm. I have a couple of ideas for how to get the bearings silent, just waiting on some bits to turn up in the post.

I have considered jeweled bearings of the type I linked. The problems are how to secure them within the grub screws (epoxy?) and what to use for the pivot/axle. Possibly round ended needle roller bearing. The smallest size readily available is 1mm diameter which would require that the hole in the jewel to be this size. Going much smaller in pivot size would make drilling the holes in the ends of the axles tricky.

Niffy
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Old 20th February 2019, 05:29 PM   #2764
super10018 is offline super10018  United States
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Niffy

Look nice! But I am wondering if there are any benefits to use needle bearings for idler wheels because belt is very flexible. Maybe high quality ball bearings?

Jim
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Old 20th February 2019, 06:07 PM   #2765
niffy is offline niffy  England
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Hi Jim,

The idlers in the photos are actually the fourth version I've tried. The first set I made, with Teflon bushes, remains the best. The pin bearings come in a close second. My second attempt did use ballrace bearings. These were a high quality miniature type, the best I could find. They were horrible. Really noisy.

To be honest I'm being terribly OCD. It's the one area of the deck that I feel could be improved. It's more about reducing platter runout than improving the idlers themselves. If my current plan fails I'll just make some bearings the same as the originals and fit the new idler wheels to them. I will get the same very quiet bearing with the improved concentricity of the new wheels. I'll also be able to run the different belt setup with the new wheels.

Niffy
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Old 20th February 2019, 08:39 PM   #2766
hottattoo is offline hottattoo  United States
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Niffy,

You put an awful lot of time and effort in your beautiful turntable. A picture is worth a 1,000 words.

You can definitely use epoxy to secure the jewels to any size grub screw you like. However (my opinion) you might be better off using piece of carbide rod that you can polish both ends and put into a U shaped, cup type bearing of Vespel or Torlon. You could drill and ream a hole through the length of yor pulley material and glue or force fit the rod in a slightly under sized hole in the pulley body.

I made my own carbise axles ( 1/16" ) using a Foredom tool running up against a diamond wheel ( on my surface grinder) at an 80 degree angle. These axles are polished on both ends and go through my magnesium carriage wheels, then enter the jewel bearings. I believe this way would produce the most robust and quiet bearing for your purpose but perhaps not as quite as jeweled bearings. Another possible advantage is that you could fill the bottom cup bearings with nano / synthetic clock oil. Hope this makes sense to you. Good luck.
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Old 20th February 2019, 09:01 PM   #2767
hottattoo is offline hottattoo  United States
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Niffy,

I forgot to mention that you put a radius and polish both ends of the rod / axle using diamond stones (ebay) and then various grades of diamond polishing compounds. There is also the advantage of using "normal" sized materials, 2mm, 3mm, 4mm diameter carbide rods instead of micro / jewelers size components. Small carbide drill blank rods are available on ebay.
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Old 20th February 2019, 09:20 PM   #2768
niffy is offline niffy  England
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Hi Joe,

The previous bearings are very similar to what you describe. The shart is stainless steel rather than tungsten carbide. The extra hardness of carbide doesn't make that much difference when used against a softer plastic. The cup/bush in made of Teflon.

For the next attempt my plan is to use round ended needles from roller bearings, 1.5mm diameter, as the shafts. These will be set in a short M3 threaded axle. The shafts will fit into cups inserted into the ends of the fixed grub screws. The cups will be made of a short lengths of Teflon tube, 2.5mm od 1.5mm id, with 1/16" delrin balls at the bottom. These will be lubricated with petroleum jelly.
The wheels are acrylic and adjustable on the axle to allow them to be centered. Not have a precision lathe requires some lateral thinking. I have built a pair of jigs, one to measure how off centre the wheel is and one to then centre it. This bit of the new idlers works superbly.

Thanks for the input.

Niffy
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Old 21st February 2019, 08:27 AM   #2769
niffy is offline niffy  England
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Hi Joe,

I was writing the reply to your first post when the addendum post came in. The advantage of the needle roller is they come pre-polished to a fine finish. I have diamond paste down to 0.5um so I can buff them up further if required.

Niffy
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Old 21st February 2019, 02:48 PM   #2770
hottattoo is offline hottattoo  United States
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Niffy,

As usual, you put a lot of time and thought into improving your turntables drive system performance. I am sure you will perfect whatever method you choose. I speak like everybody has a machine shop in their basement, like I do. Not having one, forces you to use off the shelf materials and think outside the box, in which you have done a stellar job.I could only imagine the work you would turn out if you had access to a lathe / mill etc. !!!! I will be watching, learning and contributing where I can.
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