Wednesday, January 8, 2014

Bolt Preload Calculators

This link is the Excel 2007 version of the Calculator.  This is a macro and has been trusted source code signed with a third party (Thawte) certificate so it doesn't jam up your Excel security settings if you want to download it.

It includes SAE 429 UNC and UNF bolts and ISO Metric bolts with all the common tensile strength grades.  The bolt type (in-lb or metric), thread type (fine or coarse), size and grade are selected by dropdown lists.  The preload calculation uses a user input range of torque tolerance, thread friction range and bolt head friction range.  The maximum and minimum preloads are determined and compared to the proof and tensile loads for the selected grade.  For reference the "nut factor", K is also calculated and given.

Excel Version of the Bolt Preload Calculator.
This link is a Google sheets version of the SAE 429 Bolt Preload Calculator for the shared "view only" version.  For an editable and shared version use this link.  Any changes will automatically be added to the shared version.  I would suggest making a copy of the original shared version and use and control that as you wish.

(Disclaimer:  I've just starting using Google sheets and am still learning how the Google "My Drive" and sharing system works.  This is my current understanding and seems to work with the testing I've done.  The Google scripting I've used to do the sheet calculations and load the drop-downs on the active sheet works fine and should work for the editable version.  By design the "view only" shared version of the sheet will be completely inactive.)

The Google sheets version currently only includes the SAE 429 UNC and UNF bolts with the common grades.  As mentioned Google script is used to populate the drop down lists and run the calculations.

Google Sheets Version of the Bolt Preload Calculator.
Multiple scenarios can be evaluated and saved by copying the workbook and/or worksheet.  The macro and script get copied along with the worksheet which can be named anything.  All normal spreadsheet functionality is maintained.

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