Dual-Dimension Tolerance Rounding Tool

Use this Dual-Dimension Tolerance Calculator to convert dimensions and tolerances between mm and inches. It utilizes the “inward rounding” methodology to prevent tolerance growth or inversion, ensuring your converted limits and bilateral deviations maintain the original design intent. An aid for engineering and professional drawing unit conversion.

This Dual-Dimension Tolerance Rounding Tool is designed to be an aid for professionals who convert engineering dimensions and tolerances between metric (mm) and imperial (in) units.

Therefore, its core purpose is to address the critical risk of tolerance inversion or tolerance growth that can occur when mathematically rounding converted limits. The utility applies a methodology commonly referred to as “inward rounding,” which helps ensure the calculated secondary tolerance zone remains contained within the original primary zone. Although SOLIDWORKS has similar functionality built-in, there may be other times when this calculation is necessary but not available in a particular software.

By presenting limits or bilateral deviations derived from this methodology, the tool assists in reducing manual calculation errors and provides a valuable general reference for maintaining the part’s original design intent.

Note on Use: This utility uses the online decimal.js library for precision; so whether you download the utility or use it here, you’ll need internet access. As always, the results generated should be verified by a professional and used in accordance with your organization’s standards.

Dual-Dimension Tolerance Rounding Tool

Rounded Secondary Dimension (in)
Tolerance Range Comparison (Upper Limit is Left, Lower Limit is Right)
UPPER LIMIT (+Dev) LOWER LIMIT (-Dev)
If Sec. Nom. falls outside the Secondary Range, the condition may be invalid.

This utility is based on online sources, particular assumptions and calculations. This utility should only be used as a general reference. Results should always be verified. No one is responsible for incorrect information generated by this utility. Use thereof is the sole responsibility of the user. Use at your own risk.

DualDimensionTolRoundingTool.zip

Engineering related societies

The following is a list of professional societies related to the mechanical engineering field.  These groups either have some sort of certification process or are responsible for the control of various commonly used standards.  If other societies should be added to this list, please feel free to comment with their information, or email me directly.

  1. American Society of Mechanical Engineers (ASME)
  2. ASTM International (formerly American Society for Testing and Materials)
  3. International Organization for Standardation (ISO)
  4. National Society of Professional Engineers (NSPE)
  5. Society of Plastics Engineers (SPE)
  6. SAE International (formerly Society of Automotive Engineers)
  7. Society of the Plastics Industry (SPI)

New Area on Lorono’s SolidWorks Resources

Recently, a new file area on the Lorono’s SolidWorks Resources has been created, called Engineering and Design.  The purpose of this new area is to provide some general engineering and design reference materials.  These materials are not necessarily related to SolidWorks itself, but useful to its users (and really anyone in the mechanical engineering field).  This new area will be expanded rapidly over the course of this month to include files that provide organized tables and functional calculations regarding on wire gages, positional tolerancing, sheet metal tolerance, thread sizes, metal coating and finishes, etc.

If there are tables, calculation spreadsheets or other data compilations you would like added to this area, please feel free to contact me with your files so that they may be included.  (I will not put up copyrighted material, like images of charts made by this or that publisher, without permission from the author.  However, data itself will be welcomed, preferably within an excel file.)

Also, comment here if you have any particular requests for this or any file area.

Which Way EPA?

Green industries, although growing, are still having a hard time getting the acceptance from the U.S. Government in the form of funding, supporting regulations and support from the EPA (Environment Protection Agency), or as Grampa Simpson called them, Eepah!  EEEPAH!

EPA was established in 1970.  It responsibilities cover issues dealing with the protection of the environment and public health.  They set clean water standards.  They specify limits for toxic waste sites.  They are also tasked to regulate industrial pollution, and now even the pollution from everyone’s vehicle.  Law mandates that the EPA use proven science and technical and legal data to make decisions that are in the best interest of all citizens.  (Contrary to the depiction in The Simpsons Movie, EPA doesn’t have armored tanks nor huge impregnatable city covering domes.)

In my opinion, these regulations should consider new environmental technologies.  The EPA should take a role in fostering new technologies that create solutions for environmental protection efforts.  When the EPA is doing its job, this happens.  Such efforts have already helped spark development of U.S. green industries.

The problem?  EPA is supposed to be partisan neutral.  It hasn’t be treated as such under the current U.S. presidential administration.  Its purpose and over all ability to function have been hampered on two fronts as a result of agendas that belong back in the Industrial Age. One, its budget has been substantially reduced to force it to downscale its operations.  Two, according to a recent Design World article, the head of the EPA, appointed by the President, is an individual that seems to act without regard to science or even his own staffs recommendations, in favor of the President’s agenda.  This agenda unfortunately focuses on protecting old industries, ignores the facts that those old industries can still be supported while encouraging green industry, and that old industries can actually be made safer and more efficient by using green technologies.

Beyond that, it is important to recognize that the human population is growing too rapidly for the current industrial centric paradigm to support in the long run.  I’m not talking about Global Warming.  Our planet simply does not have the resources to support the projected populations if things remain on their current path.  Being the largest consumer of resources, the U.S. bares a large portion of responsibility for these issues.  This isn’t a guilt trip.  We simply need to act in our own self-preserving interests.

New technologies need to be supported, developed and implemented to deal with the changing and currently unknown challenges 21st Century will bring.  Though some will argue that it is not the government’s job to be at the forefront of technological development, the reality is that this is a job the government takes on.  Without government “encouragement”, industry acceptance tends to lag until problems is so big that it cannot be ignored. At times, this has been to the detriment of our country, as the current fiscal crisis attests.

The EPA plays a particular role in all this by working with (and sometimes against) industry to do what is best for America’s people.  It can be a leader that creates new opportunities for U.S. industry, new jobs, new technologies, etc.  Hopefully the EPA will be able to fulfill the role for which it was established.  If allowed it, I believe it will benefit our economy (perhaps even sooner rather than later), including the creation of engineering jobs in the new and growing green industry.


Source:  Michelle Shaland (2008) What’s the real role of the EPA?, Design World – August 2008