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Old 29th May 2014, 10:17 AM   #1751
bappe is offline bappe  Sweden
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Default New link

I saw that the link above is for steel balls, here is anew one, Drilled Balls.

//Anders

Last edited by bappe; 29th May 2014 at 10:17 AM. Reason: spellcheck :)
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Old 29th May 2014, 03:33 PM   #1752
niffy is offline niffy  England
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Hi Bappe.
In your first post you quoted Bo saying "One of the features of the original arm is that the area/volume of the arm shall be as small as possible, this in order to keep the pickup of airborne feedback as low as possible. Some of the designs here follows that idea, some don´t."
I assume you are probably referring to my "bat-mobile" carriage when you say some don't. I did consider air borne feedback in the design process. However the amount of energy fed into the carriage system due to record modulation at the record/stylus interface is going to be at least an order of magnitude (probably 2) higher than the amount of energy from airborne vibrations. Building the carriage to deal with the energy from the stylus/groove interface was deemed much more important. As previously mentioned my deck has to live in a cabinet (due to pet cats). In theory enclosing the deck in this way should shield it from the majority of airborne vibrations. If airborne vibrations do present a major problem then sound quality should be better with the door shut. To be honest I struggle to hear any difference between door open and door shut, door open is very very marginally better. My advice would be to not concentrate to much on this area of your design as you may compromise other areas, arm rigidity plays a much bigger role.
I like the look of your spherical wheels. Wity my arm virtually all vertical movement is accommodated by the bearings play so I'm not sure if making them spherical will add much here. One advantage might be that they will effectively increase the diameter of the wheels which will decrease the bearing friction as seem by the cartridge. Moving the wheels further apart should also help tracking and the addition of a spar between the two rods, as you suggest is a probably needed.

I look forward to seeing what you come up with.

Niffy
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Old 29th May 2014, 06:02 PM   #1753
moray james is offline moray james  Canada
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Quote:
Originally Posted by bappe View Post
Hi All!

I have followed this thread off and on and have truly enjoyed it, there are some really great projects shared here!
The Cantus designer, Bo Hansson (RIP) was a very good friend of mine and i have used the arm in its different incarnations for over 20 years and will probably stick with the concept for another 20
One of the features of the original arm is that the area/volume of the arm shall be as small as possible, this in order to keep the pickup of airborne feedback as low as possible. Some of the designs here follows that idea, some don´t. Here is an idea of mine that does follow it and that should be fairly easy to realize in practice.
The bearings can be press fitted into the ceramic balls and getting the balls machined should not be a problem, here is one place example Kinematic Components Catalog 105-B.
For torsional strength it might be necessary to connect the arm tubes somewhere close to the bearings.
Attachment 421076

Attachment 421077

Attachment 421078

BR,
Anders
This is a great looking idea. Why not consider a shallow half round track or even a "v" track rather than the twin tubes as you could then place the pivot point closer to the surface of the disk. I love it but it's a good thing Bo is not here to see such heresy. Thanks for posting your idea. Best regards Moray James.
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Old 30th May 2014, 01:09 AM   #1754
super10018 is offline super10018  United States
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Quote:
Originally Posted by bappe View Post
Hi All!

I have followed this thread off and on and have truly enjoyed it, there are some really great projects shared here!
The Cantus designer, Bo Hansson (RIP) was a very good friend of mine and i have used the arm in its different incarnations for over 20 years and will probably stick with the concept for another 20
One of the features of the original arm is that the area/volume of the arm shall be as small as possible, this in order to keep the pickup of airborne feedback as low as possible. Some of the designs here follows that idea, some don´t. Here is an idea of mine that does follow it and that should be fairly easy to realize in practice.
The bearings can be press fitted into the ceramic balls and getting the balls machined should not be a problem, here is one place example Kinematic Components Catalog 105-B.
For torsional strength it might be necessary to connect the arm tubes somewhere close to the bearings.
Attachment 421076

Attachment 421077

Attachment 421078

BR,
Anders
Two steel balls can be too much mass. It gets complicated and not diy friendly.
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Old 30th May 2014, 01:52 AM   #1755
super10018 is offline super10018  United States
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I have been reading this thread from 1st page up to 100 now. I need to read other pages as well. This is an wonderful diy project.

Here is my plan. I am starting to order parts now. The plan is based upon, of course, Colin's wonderful and inspirational project and directdrive's suggestion to use U-groove bearing. Thanks guys! And, last, it is also inspired by Clear Audio's arm.

My idea is let the track close to surface of record as much as possible.

Almost all the parts are pre-made. Two U groove bearings are 4x13x6 sealed.

Suggestions are welcome.
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File Type: jpg diy-linear-arm1.jpg (48.9 KB, 545 views)

Last edited by super10018; 30th May 2014 at 02:11 AM.
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Old 30th May 2014, 04:12 AM   #1756
moray james is offline moray james  Canada
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Default two balls two bearings no carriage...

Quote:
Originally Posted by super10018 View Post
Two steel balls can be too much mass. It gets complicated and not diy friendly.
get a scale and weigh some bits and see. seems to me you just took simple and made it complex. just my observation. Best regards Moray James.
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Old 30th May 2014, 08:33 AM   #1757
bappe is offline bappe  Sweden
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Niffy

Yes, I was thinking of your design when i made the comment . I do think that your arm is no less than smashing and it may well be that it is better than the original Cantus. It is all about balancing different design parameters and you have chosen a different one and done a fantastic job. I do not know exactly how important this parameter is but the Cantus have lost weight and size from the first revision and each step has proved to be an improvement in performance.

Moray

A V-track is a possibility but i thought that just two simple, low friction tubes or rods was easier. A shallow half round track would also work but on my Cantus i have tried a few different bearings including flanged and others that will not rely on a sliding action for vertical movement of the arm. The plain bearing that slides has always come out on top. From a theoretical standpoint i think that the friction from sliding adds some damping at and below the arm resonance.

super10018

Sorry if i was a bit unclear, i linked to a page that showed steel balls (balls of steel...) but my text says ceramic balls. The ceramic balls will add very little weight, less than 1g for each bearing. I agree that the balls are not very DIY for most but they can easily be ordered from a number of sources i guess.


Some thoughts

The inspiration for this idea has come from this thread and i really like the solution with a plain bearing rolling between two parallel rods/tubes, it is simple and it does away with the cutting of the glass tube i.e. very DIY friendly. What bothered me a bit was the less then well defined bearing/tube contact point with most bearings, hence the ball .

BR,
Anders
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Old 30th May 2014, 08:37 AM   #1758
vynuhl.addict is offline vynuhl.addict  Canada
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Super,


As you get further through the thread the design changes alot. Namely going from a single tube 4 bearing to a 2 tube 2 bearing design with much thanks to pdr in his trials. To this day it has performed flawlessly and save for the odd swipe of the glass track with a dry qtip every two months or so it requires no maintenance .


Colin
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Old 30th May 2014, 01:13 PM   #1759
bappe is offline bappe  Sweden
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Default Some more models :)

Since the track will end up quite close to the record i thougt a swivel base could be a good idea.

I will have a chat with the prototype workshop at my daytime job on Monday

BR,
Anders

player.jpg

player2.jpg
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Old 30th May 2014, 01:56 PM   #1760
super10018 is offline super10018  United States
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Quote:
Sorry if i was a bit unclear, i linked to a page that showed steel balls (balls of steel...) but my text says ceramic balls. The ceramic balls will add very little weight, less than 1g for each bearing. I agree that the balls are not very DIY for most but they can easily be ordered from a number of sources i guess.
Sorry, it is my mistake.

It is clever idea to put the bearing inside the ball. However, it will be simpler to just make a ring to fit out racer of bearing. See the drawing.

In Colin’s approach, his system is 4 points supporting system. Yours is 4 point supporting system too. The improvement I can see is the contact area. Yours is better. However, since Colin’s approach allows slight tolerance between bearings and shims, I can’t see how much improvement is.

I also don’t see the point to use two glass tubes because it is still 4 points supporting system. Colin’s design is much simpler and more effective.

In my plan, it is 2 points supporting system. So is Clear Audio's.
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File Type: jpg ring.jpg (10.1 KB, 503 views)
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