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Re: Iteration is not required to find turns count


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6/4/2005 6:44 PM
Dr. Strangelove
Re: Iteration is not required to find turns count
Joe Gwinn wrote:
quote:
"And these inflated wires (1.62*nominal) are in a lattice of square cells? If so, the area fill factor is (1.62*d)^2/(Pi(d/2)^2)= 0.2993= 30% (assuming a perfect square lattice)."
Fat coil, yes? With all that air space, adjacent windings don't couple as well as with an orthocyclic wind.  
 
[RE: beveled blade edges]  
quote:
"Was the bevel done with a mill file, or with a grinder? Even with files, one can leave burrs that often cannot be seen, but can be felt, and will do a number on #43 wire. Grinders are worse."
I can't tell, but would imagine a grinder followed by some kind of smoothing (wire wheel, sand paper, etc.).  
quote:
"My instinct is that for reliable blade pickups, the blade core must be both radiused with a grinder and file, and then taped so that minor burrs cannot hurt the inner windings."
Polished radiused edges would also work assuming they weren't too time consuming.  
 
You need to remember that these pickups were sold on the merit of being refined to Danny Gatton's taste over a 10 year period. If taped edges had been acceptable to Mr. Gatton, then Barden would have taped them.  
 
The low fill factor suggests low winding tension used to avoid cutting the wire.  
 
-drh  
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6/5/2005 7:58 AM
Joe Gwinn

On 6/5/2005 12:44 AM, Dr. Strangelove said:  
quote:
"Joe Gwinn wrote: "And these inflated wires (1.62*nominal) are in a lattice of square cells? If so, the area fill factor is (1.62*d)^2/(Pi(d/2)^2)= 0.2993= 30% (assuming a perfect square lattice)." Fat coil, yes?"
Square lattice, yes?  
 
quote:
"With all that air space, adjacent windings don't couple as well as with an orthocyclic wind. "
True, but not clear how important it is.  

 
[QUOTE][RE: beveled blade edges]  
"Was the bevel done with a mill file, or with a grinder? Even with files, one can leave burrs that often cannot be seen, but can be felt, and will do a number on #43 wire. Grinders are worse." I can't tell, but would imagine a grinder followed by some kind of smoothing (wire wheel, sand paper, etc.).[/QUOTE]OK.  
 
quote:
""My instinct is that for reliable blade pickups, the blade core must be both radiused with a grinder and file, and then taped so that minor burrs cannot hurt the inner windings." Polished radiused edges would also work assuming they weren't too time consuming."
Yes, but polishing tends to be slow. The quickest way is probably a grinder with a rubberized adhesive wheel used as the last step.  

 
quote:
"You need to remember that these pickups were sold on the merit of being refined to Danny Gatton's taste over a 10 year period. If taped edges had been acceptable to Mr. Gatton, then Barden would have taped them."
I tend to doubt that Mr. Gatton had an opinion on core taping. Or that he could detect the presence or absence of core taping.  
 
I would guess that the classic pickup design where the wire is wound directly on the six 5mm magnets or slug poles was the model, carried over more or less directly to blade pickups, even though blades are 1.6mm, far thinner than 5mm. And it did work at first. While the pickups tended to die young, this would have been well after Mr. Gatton had moved on to another experimental pickup.  
 
quote:
"The low fill factor suggests low winding tension used to avoid cutting the wire."
Sounds right to me. Even with perfectly polished ends, the radius is small and this may have required reduced wire tension.

 
6/5/2005 8:55 PM
Joe Gwinn

Actually, I now see a simple way to show that the only the mean turn length is required, without calculus.  
 
Draw the following diagram:  
 
The Y axis (vertical) is turn length in inches (or centimeters).  
 
The X axis is the height of the turn above the core, in the same length units as for the Y axis.  
 
From the geometry, we know that the length of a turn varies linearly as a function of height above the core. At zero height, right on the core, the length is Lmin. At the top of the winding, where height equals winding depth, the length in Lmax.  
 
Draw a line on the diagram from Lmin at zero height to Lmax to Lmax at height=depth.  
 
Halfway between Lmin and Lmax is Lmean. Specifically, Lmean= (Lmin+Lmax)/2 is at height=depth/2. Mark this point on the diagram. It's right in the middle.  
 
Draw a light horizontal line through Lmean, parallel to the X axis.  
 
Now seen are two identical triangles, one to the left of and below Lmean, the other to the right and above. No matter what the values of Lmin and Lmax, these two triangles are identical, so the total area under the line from Lmin to Lmax is Lmean times Depth.  
 
This is obvious when looking at the diagram, even if the words here don't quite do it.
 
6/7/2005 12:14 AM
Dr. Strangelove

Joe Gwinn wrote:[QUOTE]Actually, I now see a simple way to show that the only the mean turn length is required, without calculus...  
This is obvious when looking at the diagram, even if the words here don't quite do it.[/QUOTE]  
 
Can you draw a crude diagram with a paint program and post a link?  
 
-drh  
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6/7/2005 6:38 AM
Joe Gwinn

On 6/7/2005 6:14 AM, Dr. Strangelove said:  
[QUOTE]Joe Gwinn wrote: "Actually, I now see a simple way to show that the only the mean turn length is required, without calculus...  
This is obvious when looking at the diagram, even if the words here don't quite do it."  
 
Can you draw a crude diagram with a paint program and post a link?[/QUOTE]Yes. Actually, I should combine the drawing with a short description of the algorithm. This will take a few days.
 
6/10/2005 2:37 PM
Joe Gwinn

On 6/7/2005 12:38 PM, Joe Gwinn said:  
[QUOTE]On 6/7/2005 6:14 AM, Dr. Strangelove said:  
"Joe Gwinn wrote: "Actually, I now see a simple way to show that the only the mean turn length is required, without calculus..." Can you draw a crude diagram with a paint program and post a link?" Yes. Actually, I should combine the drawing with a short description of the algorithm. This will take a few days.[/QUOTE]I just posted on my website (http://home.comcast.net/~joegwinn/) a three-page document with drawings, explanation, step-by-step algorithm, and a worked example.
 
6/10/2005 4:23 PM
Dr. Strangelove

Looks good, Joe.  
Thanks.  
 
-drh  
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