Tech Talk
What is the Importance of the "Blade for Thin Kerf Ripping"?
Last month this space was devoted to the advantages and potential pitfalls of Thin Kerf ripping. The bottom line to the principle of kerf reduction is simply a better bottom line. It can be very profitable, but attention to detail is critical or it could be very costly. The first installment of this also dealt with what has to be considered before the decision is made to change to thin kerf sawing. From here the machine, the set up, the material, and even the supplier have to be considered.
Working with a good supplier is critical, because these blades can be very fragile, and although you know your product and your equipment, the job of specifying what blade will run and last in your conditions, should be primarily left to them. As I mentioned before, there are too many variables to go into every application here, but by letting the experts decide what the limits are could be the difference between a great deal of success or disaster.The material is part of the equation, in that, apart from the different species, it should be in good condition; ie Smooth ( rough wood vibrates and moves while being cut, and puts unnecessary and possibly damaging strain on the blade), and it should be dry and consistent, if possible.The machine has to be in good condition. Thin Kerf Saws on an old beater are going to self destruct. Often worse are custom built machines (a tool company's worst enemy); at least old beaters can usually be rebuilt. Mounting shafts and bearings can have no run-out. A .003" run out at the shaft will translate to 5 or 10 times that at the saw tooth, and thin saws can't tolerate run out of this degree. Likewise the rollers and/or drive chains an belts have to be clean and in good condition and properly aligned. The material has to held firmly while being cut, and worn or dirty rollers may allow movement. The fence must also be relatively free of wear and be straight. Problems in any of these areas can put lateral pressure on the blade. This will create friction and heat, leading to premature wear, poor cut quality, and possibly destroy the saw plate. Mis-aligned fences or drive rollers/chains will cause saw marks on the wood. There is little point in reducing kerf if you have to plane or sand off saw marks later, and at the risk of being repetitive these blades can not take the kind of pressure poor alignment induces on them.Take a look at the dust collection. The sawing area should be free of any build up caused by poor suction, restricted or badly placed or designed hoods. Dust collection is often overlooked when tool wear is a problem, but it does play a significant role in the economies of machining wood. In this type of a somewhat delicate application, good dust collection and pick-up could be the difference in whether the tooling works or not.Thin Kerf Saws should always be mounted on Hydraulic Shafts. They run truer, are balanced better and will add tremendously to everything from edge life, to cut quality, to the overall life of the blade. Setting hydraulic shafts up in multiple blade applications requires a little more attention than say, expansion sleeves, but is not difficult. Along this same line, the spacers must be checked. They should be as big as the cut depth will allow ( but never allowed to touch the material), and machined to absolute accuracy and flatness, for maximum blade support and to keep the blade as straight, even and as cool as possible. It should go without saying here, that they must be thoroughly cleaned (along with the saw) before each use.One thing to avoid is a thin outside sliver. It can get wedged and also cause the outside blade to wander, which will eventually destroy it. In most applications the outer saw should be a standard kerf heavy duty blade.Thin blades have also been used, very successfully, for close multiple grooving in folding applications. For this type of machining there are a few other details to consider. Suffice to say, just so long as the blade manufacturer knows what you are going to do with the blades, there shouldn't be a problem.Amperage draw has to be watched carefully. Unfortunately if you rely on any other method to determine when to take the blades off, it could be too late. Cool blades run longer and cut better. By running true and maintain the conditions described here your saws will run with the least cutting resistance, and heat build up. You can improve this even more by cooling the blades while cutting. This can be accomplished with a mist of cooking oil type substance or, if this isn't possible, a jet of cold air at the teeth.A saw blade is only as good as it's last sharpening. Maintenance and sharpening standards in thin kerf ripping have to be to the highest standards. Tooth geometry and plate tension must be kept to original specs and tolerances, if you are going to get good and consistent cutting. The principles outlined here can also be beneficial in other sawing applications, with excellent results, but thin kerf sawing, as you may realize, can be very precarious, and what you could overlook in standard cutting, can't be ignored in this type of application. by: Doug Reid, President, B.C. Saw
