How to Avoid "Wavy" Cuts

Many operators know this problem: during sawing, "wavy" cuts appear. The problem is really serious, but you can solve it. Let us examine, step by step, all the factors affecting the sawing process. There are four of them: the operator, the sawmill, the blade, and the wood.   

The Operator 

The first point on our list can sometimes become the last one. Correct sawmill alignment, cutting rate, and blade choice depend on the operator. The cutting rate should be very close to the maximum for the given wood type. If the cutting rate is not high enough, the surface looks like goose bumps. If the cutting rate is too high, the blade has no time to cut, so "wavy" cuts appear.   
 
Special attention should be paid to sawmill alignment. Very often, even experienced operators don't pay due attention to the sawmill condition. They say this procedure takes too long. So they service the equipment irregularly. Of course, the adjustments and repairs to the sawmill take time. We recommend regular check-ups of the sawmill. The sawmill must also be checked when the blade guide rollers hit a log. To check does not mean to align, and this procedure takes very little time. The operator should also monitor the blade's condition.   
 

The Sawmill 

Let us view what components of the sawmill can affect the appearance of "wavy" cuts. 
 
Blade guide rollers. Proper positioning of the rollers and the blade guide arm gives added blade stability in the cut. Correct blade guide positioning is checked using the measuring tape and the alignment tool provided with the sawmill. This tool should be kept separately from other equipment. If this tool is damaged, we recommend you buy a new one. 
 
So, let us examine the rollers. They should not have any “flats”, which may cause blade vibration. There should not be any scratches or cuts on the flanges. Moreover, you should check the bearing condition, and if necessary, replace them.
 
The rollers should also be checked regularly for mounting. If they become loose or if any adjustment bolts are missing, the necessary repairs must be carried out immediately.
 
After all defective parts have been replaced, you should complete the guide roller adjustment process. To provide evenness of roller pressure and parallel cuts, you should check that the blade guide arm is running parallel to the bed rail along its whole movement. This procedure is often missed or performed incorrectly. This can result in wavy cuts. Check also for any slackness in the blade guide arm.  
 
B57 Belts. Use only Wood-Mizer-supplied belts, as they are specially designed for sawmilling. Check them often. If they are worn too much, replace them immediately, as the edge of the wheel can begin touching the blade and cause breakage.

Blade Lubrication. Use it. It keeps your blades sharp for longer. It’s something simple that many sawmillers don’t do.
 
Blade positioning on the wheels. Incorrect blade positioning on the wheels is a common cause of wavy cuts or premature blade breakage. Manufacturer guidelines regarding blade overhang on the guide wheels must be strictly followed. In most cases, this means maintaining a 3–4 mm gap between the edge of the wheel and the gullet of the blade.

Blades 

Having made sure that all adjustments of the sawmill are correct, we proceed to the main cause of "wavy" cuts - the blade. First of all, you should remember that it is essential to sharpen and set blades correctly. Very often, "wavy" cuts appear when you try to saw with a blunt blade. Too little set also significantly decreases the cutting rate. 
 
The proper geometry of the teeth allows for straight cuts and extends the blade’s lifetime. 

Regular inspection should also include checking the settings of the sharpener and the setter. Wear of clamping components leads to inaccuracies in sharpening and setting. For example, a worn sharpener clamp will result in uneven tooth height on the blade, which significantly affects cutting quality and blade life.
 

Wood 

Let us review the wood characteristics that affect the appearance of "wavy" cuts. First of all, we should note irregularities in the log. Usually, the log core has less density than the outer layers (especially in softwood species). That is why there is more sawdust while sawing the core. The blade in these layers performs poorly during sawdust removal. As a result, the back of the blade warms and expands. The blade bends, and we get "wavy" cuts. It is challenging to select blade parameters so that it cuts equally well in the inner and outer layers of a log.  In normal circumstances, the correct profile for the wood to be cut will give you good average performance. 
 
Most operators are aware of the problem of "wavy" cuts when cutting not fully frozen wood. It refers to the seasons when the air temperature is consistently below zero. Usually, fully frozen logs pose no problems. The choice of the right blade profile for frozen wood will alleviate most problems. 
 
Often, problems occur when cutting extremely pitchy wood. The problem is that sawdust and pitch stick to the blade; this is just like the blade thickness increasing. As long as the kerf is not changed, the blade sides begin rubbing against the timber in the cut, warming up, and, with a decrease in tension, "Wavy" cuts will occur. We recommend brushing or spraying a chemical agent onto the blade. Dishwashing detergent is popular and can be used in a water lube. 
 
Wood-Mizer designed the LubeMizer system, which delivers the lubrication and cleaning agents onto both sides of the blade in a precisely controlled manner. We advise you to buy this system and use it when cutting extremely pitchy wood.                    
 

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