Hi Steve, Your suspicion is right that there shouldn't be such a big difference of estimating the correct tin add.  Derrick's spreadsheet is the simplest way to work with and it shows the same results as obtaining from the formulas in IPC-JSTD-001 Handbook.  The AIM method is flawed because it doesn't take into account of the amount of tin removed from the pot.  A mass balance should look like this: Theoretical (Final) amount of tin in the pot = Tin add + Tin remained in the pot after decant, in your case, 500 (63%) = A + (500 - A) (60.25%) - this is the CASE 1 equation in the handbook. A = 34.59 lb Thus 14 lb add will not get the pot in specification at all. Yu-Shan 
> Date: Fri, 15 Mar 2013 15:13:39 -0500
> From: [log in to unmask]
> Subject: Re: [TN] Low Tin Levels in wave solder pot...
> To: [log in to unmask]
> 
> Hi Steve - looks like Derrick provided you a much better assist than I 
> could have - nice job Derrick! Love the spreadsheet - guess I can quit 
> doing it the old fashion way and now use the Excel.
> 
> Dave
> 
> 
> 
> From:   Steve Gregory <[log in to unmask]>
> To:     <[log in to unmask]>
> Date:   03/15/2013 02:29 PM
> Subject:        Re: [TN] Low Tin Levels in wave solder pot...
> Sent by:        TechNet <[log in to unmask]>
> 
> 
> 
> Hi All,
> 
> I just got an email back from a guy named Derrick Herron of Indium who 
> sent 
> me a really useful spreadsheet that makes it simple to calculate what you 
> need to take out of your pot, and how much tin you should add based on the 
> 
> numbers you get back from an analysis to put everything back into spec, 
> and 
> I thought that I would share this with everyone. Makes it dead simple even 
> 
> for me!
> 
> http://stevezeva.homestead.com/Solder_Pot_Analysis.xlsx
> 
> Steve 
> 
> 
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