Glass Canada

Technology Machinery
In-house glass fabricating, should I upgrade?

Small to medium sized glass shops can now afford to look at...

May 9, 2008
By Enzo Odorico*


Small to medium sizedglass shops can now afford to look at a growing availability of lower cost machinery.

Historically, glass shops have had limited capabilities when it comes to fabricating their own glass. A typical glass shop has a cutting table, some manual glass cutting equipment, an upright belt sander, a portable baby sander and a table top drill. Although this machinery line-up is a ‘must have’, these tools are somewhat limited in an industry in which the applications and service demands for fabricated glass are changing.

A typical eight spindle vertical polishing machine installation that does not require a large amount of floor space. Water can be recycled in a tank which sits on the floor. Compressed air requirements depend on the machine. Bevelling machines are similar, except the spindles are aligned to swivel and work more from the front of the machine to allow the cup wheels to bevel the front surface, instead of grinding and polishing the bottom of the glass edge.

With the advent of modern glass machinery, new hardware, and the availability of tempering services expanding, the past 20 years has seen remarkable growth for interior glass applications which require a greater degree of glass fabricating capabilities. Expanding applications include;
frameless glass shower enclosures, glass partitions, commercial store fronts and entrances, store fixtures, glass railings, mirror walls, tabletops, signage and so on. Glass has never looked better!
Modern glass fabrication equipment has been expensive historically, so most glass shops have turned to companies specializing in glass fabrication to fill this rising demand. Some of this demand is still probably better left to the fabricators in the industry. However, a small to medium sized glass shop can now afford to look at a growing availability of lower cost machinery, both new and used.

Almost every glass shop has the need for some level of basic in-house fabricating capabilities in the areas of edging and drilling glass. Small to medium sized glass shops should consider equipment upgrades in these two areas in order to improve the range and quality of their in-house orders, reduce labour costs and improve their ability to service customers.

With new equipment in these areas ranging as low as $15,000 to $45,000, this can sometimes be a smaller investment decision than buying a truck. Leasing and loans for new machines are also much easier to acquire when the capital cost is low.

There are three key considerations required in making a decision to upgrade: Decide if there is a need to upgrade equipment, decide which machine type best fills the defined need, and compare options.

economical vertical glass washing machine is a good investment if your
company intends to do a substantial volume of in-house glass
fabrication. A model with an open top will allow the washing of large
sized pieces of glass without taking up a lot of space.

Which machine type best fills the need?
Straight line polisher, mitre, beveller considerations: Operation of straight line polishers is very simple. The glass is transported through the machine on three conveyors; a loading conveyor for
feeding the glass into the machine, a clamping conveyor for transporting the glass over the tooling which exposes the bottom edge to the grinding and polishing wheels, and an off-loading conveyor to support the glass as it comes out of the working section. The three conveyors are synchronized to operate as one. Because these machines usually operate from right to left, this will need to be considered when positioning the machine on the factory floor. Conveyor speed is adjustable to control the rate at which glass is removed or polished. When the glass is thicker, the machine must be slowed down to allow the grinding wheels more time to grind more glass off the edge and still maintain quality. This is why more spindles allow for faster processing and better quality.

The clamping conveyor is adjusted to open or close its gap to accommodate each thickness so only one glass thickness can be processed at a time. Only the bottom edge is processed while the glass goes through the machine. Usually four sides require processing, so each piece is normally rotated and put through the machine four times.

The benefit of these machines is that the conveyor can transport the glass evenly, thus producing a straight edge. Several pieces can be loaded at the same time, one after the other with small gaps until the machine is full with glass, which greatly improves efficiency of work. All the tooling wheels are in-line which permits a progressive grinding and polishing operation that results in a finished edge in one pass, unless the glass was not cut cleanly, as opposed to several passes if using belt sanders to finish the edge. Cup style machines are the best choice and more spindles (independent motors which support the wheels) improve the quality and speed of finish.

Tooling required includes different combinations of diamond wheels for grinding that cost about $150 to $300 each. Resin wheels for fine grinding are about $100 to $200 each, and polishing wheels are $25 to $60 each for rubber, or $20 to $40 each for felt. The more expensive the wheel, the longer it lasts. A typical small to medium sized shop may be able to process a year’s worth of glass before requiring a wheel change.

common tooling configuration for a straight line polishing machine that
uses cup style wheels. The main benefit of cup style tooling over
peripheral style tooling is that the glass rides on top of the rim of
the cup wheels for even wear which also eliminates the need to adjust
wheels for glass thickness change.

Straight line mitre machines are polishers that have a section of spindles that can swivel to produce a flat edge, like a normal polisher, or a mitred edge. The machine can be set up to produce one or the other, not both at the same time. A mitre machine normally requires a minimum configuration of nine spindles.

Straight line bevellers normally require at least nine spindles to produce a consistently good bevel. They are designed much like polishers, except that the cup wheels are aligned to cut and bevel the surface along the bottom edge, as opposed to grinding and polishing the edge itself. Because of processing considerations, it is not wise to try to find an all-in-one machine that will process both straight bevels and straight polished edges.

Double sided drill considerations
A typical horizontal double sided drill with standard European drill bits is probably the best upgrade decision from a table top drill. It produces better quality holes, allows for easier handling of the glass and reduces the likelihood of scratching and breakage while drilling.

These drills use hollow core drill bits so a direct or recycling tank water supply is required to cool the bit. When drilling, water spillage on the floor is inevitable and if there is a large volume of drilling anticipated, a drain may be necessary.

Operation is simple and involves changing drill bits in the upper and lower chuck using a wrench which can be done in a matter of minutes. Two drill bits per size hole are required. Drill bits range in cost starting as low as $10 and up to several hundred dollars for large bits. The goal is to drill the glass halfway through from both sides to produce a clean hole and reduce breakage. The drilling cycle consists of drilling from the bottom first, which is usually automatic, then drilling from the top till the glass core ‘pops’ out into a catch tray.

Because glass thickness and drill tip wear will vary, an adjustment on the lower drill bit is required for each new setup. Once the setup is tested, the actual order can be drilled by marking the centre of the hole on the glass with a crosshair, usually using a grease pencil. An experienced operator can set up to change drill sizes in less than five minutes. If the drill has a laser centering light, the glass can be quickly positioned on the machine and when the cross-hair is lined up with the laser light, the drilling cycle can be started and the hole can be drilled.

A horizontal caster table with the ability to pneumatically lift the glass off the support platform allows workers to load, off-load and position the glass on the machine without it scratching against the grindings produced by drilling. The pneumatic table and the rising action of the drill bits is accomplished by compressed air and thus will require a compressed air supply. A two to five horsepower compressor is usually sufficient.

Maintenance involves cleaning the machine regularly and lubricating the chucks with penetrating oil. Air lines should be equipped with an air dryer if possible to prevent air valves and cylinders from corroding. When considering different models, the lower drill spindle shaft should be well protected from water penetration to avoid corrosion to the shaft and bearings which is the most common repair problem with these machines.


typical horizontal double sided drill with laser light for centering
hole position on glass. It has a footprint of: eight to 10 feet long,
eight to 10 feet deep and five to six feet high.

hape edger considerations
Most shape edgers suitable for small to medium glass shops are similar in design and functionality. The glass is typically clamped to adjustable suction cups, to accommodate different size and shapes of glass, which are mounted on a rotating table. The table rotates the glass, usually at an adjustable speed past the cutting wheel. The cutting wheel is mounted on a spindle that is attached to a freely articulating arm that can be controlled and moved by the operator. This arm can be locked into position for producing circles semi-automatically.

Machines are typically one spindle machines which allow you to mount one, and sometimes more, type of tool on the spindle at a time. The operator mounts the wheel(s) according to edge profile he desires. For shaping the edge, peripheral style wheels are used. For example, different wheels are required for different edge profiles such as pencil, ogee, bullnose and so on. As well,
at least one grinding and one polishing wheel is required for each profile-thickness combination that is desired. Tooling can be costly if the intended goal is to produce many profiles on many thicknesses.

The glass is centered on the table by the operator and then clamped using compressed air. As the glass rotates, the edge is processed with one wheel at a time and may take several passes to achieve the desired result. This inefficiency is why these machines are more suited for producing curved edges as opposed to straight edges. Another reason to avoid producing straight edges on this machine is that the operator requires a steady hand to grind the profile into the edge and still keep it straight. Once proficient, many edge profiles can be accomplished for most shapes, producing beautiful results.

If you wish to also produce a bevel on the glass, the machine must be capable of swiveling its spindle to varying bevel angles. It must also accommodate cup style bevelling wheels. Bevelling requires at least four stages that include one wheel type for each stage of the process. It is very time consuming and should be charged for accordingly.

Other considerations include: water containment, compressed air, availability of water and training. Training a new operator to become proficient in the use of this machine can take as much as six months.

A manual shape edging machine can produce all manners of edge profiles on curved or straight edges.

Compare options
When the need and type of machine have been determined there are a few other things to consider before making a final decision on a model:
• Work specifications (capabilities of machine).
• Machine requirements (electrical, floor space, water, compressed air).
• Installation, training and process troubleshooting support.
• Special features or design preferences.
• Ease of operation, tooling change and maintenance.
• Spare parts, service and tooling availability.
• Total cost, including delivery and installation.
• Warranty period.
Upgrading decisions include power. Machines usually require a three phase power source and can be ordered according to the customer’s voltage availability. Depending on the voltage, size and number of machines you are installing, you will need to determine whether your building’s transformer has enough power. The vendor or an electrician can help determine this.

Cleaning glass
Although this is one of the last considerations, if you are expecting to do a substantial volume of in-house glass fabricating, an economical vertical glass washing machine is a good investment. A model with an open top will allow you to wash large sized pieces without taking up a large footprint.

For many small to medium glass shops that want to grow, taking their company to the next level often starts in the shop. Increasing your company’s profit margins begins with increasing the products and services being offered and this can be accomplished by extending your glass fabricating capabilities to meet the changing demands for fabricated glass. The growing availability of lower cost machinery, both new and used puts this within the feasible reach of most glass shops. -end-

*Enzo Odorico is the president of Glass Edging Machines (GEM), a division of Horizon Glass
and Mirror, a glass fabricator operating as Adel Glass, located in Toronto, Ontario. The company has been servicing the glass industry for more than 27 years and specializes in sourcing high performance lower cost machines.