Hi walterwalter,
Indeed the measurement deck can have a small platter. It only needs to be a bit bigger than the label, I was thinking 5-6". I wasn't necessarily even planning on having it motorised. I was thinking that it might be hand cranked, although a gear-reduction motor, PWM motor controller and direction changeover switch might be more ergonomic. That way I can rotate the platter back and forth to find the exact direction of the eccentricity.
Whether I use mechanical linkages or a reflected laser to measure the magnitude of the eccentricity would require a bit more thought.
Niffy
Indeed the measurement deck can have a small platter. It only needs to be a bit bigger than the label, I was thinking 5-6". I wasn't necessarily even planning on having it motorised. I was thinking that it might be hand cranked, although a gear-reduction motor, PWM motor controller and direction changeover switch might be more ergonomic. That way I can rotate the platter back and forth to find the exact direction of the eccentricity.
Whether I use mechanical linkages or a reflected laser to measure the magnitude of the eccentricity would require a bit more thought.
Niffy
Hi Niffy
Probably posted somewhere else before:
YouTube
Or
Vinyl Turntable Equipment: Centring records
Best
Coolerooney
Probably posted somewhere else before:
YouTube
Or
Vinyl Turntable Equipment: Centring records
Best
Coolerooney
Hi Kolby
Back in #2692 I posted "The eccentricity of side A will not necessarily be the same as for side B for any particular record. Some records appear to be perfectly centred playing one side then the cartridge dances back and forth playing the other. Unfortunately you can't centre both sides of a record by modifying the hole."
One of the reasons for eccentricity is the stampers not being perfectly aligned with each other.
Many record collectors would baulk at the idea of even putting a sticker on the label of their beloved vinyl. Even if it could perfectly centre a record I think even I would draw the line at drilling holes in my records.
Niffy
Back in #2692 I posted "The eccentricity of side A will not necessarily be the same as for side B for any particular record. Some records appear to be perfectly centred playing one side then the cartridge dances back and forth playing the other. Unfortunately you can't centre both sides of a record by modifying the hole."
One of the reasons for eccentricity is the stampers not being perfectly aligned with each other.
Many record collectors would baulk at the idea of even putting a sticker on the label of their beloved vinyl. Even if it could perfectly centre a record I think even I would draw the line at drilling holes in my records.
Niffy
Great, except for the part about drilling a whacking great hole through all your records. The laser system is very similar to what I was thinking of.
Niffy
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Sacrifices, sacrifices. 😀😀😀😀
Btw, Igus has very small clips dry bearings, specially for thin metal- or similar- to reinstate the 7 mm hole, (you would need to ream it 0,24mm )
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LOL Didn't realize that and didn't read that post .
Solution?
Buy two examples of each record and punch different holes in them, one for side A and one for side B....
😎 
Hi Coolerooney,
The non-concentric rings in the link you posted could be adapted for the adjustment part of my clamp idea. I think my adjustable clamp idea has the edge simply due to ease of operation. Having to get the drill press out every time I buy a record isn't particularly user friendly.
Niffy
The non-concentric rings in the link you posted could be adapted for the adjustment part of my clamp idea. I think my adjustable clamp idea has the edge simply due to ease of operation. Having to get the drill press out every time I buy a record isn't particularly user friendly.
Niffy
Hi Niffy
On the eccentricity bit:
Is it correct you csn only adjust for the X axis
When the Y is adjusted, then you are compromising the stylus position
Can the hole be centered, but the grooves off center?
Best
Coolerooney
On the eccentricity bit:
Is it correct you csn only adjust for the X axis
When the Y is adjusted, then you are compromising the stylus position
Can the hole be centered, but the grooves off center?
Best
Coolerooney
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If you are referring to the non-concentric rings from the link then both rings have to be rotated to centre the record. This will make adjustment quite fiddliy.
Can the hole be centered, but the grooves off center?
This is the definition of eccentricity.
Niffy
No. In my design I don't have to change the size of the hole or move the platter.
Instead of having to spindle sticking up from the centre of the platter I have it sticking down from the clamp. The only thing that moves in my design is this downwards facing spindle. No modification of the record required and the platter remains balanced.
Niffy
Really an excellent idea,Niffy, finally thought in a correct way. (and comfortable too)
I am impatient to understand how the spindle of the centering device will be connected to that of the platter (hollow?). Because it is clear that it must be in mechanical continuity (resonances)
carlo
A - B sides center misalignment - no surprise: the guide hole is always drilled into the master at the end of the process, and separately: so how could be both (or even one) perfectly centered?
Preparation of stampers GZ Vinyl
I am impatient to understand how the spindle of the centering device will be connected to that of the platter (hollow?). Because it is clear that it must be in mechanical continuity (resonances)
carlo
A - B sides center misalignment - no surprise: the guide hole is always drilled into the master at the end of the process, and separately: so how could be both (or even one) perfectly centered?
Preparation of stampers GZ Vinyl
Hi Carlo,
At the centre of the platter is a 4mm diameter post. This will probably be about 30mm tall with a short threaded section at the top. This is like a skinny spindle. The actual spindle protrudes from the bottom of the clamp. This will be hollow with an inside diameter of 5.5mm. This will allow the spindle to be moved relative to the post by up to 0.75mm. It is this movement that is used to centre the record. The upper part of the clamp rotates independently of the lower part (that houses the movable spindle) and is internally threaded to take the threaded end of the post that protrudes from the platter. In this way it is a conventional screwdown clamp that presses the record firmly onto the platter.
As with my current screwdown clamp I would have a slight bulge in the centre of the platter that forces the edge of the record down as the clamp is tightened (Reflex clamp). This is very effective at flattening warps.
In combination this design of clamp will simultaneously flatten and centralise the record.
Niffy
Hi Niffy, I imagined that the centering device was based on eccentricities. and what you say is really convincing.
Among other things. a clamp, unlike monster weights, is a clever solution. I've been building a turntable for too much time, never being able to build a spindle bearing with satisfying tolerances (I'm a fundamentalist, for me diy must be done from scrap, not assembling).
I started to build a platter with a small taper, so that the clamp would force the disc on the outer edge. Tests were good.
But I'm lazy when listening, and so I just try to store well the discs, avoiding warps as possible
Tx Coolerooney: may work, but how to impede the balls to go everywhere, or outside?
carlo
Among other things. a clamp, unlike monster weights, is a clever solution. I've been building a turntable for too much time, never being able to build a spindle bearing with satisfying tolerances (I'm a fundamentalist, for me diy must be done from scrap, not assembling).
I started to build a platter with a small taper, so that the clamp would force the disc on the outer edge. Tests were good.
But I'm lazy when listening, and so I just try to store well the discs, avoiding warps as possible
Tx Coolerooney: may work, but how to impede the balls to go everywhere, or outside?
carlo
Hi Carlo
The slight curve keeps it in check
The bigger the radius, the better= less friction
Best
Coolerooney
The slight curve keeps it in check
The bigger the radius, the better= less friction
Best
Coolerooney
Hi Carlo,
I'm completely with you on wanting to build everything yourself. Apart from the cartridge and motor I built my entire deck from scratch. It took over six years to complete including the design stage and all the testing and measuring. Although it is completely off topic for this thread I did build my own main bearing without the use of fancy lathes or milling machines. The bearing is ultra low noise, self centering, has excellent mechanical grounding and only disipates just over a milliwatt (a typical bearing disipates over a hundred milliwatts). I did spend a lot more time building rigs, jigs and testing than I did actually building the bearing itself. The main component of the bearing was hand forged from a cobalt drill bit which was also heat treated. It has been in the deck for 6 or 7 years without any sign of wear. As you seem to be an expert at thinking outside of the box I'm sure you'll find a solution.
Niffy
I'm completely with you on wanting to build everything yourself. Apart from the cartridge and motor I built my entire deck from scratch. It took over six years to complete including the design stage and all the testing and measuring. Although it is completely off topic for this thread I did build my own main bearing without the use of fancy lathes or milling machines. The bearing is ultra low noise, self centering, has excellent mechanical grounding and only disipates just over a milliwatt (a typical bearing disipates over a hundred milliwatts). I did spend a lot more time building rigs, jigs and testing than I did actually building the bearing itself. The main component of the bearing was hand forged from a cobalt drill bit which was also heat treated. It has been in the deck for 6 or 7 years without any sign of wear. As you seem to be an expert at thinking outside of the box I'm sure you'll find a solution.
Niffy
Sorry Coolerooney, I have trouble understanding the CAD, not noticing the small concavity (studied using the slide rule, il tecnigrafo (drafting table?) and Cartesian projections).
Your solution is perfect if the load is only longitudinal, but unfortunately the situation is more complicated, we are also trying to counter act the lateral load of the stylus drag. (Attachment)
In my solution the load N (10.6 gr) is constant, and to rotate laterally the spheres should rub against three points. In yours under side load N may vary from 7,5 to 57.4 gr, and no friction prevents it from sliding sideways.
Then there a bigger problem to overcome, owning just a cheap minilathe: to make such guides are needed an excellent mill and a linear surface grinder, and more to be able to use them well.
NIffy - TT spindle - i've tried several, starting from a VPI like (I love the mouse-trap tech, the famous round rod in a square bushing) = wobble - And others with various couplings, up to the ancient method used for watchmaker lathes spindles: hard steel, undersized bronze bushing, sledge hammer. Always getting more noise than in my old Lux, heavily modded of course. I will end up buying a lapped rod and a sintered bushing. (what a shame!)
I've seen some photos of your spectacular turntable, and it's incredible to think that it's done with just a few tools. Unbelievable for all those hi-tech lovers who ignore that lathes and mills that produce those CNC machines still need cast iron sliding surfaces hand scraped by someone who knows his trade.
carlo
Your solution is perfect if the load is only longitudinal, but unfortunately the situation is more complicated, we are also trying to counter act the lateral load of the stylus drag. (Attachment)
In my solution the load N (10.6 gr) is constant, and to rotate laterally the spheres should rub against three points. In yours under side load N may vary from 7,5 to 57.4 gr, and no friction prevents it from sliding sideways.
Then there a bigger problem to overcome, owning just a cheap minilathe: to make such guides are needed an excellent mill and a linear surface grinder, and more to be able to use them well.
NIffy - TT spindle - i've tried several, starting from a VPI like (I love the mouse-trap tech, the famous round rod in a square bushing) = wobble - And others with various couplings, up to the ancient method used for watchmaker lathes spindles: hard steel, undersized bronze bushing, sledge hammer. Always getting more noise than in my old Lux, heavily modded of course. I will end up buying a lapped rod and a sintered bushing. (what a shame!)
I've seen some photos of your spectacular turntable, and it's incredible to think that it's done with just a few tools. Unbelievable for all those hi-tech lovers who ignore that lathes and mills that produce those CNC machines still need cast iron sliding surfaces hand scraped by someone who knows his trade.
carlo
Attachments
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