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Life of a Blade

Started by just_sawing, March 23, 2011, 08:42:07 AM

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just_sawing

As some of you know we sharpen blades here for the public.
There have been many questions on blades and while cleanning a customers blade I saw a good example of a failure before it broke on your mill and thought I would share.
You always here that when you sharpen a blade you need to hit the gullet. If you look at the pictures you can see why. If this blade had been pulled off maybe 300 feet of wood before this these fracturs would be micro scopic at the gullet area.
The cracks in your and my blades start their life so small you can't see them. THey then will go from nothing to where these are quickly. What effects them is all the dynamics of the machine.
How Tight the blade is.
How sharp
How much set
What type of wood
How much water.
Everything is related but what we have firgured out is this. Your blade starts with low stress of being sharp, cool, and having a kerf that keeps it this way. The natural act of cutting destroys that blades happy world and when it changes heat builds water cools and that cycle continues until the metal cracks.

https://forestryforum.com/gallery/displayimage.php?pos=-95620
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www.http://haneyfamilysawmill.com

just_sawing

HAd trouble with a loose nut between the ears but I now have a picture of what I am talking about.
You can follow me at
www.http://haneyfamilysawmill.com

backwoods sawyer

When they get to that point, you usually can hear them ticking. A little silver solder with a light grind can save a crack like that. Just be sure to use a center punch on both sides to stop the crack from continuing, and be sure to grind the gullet when you sharpen the saw to clear any other micro cracks that have developed. A happy saw makes for a happy sawyer.
Backwoods Custom Milling Inc.
100% portable. . Oregons largest portable sawmill service, serving all of Oregon, from our Backwoods to yours..sawing since 1991

just_sawing

This blade went to the scrap heap. I plan to post a pic on the next one that I see, but are any of you seeing cracks develope on the back of the blade?
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tyb525

Cracks in the back of the blade can be caused by running the guides too far behind the blade, meaning when the band hits the wood, the band is pushed too far back against the flange. The blade guides should be adjusted so that the flange is 1/16" to 1/8" from the back of the blade when not under load.
LT10G10, Stihl 038 Magnum, many woodworking tools. Currently a farm service applicator, trying to find time to saw!

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