A single issue I would like to help sawyers better diagnose is the aggravating problem of dealing with the timely breaking of bandsaw mower blades.
This can only be answered with a series of questions to troubleshoot the problem correctly. If you call us with this problem, here is what I will ask:
Question… What kind of strap wheels do you have?
I have found in recent times that most major mfg’s get away with applying untrue band wheels for the straightforward reason that there are so many regions for which blade breakage might be blamed.
Band wheels which might be untrue will snatch the blade typically apart. Example: Some sort of 19-inch wheel is usually 4. 97 ft throughout the wheel (circumference). A tiny band speed of 4970 ft per minute would that wheel turn 1000 RPM.
Which is 16. 66 times per second. Multiply sixteen. 66 RPS x four. 97(cir) = 82. eighty feet per second associated with the band being pulled via his cut. So if you’re using a 13’2″, for example, which blade makes a total revolution 6. 24 occasions per second? During every revolution of the band, you will find two wheels it must bypass. So 2 x six. 24 equals a minimal 12 times per 2nd that a band goes around the wheel. That’s a mile every sixty seconds!
When the band wheels turn out to be the culprit of broken cutting blades, I find they are usually out of round by a minimum. 015 of an inch or even worse.
Now multiply two wheels x. 015″ from round and you get. 030″ that the band wheel is snatching (stretching the blade) per revolution. There is a. 030″ stretch happening in the area between guides and another. 030″ in the non-cutting area. This particular totals a stretch of the edge or a potential stretch from the blade by 60 countless numbers (1/16th of an inch). This particular shock is happening on 12 occasions per second!
The music group simply can’t take these penalties.
Many V-belt sheaves (pulleys) are out of round through. 015″ thousands and have the v-belt tucked in the v-grove. This v-belt becomes a rubberized shock absorber. This seat belt is the only reason the v-belt sheave can work, becoming so out of round.
The actual v-belt shock absorber must be changed on regular periods. If the belt gets used internally (which you cannot notice or measure), it stops working internally and loses the ability to absorb shock. At this stage, the blade is struggling greatly, and blades start to break, seemingly without a trigger.
Question… Were the mower blades rising or diving ahead of they broke?
If they were, that would account for the breakpoint, and diagnosing the reason for typically the rising or diving could be the next step, which is frequently a blade body flatness issue. A great amount of stress and heat is currently being administered to the band. A fantastic cutting sawmill blade gets the least amount of stress.
Problem… What kind of blade guides are there?
I believe that roller courses are the best for cutting 6 inches or wider. I possess proved this in hundreds of instances. I believe that sandwich courses are the best for narrow reductions such as pallet resaws lowering 6 inches or less.
When using sandwich guides, significantly, your wheels are real. If the wheels are not real with sandwich guides, typically, the blade will hammer the guides up and down as the tire goes up and down with every single revolution.
Most resaws get steel wheels, but for individuals who end up with belted wheels, I would suggest applying roller guides because the added wheels are out of round; the cutting tool life will always be less than your competitor who has true stainless steel wheels.
Question… What kind of tensioner do you have on your sawmill?
I love tensioners that can give as well as take. When the blade extends during the cut and warms up, a spring or even an air tensioner will take the actual slack, and when the music group is out of the cut, it will cool down, and the tensioner will offer back to the band.
The hydraulic tensioner is lifeless tension and will not take or even give during the sawing procedure. I am not saying Hydraulic will not work, because many of you reading this article understand you are sawing every day by using it, but it contributes to bad blade life.
Question… Would the blades break from the top or the back?
This is important to see. The first break will have discolorations, and the last will be bright steel. A music group is breaking from the front because of stress. It could be through sawing stress, too much edge tension, bad wheels, or even grinding stress.
When the edge breaks from the back again, I have found that 95% of the time, it has taken on harm from something dragging within the back of the blade. Like a bearing that should be spinning readily but is dragging about the back of the blade, do away with a bolt, or do away with a guard.
All of these things make an instant heat that crystalizes the surface of the back of the cutting tool and causes tiny fractures to form. To identify this, fold the blade and look at the back of the blade, and you may notice multiple cracks. Almost all sawmills that use backup bearings on the guide system require inspection daily.
Question… Do the actual blades break in the first operation or after sharpening?
If they are busting on the initial run must identify if you’re running your cutting blades too dull rather than altering them at the first indication of dulling.
Secondly, many people report that it splits in the gullet after they develop the blade. This could be brought on by running too dull or grinding too hard in the gullet. If you’re grinding so hard and fast that it leaves a huge burr on the back part of the gullet, it is not great for the blade. Grind as lightly as possible to allow the actual grit of the rock to slice rather than melt the metal away. A ceramic Stone works best on the Cook’s Kitty Claw sharpener.
I hope it has helped you with a little more understanding of how to troubleshoot busting blades. Please keep in mind that whenever you make a correction, you will need to use a new sawmill blade to verify if you have fixed your problem. The stressed blade will never operate like a new blade.
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