Why Do I Have To Roll My Blades?

Why Do I Have To Roll My Blades?

by Tim Cook

Why do I have to roll my blades? I should not have to! The mfg that made my mill said that I will not have to! I don’t want to roll my blades! I am not going to roll my blades!

If you read much on forums or talk directly to band saw blade or sawmill manufacturers trying to sell you on their product you may hear that if you purchase their sawmill or their blades then you won’t have to roll them.  They may say things like “Our sawmill has belted wheels that do not cause the blade to have to be rolled...” or go even so far as to say “The Cooks sawmill has steel wheels and that is why you have to roll their blades or “Their blades are made of a steel that has to be rolled…”  Here is the cold hard fact of the matter:  there are no exceptions to the rule of anti-clastic curvature; NO EXCEPTIONS.

There are a multitude of problems that sawyers experience that are caused by anti-clastic curves that are simply blamed to something else.  I have heard sawyers say things like “I have never rolled my blades why do I want to start now?” My answer is “Do you want to saw faster and straighter?”

Here is where pride can get in the way. If I share factual and provable information that a sawyer does not know after declaring that he already knows what he needs to know then it is automatic refusal of information. Because after all is said we don’t want to think that someone knows more that we do.

How could a sawyer saw for 8 yrs for example and never roll a blade and now he needs to?  Simple.  We can only do as good as we know.  Sometimes we simply don’t know better so we can’t do it.  Here is what one sawyer told me:  “I have never rolled my blades and why should I start now because I get 15 sharpenings on my blades and I am happy”.  He even said they cut great!  So I immediately considered what he calls great and what I call great are two different things.  So I ask him if he sometimes sharpens a blade and it only cuts one log and then he has to pull it. He said yes.  So I ask if he counted that as a sharpening, and he said ‘of course’.  I told him that particular blade should not be counted as it did not perform even up to a minimal standard. I also told him that if he would keep up with that blade he would find it never cuts much lumber.

The problem is that I was taking away his bragging rights on 15 sharpenings.  Sometimes sawyers like to count sharpenings when they should be counting lumber sawn per blade.  So I ask him to put a straight edge utility knife blade in the straight area between the guides across the width of the blade so he could witness for himself that the blade is not flat and has a high middle line ridge (which makes a blade want to dive down as well as pulls extra hp and acts like a dull blade). He found just what I described.  So he decided to purchase a roller and his blades started cutting much longer and faster with each band cutting very good every time installed.  Then the sharpening count went down and the lumber amount went up…so now he spends less time sharpening and more time sawing.

The fact is - we sell more rollers to people who have belted wheels than to steel wheel customers.  Why is that?  Physics.  Specifically, anticlastic curvature.  It happens on all wheels on all sawmills with all blades. NO EXCEPTIONS.   So why do sawmill manufacturers with belted wheels still say you don’t have to roll if you use their mill? Some are so bold as to call it voodoo or a sales gimmick to sell band rollers. Actually it would be easier if we didn’t sell band rollers at all and just do what most sawmill and blade manufacturers do and blame bad sawing blades on your machine, your sharpening, or your setting.  Better yet (for them) they can sell you the next best hook angle they have to offer to fix your sawing woes.

Rather, we want to educate you so you have facts in order to help you saw straighter and faster which saves you money on blades and potentially makes you more money on lumber production.  Isn’t that what any good company would do? What we do is educate people so that they can end up making any blade cut better.  What would people say if I said that rolling only works on our blades?  Maybe that will entice the other manufacturers to start saying ‘No it doesn’t, it works on ours as well’. Who knows…

Either way someone is not telling the truth.

Here as some basic rules:

1.  Wheels that are true cause less blade body curvature and will saw faster

2.  Belted wheels are never true and therefore cannot allow for optimum performance

That is why we choose to offer steel wheels because we can grind the wheels with the perfect crown to be perfectly true and true steel wheel will saw faster than belted wheels because it is true.  Steel wheels don’t change day to day. 

So at the end of the day you really need to consider some credentials, some qualifications if you will of those making this or that claim.  I will give you a few:  We have been rolling and flattening blades since 1992, prior to that we were experienced in tensioning wide blades and circle saws which has altogether led to a long history of understanding steel flatness and tension. We have rolled and taught people to roll hundreds of thousands of blades. Our success ratio is 100%; meaning that 100% of the time rolling works and anybody who has properly used a roller knows that to be a fact. It always increases production and it always causes the blade to run longer between sharpenings.   If you don’t believe it, try it for yourself. Keep a blade ‘journal’, put what I’m saying to the test and see the results for yourself.  We have thousands and thousands of logged blade journals from experimenting and field testing and the results prove over and over again that flattening a blade improves both performance and life.

Essentially we’ve concluded that it takes 3 things for a blade to perform consistently every time:

1. It must be sharp

2. It must have enough set to clear the body; not perfectly set but enough to have clearance for the band body to clear through the cut

3. It must be flat – It is more important how flat a blade is rather than how perfect the set might be

The reason is when you saw three things are happening to the blade:

1. Teeth are getting dull

2. The set is wearing down

3. The blade body is changing in curvature

Set can be off .005 + from side to side as long as the lowest side is clearing. The flatness needs to be within .001 to .003 and the dished side must be controlled to be on the inside of the blade (the side that rides against the band wheel) and the closer to .001 the better.

Additionally, most people do not know that the vertical alignment of the band wheels (on a horizontal mill) works hand in hand with the flatness of the blade (we have an article online explaining in detail about vertical alignment). That is why one person may like more or less dish on the inside of their blade. The understanding and use of a roller will help a person decide whether to adjust the vertical alignment of his mill or not.  We build our sawmills so alignment can be adjusted at any time if desired.  However, there are manufacturers welding them in rigid without adjustment. While trying to simplify it for the sawyer they have actually limited the sawyers ability to tune their own sawmill.

If I could only have only one machine at my sawmill and could not afford the setter and sharpener I would choose the Band Roller first.  Because sometimes new blades are not of the flatness that a particular sawmill may need.  Even though you may have a lot of trust in your mfg, the fact is not every sawmill coming out of the same facility is exactly the same. They are not all built by the same person on the same jig set up.  Even car companies who use some the highest technology in the world for assembly know that to be a fact.  So every sawmill can be slightly different even when built by the same company.  With a roller you can adapt the blade to saw straight on any machine if it is set and sharp.

In conclusion:  Do you want to saw straighter and faster with lower tension?  You can accomplish that by maintaining flatness. Those who don’t are not going to get max performance from either their blades or their sawmill; it’s a fact. If you want to take the mystery out of why some blades cut good and some don’t  then it is simple - flatten your blades. Do you want to stop the blade from rising or diving when you enter the cut or as you saw a knot?  You now have the answer.

Our goal is to help you make more money. This can be a tiring process because of the excess of bad information that seems to be propagated by companies who should know better.  Telling people what they want to hear does make things easy but we will always give you the truth and it can help you make more money. We have even had a few sawyers tell us that this information kept them from going out of business. So if you haven’t tried rolling blades, give it a try. It will change your view and your profitability.