Resolving Crooked Cuts - Lesson #6

By Larry Anderson
Technical Advisor

Analyzing Issues Related To The Blade:


1. A dull blade will generally cut crooked.

2. A blade should be discarded if the cut time grows by more than 50%. For instance: 20 cuts have been made and the cut time has been 10 minutes per cut. Without making any other adjustments and the cut time becomes 15 minutes chances are very strong that this 15 minute cut will be crooked.

3. When the cut becomes slightly crooked the operator must reduce the feed force of the saw.

4. The rate of the fall must not be faster than the cut. Meaning that there must be a "hole" for the blade to fall into. If there is no hole and the rate is faster than the cut, the cut will generally be crooked.

5. The guide arms must be closed to as close to the piece as possible. For instance: There have been calculations made that a 1" .035 blade must have no more than seven inches exposed between the guide arms. There can be no guarantee of a perfect cut if the blade is exposed more than seven inches. With 1-1/4" .042 blade the same applies except the opening can be 11" and the expectation can be a nearly perfect cut. So what to do if you have to cut a 14" piece with a 1" blade? Again, use the same speed (SFPM) but slow down the feed. This type of cutting has a great potential for early blade failure and is most certainly a cause for crooked cuts.

6. Blade being used should have 12 teeth in the material. Obviously this rule is hard to control. Basic rules of the road: Never have more that 24 teeth touching at one time. For instance: A 4-6 blade has an average of 5 teeth per inch of blade. The operator wants to cut a 3" round solid, meaning that on this piece there are 15 teeth touching (3 x 5 = 15). As mentioned earlier, twelve teeth might be ideal and 24 is maximum, therefore a 4-6 blade would be optimal for this cut. Every shop should have several different tooth sizes to handle the variety of pieces that the operator needs to cut. Wrong selection of tooth sizes can cause a crooked cut.

7. If the coolant is not lubricating the blade the blade will get hot, the blade will be ruined and the cut will be crooked.

8. Different types of materials must be cut with different speeds. If the operator fails to change speeds when changing types of material the blade will become dull and the cuts will become crooked. A sawing myth: Many people who have crooked cuts assume that "ONE SIDE" of the blade i.e. the set has become worn thus causing the blade to cut crooked on that direction. This is pure fiction. The blade will cut crooked because it is dull and never because of loss of set on one side of the blade.

If you have started to have crooked cuts there is a lot to think about. If you are cutting "expensive" material you must solve this problem in a hurry. Cutting 100 pieces that you have to throw away can be an expensive enterprise.