Estimating Blade Sharpness by Temperature

      Blades heat up more as they get dull, but other factors can also have this effect. March 31, 2008

Question
I have been thinking about ways I could improve on my saw blade sharpness status. I don't think I get the most out of my blades because I am guessing when to change a blade out. Some blades get left on too long, others are taken off too early. I recall reading about measuring the sawdust temperature to determine if the blade is sharp. I know folks watch the blade cut and look for change in accuracy to determine if the blade is sharp. Isn't there a way to measure sharpness as the saw is running?

Forum Responses
From Professor Gene Wengert, forum technical advisor:
There are two issues with blades. The first is the sharpness of the teeth. As a tooth dulls, it takes more power. So if you had an ammeter on the saw's motor, you could estimate the increased power required as the saw dulls. Unfortunately, the thickness of the piece and the hardness of the wood also change the power. So, this is not practical until the saw gets extremely dull, which is way too late to know that it is dull. So, experience and length of time since the last sharpening are the usual manner of estimating dullness. A duller saw means more heating, so the temperature of the saw near the teeth or the temperature of the sawdust would estimate dullness, but again, the depth of cut and the density of the wood also affect the heat, as well as saw tension.

The second issue is the tension in the saw. Saw tension helps a blade run straight. Lack of adequate tension means wobble or wandering. Tension is put into the saw by "hammering" it, in the old days. Today, hammering is often done by rolling the saw. Tension is very important in wide band saws and large diameter circular saws. It is possible to measure the lack of tension by measuring the saw variation or wobble. This is often done with band saws in large, modern, commercial operations.



Would you like to add information to this article?
Interested in writing or submitting an article?
Have a question about this article?


Have you reviewed the related Knowledge Base areas below?
  • KnowledgeBase: Knowledge Base

  • KnowledgeBase: Primary Processing

  • KnowledgeBase: Primary Processing: Sawmilling


    Would you like to add information to this article? ... Click Here

    If you have a question regarding a Knowledge Base article, your best chance at uncovering an answer is to search the entire Knowledge Base for related articles or to post your question at the appropriate WOODWEB Forum. Before posting your message, be sure to
    review our Forum Guidelines.

    Questions entered in the Knowledge Base Article comment form will not generate responses! A list of WOODWEB Forums can be found at WOODWEB's Site Map.

    When you post your question at the Forum, be sure to include references to the Knowledge Base article that inspired your question. The more information you provide with your question, the better your chances are of receiving responses.

    Return to beginning of article.



    Refer a Friend || Read This Important Information || Site Map || Privacy Policy || Site User Agreement

    Letters, questions or comments? E-Mail us and let us know what you think. Be sure to review our Frequently Asked Questions page.

    Contact us to discuss advertising or to report problems with this site.

    To report a problem, send an e-mail to our Webmaster

    Copyright © 1996-2014 - WOODWEB ® Inc.
    All rights reserved. No part of this publication may be reproduced in any manner without permission of the Editor.
    Review WOODWEB's Copyright Policy.

    The editors, writers, and staff at WOODWEB try to promote safe practices. What is safe for one woodworker under certain conditions may not be safe for others in different circumstances. Readers should undertake the use of materials and methods discussed at WOODWEB after considerate evaluation, and at their own risk.

    WOODWEB, Inc.
    335 Bedell Road
    Montrose, PA 18801

    Contact WOODWEB











  • WOODWEB - the leading resource for professional woodworkers


      Home » Knowledge Base » Knowledge Base Article