My Linear Tracker (a new variation perhaps?)

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hello everyone,

I´ve been using this arm for a year now and I´m very happy with it, the main design goal was simplicity and overall low mass horizontal and vertical, I wanted to eliminate the use of air bearing with the corresponding air pump, after a lot of tinkering with different carriage designs like magnetic, hydraulic... ball bearing is in my opinion the more elegant approach for a linear tracker and I finally got to a design that gave me what I was looking for.

the arm is clearly based on the concepts used in the engineering masterpiece the "Opus Cantus" and the "Souther" at first I was going for a copy of those designs but I thought it could be made more simple and this is the result:

b3PqeJp.jpg


as can be seen the whole carriage and arm becomes a type of "linear ball bearing" this is an illustration of the basic concept ( "thrust ball bearing")

mAyD6TW.jpg


all the rods are from a normal telescopic tv antenna:

riGcGnF.jpg


surprisingly this rods work very well, they are smooth, easy to work and they are everywhere!!! I did try glass rods and it also worked but I could not find them with an adequate diameter so the carriage was bulky and I ended up using the antenna rod.

as can be seen the ball is placed in the middle channel formed by the two circular rods put side by side, the contact points are four per each ball :

6L1daoV.jpg


side view with the contact points:

Ku21Sep.jpg


as you could imagine while traveling the disc from start to finish the two balls change position in relation to the upper carriage this might seem like a mayor problem limiting the arm range but in practice is not even a concern :

2M94YW3.jpg


q4zzWS9.jpg


(please don´t mind the cables, I was doing some tests for mono connection)
the movement of the arm is very smooth and free from malicious drag, it goes very well with high compliance carts.
 
This looks very intriguing! Do the ball bearing maintain a constant distance relative to each other as the top carriage moves along? It seems from your description that they don't. If they don't, I'm assuming you have to re-position them with every side played?
Regards
Chris
 
This looks very intriguing! Do the ball bearing maintain a constant distance relative to each other as the top carriage moves along? It seems from your description that they don't. If they don't, I'm assuming you have to re-position them with every side played?
Regards
Chris
they keep the same distance to each other during play, there is no need to repositioning them for every side of the disc.
Hi,
the underlying principle behind this kind of bearing has been granted a Patent to D.Mankovitz in 1961 under license number US3,006,652
The patent describes a more complicated ball-track member though.

jauu
Calvin
EXCELENT!!!, yes it seems to be the same principle, I think is not much more complicated but it seems very bulky and a lot heavier , aesthetically I imagine something like a RABCO.
any real pictures of this design? seems that it never went into production a quick search only direct me to another post on this forum by moray james pointing out the patent
http://www.diyaudio.com/forums/anal...ntus-parallel-tracking-arm-6.html#post2162673

funny who everything goes around, I was reverse engineering the Opus Cantus while imagining my arm, this type of design should be more known, my own experience with this principle is brilliant.

Clever.
There are the issues of the flatness of the rods, and the added moving mass of the double rods that move with the arm...
_-_-
I´m surprise with this rods and the application, the rods are really smooth, flatness is very good and they are very light the major part of the whole weight is compose of the cartridge itself and the counter weight, this type of antenna are ubiquitous and cheap, I was thinking in a more "professional" or expensive material but there's no need , surprisingly everything works fine as it is.
 
That's fascinating! I'm assuming that the two rods (both top and bottom) are 'glued' together and that the clips attached to the top rail don't touch the bottom rail but help stop it falling off. Are these assumptions correct? Also-what size ball do you use-5mm?
Thanks
Chris
 
That's fascinating! I'm assuming that the two rods (both top and bottom) are 'glued' together and that the clips attached to the top rail don't touch the bottom rail but help stop it falling off. Are these assumptions correct? Also-what size ball do you use-5mm?
Thanks
Chris

exactly! your assumptions are correct.
I only added the "clips" for safety or precaution in case I mishandle the carriage it doesn't fall apart. the clips don't do anything in normal operation.
yes the ball is around 4 mm.
 
Hi Soyuz
Congrats with a simple and capable design. I have used a similar (almost identical) arm for the last 3 years, and it have behaved flawlessly. At the moment I am making some small adjustments, because I want to reduse the amount of dust and other airborn debrie, that settles on the rails and balls. In my new version the four rails are 3mm. carbon tubes, and the balls are Rega size ceramic types. Have you had any problems with dust?
Steen
 
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Hi Soyuz
Congrats with a simple and capable design. I have used a similar (almost identical) arm for the last 3 years, and it have behaved flawlessly. At the moment I am making some small adjustments, because I want to reduse the amount of dust and other airborn debrie, that settles on the rails and balls. In my new version the four rails are 3mm. carbon tubes, and the balls are Rega size ceramic types. Have you had any problems with dust?
Steen
I'm not having problems with dust at least not to worry me, in general I use a Q-tip and is ready to go (once every 4 or 5 days something like that )

yep, lots of materials to try and play with...
I wanted to try polymer or nylon for the ball but never got to it, I also want to try a wooden wand in the future, I'm planning on getting a test record to take critical measurements for the different materials but right now I´m just enjoying the arm as it is

this type of design is proving to be worthy of consideration.
 
....I´ve been using this arm for a year now and I´m very happy with it, the main design goal was simplicity and overall low mass horizontal and vertical, I wanted to eliminate the use of air bearing with the corresponding air pump, after a lot of tinkering with different carriage designs like magnetic, hydraulic... ball bearing is in my opinion the more elegant approach for a linear tracker and I finally got to a design that gave me what I was looking for. ....

Hy Soyuz.
Congrats with your first "linear tracker" embryo.
Chapeau bas ... hoedje af .

FYI.
I sent you a copy-scan from my old archive "Radio Bulletin " (Dutch) anno 1960 apr. page 308 (fig 99) with a brief description (& fig) with the same concept. The ref. name (probably diy constructor) Mr Percy WILSON ....
I hope to see soon your "end" model (& not the last, I presume)....
Do it.
Allez, salukes.
Karel
 
I sent you a copy-scan from my old archive "Radio Bulletin " (Dutch) anno 1960 apr. page 308 (fig 99) with a brief description (& fig) with the same concept. The ref. name (probably diy constructor) Mr Percy WILSON ....
I hope to see soon your "end" model (& not the last, I presume)....
Do it.
Allez, salukes.
Karel
once again thank you very much Karel for the scans, a very beautiful and interesting design.

compilation of "side view" diagrams:
Percy Wilson
zkGuVIf.png


3WjYIbL.png


The arm I'm currently using:
VeNn4ZP.png


Mankowitz (the arm is tilted, this image is a more clear representation ):
DQWwqmt.png
 
Hello Arch-agreed-as long as in practice they don't slip or stick. The elegant simplicity appeals to me.
Chris

Hi Chris,
A few days ago I took my four 10mm tubes, taped them together in 2 pairs, placed them on a level surface with two 4mm balls between them and just played with them for a short time. Was amazed by the lack of friction in both horizontal and vertical planes. The freedom of vertical motion could wind up being detrimental ????. Have had a sudden increase of activity in my clock shop so have not built a functioning arm yet, but it isn't far away. Getting rid of all those balls and races certainly is attractive.
Rgds,
BillG
 
Hello Arch-agreed-as long as in practice they don't slip or stick. The elegant simplicity appeals to me.
Chris

As I said in a previous post, I have had this design up and running for almost 3 years without any misbehaving. Only reason for redesigning, is the wish to make it less exposed to dust, and getting the balls closer to the record surface. This will implement some sort of sliding arrangement to move the carrige out of the way, in order to change records. Spring is on its way here in snowy Norway, so this may have to wait til october:eek:
Steen
 
Hi Everyone
I've got all the parts lying around and did a similar thing to Bill with two alu tubes. Sure enough, the lack of friction was incredible. I don't think there will be an issue on the vertical plane as long as the rods are well secured and horizontal. I believe it's a couple of hours work so I should have something up and running well before Easter.
Chris
 
Hi,

I also wondered about the vertical friction maybe beeing too high to allow the cart to track warps properly.
If that is the case than a slight modification might solve the issue.
If one looks at the crossectional drawings 1 and 3 in #11 it is obvious that each ball contacts the lower and the upper 'rail' in two points each.
A tiliting of the cartridge beam in vertical direction opposed by the friction between the ball and the upper 'rail'.
If the upper 'rail' is made from a curved track instead of two rods, a cartridge beam attached to the curved track could tilt nearly frictionless, as the ball and the 'rail' would contact in only one point.
The curved track could be a section cut from a tube with a diameter a bit larger than the ball's.
It could also be a complete tube like in drawing 1 the 'upper carriage' but without the W-shaped part named 'Slede met V-Groef'.

jauu
Calvin

p.s just in case the idea would be new and would hold enough invention depth to grant a patent, this is now known art and open source to anybody :D
 
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Hi Calvin

this is now known art and open source to anybody :D

That is true for Europe but not for the United States. In the US, one is allowed a one year grace period after making an invention public. Aside from that, I don't think the idea is patentable because the drawers in file cabinets have been operating that way for decades.

That does not mean that this idea wouldn't make a great tone arm.

Sincerely,

Ralf
 
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