Understanding Blade Flatness

Let me share a little history of how I came to understand the role that blade flatness plays in consistent cutting.

Since we starting offering sawmill band blade rolling equipment to the thin kerf industry about a year ago, I spend quite a bit  of time on the phone dealing with the same issues and questions from those who question or even refuse to believe the role that blade flatness plays in consistent cutting.

So I am going to list the statements or questions I hear most often and if you find your thoughts listed then please read this article.

Here are frequent comments and questions concerning flattening or rolling bandsaw blades:

Do you really think the flatness of a bandsaw blade is that important?

I have never flattened a blade before, why should I do so now?

I have heard other band saw distributors say it is all in a man's head.

I don't want to roll a band.

Do you really think it makes a difference in the winter (frozen logs)?

My blades are sawing up and down and my lumber looks bad!

I don't believe that it will help me.

My sawmill manufacturer said it does not make any difference.

My blades are cutting good. Just some of them want to dive in the cut. I think it is soft teeth and they get dull easily. It can't be a flatness issue.

When my sawmill blades dive I always thought it was the “set” difference. But come to think of it, I have never stopped a blade from diving by changing the set.

Why should a new sawmill blade have to be rolled?

The band manufacturers should make blades that do not need rolling.

Blade Flatness Does Plays a Role in Consistent Cutting...

I have been rolling sawmill blades of the 1-1/4 to 2 inch wide since 1992. Before that I benched and repaired wide bands and I hammered and repaired circle saws. I followed the footsteps of my father who was one of the most persistent hard working saw repairmen that I know. He instilled in me the desire and drive to solve any and every problem that would arise with saw blades. He also instilled in me honesty and integrity. He taught me that having accurate facts is the only way to solve problems.

I know with confidence that flattening bandsaw blades does make a difference and that difference is improved and perfected performance. Simply put: If you want to run at optimum cutting speeds with accuracy, you will have to roll your bands.

If you like limping along occasionally running good and sometimes cutting mediocre and sometimes just plain not being able run, just keep doing what you have been doing and you will receive the same results. But, if you want to improve you will do well to listen to what I have to say.

I can assure you that I have put much time, study and experimentation coupled with customer feedback into this process.  This allows me to deliver accurate and improved information to the cutting industry. The information that I give about band saw rolling is very true and accurate.

To the many sawyers who have learned the truth of flattening and rolling this information is like preaching to the choir. You are sawing faster and more efficiently than those who do not roll their bands. This information is for those who do not understand the truth. You are not sawing as fast or efficiently as those who have learned to roll, you also are wasting time and energy when your blades don't cut well. If you will put forth the effort to understand what I am sharing with you, it will be to your benefit.

I want to share a little history of how I came to understand the flattening process.

In the late 1980's the thin kerf band market started taking off and doing things that many of us thought impossible. The technology moved forward with a fast pace. Men began to saw better and faster with 1-1/4 wide bands, and the industry became more dependant on thin kerf bandsaws. Therefore, a greater demand on Saw manufacturers to produce better and stronger blades came into play. This demand was also put on the welding distribution centers. In my desire to grow my sales and provide a consistent product for my customers I kept running into a problem that was a mystery.

Here is the problem: Customers would have some blades that cut very good and some blades that cut mediocre and some that just would not cut at all. Everyone in the industry would say we just got a bad batch of steel. Those blades that cut mediocre would quickly become worse and soon would not cut.

A person could sharpen and set the blades and they would cut for a few cuts and begin to dive, acting like a dull blade. Some would say these blades are soft and will not hold their set. Some would say the tooth is soft and will not stay sharp. Regardless, the blades would only cut very little and very slow before they began acting like a dull blade.

I would get the blades returned and report to the manufacturer that the customer thinks this is bad batch of steel. I worked very closely with Dave Purinton with Simonds Red Streak. Frankly, I believed that some steel was good and some was bad. I provided Dave with these so called bad blades for analysis in their lab. Simonds would report that the steel tested to be within specification and the tooth hardness was within spec. I think that even Dave thought for some mystical reason that some steel just did not perform well. Even so Simonds would credit customers for what we thought was bad steel.

This problem ate at me. I was convinced, when told by Dave, that the processes of manufacturing the steel are guarded closely by quality control for consistency of material and heat treating. Upon this conviction I wanted to find a cure. So I asked customers who got good blades to send me a sample and send a sample of blades that would not cut. I cut the blades into pieces and would sit and examine the blades.

One day I remembered an article that was written in a book about sawblades in my Dad's library. The article was written in 1950, and one paragraph mentioned flatness of 2 inch blades. The author said: “Most people do not understand that these narrow bands have to be tensioned and flattened just like the wide bands do”. He went on to say that many people did not know how he ran narrow saws to cut as straight as he made them cut. I decided to put this information into practice based on my experience of wide bands.

I first concentrated on tension and did not consider flatness. I was successful, but just by coincidence. The coincidence was that my adapted roller happened to change the curvature that was causing the problem.  It made the band flatter, and that improved performance. Although I was concentrating on the tensioning side of things I was about to discover the true solution. I was taking bands that were diving and would not cut, and tension rolling (also called benching) them and they would cut better than average. But, customers would occasionally say some blades are not cutting as well as others. So I persistently continued to experiment and soon found that flatness was the key.

So I put my main concentration on flatness as I experimented, and for the blades that I shipped to customers. This proved to be the consistent thing that solved the mystery of the diving blades.

Now, even today I continue to prove and solve problems that seem a mystery to many people simply by flattening the bands. For Several years I did not tell anyone what I had learned. But about 7 years ago I decided to share my discovery with the thin kerf industry.  I started telling the industry about this solved mystery. Many understood quickly, but many did not want to understand. For those who understood and put the knowledge into practice, they improved to maximum performance. For those who would not take the knowledge, they still get the same mediocre results.

This is accurate: There are 3 parts to band blade performance.

#1 is the blade must be sharp.

#2 the blades must be set enough to clear the blade body

#3 the blade MUST BE FLAT.

This is also accurate: Today there are 2 types of sawyers.

#1 Sawyers who are the wisest and most productive; these sawyers have the equipment to Sharpen, Set and Flatten their blades. They understand all 3 parts to blade correctness.

#2 Sawyers who reject flattening their blades although they will sharpen and set. They believe that the set or bad steel makes a blade dive. These sawyers will improve performance and consistency if they will open their mind and learn this technology. If they don't they will be the only ones who are left behind, fighting the battle of lower rate performance.

It is to your benefit to take this knowledge that I’m sharing with you and make it your own.

Until Next Time,

 

 

aka... the "Saw Doctor"
Co-Owner CooksSaw.com
Leaders in Bandsaw Technology!