Glass stair railing design
Glass stair railing design is popular nowadays but it requires experience in assembling and fabricating with thick heavy sheets of glass. As well, you need to control costs since even with modern CNC glass cutting machines there is a lot of waste which the contractor has to pay for
Glass stair railing panels also have to be tempered which means they have to be accurately cut first time because the tempering process does not allow you to go back and make changes to the size of panels if holes do not line up to stair treads.
Designing for stair treads & handrails
Glass panels are attached to the stairs using metal fasteners. The fasteners for stair treads and handrails require oversize holes to be made in the glass for plastic bushings. That way metal fasteners do not make contact with the glass. Tempered glass and metal really, really do not get along!
The oversize holes also accomodate minor adjustments necessary to align neighbouring glass panels as well as attachment points in stair treads that might be slightly off center due to site conditions.
3d layout of the panels helps because you can visualize the installation of the panels to make sure there wont be any interference points. It also allows you to turn the glass panel drawings into DXF files which can be loaded directly into a CNC glass cutting machine.
CNC glass cutting problems
In some shops plywood templates are made to the exact size of the required glass panels then these are photographed, the photos scanned and then the scans sketched over to provide CAD information for CNC glass cutting. This process can cause all sorts of errors.
By scanning digital photographs, errors can be caused by shadows and improper lighting of the plywood templates. The person sketching in CAD over top of a photograph, or the scanner reading a photo and recognizing the edges of the panel can mistake a shadow for an edge, causing expensive mistaken dimension errors.
To make this worse, the carpenter or contractor ordering the glass has to pay for the entire sheet of thick glass used in the cutting process including the scrap. Something that is often overlooked in price per square foot estimates. Stair panels are often irregular shapes the leave large amounts of offcuts. Its not uncommon for the price of a panel to be doubled due to scrap.
3D Design as a stair tool
Providing the glass cutter with DXF files eliminates errors due to sketching over a photograph, or depending on scanning software to recognize edges. It also gives the carpenter a means to check fit and alignment before commiting to an expensive glass purchase.