We know the life expectancy of your blades is one of the most significant issues you face as a sawmill operator.
Understandably, you want to get the most out of each blade. Since there are so many contributing factors, blade performance is not always a simple issue. For example, blade life can be determined by the species being cut, the amount of dirt on logs, the thickness and profile of the blade, whether or not you use a lube system and the type of blade guides you have on the mill.
Even so, maintaining the blades correctly is the key!
So, this article addresses cleaning, setting and sharpening your blades. Whether you do it yourself, send them to a local service or use Wood-Mizer’s ReSharp programme, it is important to understand the right technique. Five steps….
Wood-Mizer recommends that you maintain your blades with five steps: Initial wash, Grind, Wash and de-burr, Set and Grind Again. Initial washing
cleans the blade to its original surface and removes debris so that setting, gauging and inspection are accurate. Grinding
alleviates gullet micro cracks, removes dullness and re-establishes proper tooth configuration, critical in maintaining the symmetry of all tooth angles for maximum performance. Washing/de-burring
. Without proper washing/de-burring, you will get asymmetrical angles that cause below-standard cutting performance, resulting in poor quality lumber and fee rates. Setting
puts the teeth in accordance with the Wood-Mizer pattern and sets face and back angles to the required blade profile. The final grinding
will 'true-up' unwanted twisting of the face angle and tip dullness. In this final grind enough material should be removed to eliminate tip dullness and gullet micro cracks, for increased sharp- and flex'-life. A sharp blade, properly aligned on the mill, saws with less effort and stress to the band, improving the life and cutting speed of the blade. Step 1: Initial wash - recommended
The initial wash can be done in two ways, either with or without Wood-Mizer specialized washing machinery. The initial wash in the 'field'
: Before taking the blade off the sawmill, when it is ready for changing, take an extra moment while the blade is running to flush away all the sap built up on the blade by flooding with lube for at least 15 seconds to remove as much sap as possible. If this process does not remove all the sap, we recommend letting the blade soak overnight in a tub of diesel fuel and then rub it with a wire brush to remove sap. The other possibility is to use our specialized washing machine
or contact our ReSharp service, where such equipment is a part of the blade re-manufacturing process. The washing machine removes (within one cycle) all the stains and dirt from the blade. After removing the blade from the washing machine and holding the teeth pointing away from you, use a shop towel to wipe down the blade. This step removes debris and water from the surface.
The final result of those two processes is a clean blade ready to inspect for damage and decide if it is worth sharpening. The blade is free of sap and you have good reference points for the next step. Step 2: Grind
Grinding squares up each tooth face with the body of the blade. Often, chipping or side wear (dullness) can cause the tip of the tooth to be thinner, so the first grind must eliminate such tip damage, bringing it back to full thickness. This is essential for proper setting. The blade is now ready to be de-burred and set. Step 3: Wash and De-burr
Although similar to initial wash, the wash-and-de-burr stage is different during blade 're-manufacture'. It can be done with or without specialised cleaning equipment but the special kit saves time by washing and de-burring simultaneously.
However, manual de-burring can be done by taking a wooden block and scraping the inside of the blade, to remove the grinding burr – most importantly from the top of the tooth, so that you got an accurate set measurement. Step 4: Set
The teeth in our blades are set in a three tooth pattern: left-right-centre. In setting, leave the centre tooth at zero and re-set all the teeth consistently so you have the same degree of twist from side-to-side. This way, your blade is symmetrical and will perform consistently. Step 5: Grind again – Recommended
The second grind squares the face angle to the blade and ensures symmetry.
If you try shortcuts in blade sharpening you face pitfalls. For example, many people will set first and then grind, compromising blade symmetry. Typically, blades are duller on one side than the other. If one side of the blade is sharp while the other side is dull and both sides are set at the same degree, grinding will cause the sharp side of the blade to end up with less set because the dull side requires more grinding. Additionally, if the blade is set first, it is impossible to tell how much set is left in the blade after sharpening. Think about it….
So, the next time you sharpen your blades or have someone sharpen them for you, consider the process. You will find that your blade performance will improve.
For sawyers who want to spend time sawing instead of sharpening, Wood-Mizer’s ReSharp service re-manufactures every blade that comes in for sharpening.…
Blades are inspected for obvious damage and run through our cleaning machines using hot water and steel brushes.
Next, the blades are again passed through our cleaning machines which wash and de-burr.
We set the blade using computer technology that does the following: 1) Checks for pattern errors
2) Has a bend-back feature that corrects those wild teeth that leave lines on your boards
3) Sets the blade to customers' specifications
Then, using CBN technology we grind the blade to re-establish proper tooth configuration.
If you want your blades 're-manufactured' to Wood-Mizer standards, send your blades to one of our ReSharp facilities. We have programmes in place to make shipping easy for you.
With a better knowledge of the desired end result, you are more likely to sharpen blades that perform consistently and to their full potential.