Clear directions for correct fabrication

Dos and don’ts of drawing pieces
By Matt Green
May 1, 2007

There is nothing worse than ordering glass from an outside source, only to discover when it arrives that it is not fabricated correctly. The cost can mount if the product is heavy glass with notches or holes fabricated in it or is tempered. It is costly to reorder and wait for glass to be redone. This is a no-win situation for everyone.

The finished product is a result of several different processes. Obviously, if the glass is not measured correctly or presented to the fabricator in an incorrect format, it would be doomed from the beginning. Therefore, a discussion of the dos and don’ts of drawing fabricated pieces might be helpful.

Let us say that the field measurements have been taken and the glass is ready to be ordered. I have had drawings submitted for fabrication so badly that it was hard to tell if it was even a piece of glass, much less which side was out of square on it. There are several ways to prsent the out of squares for a piece of glass so that the fabricator understands them. The examples below are the best two methods. Both are of the same piece of glass with the variation from square shown in a different format. The first is my favorite with defined markers showing the direction that the glass is out of square. The second is with hashed markings showing where the glass line would be if it were square. The solid lines are the actual glass. Both methods have the amount of deviation from square clearly marked on the drawing. Both examples are acceptable for fabrication.

Here are some examples of what not to do. Drawing the glass out of proportion for the actual dimensions of the glass is definitely wrong. An example might be if the glass is narrower than it is tall, and the drawing is wider than it is tall, or perfectly square. This greatly increases the odds of the glass being fabricated incorrectly.
Example of a typical structural heavy glass shower door.
Dimensions might be interpreted in-correctly if the clarity of the drawing becomes distorted in the faxing process or for any other reason. Make sure to have all pertinent information written on the drawing in a clear legible manner. Do not congest measurements together if possible. Another example of what not to do would be breaking the glass down on the drawing into “quad” dimensions. This method shows the out of squares to the glass. However, if there are dimensions for notches or holes in the glass, then the measurements will become too congested for clarity. Most likely fabricators will have to use this method to optimize for cutting, but it is best to let them do this. The cleaner and less congested the original sketch, the better.  

Drawing notches and holes for fabrication
Once the glass has been cut and the edgework done, the next step in the fabrication process would be holes and notches. Hole and notch measurements should be from the edge of the glass to the centerline of the hole or notch.

Any other information necessary for fabrication should be included also. For instance, the preferred logo location and hole diameter. If applicable, a separate notch detail should be included.

In short, when ordering glass for fabrication, make drawings on a clean sheet of paper without grid lines. Have out of squares, notches and holes clearly marked so that the fabricator understands exactly what you want. Also include any other important information such as logo locations on tempered glass. The finished product depends on how you present it for fabrication.

This example shows the same piece of glass drawn out of proportion to the actual measurements.


The author is office supervisor, M3 Glass Technologies, Irving, Texas, 972/790-4527,,