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Discussion Starter #1
HI friends....
I need Help.
I have measured my Guardala MBII (wwbw) and I want to understand with you if the facing in a good or is a wrong curve.

Thanks


View attachment 242064
 

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I don't understand the use of the term 'radial' for a facing curve. As you can see from the plot, there is no radius - its a spiral curve, or simply a 'spline' curve that is manufactured, not predicted by a formula. If this mouthpiece is one of the hand-mades, that's a remarkable facing. Possibly it is a 'Laser-Trimmed'? In any event it doesn't need anything as far as the facing goes although I'd like to see the relationship with the table if I were examining it. Also the 'Laser-Trimmed' ones can usually benefit from some 'cleaning up' in the throat/back of window area.
I guess the bottom line is, if it plays to suit you don't mess with it.
 

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Discussion Starter #5
My Guardala is refaced......
One more questions!

Any of you can tell me to facing curves of original Guardala MBII Handmade o LT?
 

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I don't understand the use of the term 'radial' for a facing curve. As you can see from the plot, there is no radius - its a spiral curve, or simply a 'spline' curve that is manufactured, not predicted by a formula...
It is compared to an elliptical curve - it is hard to visualize the ellipse because the scales are not equal.
 

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I've seen that kind of curve on several mouthpieces that I really like. I call it a "belly curve", because it's like a radial curve got fat in the middle. Looks fine to me, though I think the facing might be a little long. It would be for me... of course 0.110" is more open than I prefer too, though not by much.
 

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Handmade Guardalas vary more than the WWBW LTs that were CNC faced. I have not seen enough of the PMS DG’s to comment on them other than they are a little different too.

The WWBW LTs usually have a 52-54 facing length. The facing has a small hump in the curve where the heart of the reed is and then gets flatter towards the tip. The opposite of what a nice (IMO) elliptical curve has. This basic shape is pretty consistent on LTs but then there are some random irregularities present. Unevenness left to right and some small bumps and flat spots.

The curve you posted is a much better quality than a stock LT facing curve.
 

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I don't understand the use of the term 'radial' for a facing curve.
I don't know where the convention came from but ok, it's maybe not the best choice. 'Radial' denotes a curve that is a circular section, which this one probably is, according to the spreadsheet.

An aside about glass gauges: As far as the apparent deviation from a 'radial' curve, don't read too much into 0.1mm sized discrepancies in a glass gauge measurement. I have never seen a gauge that anybody can measure a facing with that much accuracy on, or one with lines less than 2 or three times that thickness. Almost always the lines are 1mm apart. If you have one of the LAW gauges with 0.5mm graduations, and 10x or better magnification, and a fixture (rather than your hand) holding the gauge to the mouthpiece, I can believe 0.125mm (0.25 on the gauge) precision and +/- 0.25 accuracy might be achievable.

But with standard gauges used as intended, anything finer than 0.5 (0.25mm) precision and accuracy (probably twice that, really) is entirely imaginary and simply beyond the capabilities of the equipment, regardless of who is using it. So take any facing curve numbers -- even your own -- with a grain of salt.
 

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I can read to the nearest .1 on the glass gauge (.05 mm). This is about the thickness of the (thin) lines on the LAW glass gauge. It is repeatable for me about 80% of the time. So some numbers are +/- .1 when I repeat a measurement. Usually off in the same direction due to not having the same zero point when placing the gauge back on the mouthpiece. I agree that this is finer than what mere mortals can do. ;)
 

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Discussion Starter #11
Hi mister. One guardala mbii with tip opening 0.110 and facing lenght 44mm is good?
 

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No. The facing length of 44mm is way too long for a tenor Guardala. They should be 48-53 on the glass gauge = 24-26.5 mm.
 

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Discussion Starter #13
24-26,5 with 0.0015 feeler gauge?
 

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Discussion Starter #14
however I had made a measurement error. My Guardala Mouthpiece after the last one refacing is 22mm (facing lenght) and tip opening .110. facing curve 44-38-30-26-20
 

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My problem is I'm an engineer, so to say 'radial' means a circular curve (constant radius). 'Ellipse' means a simple combination of circular curves to form an oval. Mouthpiece facings, at least all the ones I have encountered, are similar to the one plotted above, where they take off from the table in a short-radius arc, but quickly become spirals, flattening near the tip. When DG made his mouthpieces, which are now among the most valuable in the world, this is the facing type he used. So when artisans speak of 'radial' and 'elliptical' facings, they either have developed something completely new or are using 'lingo' known only to them. I can't see an arc working for a facing (near the tip). An ellipse near the tip possibly could work but why not use the flattening near the tip which has always produced the greatest mouthpieces of the most value?
 

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My problem is I'm an engineer, so to say 'radial' means a circular curve (constant radius). 'Ellipse' means a simple combination of circular curves to form an oval. Mouthpiece facings, at least all the ones I have encountered, are similar to the one plotted above, where they take off from the table in a short-radius arc, but quickly become spirals, flattening near the tip. When DG made his mouthpieces, which are now among the most valuable in the world, this is the facing type he used. So when artisans speak of 'radial' and 'elliptical' facings, they either have developed something completely new or are using 'lingo' known only to them. I can't see an arc working for a facing (near the tip). An ellipse near the tip possibly could work but why not use the flattening near the tip which has always produced the greatest mouthpieces of the most value?
The plot is deceptive because the axes are not equal. I've been through the same thing before. Replot the data, and it becomes apparent.
 

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My problem is I'm an engineer, so to say 'radial' means a circular curve (constant radius). 'Ellipse' means a simple combination of circular curves to form an oval. Mouthpiece facings, at least all the ones I have encountered, are similar to the one plotted above, where they take off from the table in a short-radius arc, but quickly become spirals, flattening near the tip. When DG made his mouthpieces, which are now among the most valuable in the world, this is the facing type he used. So when artisans speak of 'radial' and 'elliptical' facings, they either have developed something completely new or are using 'lingo' known only to them. I can't see an arc working for a facing (near the tip). An ellipse near the tip possibly could work but why not use the flattening near the tip which has always produced the greatest mouthpieces of the most value?
The formula used by "artisans" who speak about "radial" and "elliptical" curves is available online. If you look for it, you'll see there is nothing new being developed and no new lingo.
 
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