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Old 14th February 2020, 09:26 AM   #3411
dahlberg is offline dahlberg  Sweden
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I'm quoting myself here but...

Quote:
Originally Posted by dahlberg View Post
From true point:

Quote:
Notes: When used horizontally, the pivots should not bottom against the radius of the jewel. A degree of looseness is required which is called 'end shake'.
Click the image to open in full size.
The top part of the drawing shows such a solution. Why this is I don't know but I suspect that true point knows what they are saying. For a bigger pic see:

http://www.dahlbergaudiodesign.se/images/linear_8.png

Edit: When applying this way of thinking a holed jewel with a hole the same radius as the contact radius of the vee schould function similarly. The smallest holed one from true point was 0,3mm, therefore in the drawing.
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Last edited by dahlberg; 14th February 2020 at 09:42 AM.
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Old 14th February 2020, 10:52 AM   #3412
warrjon is offline warrjon  Australia
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Quote:
Originally Posted by dahlberg View Post
Edit: When applying this way of thinking a holed jewel with a hole the same radius as the contact radius of the vee schould function similarly. The smallest holed one from true point was 0,3mm, therefore in the drawing.

With a conical ring jewel + end cap the contact point will be smaller than your 2nd picture. A straight ring jewel will be similar but it has much higher contact surface and therefore friction.


A 0.3mm hole is very difficult to drill in a hard bearing.....
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Old 14th February 2020, 10:56 AM   #3413
dahlberg is offline dahlberg  Sweden
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Maybe a 0,1mm brass 3D printer nozzle could work.

Click the image to open in full size.

1 Pieces 0.1mm 3D Printer Part Extruder Brass Nozzle Head For 1.75mm V6 Head Hot | eBay
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Old 14th February 2020, 11:22 AM   #3414
dahlberg is offline dahlberg  Sweden
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0,1mm brass nozzle vs vee jewel bearing. The idea here is that the nozzle is easily avaliable and sheep.
The no radius pivot is also easy to manage.

Click the image to open in full size.
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Last edited by dahlberg; 14th February 2020 at 11:24 AM.
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Old 14th February 2020, 02:55 PM   #3415
super10018 is offline super10018  United States
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How about the tip of the ballpoint pen as the pivot?
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Old 14th February 2020, 05:13 PM   #3416
niffy is offline niffy  Europe
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I've been punching some numbers.
If you use sapphire vees with a cup radius of 0.1mm you will not be able to use tungsten carbide pivots with a tip radius of 0.05mm as the contact stress will be too high (a 2:1 ratio with the cup, as generally recommended). If you use steel pivots with a tip radius of 0.05mm the contact pressure will still be a little excessive. If you increase the radius of the tip of the pivot to 0.075mm the maximum contact pressure will be decreased to a just usable amount for carbide and a quite usable level for steel. I am assuming a 50g carriage mass and reasonably careful handling.
Brass would not be suitable for making pivots.

Even the finest tipped ball point pen has a tip that is way to big for this purpose. I used hardened sewing pins to make my first pivots. I used prym brand as these seem to be very high quality. I carefully rounded the tips to a radius of 0.125mm and then polished them. Rounding the tips to 0.075mm shouldn't be much more difficult. Use the shank of a 0.15mm drill bit as a visual reference. A microscope will help.

Finding tungsten carbide pivots in this size will not be easy.

Niffy
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Old 14th February 2020, 09:06 PM   #3417
warrjon is offline warrjon  Australia
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The problem is souring the VEE jewel. I have not been successful. True Point could offer S222 with radius of 0.08-0.1 which I thought I was too small they did not have S24 jewel with 0.5 radius. I emailed Swiss Jewel and never heard back.


Been thinking about to make VEE's, brass (the easily obtainable) I do not think is going to be hard enough. So thoughts went to O1 tool steel it's machinable and can be quenched hardened. Drill ends, the bit that goes in the chuck is not hardened and could possibly be used for the VEE, then hardened. Carbide inserts have the tip radius specified in the part number I have inserts with tip radius of 0.4mm to machine the VEE.


If all else fails back to ceramic ball race bearings.....


.
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Old 14th February 2020, 10:37 PM   #3418
dahlberg is offline dahlberg  Sweden
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Ok, first reply about the vee's.

Quote:
hello,
pleased to receive your inquiry, we can produce your drawing bearings.
How many pcs you need this time?

Welcome tell us sample quantity you like.

Thanks&regards
Linda


Response:
Very nice to hear from you, I wasn't expecting such a quick response. I will have to get back to you
about the specifications but it will not change that much. It's the vee radius that might have to be a
bit bigger, somewhere around 0,2-0,3mm schould be close to the final order. All other as in the drawing.
If you could give me quotes for both 50, and as an alternative 100pc.

Best regards. Bengt Dahlberg
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Last edited by dahlberg; 14th February 2020 at 10:54 PM.
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Old 15th February 2020, 05:34 AM   #3419
niffy is offline niffy  Europe
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Nice. Can they supply pivots as well?

Niffy
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Old 15th February 2020, 07:43 AM   #3420
nocdplz is offline nocdplz
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....The no radius pivot is also easy to manage....

Does it mean doing? in which way? For such dimensions and tolerances watchmakers have to use a Jacot tool, and to know well how to. Just to burnish what previously made on their high precision lathes.
In our studio I drew along forty years with Rapidograph 0.1 mm, wondering how the hell they built them (a 0,1 tube with far smaller rod inside), and gaining an almost mystical respect for those capable of such tolerances. (dozens broken just to clean them). A < 0.1 mm smooth conical tip is far beyond my skill/tools: all my compliments, guys.

my 2 cents
Brass is not bronze, and bronze is for lubricated sliding bushings, too soft even for ball races. A 0,1 vee bearing will get a result similar to teflon (indent due load); but what would be increased friction on teflon (resilient), will be some play on brass. Hss on Hss - one of the principle of a sliding bearing is that one part has to be different, a bit softer than the other, with a smoothing, not gripping behavior. To make a jewel bearing seems to be needed a jewel

carlo
From web it seems that nobody has Vee jewel bigger than 2 mm. while rings and cups go up >> 5 mm . Strange, since vees are used for devices far bigger than watches
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