Vive la différence
By Trevor Shpeley
June 21, 2016 - When it comes to saw filing, definitive rules are hard to come by. What works for one saw filer might be a disaster for another. If you have two mills from the same company manufacturing the same products with similar equipment, the natural assumption from mill managers and purchasing agents is that standardization should be possible and profitable – and sometimes it is. But more often than not, the success of the first mill can be difficult to duplicate in another.
The problem with attempting uniformity between sawmills is that every combination of machinery, employees, wood diet and environmental conditions produces a different animal. The same can be said for saw filers. How a person sees light and shadow, how tall they are, their physical strength, their experience, and even how they hold their hammer, will all affect how that person works a saw and what the end result will be.
Sure, there are basic standards within the trade that you can reasonably expect to be consistent – tire-lines will be more or less where you expect them to be; saws will be as level as possible and tension will be the correct amount to run properly for the application. But here’s the rub, it’s how the combination comes together that is more important than what each individual component looks like, and that is controlled by the experience and preferences of the filer.
For example, a question that gets asked often is, “Why do they all have their own saws? Aren’t they doing them all the same? Shouldn’t they be able to have ‘common’ saws?” The simple answer is, “No, not usually.” Whenever circumstances force filers to work each other’s saws the result is seldom ideal. Cracks appear in saws that have never cracked and benchmen are heard grumbling about how their saws have been changed by the other benchman. Theoretically, they haven’t been changed at all since they all have the same target, but in reality, small changes in a balanced pattern can have large consequences.
One of the variants is in how a filer gauges tension. In a bandsaw for instance, the two most popular methods are “light gap” and “black to the gauge.” In the first, the saw gauge is ground so that when held to the saw, a thin sliver of light shows from edge to edge and the filer uses that gap to tell if the tension is uniform and that the amount is appropriate. A small amount of pressure is then applied to the gauge and if all is well then everything would go black. Most benchmen use this method but it is subjective to the way a benchman holds his gauge, the pressure that is applied, etc. The filer gets used to seeing what he expects to see in a properly benched saw. Someone else may view the same saw differently.
Other filers prefer to use a tension gauge that is ground to the curvature of the desired tension. When the saw has been levelled, the filer looks for no light between the tires when the gauge is held against the saw. The disadvantage to this method is bumps and tension problems can masquerade as “perfect” if a benchman isn’t very careful with what they’re doing. The black-out method is more often used by very experienced filers. Again, the angle of the gauge, the pressure applied, all change the sight picture for different filers. Is there a right way and a wrong way? To a certain extent, yes - you can’t just do whatever you like and expect a positive result - but a filer that is confident in his chosen method will produce a better product every time.
When it comes to levelling, I myself prefer to use levelling rolls whenever practical. I believe that it does less damage to the saws, produces less filer-created bumps and is faster. My colleague, who is an excellent benchman, prefers the hammer. He isn’t wrong and neither am I, both methods work and the saws look a little different afterwards but everything runs and it runs properly. Metcalf vs diamond dresser, this brand of saw vs that, a V-gauge vs an RPM gauge, the list goes on and on…
The bottom line is that there is no bottom line. A saw has been done properly when a filer has put all of his/her knowledge and skill into the task and the saw subsequently performs properly for the full length of its run. Almost every filer will produce a different looking saw from one done by an equally skilled co-worker but they will usually run uniformly. That’s the beauty of saw filing.
Trevor Shpeley is the head filer for Tolko’s Kelowna division and is currently the financial secretary for the BC Saw Filers Association.