By John P. Lloyd
There are two basic types of straight line edgers on the market today. One uses cup wheels, and the other uses peripheral wheels. Here we will discuss the difference between the two, and advantages and disadvantages of both.
Cup Wheel Edger
First, let’s take a look at the actual tooling for a typical straight line edger.
Here’s a cross section for a typical diamond or polish wheel. A diamond and or polish wheel in a cup wheel edger is formed in this manner:
The result is that the glass is ground and polished by the face of the wheel, and will produce only a flat grind. Arrises are produced by additional positions (motors, spindles with grinding wheels) mounted at 45 degrees, and grind and polish the arris.
Advantages are the following:
- Ability to change over between different thickness of glass instantly.
- Low inventory of diamond and polish wheels.
- Quality of the finish: Excellent, depending on how many spindles are used.
- The ability to process laminated glass with no major problems
- The cup wheel edger can only do a flat with seams (FA) profile edge.
The Peripheral Wheel style Straight Line Edger
The Diamond and Polish wheels work in this manner:
The result is that the glass is ground and polished on the edge of the wheel, producing a profile consistent with the particular shape of the wheel. This type of machine is capable of doing flat with seams, pencil edge, OG, etc. Quality of the edge is also excellent.
Advantage of this type of machine:
- The ability to do many different profiles.
Disadvantages of this type of machine:
- It is necessary to keep different sets of diamond and polish wheels on your shelf to do the different profiles.
- It is necessary to keep different sets of diamond and polish wheels on your shelf to do different thickness of glass (more on this later).
- It is necessary to change over diamond and polish wheels when changing thickness and or profiles (more on this later).
Let us now discuss the typical needs of a first-time machine buyer, who is considering purchasing a 2 to 4 spindle peripheral machine verses purchasing a 4 to 6 spindle cup wheel machine. For simplicity’s sake, we will discuss using a 2 spindle peripheral wheel edger verses using a 4 spindle cup wheel edger.
If a prospective machine buyer were to obtain pricing for wheels to fit a 2 spindle peripheral wheel edger verses a 4 spindle cup wheel edger, it would be quickly apparent that a cup wheel is more economical to run. Both, will, in fact product more or less the same quality edge, which in this case would be a semi-polished edge.
Also consider that the peripheral wheel machine will be limited to processing only 1 profile per set of wheels. While it is possible to process more than one thickness of glass with a peripheral wheel machine many users of peripheral wheel machines prefer to change wheels when changing thickness. I’m sure that there will be a few who will argue this point, but I base my opinion by my own experience, and those of the many companies that I have dealt with over the years. It is also an absolute must to change wheels when changing profiles, such as going between FA (flat with arrises) to PE (pencil edge).
Which machine is the right one for the first-time buyer?
|Cup Machine||Peripheral Machine|
|Higher initial machine cost||Lower initial machine cost|
|Lower overall operation costs||Higher overall operational costs|
|Only able to process flat/arris edge||Able to process flat/arris and pencil edge|
|Changeover between glass thickness takes only seconds||Changeover between glass thickness takes an average of 15 minutes|
|N/A||Changeover between glass profiles takes an average of 15 minutes|
*One important thing to take in consideration is that the above machines only produce a satin to semi bright edge.
If the company seeking their first machine needs a high-quality bright edge, then the only type of machine for consideration is the cup wheel machine.
For this type of work, at least 6 spindles would be needed, and at least 8 spindles if the company wants to produce ¾” “furniture quality” edges.
This information is presented for the prospective buyer who has a need to know the insides of the machine that they are considering — a consumer armed with facts will be able to make an intelligent decision that will bring the best value for the investment.