A glass drawing may identify the outer shape and part number, yet a short note arrives during the quotation: “Add a hole near this corner.” It sounds like a minor detail. For a pane that will be toughened, however, it cannot always be treated as a finishing instruction to be added at the end.
The hole’s position, the face from which it is dimensioned and the requested edge finish need a shared definition before manufacturing. This article does not prescribe measurements for a vehicle or building project. It explains how purchasing and engineering teams can describe a toughened-glass part so that the supplier is reviewing the same geometry and the same processing sequence.
01 / 05
The outside dimensions do not describe the whole part
Width and height attract attention on a glass drawing. In use, however, the part is also defined by its outline, holes and cut-outs, edge treatment, installation orientation, surface treatment and the reference side used for measurement. Two panes with the same outside dimensions may not be interchangeable if one of those details is unclear.
A hole for a fixing, pin, connection or cable route is more than a circle on the page. The drawing should make clear how its centre is located from agreed edges or datum lines; whether the view is from the front or back; which way the part is oriented; and whether the requested feature is a straight hole, a cut-out, a stepped geometry or another form. The exact terms vary from project to project, so the symbols and notes need to be understood the same way by the customer and processor.
The relationship between the outer contour and each hole matters too. If a hole is shown but its centre is not dimensioned, a supplier may be left to estimate its location from the picture. A photograph or physical sample can support the discussion, but it does not automatically establish which reference controls. When both a drawing and a sample are supplied, state whether they agree and which one is the latest approved reference.
Hole and edge details belong in the part definition, not a note to be sent later. Before confirming toughening, separate settled features from open questions. That gives the project and supplier a shared starting point.
02 / 05
Why the sequence changes before toughening
Toughened glass is not simply an unfinished pane with a different label. Pilkington’s product guidance for its toughened glass says that cutting, drilling and edge work must be completed before toughening. AGC’s installation guide gives the same processing order for its specific Lacobel T and Matelac T product families, stating that cutting, drilling and edge finishing must precede tempering and that no further processing is possible afterwards for those products.
These sources do not describe the same product or production line. AGC’s instruction applies to the named coated product families; Pilkington’s page describes its own toughened-glass product. A processor should not transfer one manufacturer’s product instruction automatically to every glass composition, coating or plant. The applicable product documentation and the supplier’s confirmation should control the project.
Raise hole and edge requirements before agreeing the tempering route. If a hole changes later, ask what needs review rather than assuming the existing pane is unchanged. A new drawing revision or sample review may be needed, depending on the product; the supplier should confirm.
The sources do not set a universal hole size or edge distance. Those values depend on material, design and product requirements. For the products cited here, geometry-related work is planned before heat treatment; confirm the applicable instruction for the product you are quoting.
03 / 05
What information should the drawing show?
A drawing should let a technical team that has never seen the part interpret it consistently. Start with the view and orientation: which face is shown, which side will face the vehicle or equipment, and whether the part is left- or right-hand. Then locate the centre of each hole from agreed reference edges or datums. A note such as “near the corner” or “match the sample” may not fully define a production feature.
Next clarify what kind of opening is required. Is it a straight hole, a notch, a stepped hole or another cut-out? Is there a requirement for edge finish, surface side or a connection component? The drawing should carry the detail the real project needs without making assumptions on behalf of the processor. If a tolerance or inspection method has not been agreed, mark it as an open technical question rather than supplying a guessed value.
Ekol Glass’s technical-drawing checklist recommends showing hole centres, cut-outs, reference edges, units, viewing direction and revision. That does not mean every project uses one standard tolerance. It helps the people on each side work from one definition. If a drawing and sample are sent together, identify which one provides the controlling dimensions.
The Ekol custom tempered-glass page lists holes, cut-outs, edge work and tempering assessment among its project options. That is not a guarantee that every size or geometry is automatically manufacturable. A technical review and manufacturability response are still needed before the part is confirmed.
04 / 05
What changes when the revision changes?
If a hole centre or cut-out changes, sending only a revised dimension in an email can leave two versions in circulation. The new drawing should identify the part, revision, affected feature and whether the previous file has been superseded. If a sample is involved, say which revision it represents. This makes it easier for purchasing, engineering and production to keep one reference in front of them.
A change can affect the process plan even if the outer contour stays the same. Tell the supplier when the change was made and which revision was used for the existing quotation or sample review. An offer prepared against an earlier drawing may need to be reviewed against the new request. This is not a prediction about extra cost or delay; it is a way to keep the quotation tied to the right part definition.
For a sample, state whether it is approved or only a reference. A photo cannot replace the dimension, orientation and revision. Mark unknowns “to be confirmed” rather than presenting the plan as final.
The central point is simple: the hole is part of the geometry and processing sequence, not a small decoration added to a finished pane. Reviewing hole and edge details before the drawing is released helps clarify which definition the supplier should use and what must be completed before toughening.
05 / 05
Five checks before you request a quotation
Before sending the file, look for five answers in the same package:
1. What is the glass used for, and which way will it be installed?
2. Which drawing revision defines the hole centres, cut-outs and edge work?
3. Does the drawing show its units and the side used as the reference?
4. Is toughening required, and has the processing order been confirmed for the product family?
5. Do the sample, part number and latest drawing refer to the same version?
If one answer is not known yet, leave it as an open question. Do not create a measurement or tolerance in place of technical review. Ekol Glass’s custom tempered-glass page asks for the application, a dimensioned DXF/DWG/PDF drawing, quantity and any additional processing; its drawing checklist also recommends flagging missing dimensions and assumptions clearly.
This checklist does not replace a product standard. The requested holes, edges and glass construction should be confirmed for the actual project with the technical team and supplier. The aim is that, before a quotation is prepared, everyone is discussing the same geometry and the same sequence of work.
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