Dull blade

[Old guy, new pa]

Morning guys and gals, have a stupid question.  How do you tell when your blade is getting dull? I would like some warning that it is getting dull before it starts cutting wavy.  Hydraulic machine, so I can't tell how hard it is pushing.
Thanks in advance
Rick

[Southside]

You can hear it, also the sawdust changes. A sharp band will have a tight stream of corse sawdust coming off the band like a garden hose on "jet" setting and it will be more like cracked corn than corn starch. If you are seeing waves in the lumber it's already too dull and should have been changed before.

[Brad_bb]

Keep in mind that a band can last several logs or only one cut.  If it hits dirt, or sand, or a stone in the bark, it can dull it instantly.  

Think about the sharpness of a band being 0 to 100 percent.  On that scale, 50 percent cuts poorly and you might get waves or even a dive.  You want to cut wood in the 80+ range.  When I cut Osage I want to cut in the 90+ range.  So to stay in that range, I have to change bands more often.  That means less than one band per log If you're cutting boards.  I cut braces so I get about 1 band per log.

If you're cutting walnut, Ash or cherry the band will stay sharp much longer if you don't hit dirt/sand/stone or metal.

Bands are good for a certain number of cycles going around the band wheels.  The band it bent around the wheels and then unbent in between.  Eventually the band will fatigue from bending around the wheels and straightening out (cycles).  So sharpening is not what's going to wear your band out, it's cycles around the wheels.  So you can sharpen more often to keep your band sharp.  Your not going to consume your tooth from sharpeing before your band wear out from fatigue.  That failure is in the form of developing cracks in the gullet, and if you keep running it, eventually it will come apart/break.

This is just the way I think about it.

EDIT: I don't have a de-barker, but try to debark by hand.  I can't always completely debark though.  A de-barker will help sharp bands last longer.

[kelLOGg]

I have noticed that when my band starts to get dull it will jump forward when it exits the cut. The duller it is the more it jumps. Still cuts well but the jump serves as an indicator the sharpening is on the horizon.

[Sixacresand]

It may be just on my mill, but it is pass time to change when I hear a slight roaring sound.  The roaring occurs way sooner than squealing.   If logs are sinfully drug through the dirt to the mill, then count on frequent blade changes, even if you have a debarker.  For me, the opening face is always the one that produces the slab containing the most dirt.  

[Magicman]

My Debarker gets constant use, even on seemingly clean logs.  If I am sawing through bark, it's running.

While sawing I am constantly looking for indicators.  During normal sawing I am checking the blade by 10:00.  If it is not changed then it will be changed at noon regardless of how sharp it is.  I normally use 2-3 blades per day.

A blade that is not sharp is too dull to saw with.

[Nomad]

     A tip for someone trying to learn. 
     Touch your thumbnail to the outside corner of a tooth.  It should be "sticky" sharp.  Meaning that your nail should stick to it with no pressure.  If you need pressure to make it stick it's dull.  If it won't stick at all but just scratches, it's beyond dull.  If it doesn't even scratch, you're wasting your time and ruining wood.

[Les Staley]

Nomad, thanks for that. I used to fish salmon tournaments in Lake Michigan and if a hook wouldn't hang from your thumbnail vertically it needed to be sharpened.  Made a big difference on hookups while trolling.  

[jb616]

I run my hand over an area where there is a knot. if it is starting to get "Wavy" i change the blade. my saying? "Dull Blades make Bad things happen" Don't wait until it is real dull because you will have unusable lumber.