GeoTol Applications and Tolerance Stacks

The GeoTol Applications and Tolerance Stacks Program is an advanced tolerancing course for design engineers, drafters, manufacturing engineers, quality engineers and others involved with tolerance analysis or drawing review. Anyone looking for a deeper understanding of how to apply geometric tolerancing and perform tolerance analysis will greatly benefit from this course.

Prerequisite: GeoTol Pro Fundamentals Program Level 1 and 2.

General Description

In our 30 years of teaching the subject we have found people may understand the fundamentals of GD&T such as datums, position with MMC and RFS modifiers, parallelism, profile etc. However they still lack the intimate knowledge of how to expertly apply geometric tolerancing and perform tolerance stacks and analysis to clearly define and optimize their product design.

The Applications and Tolerance Stacks course teaches personnel how to apply GD&T and perform tolerance stacks using a series of case study problems including sheet metal, machinings, plastic parts, castings etc. The entire course is 17 units where students can do all or select certain problems to customize to program to meet their needs. The first 6 units cover tolerance stacks while the remaining 11 units contain the case study examples where students must establish datum reference frames and apply geometric tolerancing based on clearly defined functional requirements. Afterwards, they must perform tolerance stacks to ensure design requirements are met. The problems start off simple but gradually increase in complexity. Students will apply concepts they learned in early lessons to progress to the next higher lesson.

Both the Applications and Tolerance Stacks units are in the same textbook so a lesson in the Stacks section can be taught with an alternating lesson in the Applications section. This provides variety in the program and makes the stacks calculations less taxing on the students. This also links the idea that proper selection of the datums, as well as position and profile values on individual parts has a great effect on the accumulation in the overall assembly.

Tolerance Stacks Units 1-6

Tolerance stacks are an important tool used to evaluate the variable features and dimensions of a single part or an assembly of parts. Tolerance stacks are used in the calculation of fits and fit-ups, tolerance accumulation/allocation, datum selection and the use of feature modifiers and datum modifiers.

The Tolerance stacks section is designed to teach students how to calculate linear, axial and orientation stacks using parts toleranced with either plus minus or geometric tolerancing. The instruction is reinforced with student hands-on exercises consisting of a variety of case studies on both details and assemblies. This program provides creative procedures using tables and simple formulas to break the most complex problems into simpler segments. It gives tips and suggestions on how and when to add up form, orientation and location variations due to a variety of manufacturing processes.

The basic stack procedures can be used individually or in combination on simple or very complex examples. The students usually use calculators but may also use laptops. A customized Excel spread sheet accompanies the program. All the boundaries are calculated manually prior to using the spreadsheet or viewing the solutions. The program generates a lot of questions, conversation and student involvement. The exercises build the knowledge and improve participant’s confidence in properly applying and interpreting geometric tolerancing.

Design Applications Units 7-17

Proper application of geometric tolerancing is important in order to communicate the design intent of a part. Selection of datums, position and profile values, datum and feature modifiers will have a large effect on how a part may be measured and/or manufactured. A fundamentals course on geometric tolerancing will teach the basics of the symbol meanings and how to interpret a completed drawing, but often leave the student struggling on the application of the symbols to a blank drawing. This Applications section is designed to teach the student how to tolerance parts through real case study examples.

The applications section contains 11 units, each representing a different part or assembly of parts with certain tolerance related design requirements. The parts and assemblies include a variety of types such as milled, turned, sheet metal, plastic, weldments and castings. This program is customizable and the student may pick and choose the case study problems in their area of interest.

The introduction unit will provide a brief review of the philosophy of geometric tolerancing, the necessary fastener formulas and a few sample toleranced drawings. The following units contain exercises that gradually grow in complexity to increase the student’s confidence in properly applying and interpreting geometric tolerancing. The program generates a lot of questions, conversation and student involvement.

After applying the tolerancing, there are a variety of recommended linear, axial and orientation tolerance stacks to ensure functional requirements are met. In order to complete the tolerance stack exercises in this applications section, the student must complete certain units in the stacks section. The prerequisite for each stack problem will be listed on the exercise.

How to take this Applications and Stacks course

This course is presented seminar style with students watching video lessons from Scott and Al and then completing the exercise modules in the companion GeoTol Applications and Tolerance Stacks text. Solutions are provided at the end of each video lesson.  This course provides complete flexibility in the learning process and can be customized to meet your interests.  Students can use this course to learn only tolerance stacks, only design applications or a combination of both. The tolerance stacks sections must be completed sequentially in order from unit 1 to 6.

The applications section may be taken in any order, applying tolerance to sheet metal, machined parts, simple or complex problems. To make the learning experience exciting, look over the units in the Applications and Tolerance Stacks book and pick an application problem that interests you.  Select the Applications unit from table of contents of this program and watch and solve the video lesson in the unit.  Afterwards, complete the corresponding lesson in the stacks units.   This will allow you to first solve a case study problem from the applications and then perform the necessary stack in the problem.  This inserts variety in the lessons and allows you to apply your knowledge to practical applications.   It is usually best to start with the earlier simpler units and graduate to the more complex problems.

In some of the application problems there will be necessary stack prerequisite units the student must first complete. The prerequisites for the stack exercises are shown in the book following the title page of each unit and at the beginning of every unit in this course.

To move from one lesson to another within the course open the unit of interest 1 thru 17.  At the beginning of each unit there are links to the sub-unit modules shown as letters of the alphabet.

The solutions for all problems are provided by Scott and Al at the end of each exercise. There is also a solutions manual available for this book available at  To get the most out of this course, do not peek at the answers until you solve the problem.



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