Bolt Stress and Reserve Factor Program

I do a lot of work as a Stress Engineer and regularly need to calculate loads in bolts to ensure that they are not going to break. This is a heavyweight, industrial use program that I have incorporated in my workflow, that may also be useful to a number of people. This program is used to calculate the reserve factors in bolts of various sizes knowing the loads that are applied. The program is in common engineering metric units, length is in millimeters and force in Newtons. The bolts considered are British Standard Metric bolts, which use dimensions applicable to coarse metric bolts & screws worldwide, covering the range M4 to M36 excluding most of the non-preferred sizes (eg M7, M9 & M33). The materials available from the dropdown list cover most carbon and stainless steel grades commonly used in general engineering. It is possible for the user to expand the size & material lists using a text editor. The program window is as below:


The Bolt Group Analysis Program is a 32 bit Windows based program designed to analyse the loads in a group of bolts. It comes with a 2 page pdf help file, advice on reserve factors and a simple red colour indication of when a bolt is over stressed (as shown above). All the calculations are listed in the help file, and enough information is presented that a stress engineer can check the calculation if necessary. If you need a report on the reserve factors, the 'Copy Calcs' button grabs a screenshot of the program and that can be pasted into a report for future verification.


The program may be downloaded below:

Bolt Stress and Reserve Factor Program, zipped (304 kb)

The program is known to work in Windows XP, Vista, Win 7, Win 8 & Win 10. There is no reason why it shouldn't work in Win 95, 98, ME or NT. Download the zip file and extract into any convenient directory, then run "BoltStresses.exe". It is a single file exe, no clutter is left anywhere else on the machine. It uses two .csv files ('BoltData.csv' and 'BoltMaterial.csv') which mat be edited. The source code is included so you can verify the program yourself. The help file is in the PDF file 'BoltStressesHelp.pdf'.

Update History

21 Sept 2020: Added M1.4 to M3.5 thread size data after end of more standard engineering sizes.

Chestnut Pens Miscellaneous Pages Home
Chestnut Pens Home