Perhaps someone might care to comment on my use of Keith's spreadsheet  
for plotting radial curves.  I'm having pretty good luck, but am  
running into one sticking point.

Here are some numbers from my spreadsheet (slightly adjusted from the  
defaults):

R - 9.7
M - 56.7

F              Target    Actual     Diff
0.0015    48.0        48            0.0
0.005      40.9        41           -0.1
0.010      34.3        34            0.3
0.017      27.5        27            0.5
0.026      20.6        21           -0.4
0.037      13.7        14           -0.3
0.044      9.8           7              2.8
0.060      2.0

I'm using the MOJO glass and feeler gauges.  As you can probably tell  
from the above data, I'm counting back from the tip when calculating  
the curve.  I used a caliper to measure the tip rail and compared that  
to the glass gauge (which read 2).  There was mention in an earlier  
thread of using this method vs. just calculating from 0, but I didn't  
get the impression that a consensus was reached.  Are most folks  
calculating their curves from the tip or from the inside of the tip  
rail?

When applying the curve, I attempt to hit several data points with  
each swipe in order to get a smooth curve with no flat spots.  This  
seems to work well, except that I invariably end up way short on the  
largest feeler before the tip.  This is illustrated on the .044 feeler  
numbers above.  I find it nearly impossible to bring this one spot  
into perfect radial alignment without inadvertently opening the tip.   
Anyway, this happens so consistently that it makes me wonder if I'm  
not using the spreadsheet correctly.

Kind Regards,
Walter Hoehn

P.S.  No jokes about my small tip opening ;-)

--- In MouthpieceWork@yahoogroups.com, Walter Hoehn <wassa@...> wrote:
>
> Perhaps someone might care to comment on my use of Keith's spreadsheet  
> for plotting radial curves.  I'm having pretty good luck, but am  
> running into one sticking point.
> 
> Here are some numbers from my spreadsheet (slightly adjusted from the  
> defaults):
> 
> R - 9.7
> M - 56.7
> 
> F              Target    Actual     Diff
> 0.0015    48.0        48            0.0
> 0.005      40.9        41           -0.1
> 0.010      34.3        34            0.3
> 0.017      27.5        27            0.5
> 0.026      20.6        21           -0.4
> 0.037      13.7        14           -0.3
> 0.044      9.8           7              2.8
> 0.060      2.0
> 
> I'm using the MOJO glass and feeler gauges.  As you can probably tell  
> from the above data, I'm counting back from the tip when calculating  
> the curve.  I used a caliper to measure the tip rail and compared that  
> to the glass gauge (which read 2).  There was mention in an earlier  
> thread of using this method vs. just calculating from 0, but I didn't  
> get the impression that a consensus was reached.  Are most folks  
> calculating their curves from the tip or from the inside of the tip  
> rail?
> 
> When applying the curve, I attempt to hit several data points with  
> each swipe in order to get a smooth curve with no flat spots.  This  
> seems to work well, except that I invariably end up way short on the  
> largest feeler before the tip.  This is illustrated on the .044 feeler  
> numbers above.  I find it nearly impossible to bring this one spot  
> into perfect radial alignment without inadvertently opening the tip.   
> Anyway, this happens so consistently that it makes me wonder if I'm  
> not using the spreadsheet correctly.
> 
> Kind Regards,
> Walter Hoehn
> 
> P.S.  No jokes about my small tip opening ;-)
>

You seem to be using the spreadsheet right, as the plotted target curve looks fine.  Wait.  Is that next to last feeler .44 or .49?

With my feeler set, it would be a .049" feeler, not .044".

You should be zeroing the glass gage zero at the very tip of the mouthpiece, not inside the tip rail.

Your last reading of 2 would correspond to a tip rail thickness of .039" = 1 mm = 2 on the glass gage scale.  The .060" would be the tip opening measured with your calipers to the inside of the tip rail.  

Being how the tip of a mouthpiece has more material in it than the side rails, you need to "dig in" a little at the tip to get it to open up while taking a facing curve swipe.  But you should not have a visable flip there when trying to make a perfect radial facing curve.  

Email me your filled-in spreadsheet and I will take a look at it.


      

On Jul 17, 2009, at 8:41 AM, Keith Bradbury wrote:

>  With my feeler set, it would be a .049" feeler, not .044".

I'm not sure how I got that confused.  Thanks to both you and Morgan  
for catching my error.  That certainly accounts for most of the  
discrepancy I was noticing.
> You should be zeroing the glass gage zero at the very tip of the  
> mouthpiece, not inside the tip rail.
>
Yup.
> Your last reading of 2 would correspond to a tip rail thickness of . 
> 039" = 1 mm = 2 on the glass gage scale. The .060" would be the tip  
> opening measured with your calipers to the inside of the tip rail.
>
Sounds Right.  Do you feel this is the optimal way to plot a curve,  
or do you usually start from 0?
> Being how the tip of a mouthpiece has more material in it than the  
> side rails, you need to "dig in" a little at the tip to get it to  
> open up while taking a facing curve swipe. But you should not have  
> a visable flip there when trying to make a perfect radial facing  
> curve.
>
Right.  Now that I'm using the right numbers, my previous work sort  
of magically lines up... funny.  I've followed the past discussions  
about flip tips etc., but at this point I'm not continuing the curve  
past the tip rail.
> Email me your filled-in spreadsheet and I will take a look at it.\
>

OK.  Thanks.


-Walter

>>>>>>>>>>
> Your last reading of 2 would correspond to a tip rail thickness of . 
> 039" = 1 mm = 2 on the glass gage scale. The .060" would be the tip 
> opening measured with your calipers to the inside of the tip rail.
>
Sounds Right. Do you feel this is the optimal way to plot a curve, 
or do you usually start from 0?
<<<<<<<<<<

I like working this way.  I find measuring the tip opening at the very tip difficult and less meaningfull.

I also would recommend that you measure your feeler gages with a micrometer or at least your calipers.  Measure them around the edge you use with the glass gage.  Some might differ from their markings by .0005-.0010".  Use the measured values in the spreadsheet.  It will not make a big difference but we should strive to rid ourselves of all the simple "errors".