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How do you determine its time to change out blade.

Started by Mt406, May 02, 2016, 09:42:26 PM

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Mt406

I know the answer when its dull.
OK being a band saw green horn.
this is how I did it.

It was taking more power to maintain speed ( loading engine down)
When blade came out of log the carriage would pick up speed.
Dulling on tips of teeth.

Thanks
 

Cazzhrdwd

Quote from: Mt406 on May 02, 2016, 09:42:26 PM
I know the answer when its dull.
OK being a band saw green horn.
this is how I did it.

It was taking more power to maintain speed ( loading engine down)
When blade came out of log the carriage would pick up speed.
Dulling on tips of teeth.

Thanks


New blades will cut straight when dull, as you said just slow. That is one sign of needing to be changed.

Most of the time for me, the cut gets a little wavy.
96 Woodmizer LT40Super  Woodmizer 5 head moulder

Mt406

The waves you are talking about maybe 1/4 apart.

Kbeitz

wavy... Really dull blade.... One of my very first cuts with junkyard blades...

wavy



 
Collector and builder of many things.
Love machine shop work
and Wood work shop work
And now a saw mill work

Bandmill Bandit

each species is a bit different, but the mill will tell you by sound and feel as well as the quality of the sawdust coming out of the chute AND you will start to see strings that get longer and more ragged with most woods.
Skilled Master Sawyer. "Skilled labour don't come cheap. Cheap labour dont come skilled!
2018 F150 FX4, Husqvarna 340, 2 Logright 36 inch cant hooks and a bunch of stuff I built myself

YellowHammer

Good question, here are a few personal experience favorites on my list :D

When the band jumps up or down when you exit the log.

When the band doesn't follow the debarker groove anymore.

When the saw dust rooster tail starts jumping up and down when it didn't used to.

When the saw is loading up but you are not sawing any faster.

When they look like Kbeitz's boards.

When they start to leave blue streaks on the boards indicating the set is reduced enough for the body to rub the kerf.

When you see torn fibers on the surface of the boards.

When you see torn strings on the kerf exit.

When you are about to saw a customers high dollar log.

When you have no more sharp bands to change to so you're stuck with the one already on the saw.

When you start hearing a rhythmic "schiick, schiick, schiick" sound.

When you hear a loud "bang" and the band is not a band anymore. Typically not long after hearing the "schiick" sounds.

When you hear a "zing" indicating you struck iron.

When you say to yourself "that doesn't sound right...."

When you see that your shiny silvery band has turned black.

When you see smoke coming out of the log, typically when sawing dried beech, hickory or pecan.

When you cut a notch into your backstops.

When you just barely skim the paint off the log clamp.

When it's lunchtime. ;D

When it's quitting time  8)

Have fun, be safe.

YellowHammerisms:

Take steps to save steps.

If it won't roll, its not a log; it's still a tree.  Sawmills cut logs, not trees.

Kiln drying wood: When the cookies are burned, they're burned, and you can't fix them.

Sawing is fun for the first couple million boards.

Be smarter than the sawdust

Ox

This is the only time a manual mill is better.  It'll let you know quite readily when it's time to change blades!

Technically, when you look at a tooth and the sharp, perfect corners are a little rounded and shiny, it's no longer sharp.  It'll still cut, but for how long?  Nobody ever knows.  I'll usually push mine until it starts getting just a little wavy in a knot somewhere.
K.I.S.S. - Keep It Simple Stupid
Use it up, wear it out, make it do or do without
1989 GMC 3500 4x4 diesel dump and plow truck, 1964 Oliver 1600 Industrial with Parsons loader and backhoe, 1986 Zetor 5211, Cat's Claw sharpener, single tooth setter, homemade Linn Lumber 1900 style mill, old tools

Kbeitz

And sometimes it's not the blade...

If your RPM drop for any reason like belts slipping.
Or very knotty boards or stress.
Metal deflection.

You will think your blade is dull...
Collector and builder of many things.
Love machine shop work
and Wood work shop work
And now a saw mill work

DMcCoy

I look (feel) around the knots on the cant for slight bumps or dips after I start to wonder how much longer I can get out of a blade.  If my logs are clean or I debark them then I start checking after @1 1/2 hr.  Dirty or bark on, 1 hr tops.   Usually it is bumps that show up.

Just like a chain saw chain, the longer you run it dull the more rounded the cutting tip gets and the more metal you need to remove when sharpening.  The older I get I find my attitude has changed.  I change saw blades and chain saw chains much earlier than I used too.  Faster cutting and faster sharpening.  I also have my own sharpening equipment so that really helps make the decision easier.  If I had to pay to have them sharpened I know I would be inclined to run them too long.
My 2 cents

Ox

x2 on #7 and #8!  Well said, guys.

Sometimes it's boggling to the mind how many variables there are that can affect milling.  It seems like it's a small miracle to be able to produce nice lumber as everything has to be just about perfect!
K.I.S.S. - Keep It Simple Stupid
Use it up, wear it out, make it do or do without
1989 GMC 3500 4x4 diesel dump and plow truck, 1964 Oliver 1600 Industrial with Parsons loader and backhoe, 1986 Zetor 5211, Cat's Claw sharpener, single tooth setter, homemade Linn Lumber 1900 style mill, old tools

Chuck White

When you can't maintain the feed rate you had been sawing at.

You can also tell by a change in your sawdust texture!
~Chuck~  Cooks Cat Claw sharpener and single tooth setter.  2018 Chevy Silverado and 2021 Subaru Ascent.
With basic mechanical skills and the ability to read you can maintain a Woodmizer  LT40!

AnthonyW

I have never noticed any difference in the saw dust texture or the stringy edges (but that may be a result of cutting EWP). For me it is waves. I watch the blade during the cut and then after off bearing, I will sweep my hand down the log to check for wave while returning the head. As soon as I sense the slightest wave, the blade comes off. If I hit metal, I balance the size of the metal versus the damage to the teeth. For example, I hit a large finish nail a while back (as long as 16d framing nail but smaller in diameter). It took out 6-8" of teeth. I know that dull spot will effect the cut, but I didn't want to install a new blade and trash it as well if there was anymore metal. So being a small section of blade and a small diameter nail, I slowly (less than half speed) cut the next piece. The cut was straight and found no additional metal, I shut down immediately and changed blades.
'97 Wood-Mizer LT25 All Manual with 15HP Kohler

Mt406

From the sounds of it I changed at the right time.
There was about 6 hrs on blade maybe 1000bf of lodge pole.
The wood was dry maybe 15% moisture bark was goin, with many checks.
The big checks I set up to carry saw dust and dirt out of cut. would also lose only one or two boards because of check.
I did see somw of the things mentioned I will have to look at the saw dust to see the difference.

Thanks 

Chuck White

~Chuck~  Cooks Cat Claw sharpener and single tooth setter.  2018 Chevy Silverado and 2021 Subaru Ascent.
With basic mechanical skills and the ability to read you can maintain a Woodmizer  LT40!

Bandmill Bandit

On Knotty knarley white spruce you could change blade after every cut and it wouldn't make much difference. i have given up trying to get straight lumber out of those logs.
Skilled Master Sawyer. "Skilled labour don't come cheap. Cheap labour dont come skilled!
2018 F150 FX4, Husqvarna 340, 2 Logright 36 inch cant hooks and a bunch of stuff I built myself

sandsawmill14

Quote from: Bandmill Bandit on May 03, 2016, 11:06:10 PM
On Knotty knarley white spruce you could change blade after every cut and it wouldn't make much difference. i have given up trying to get straight lumber out of those logs.

dont worry it'll plane out ;D
hudson 228, lucky knuckleboom,stihl 038 064 441 magnum

Chuck White

Quote from: Bandmill Bandit on May 03, 2016, 11:06:10 PM
On Knotty knarley white spruce you could change blade after every cut and it wouldn't make much difference. i have given up trying to get straight lumber out of those logs.

The only way I've ever gotten straight/flat boards when sawing Spruce was saw only large logs, 20"+, and when sawing small logs, tighten the tension some more and slow the feed speed down to about 1/3 of what I normally saw at.

~Chuck~  Cooks Cat Claw sharpener and single tooth setter.  2018 Chevy Silverado and 2021 Subaru Ascent.
With basic mechanical skills and the ability to read you can maintain a Woodmizer  LT40!

thecfarm

I idea what you have for a mill. But on my manual mill,I can hear the blade and tell when it's dull too. A new one cuts real quite. Or should!!!  :)
Model 6020-20hp Manual Thomas bandsaw,TC40A 4wd 40 hp New Holland tractor, 450 Norse Winch, Heatmor 400 OWB,YCC 1978-79

Bandmill Bandit

Quote from: Chuck White on May 04, 2016, 07:20:21 AM
Quote from: Bandmill Bandit on May 03, 2016, 11:06:10 PM
On Knotty knarley white spruce you could change blade after every cut and it wouldn't make much difference. i have given up trying to get straight lumber out of those logs.

The only way I've ever gotten straight/flat boards when sawing Spruce was saw only large logs, 20"+, and when sawing small logs, tighten the tension some more and slow the feed speed down to about 1/3 of what I normally saw at.

Yea I do that too BUT when half the branches were big enough to get 2, 6 foot 2x4s out of and the knots are so close together even that doesn't help much and the planer sorta gets them smooth but boy are those planks hard on knives.

The last one I cut last night I got a 21" X 21" can't with 2 corners about 30% wane. Got 25 4x4s total and 22 of them were good (and wavy). He is using them for fence posts around his wife's garden and she was tickled pink with the wavy lumber. She is gona paint them red a white and do it so it makes the wavy cut shows up more.

I have an LT40HDG28 and YES you can hear the "whine" blade go harmonically flat as the blades dull.   
Skilled Master Sawyer. "Skilled labour don't come cheap. Cheap labour dont come skilled!
2018 F150 FX4, Husqvarna 340, 2 Logright 36 inch cant hooks and a bunch of stuff I built myself

Ox

That's gotta be the first time I've ever heard anybody wanting and liking wavy lumber!  :D  I swear...
K.I.S.S. - Keep It Simple Stupid
Use it up, wear it out, make it do or do without
1989 GMC 3500 4x4 diesel dump and plow truck, 1964 Oliver 1600 Industrial with Parsons loader and backhoe, 1986 Zetor 5211, Cat's Claw sharpener, single tooth setter, homemade Linn Lumber 1900 style mill, old tools

Magicman

Just ask her to please not tell anyone who her sawyer was.   ;D

Happy Birthday Ox.   :)
Knothole Sawmill, LLC     '98 Wood-Mizer LT40SuperHydraulic   WM Million BF Club Member   WM Pro Sawyer Network

It's Weird being the Same Age as Old People

Never allow your "need" to make money to exceed your "desire" to provide quality service.....The Magicman

Bandmill Bandit

Quote from: Magicman on May 05, 2016, 08:40:02 PM
Just ask her to please not tell anyone who her sawyer was.   ;D

Happy Birthday Ox.   :)

Thanks MM and dont worry I made sure of that BUT her daughter want 16 more just like those and she want them with more pronounced waves.

Who would have ever thought there'd be a market for wavy lumber.
Skilled Master Sawyer. "Skilled labour don't come cheap. Cheap labour dont come skilled!
2018 F150 FX4, Husqvarna 340, 2 Logright 36 inch cant hooks and a bunch of stuff I built myself

Magicman

Want me to send you some blades?  Well, what are friends for??   ???   :D
Knothole Sawmill, LLC     '98 Wood-Mizer LT40SuperHydraulic   WM Million BF Club Member   WM Pro Sawyer Network

It's Weird being the Same Age as Old People

Never allow your "need" to make money to exceed your "desire" to provide quality service.....The Magicman

red

Honor the Fallen Thank the Living

4x4American

 :D :D :D :D  YellowHammer!  Good list, got a good laugh and learned a few things...I knew that rooster tail was saying something, but I wasn't sure what language..
Boy, back in my day..

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