Dimensioning Rules for Tapers, Threads and Chamfers in Technical Drawing

Technical drawing is a very important communication language between engineers and people dealing with the manufacturing and design of technical parts. So, this communication tool has strict rules to be obeyed when reading and creating technical drawings. If you know and obey these rules, you can understand all kinds of engineering drawings wherever it comes. 

On mechanicalland.com, there are lots of informative articles about technical drawing rules. Dimensioning rules are also very important. In this article, you can find general dimensioning and placement rules for tapers, threads, and chamfers in technical drawings.

Check: Textbook Recommendation to Learn Engineering Drawing 

How to Dimension the Tapers? 

Standard tapers are used in machine spindles, attachment shanks of the machine tools, and pin attachments. These tapers must be indicated properly. 

Image Source: FREDERICK E. GIESECKE, SHAWNA LOCKHART, Technical Drawing With Engineering Graphics 15th Ed., Pearson, Pg.524

– The dimension must be placed on the bigger diameter of the taper. 

– Taper must be shown laterally in technical drawing like above. The diameter of the bigger hole is indicated with its tolerances

– The length and the taper angle can be indicated on the technical drawing but also there are some standard indications like above. Standard tapers can be noted by giving a leader indicating the standard taper. 

– Another dimensioning rule for taper is by giving the amount of taper per unit diameter. Such as TAPER 0.125:1 ON DIA which means 0.125 tapers are given for each 1 unit of diameter indicated on the technical drawing. 

How to Dimension Chamfers in Technical Drawing?

Chamfers are also used on most mechanical elements such as shafts. They are created as slopes at the end of the round mechanical elements. 

The dimensioning of the chamfer is very simple on technical drawings. You just need to give the length of one edge and the corresponding angle to it. 

Dimensioning the Threads in Technical Drawings

Threads are the major geometrical shapes of screws and screw holes. If machinery has screw holes or screws they must be dimensioned properly. 

Dimensioning threads(Image Source: McGill.ca)

Internal threads must be dimensioned from their top view and the external threads must be dimensioned from the front view. 


Dimensioning the threads, tapers, and chamfers is very simple in technical drawings as you see above. 

Do not forget to leave your comments and questions below about how to dimension the threads, tapers and chamfers. 

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