Hi Carlo,
I tried multiple ways of dressing the cable with no success. The wires are dressed to the left so if they were causing this issue the they would be dragging the carriage to the left so CL would be offset to the right.
I'm going to add a wire ring from the back of the top cross bar to hold the wires.
I'll carefully go through each system, carriage, rail bearings and test each one. I must confess I am surprised I have this problem. I have a tonearm alignment rig that I use to set the arm up it uses an M4 bolt ground to a point with a small radius. With this on a blank record the carriage moves with the slightest touch and stops.
I tried multiple ways of dressing the cable with no success. The wires are dressed to the left so if they were causing this issue the they would be dragging the carriage to the left so CL would be offset to the right.
I'm going to add a wire ring from the back of the top cross bar to hold the wires.
I'll carefully go through each system, carriage, rail bearings and test each one. I must confess I am surprised I have this problem. I have a tonearm alignment rig that I use to set the arm up it uses an M4 bolt ground to a point with a small radius. With this on a blank record the carriage moves with the slightest touch and stops.
The cables often exert a resistance higher than that of the bearings (the good ones of course): therefore it is necessary to reduce their diameter beyond the limits of decency, and limit twisting as possible. On Lil Casey i came up to a double full loop around the rail which works really well. (by measures - LC has never had skipping, in normal conditions). The cable introduces variable springy stresses (if you balance it in the center it first pushes, and then pulls) - As I said several times it's not easy understandable how certain linear arms, or rotating heads, with plastic coated (!) wires can sound so wonderfully as claimed. Not to mention some pipes of the air bearings.
Imho the brush averages the stresses coming from many dozen of grooves (every bristle follows them as the cantilever does) and from the defects of the disc, clearly damping them. To do this it needs a significant amount of additional VTF. This represents a considerable help, sometimes decisive, to overcome the friction of the carriage of a linear one, which now is moved by the brush much more than by the cantilever, with a force many times higher. Unfortunately that the cantilever moves with respect to an elastic, "jelly" support instead than to the "rigid" mass of the arm, does not seem a convincing solution, almost never followed by anyone.
From the described behavior (excellent normally, but easily stumbling ) it seems like a stiction problem: in motion the friction is very low, but the start is problematic; which, with the loads generated by those micro tips is not surprising. Using very different materials, not self engaging, for the axle and the bush is probably indispensable.
carlo
Imho the brush averages the stresses coming from many dozen of grooves (every bristle follows them as the cantilever does) and from the defects of the disc, clearly damping them. To do this it needs a significant amount of additional VTF. This represents a considerable help, sometimes decisive, to overcome the friction of the carriage of a linear one, which now is moved by the brush much more than by the cantilever, with a force many times higher. Unfortunately that the cantilever moves with respect to an elastic, "jelly" support instead than to the "rigid" mass of the arm, does not seem a convincing solution, almost never followed by anyone.
From the described behavior (excellent normally, but easily stumbling ) it seems like a stiction problem: in motion the friction is very low, but the start is problematic; which, with the loads generated by those micro tips is not surprising. Using very different materials, not self engaging, for the axle and the bush is probably indispensable.
carlo
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Hi Carlo,
I am using the same wire as my current LT. It is cotton wrapped litz copper and quite floppy. It does need support to stop it hanging maybe it is pulling the back of the carriage down reducing VTF. I am going to add a hook to hold the wiring similar to what my current LT has.
Stanton/Pickering are famous for the brush, as you say it provides damping of both lateral and vertical cartridge movement. The Stanton requires 1gram additional for the brush and I mostly track with the brush at 1.75 to 2.00 grams.
I am using the same wire as my current LT. It is cotton wrapped litz copper and quite floppy. It does need support to stop it hanging maybe it is pulling the back of the carriage down reducing VTF. I am going to add a hook to hold the wiring similar to what my current LT has.
Stanton/Pickering are famous for the brush, as you say it provides damping of both lateral and vertical cartridge movement. The Stanton requires 1gram additional for the brush and I mostly track with the brush at 1.75 to 2.00 grams.
Found a couple of issues with the wheels.
1 - One pin was off centre. I think this happened when I machined them and turned it around in the collet.
2 The same wheel I found the carbide ring is oval by +-0.1mm
Add these 2 things together and it made miss tracking inevitable. I plan to remake the wheels this time I will make the rings from some 4140 high tensile steel I have at least this way I know they will be concentric.
Tracking is pretty good now and only the cable dressing causes it to miss track.
YouTube
Sound WOW. The first thing that is noticeable is reduced surface noise and reduction in clicks and pops on Boz Scaggs Middle Man. Then you notice the improvement in detail, the rattle of a snare and the ring of a bell.
I'll NEVER go back to a pivot arm after hearing this
1 - One pin was off centre. I think this happened when I machined them and turned it around in the collet.
2 The same wheel I found the carbide ring is oval by +-0.1mm
Add these 2 things together and it made miss tracking inevitable. I plan to remake the wheels this time I will make the rings from some 4140 high tensile steel I have at least this way I know they will be concentric.
Tracking is pretty good now and only the cable dressing causes it to miss track.
YouTube
Sound WOW. The first thing that is noticeable is reduced surface noise and reduction in clicks and pops on Boz Scaggs Middle Man. Then you notice the improvement in detail, the rattle of a snare and the ring of a bell.
I'll NEVER go back to a pivot arm after hearing this
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Hi Warrjon,
Excellent news on getting your arm to track.
My first attempt at making pin bearings failed because I couldn't get them concentric. I was lucky with my carbide rings as they were only 10um off circular. I made my wheels with a slightly oversized hole and an alignment jig to get them as accurate as possible. As you are planning on making wheels from steel you could experiment with different edge profiles. I did find that the carbide wheels gave notably lower rolling resistance and did sound better. It might be worth trying a different source for the rings.
Once you hear an arm with virtually no bending mode resonances you will NEVER go back to any other type of arm.
The reduction in surface noise is a very good sign. When the stylus hits a dust mote it produces a strong impulse. The majority of what you hear as a tick or pop is the arm resonating in response to this impulse. If you can't hear much surface noise it means that the arm isn't resonating. The same resonance is happening all the time (at a lower level) due to the modulation of the groove. This masks and veils the sound.
Niffy
Excellent news on getting your arm to track.
My first attempt at making pin bearings failed because I couldn't get them concentric. I was lucky with my carbide rings as they were only 10um off circular. I made my wheels with a slightly oversized hole and an alignment jig to get them as accurate as possible. As you are planning on making wheels from steel you could experiment with different edge profiles. I did find that the carbide wheels gave notably lower rolling resistance and did sound better. It might be worth trying a different source for the rings.
Once you hear an arm with virtually no bending mode resonances you will NEVER go back to any other type of arm.
The reduction in surface noise is a very good sign. When the stylus hits a dust mote it produces a strong impulse. The majority of what you hear as a tick or pop is the arm resonating in response to this impulse. If you can't hear much surface noise it means that the arm isn't resonating. The same resonance is happening all the time (at a lower level) due to the modulation of the groove. This masks and veils the sound.
Niffy
Hi Niffy,
Many thanks to you for sharing your design. I'm not big on reinventing the wheel so copying your carriage initially worked well. I think I might order a couple more carbide rings and see if I can get 2 good ones.
I am going to make a new carriage that fits the Stanton better, I currently have a 1.6mm spacer under the cartridge to lower the stylus.. The rail is too close to the record surface, I will lift it up another 2-3mm. If the record has a warp the stylus drags intermittently and at the end of the LP the rear of the arm touches the record surface when cued up. I don't have may records with warps but Stevie Wonder yesterday I had to stop the TT push the arm back 1/2 way then move the carriage back to the park position.
Many thanks to you for sharing your design. I'm not big on reinventing the wheel so copying your carriage initially worked well. I think I might order a couple more carbide rings and see if I can get 2 good ones.
I am going to make a new carriage that fits the Stanton better, I currently have a 1.6mm spacer under the cartridge to lower the stylus.. The rail is too close to the record surface, I will lift it up another 2-3mm. If the record has a warp the stylus drags intermittently and at the end of the LP the rear of the arm touches the record surface when cued up. I don't have may records with warps but Stevie Wonder yesterday I had to stop the TT push the arm back 1/2 way then move the carriage back to the park position.
Hi Warren, again congratulations for the superb realization, with a "Swiss watchmaker" level of precision.
Maybe the ideal for a perfect concentricity would be to turn between the centers a monolithic wheel, (pivots included). But for sure - apart from the difficulty - the same material would not be adequate both for wheel and pivot.
naive question: couldn't the carbide rings be rectified after they are mounted on the wheel? (running on their own pivots)
The improvements you are about to build will certainly make that residual bending on eccentricities disappear.
carlo
Maybe the ideal for a perfect concentricity would be to turn between the centers a monolithic wheel, (pivots included). But for sure - apart from the difficulty - the same material would not be adequate both for wheel and pivot.
naive question: couldn't the carbide rings be rectified after they are mounted on the wheel? (running on their own pivots)
The improvements you are about to build will certainly make that residual bending on eccentricities disappear.
carlo
Hi Carlo,
Only need to turn between centres for long shafts. My wheels are made in 1 piece aluminum with rings interference fit. I just used a test indicator to true up the rings when I turned them around before I ground the second pivot, this is how I know one ring is oval.
The rings could be ground concentric but I do not have a small diamond grinding wheel to true up the ring, so I might make a new set of wheels with rings made from high tensile steel. 4140 machines beautifully and comes off the tool shiny, it's not as hard a carbide but at least I can do this immediately. If I order new rings now they will get here in June.
I played a few LP's today and the miss tracking is still there. I marked the RH wheel and the miss tracking happens at the same point on the wheel, I have turned the wheel so it is at a different point on the rail but still miss tracks at the same wheel point. So the main issue is the out of round in the ring.
Only need to turn between centres for long shafts. My wheels are made in 1 piece aluminum with rings interference fit. I just used a test indicator to true up the rings when I turned them around before I ground the second pivot, this is how I know one ring is oval.
The rings could be ground concentric but I do not have a small diamond grinding wheel to true up the ring, so I might make a new set of wheels with rings made from high tensile steel. 4140 machines beautifully and comes off the tool shiny, it's not as hard a carbide but at least I can do this immediately. If I order new rings now they will get here in June.
I played a few LP's today and the miss tracking is still there. I marked the RH wheel and the miss tracking happens at the same point on the wheel, I have turned the wheel so it is at a different point on the rail but still miss tracks at the same wheel point. So the main issue is the out of round in the ring.
"Turning between centers" is said to be the best way to get no runout (oh, holy wisdom of our ancients - without our so comfortable chucks..) but I never use it because with small pieces you don't know where to put the dog. I just never remove the cantilevered part from the chuck till the end, and try to bore all the holes (even to 2 mm, with some small tools I made).
It's really strange that such a small runout can cause mistracking - the only effect should be to lift the carriage (slowly, during half a turn) a truly ridiculous acceleration. Imho there is a problem of matching between V cup and pivot. Using a material softer than the other (brass vs steel - steel vs sapphire) there is adaptation during the running-in (the harder machines the softer one), with the same material there is just reciprocal scratching (we are avoiding lubrication for known issues)
carlo
if i were you i would try to use the finest polishing powder inside the Vee and move the carriage by hand several times, then clean all and try again
It's really strange that such a small runout can cause mistracking - the only effect should be to lift the carriage (slowly, during half a turn) a truly ridiculous acceleration. Imho there is a problem of matching between V cup and pivot. Using a material softer than the other (brass vs steel - steel vs sapphire) there is adaptation during the running-in (the harder machines the softer one), with the same material there is just reciprocal scratching (we are avoiding lubrication for known issues)
carlo
if i were you i would try to use the finest polishing powder inside the Vee and move the carriage by hand several times, then clean all and try again
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Hi Carlo,
I am only making an assumption the oval ring is the issue as the miss tracking happens at the same point on the wheel. The stylus has to pull the carriage over the hump???
My Vee's and pins are polished with diamond paste to 1micron. I took a picture of the Vee and all I could see was the reflection of the camera. The problem is not the Vee. I have swapped the wheels from left to right and the problem follows the wheel. Vee's are high tensile M3 set screws that were forged with a HSS/cobalt pin at 90deg and pins are 1.5mm HSS drills cut off and 60deg vees ground on the tip.
Plan tomorrow is make a set of wheels for the Boca bearings and install them on the current carriage. If I make the rings 2.5mm wide with 4mm diameter rail rods should work.
I am only making an assumption the oval ring is the issue as the miss tracking happens at the same point on the wheel. The stylus has to pull the carriage over the hump???
My Vee's and pins are polished with diamond paste to 1micron. I took a picture of the Vee and all I could see was the reflection of the camera. The problem is not the Vee. I have swapped the wheels from left to right and the problem follows the wheel. Vee's are high tensile M3 set screws that were forged with a HSS/cobalt pin at 90deg and pins are 1.5mm HSS drills cut off and 60deg vees ground on the tip.
Plan tomorrow is make a set of wheels for the Boca bearings and install them on the current carriage. If I make the rings 2.5mm wide with 4mm diameter rail rods should work.
My hypothesis is that if there is a simple runout, the carriage has to lift and lower just by the same measure, i.e. very little and very slowly (1/2 turn = 4 times during the whole LP). If instead you think there is a "bump" on the ring, this is really a stumbling block.
My Vee's and pins are polished with diamond paste to 1micron.
yes, but each one alone, or pivots against the mating Vee?
Because if by itself, a minimal lack of roundness may increase the load during rotation and blocks everything - and always in the same point of the wheel, as you noticed
Between hss and screw steel probably the difference is too little - no sliding bearings are made that way
c
my mistake - before i said brass vs steel; i meant bronze vs steel, nobody manufactures brass bushings - a simple file shows the difference
My Vee's and pins are polished with diamond paste to 1micron.
yes, but each one alone, or pivots against the mating Vee?
Because if by itself, a minimal lack of roundness may increase the load during rotation and blocks everything - and always in the same point of the wheel, as you noticed
Between hss and screw steel probably the difference is too little - no sliding bearings are made that way
c
my mistake - before i said brass vs steel; i meant bronze vs steel, nobody manufactures brass bushings - a simple file shows the difference
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Hi Carlo, Warren,
Carlo said "a truly ridiculous acceleration". It is not the acceleration that is the problem. With an eccentric wheel the carriage has to rise and fall as the wheel rotates. This has exactly the same effect as if the rail was being tilted in the same way as your sine bar.
The steel wheels that I made were oval by about 1/20mm and still worked very well. Which makes me think that there might also be a problem with the pivots and/or the vees. What radius are the pivots and vees and what materials are they made of? Maybe try slightly increasing the end shake. Don't worry too much, it took me ages to get mine working as well as they do now. I'm sure you will get there.
One of the most important components of my arm is the record clamp. The arm was designed to be used with a warp flattening clamp. The carriage of my arm rides only 2.5mm above the record surface. Without the clamp a bad warp could easily hit the bottom of the carriage. As the effective length is only 55mm flattening of warps is essential to minimise warp wow and will reduce VTA variation. Try making a clamp rather than a new carriage.
Good luck
Niffy
Carlo said "a truly ridiculous acceleration". It is not the acceleration that is the problem. With an eccentric wheel the carriage has to rise and fall as the wheel rotates. This has exactly the same effect as if the rail was being tilted in the same way as your sine bar.
The steel wheels that I made were oval by about 1/20mm and still worked very well. Which makes me think that there might also be a problem with the pivots and/or the vees. What radius are the pivots and vees and what materials are they made of? Maybe try slightly increasing the end shake. Don't worry too much, it took me ages to get mine working as well as they do now. I'm sure you will get there.
One of the most important components of my arm is the record clamp. The arm was designed to be used with a warp flattening clamp. The carriage of my arm rides only 2.5mm above the record surface. Without the clamp a bad warp could easily hit the bottom of the carriage. As the effective length is only 55mm flattening of warps is essential to minimise warp wow and will reduce VTA variation. Try making a clamp rather than a new carriage.
Good luck
Niffy
Hi Niffy, I've called acceleration because the lifting and lowering of the carriage, due to the runout, sum - substract to that of gravity. Forgive me, what's the correct term - force? However - with the runout mentioned by Warren - probably a too small effect to induce mistracking, as your experience also shows.
I looked again at the video of the eccentricity, comparing it with the one of Lil Casey, posted long time ago. The movements of the stylus are more evident (almost invisible to the naked eye, on LC), which normally indicates a level of friction still too high. However that cartridge uses the brush, so I have no experience to judge.
c
I looked again at the video of the eccentricity, comparing it with the one of Lil Casey, posted long time ago. The movements of the stylus are more evident (almost invisible to the naked eye, on LC), which normally indicates a level of friction still too high. However that cartridge uses the brush, so I have no experience to judge.
c
Firstly I appreciate the input, sometimes one can not see the forest for the trees.
Pin radius is 0.125mm and pins are HSS 1.5mm drills
Vee radius is 0.25mm radius Only the bottom of the Vee is highly polished
I am thinking of a ring to hold the outside of the record flat. I just need to find a suitable material large enough so I can machine it.
I played Neil Diamond Stones today which is quite off centre. You could hear the distortion in left and right channels as the carriage traversed back and forth. So I have a few challenges to overcome. A perfectly flat on centre record sounds great.
Pin radius is 0.125mm and pins are HSS 1.5mm drills
Vee radius is 0.25mm radius Only the bottom of the Vee is highly polished
I am thinking of a ring to hold the outside of the record flat. I just need to find a suitable material large enough so I can machine it.
I played Neil Diamond Stones today which is quite off centre. You could hear the distortion in left and right channels as the carriage traversed back and forth. So I have a few challenges to overcome. A perfectly flat on centre record sounds great.
Attachments
First. Thanks Warren, for explaining more about linear tone arm I am considering this.
Using a bearing Thk lm stroke.model ST 10. 0.0008 friction coifficiant possible. I think with tweaks I can cut the friction by half.
Polished tungsten carbide rod
Similar to old Japanese diy linear tone arm.
Any foreseable problem?
Thank you in advance
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Hi Anthony,
From the 2 LTA I have built I would endeavor to make the arm wand as short and stiff as possible, it really does make a HUGE difference.
My first LTA used a 6mm OD carbon fibre tube I stuffed with balsa core. My 2nd is a copy of Niffys carriage which is extremely stiff. The difference is significant, although there are a lot of other changes.
From the 2 LTA I have built I would endeavor to make the arm wand as short and stiff as possible, it really does make a HUGE difference.
My first LTA used a 6mm OD carbon fibre tube I stuffed with balsa core. My 2nd is a copy of Niffys carriage which is extremely stiff. The difference is significant, although there are a lot of other changes.
I made a new set of wheels today using Boca ABEC9 hybrid bearings.
I have played LP's all afternoon 8 so far. The miss tracking has gone. I can still see the CL moving back and forth as the carriage tracks a significant off centre record but the Left and Right channel distortion is gone.
I can live with this now until I male a new carriage and re-fit the pin bearings
I have played LP's all afternoon 8 so far. The miss tracking has gone. I can still see the CL moving back and forth as the carriage tracks a significant off centre record but the Left and Right channel distortion is gone.
I can live with this now until I male a new carriage and re-fit the pin bearings
