Judging bandsaw blade longevity

How to tell when blades are dull, and reasons they might dull quickly. August 12, 2001

How do you know how worn your bandsaw blades are? I have some that have cut around 50,000 bf on a set of ten bands and are still cutting and some that have done 15,000 bf and now don't cut so well.

Forum Responses
Do you sharpen your own or use a service? I use my bands till they break or get so small they won't sharpen. Are you setting for the kind of wood you cut, and did you hit anything? Also, are the bands the same brand?

From contributor T:
Narrow your observation and judge each band separately. When you order 10 bands, they may have come off of the same bulk reel or they may not have. Differences in performance can be found from blade to blade and identified, whereas the differences in performance from box to box may not be able to be identified.

By keeping a record on each blade you will also be able to compare your sharpenings to the factory's and the blade longevity based on the types of wood it has cut, etc.

When I first started sawing I was very particular and had reams of paperwork on each blade. The longer I saw the less critical I become and now depend on memory, which is quite inaccurate, or pay little attention at all unless there is a major problem.

I accept the fact that some blade stock will perform better than other stock and spend my time cutting wood rather than worrying too much about it.

From the original questioner:
I sharpen and set my own bands. I have found that once my bands get old, they will not hold a set and if they do, they lose it quickly. As for sharpness, I have found that even when they're old, I can put a good edge on them. The main reason I cannot sharpen a blade is because I have not kept the teeth consistent. I have heard the expression "like a limp noodle". I found that very descriptive when opening up an old band.

From contributor T:
You're right about a blade getting limp, but I have still used them with good results.

Losing the set might mean that
1. You aren't setting them aggressively enough or
2. The band is riding on the wheel or hitting the guide.

If you are using roller guides without the ability to compensate for a smaller width, there may be a stopping point at which you should "can" the blade.

To keep the teeth consistent almost requires an automatic sharpener with a cam and a very good (clean) clamping device. If the blade slips or moves while you are grinding, not only will the hook change, but so can the face angle.

I am guilty of not cleaning my sharpener frequently enough and the buildup of old stone, dirt, grease and metal filings in the clamp has put me on the job with almost useless blades.

Check your clamp.

When the blade gets down to around 1 inch wide, I toss it. I know it'll break if it's worn too much.

Does anyone have a good way to carry blades when you go out on a job? I have 3 different blades, the 9 degree and 10 degree in .045 and the .055 thick blade. If I get the 9 and 10 degree mixed up after using them, I cannot tell them apart. The Woodmizer boxes do not stay together very well after you open them, and I think they have some new carrying case but I would need three of them.

From contributor T:
I don't suffer from that problem since I use one blade configuration and create my own variation if I need it. But, having access to all this wood, I think I would build a customized box/shelf on my truck to keep them separate. That wouldn't be a bad idea even with one blade configuration, to neaten up the truck.

I've got another idea. I've used this to identify blades on the job that I miss-set or noticed something wrong with. I used a thin line magic marker and wrote with indelible ink on the inside of the blade. I noticed that the writing on the inside of the blade goes away the next time the blade is used because it contacts the guide wheels and blade wheels.

When I had a blade with damage, I would write on the outside of the blade and that writing would many times last through one or two sawing cycles because it doesn't touch much. Maybe you could write your own code on the outside of the blade in several places.

My sharpening service stamps a dot near the weld every time a band is sharpened. This way I know how many uses I am getting. When they start breaking before 4 uses, I look for alignment problems and bad tires. When that doesn't work I change manufacturers.

As for blade storage, a 3/8 plywood box carries 8-9 blades with cardboard in between. Rope handles for ease of handling. I bring a metal detector when I cut out for peace of mind.

I store my blades in a $4 trash can. I have one for sharp blades and one for dull.