Collet Torquing, Collet Maintenance, and Bit Breakage

      Fine points relating to collets and bits. June 17, 2009

For those using a torque wrench on ER-32 collects would you mind posting what you are using for a setting? We've broken a lot of bits on a current job and I'm trying to determine the cause. My suspicion is worn collets but I'm also wondering if our 115 to 120 ft/pd setting on the ER-32 collet nut torque wrench is high enough. I'm seeing collet scoring on the bit shanks so it seems either worn collets or not enough holding pressure.

Forum Responses
(CNC Forum)
From contributor D:
Thermwood recommends 80 - 100 ft. lbs. for an ER-32.

From contributor J:
Techniks recommends a torque of 112 ft/lbs for ER-32.

From the original questioner:
I misread the dial on our wrench. I'm actually running at 108 ft/lbs so that is pretty close to the Technik’s chart.

From contributor M:
Check the diameter of your tooling. Also check if the finish of the tooling is a shiny polished look or a matt finish. I had a vendor that changed to the shiny ones and they kept breaking. The vendor said it had to be on my end so I changed the collet, holder, nut and used the same nc file that I have used for years and they still broke. I bought someone else bits and have not had that problem again. After a year or so I talked with that same vendor again and they admitted that I was not the only one that this had happened to and said that they went back to the old finish.

If you have a lot of time on your collets, I have heard you should change them every six months. Ask your vendor if they have recently changed who they get their blanks from or if the content has changed. I have also heard that there can be a big difference between content of the bit blanks.

From the original questioner:
I had not heard of the polish of the blank being an issue before. I have tried to use Onsrud tooling every since they came to my shop to help with breakage problems when I got my first router. They have been good to me along the way, including replacing a whole tray's worth of bits that they conceded were a "bad batch". My bits are indeed "shiny" but I'm pretty sure the most recent problem is due to worn collets. I have been negligent in replacing them as soon as I have. I ordered several new collets this afternoon.

From contributor C:
If you’re looking to improve your tool life, increase your feeds and get a better finish. We’ve had great success eliminating the collet type holders completely! A hydraulic, heat shrink or Tribos style tool holder will definitely improve all the above and take bearing nuts and collets out of the equation. In “high-end” architectural millwork shops and MDF door applications it is something that’s becoming very popular on all brands of CNC’s.

From contributor K:
On the subject of collet wear, we try and set up tools with dedicated tool holders and collets so even if a tool has not been used in a while it has not been removed from the tool holder. Is collet wear a concern when doing this or is it just an issue when changing bits in the same tool holder often?

From contributor C:
As a “general” rule of thumb, collets should be replaced after 600 hours of run time. Side load and vibration during cutting operations, along with thoroughly cleaning the collet when changing the tools all impact collet life. Not to mention the proper torque which was addressed above. Adding a bearing nut vs. a standard nut will give you a more consistent and accurate way to ensure collets are tighter and truer. Collet maintenance is one of the areas we find people less educated on and it impacts tool life, cut quality and most importantly safety!

From contributor C:
This is the system we use in our Technology Center. It's by Technics.

Click here for higher quality, full size image

From the original questioner:
I have a different tool holder but that is the torque wrench I use. I got it from CT Saw and Tool.

From contributor Y:
Fischer Precision Spindles has a very simple torque wrench that takes the guesswork out of settings. Highly recommend it and it is priced right.

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: Computerization

  • KnowledgeBase: Computerization: CNC Machinery and Techniques

    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 © 1996-2019 - 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