Quote super10018, seems an overkill.
For me the first part of the game - after making the best possible passive linear tracking arm - is far beyond my skill
On my arm the only visible issue is the positioning on a track, because when the cart (+rail) is lifted, the cable moves it.
But I am interested instead in the theoretical problem: since we all are chasing the last milligram of friction of the carriage seems strange to ignore the cables mechanical action, which can bring more, and on both channels
carlo
For me the first part of the game - after making the best possible passive linear tracking arm - is far beyond my skill
On my arm the only visible issue is the positioning on a track, because when the cart (+rail) is lifted, the cable moves it.
But I am interested instead in the theoretical problem: since we all are chasing the last milligram of friction of the carriage seems strange to ignore the cables mechanical action, which can bring more, and on both channels
carlo
One of my friends just finished assembling the arm. A lot of trials ahead (including audiophiles listening expertise), but it is already functionally OK. Thanks for designing and sharing, Carlo.
wow
Bràvo! (in real Italian, with the accent on à, not on ò ) for the realization to anyone who has done it, and above all thanks to Walter&friends for the trust in my work and the courage to try such a risky road.
I believe that the strengths and weaknesses of the linear arms should be discussed from the beginning, without prejudices and factiousness: this was the objective of the "provocation" Lil Casey.
carlo
Now enjoy your new arm, considering for the future that the mk2 light version not only has better measurements but sounds also better, especially with warped discs -
If you want I will be glad to discuss with you the details in Diy private message, without boring this thread
Bràvo! (in real Italian, with the accent on à, not on ò ) for the realization to anyone who has done it, and above all thanks to Walter&friends for the trust in my work and the courage to try such a risky road.
I believe that the strengths and weaknesses of the linear arms should be discussed from the beginning, without prejudices and factiousness: this was the objective of the "provocation" Lil Casey.
carlo
Now enjoy your new arm, considering for the future that the mk2 light version not only has better measurements but sounds also better, especially with warped discs -
If you want I will be glad to discuss with you the details in Diy private message, without boring this thread
Last edited:
Carlo, thank you. The arm isn't my. Friend, who had made it, doesn't speak English. Anyway, if he will have any further questions, I can write and discuss with you.
For now, the arm together with turntable went to respectable audiophile home to undergo sonic expertise. By the way, the turntable on the picture was built by the same guy, named Eduard.
Second picture here taken in the Eduard's workshop.
For now, the arm together with turntable went to respectable audiophile home to undergo sonic expertise. By the way, the turntable on the picture was built by the same guy, named Eduard.
Second picture here taken in the Eduard's workshop.
Attachments
Congratulations to Eduard for the construction, and to you that surely have played a significant role.
I think there is little to say: well done guys. As you can see the main problem is the weight, every gram in the rail and levers differentiates the vert. mass more from the horizontal one, and that is no good, for me.
Then we have to deal with resonances, since the cut tube is prone to. With aluminum there was a clear improvement using delrin balls, the carbon one is instead completely quiet.
When I heard the Lil Casey playing the first time, it made me laugh: why no one in a hundred years has thought such a trivial idea? Was I the only human being listening to an arm like that, so simply effective? I am very pleased not to be alone anymore ...
carlo
May I doubt the golden ears? put behind a curtain two very different TT but with two identical cartridges , and let's see what happens -
I think there is little to say: well done guys. As you can see the main problem is the weight, every gram in the rail and levers differentiates the vert. mass more from the horizontal one, and that is no good, for me.
Then we have to deal with resonances, since the cut tube is prone to. With aluminum there was a clear improvement using delrin balls, the carbon one is instead completely quiet.
When I heard the Lil Casey playing the first time, it made me laugh: why no one in a hundred years has thought such a trivial idea? Was I the only human being listening to an arm like that, so simply effective? I am very pleased not to be alone anymore ...
carlo
May I doubt the golden ears? put behind a curtain two very different TT but with two identical cartridges , and let's see what happens -
Walter, I would be curious to know how Eduard built the carriage and the bearings, and how thick is the rail. His eccentric lifter is really nice and maybe I will copy it. With mine to raise the rail you have to lower the lever, which is counter intuitive.
Now some "trade - well a bit exaggerated - diyer's secrets".
Carriage - it is necessary to use spheres with a diameter that gives a support at 45 ° on the tube, that is centered with respect to those on the T: this way the rolling planes are parallel and the friction at minimum
Resonances of the rail are silenced with a strip of self-adhesive velvet in the inner upper part (same for plugs contact)
Pentips are inserted in a small tube and separated by 1-2 mm of O-ring chord (very elastic and durable). This ensures that the pressure is uniform and easily adjustable
Cables are grounded with a spiral of the same wire around only before the loop, for flexure issues (a bigger loop may be better)
Anti tilting CW adjustment must be get with dynamic checks, and is related to the VTF - the new smaller rail (12mm), provides a better self centering - the most favorable position found was with the radius aligned in the middle of the cantilever = 2 mm overhang. Variations in stylus drag during play bring no visible motion, but if someone made poltruded doublevee profiles ....
The rest was already said it in the old posts and drawings, and you've interpreted it beautifully.
carlo
beautiful TT too
Now some "trade - well a bit exaggerated - diyer's secrets".
Carriage - it is necessary to use spheres with a diameter that gives a support at 45 ° on the tube, that is centered with respect to those on the T: this way the rolling planes are parallel and the friction at minimum
Resonances of the rail are silenced with a strip of self-adhesive velvet in the inner upper part (same for plugs contact)
Pentips are inserted in a small tube and separated by 1-2 mm of O-ring chord (very elastic and durable). This ensures that the pressure is uniform and easily adjustable
Cables are grounded with a spiral of the same wire around only before the loop, for flexure issues (a bigger loop may be better)
Anti tilting CW adjustment must be get with dynamic checks, and is related to the VTF - the new smaller rail (12mm), provides a better self centering - the most favorable position found was with the radius aligned in the middle of the cantilever = 2 mm overhang. Variations in stylus drag during play bring no visible motion, but if someone made poltruded doublevee profiles ....
The rest was already said it in the old posts and drawings, and you've interpreted it beautifully.
carlo
beautiful TT too
Last edited:
Carbon tube - try on Amazon or model shops; here in Florence i go to a retailer of kites and spares.
2 mm thick aluminum is too heavy (knowable from the CW size); on my mk1 was 1mm and was too much too - reduced to 0,4 mm on lathe brought to bad resonances.
Bearings: 8 or 4?
Before audiophile's verdict, what are Eduard's and your first impressions? The first impact is more significant than the opinion after getting used, imho.
carlo
2 mm thick aluminum is too heavy (knowable from the CW size); on my mk1 was 1mm and was too much too - reduced to 0,4 mm on lathe brought to bad resonances.
Bearings: 8 or 4?
Before audiophile's verdict, what are Eduard's and your first impressions? The first impact is more significant than the opinion after getting used, imho.
carlo
On my Mk1 there were 8 too, but 4 ball bearings may be easily enough, and maybe even better than pen tips.
If the prototype makes you think -like me- to go ahead, here are some ideas for the carriage tilting problem, avoiding the small CW and its boring set up.
The solution at the bottom is very simple, just replacing the balls with 2 turned bicones. But first we should find a 12x1 square carbon profile, that seems unavailable.
Have fun - carlo
If the prototype makes you think -like me- to go ahead, here are some ideas for the carriage tilting problem, avoiding the small CW and its boring set up.
The solution at the bottom is very simple, just replacing the balls with 2 turned bicones. But first we should find a 12x1 square carbon profile, that seems unavailable.
Have fun - carlo
Attachments
+1 on the clever idea. The tips of the cones and their bases will travel the same distance but their diameter will be different which means that there must be a certain amount of sliding taking place for the cones to roll. This will result in greater friction than balls. I had great success using items originally designed as jewellery in my arm, the rings I used for my wheels. Have a look at titanium body piercing jewellery. You can get a whole range of cones. Most seem to have a tip angle of 55-60° but some are available with more obtuse tips if you look hard. They are internally threaded so two can be screwed together back to back. I don't know how accurately they are made, the rings I purchased where very accurate. Being made of titanium they will be light and hard, both desirable properties.
From your drawings I think the second down on the right looks the best option. It will be heavier than the cones but also much more stable and lower friction.
Niffy
From your drawings I think the second down on the right looks the best option. It will be heavier than the cones but also much more stable and lower friction.
Niffy
Thx Super, thx Niffy: clever? hopefully - more friction? hopefully not.
In a non recirculating bearing there is no motion of the balls surface relative to rails (then no sliding): in the actual solution every ball has 3 contact points (x4 balls): with the bi-cones 4 contact lines (x 2 bicones). Unfortunately the bicones must be turned precisely with 45°+45° to sit perfectly on the upper and lower V profiles - this ensure no possible tilting (and no chattering). Being of 4mm diam. weight doesn't care - brass or inox will be ok
The non recirculating bearing is far different from wheels, since there are no axes issues (in doubt ask Egyptians for moving their pyramids)
The sol. 3 is the most used for recirculating bearings. in this case maybe better the sol. 2 (better distributed weight) but the rail could be heavy and/or flexible = to avoid.
For now i will not test these solutions. The actual is plainly working: once set up the CW for that cartridge there no need of further interventions. No problem if you don't sell tonearms.
It was just the last aspect still to investigate and tweak
carlo
In a non recirculating bearing there is no motion of the balls surface relative to rails (then no sliding): in the actual solution every ball has 3 contact points (x4 balls): with the bi-cones 4 contact lines (x 2 bicones). Unfortunately the bicones must be turned precisely with 45°+45° to sit perfectly on the upper and lower V profiles - this ensure no possible tilting (and no chattering). Being of 4mm diam. weight doesn't care - brass or inox will be ok
The non recirculating bearing is far different from wheels, since there are no axes issues (in doubt ask Egyptians for moving their pyramids)
The sol. 3 is the most used for recirculating bearings. in this case maybe better the sol. 2 (better distributed weight) but the rail could be heavy and/or flexible = to avoid.
For now i will not test these solutions. The actual is plainly working: once set up the CW for that cartridge there no need of further interventions. No problem if you don't sell tonearms.
It was just the last aspect still to investigate and tweak
carlo
Carlo, I've got brief impressions from Eduard's listening session in really advanced and expensive audiophile setup. Together with Mc cartridge your arm sonically outperformed everything they heard before. Big surprise, because they have a lot of experience with different components, including very advanced and expensive ones.
I hope to participate in listening pretty soon, and make up my own opinion.
Walter
I hope to participate in listening pretty soon, and make up my own opinion.
Walter
Last edited:
Great news Walter, thanks a lot. Hope that also Eduard will be satisfied with his great work.
Even if - like I said - my goal is to make arms that sound the same as my references; if instead they sound different (better or worse to my ears) there something to worry about. It is easy to fall in love with new things, especially our creatures.
However the Lil Casey, especially the carbon one sounds good, very clean. If you reduce the weight it will sound good even with high compliance cartridges, which was a difficult task.
Maybe bypassing the issue of wand's negative lever is useful for something.
Niffy - explaining better - it is clear that the peripheral speed on a cone is variable, if I had a 1 m wheel I would worry: but here there is a 4mm element, a load of 7-8 grams and a speed of 20 cm/h, and there is the chance to reduce the conical surface to the minimum necessary to avoid every possible tilting
My point of view is practical, the real problem is that there are no poltruded profiles like the rail for solution 3, nor even a simple square > 8 mm
carlo
Even if - like I said - my goal is to make arms that sound the same as my references; if instead they sound different (better or worse to my ears) there something to worry about. It is easy to fall in love with new things, especially our creatures.
However the Lil Casey, especially the carbon one sounds good, very clean. If you reduce the weight it will sound good even with high compliance cartridges, which was a difficult task.
Maybe bypassing the issue of wand's negative lever is useful for something.
Niffy - explaining better - it is clear that the peripheral speed on a cone is variable, if I had a 1 m wheel I would worry: but here there is a 4mm element, a load of 7-8 grams and a speed of 20 cm/h, and there is the chance to reduce the conical surface to the minimum necessary to avoid every possible tilting
My point of view is practical, the real problem is that there are no poltruded profiles like the rail for solution 3, nor even a simple square > 8 mm
carlo
Last edited:
Hi Carlo,
When I suggested using body piercing jewellery cones for making the double cone rollers I was aware that getting a carbon fibre profile to exactly match the angle would be impossible. Even 90° L-section of the size you require doesn't seem to be available. You can however get flat strips in numerous sizes, from 0.5mm thick and 3mm wide. With a bit of care you could make a gluing jig that would allow you to make your own L-section out of a couple of strips. Most carbon fibre strips are made with unidirectional fibres in an epoxy matrix. Gluing two of these strips edge to edge with epoxy glue can result in an L-section pretty much as good as if it were extruded in that form originally (especially if you cure the glue in your oven). You also have the advantage with this method of being able to make the L any angle you desire so it could match the jewellery cones.
Somewhere in my scraps bin I have some 0.2mm woven carbon sheet. Laminating a material like this with balsa wood can make a very light yet rigid structure. This could be used to make a support structure for the L-section.
Niffy
When I suggested using body piercing jewellery cones for making the double cone rollers I was aware that getting a carbon fibre profile to exactly match the angle would be impossible. Even 90° L-section of the size you require doesn't seem to be available. You can however get flat strips in numerous sizes, from 0.5mm thick and 3mm wide. With a bit of care you could make a gluing jig that would allow you to make your own L-section out of a couple of strips. Most carbon fibre strips are made with unidirectional fibres in an epoxy matrix. Gluing two of these strips edge to edge with epoxy glue can result in an L-section pretty much as good as if it were extruded in that form originally (especially if you cure the glue in your oven). You also have the advantage with this method of being able to make the L any angle you desire so it could match the jewellery cones.
Somewhere in my scraps bin I have some 0.2mm woven carbon sheet. Laminating a material like this with balsa wood can make a very light yet rigid structure. This could be used to make a support structure for the L-section.
Niffy
Thanks for tips, Niffy - it's more or less the way I was thinking - you'll notice that all the solutions, except the last two, are assembled with L profiles cut from squares (available up to 8x8), since we need an exact angle, a perfectly straight profile and a great finish. Poltruded profiles are much worse than arrows: not only heavier and less sturdy but with more glass than carbon inside (eastern products...)
Would it be possible** to build a light rail wrapping the carbon fabric around an internal removable core, with the necessary precision and finish?
Making the bicones on the lathe asks only some attention in setting the cutting angles.
Those ideas were sketched for those willing to replicate the Lil Casey by trying another step forward. For now the current one seem really ok to me, comforted also by the results obtained by Eduard and Walter.
Carlo
**balsa wood: when i was a teen i build indoor flying models (less than 2 g!);if I had now those surgeon's hands...
Would it be possible** to build a light rail wrapping the carbon fabric around an internal removable core, with the necessary precision and finish?
Making the bicones on the lathe asks only some attention in setting the cutting angles.
Those ideas were sketched for those willing to replicate the Lil Casey by trying another step forward. For now the current one seem really ok to me, comforted also by the results obtained by Eduard and Walter.
Carlo
**balsa wood: when i was a teen i build indoor flying models (less than 2 g!);if I had now those surgeon's hands...
Last edited: