Page 2 of 10 FirstFirst 1234567 ... LastLast
Results 16 to 30 of 149
  1. #16
    Join Date
    Dec 2013
    Location
    San Antonio, Texas, USA
    Posts
    3,070

    Default

    Here's a somewhat better correlation but this one still isn't strong enough to impress a sociologist.
    Std dev of hardness vs hardness for saw files 041815a.jpg
    Innovations are those useful things that, by dint of chance, manage to survive the stupidity and destructive tendencies inherent in human nature.

  2. # ADS
    Google Adsense Advertisement
    Join Date
    Always
    Location
    Advertising world
    Posts
    Many





     
  3. #17
    Join Date
    Dec 2013
    Location
    San Antonio, Texas, USA
    Posts
    3,070

    Default

    Here's a hardness vs. user rating plot with each file identified.

    HRC hardnsss vs. user rating by file type 041815a.jpg
    Innovations are those useful things that, by dint of chance, manage to survive the stupidity and destructive tendencies inherent in human nature.

  4. #18
    FenceFurniture's Avatar
    FenceFurniture is offline The prize lies beneath - hidden in full view
    Join Date
    Oct 2010
    Location
    1017m up in Katoomba, NSW
    Posts
    10,651

    Default

    Quote Originally Posted by Heavansabove View Post
    And 7A at 18.51, surely would not cut at all?
    Peter, in the report you are in the middle as Tester B. You didn't think much of 7A (Bahco 5" DEST) but interesting to note that you said it "cut quickly".
    Regards, FenceFurniture

    COLT DRILLS GROUP BUY
    Jan-Feb 2019 Click to send me an email

  5. #19
    Join Date
    Dec 2013
    Location
    San Antonio, Texas, USA
    Posts
    3,070

    Default

    I think that in the cases of files 4A, 7, 7A and 12 the annealing of the tang softened the steel quite far up the bodies of the files - this could be considered a measure of manufacturing consistency or lack thereof. Note that the tip measurements for those files are higher. The plates I've prepared thus far are based on the average of all measurements for all files and thus the files with softer tangs will lower apparent hardness. I'll work up the figures with the tip data alone later.
    Innovations are those useful things that, by dint of chance, manage to survive the stupidity and destructive tendencies inherent in human nature.

  6. #20
    Join Date
    May 2008
    Location
    Australia
    Posts
    2,357

    Default

    Quote Originally Posted by rob streeper View Post
    Here's a hardness vs. user rating plot with each file identified.

    HRC hardnsss vs. user rating by file type 041815a.jpg
    Hi Rob. Is it possible to display a mean average of 1095 saw plate hardness within this graph.

    Stewie;

  7. #21
    Join Date
    Dec 2013
    Location
    San Antonio, Texas, USA
    Posts
    3,070

    Default

    Innovations are those useful things that, by dint of chance, manage to survive the stupidity and destructive tendencies inherent in human nature.

  8. #22
    Join Date
    Feb 2006
    Location
    Perth
    Posts
    27,757

    Default

    Quote Originally Posted by rob streeper View Post
    I think that in the cases of files 4A, 7, 7A and 12 the annealing of the tang softened the steel quite far up the bodies of the files - this could be considered a measure of manufacturing consistency or lack thereof. Note that the tip measurements for those files are higher. The plates I've prepared thus far are based on the average of all measurements for all files and thus the files with softer tangs will lower apparent hardness. I'll work up the figures with the tip data alone later.
    Good idea. I'd leave the tang data out altogether.

    Are all the testers filing the same materials?

  9. #23
    Join Date
    May 2008
    Location
    Australia
    Posts
    2,357

    Default

    Hi Rob. Excellent work.

    Stewie;

  10. #24
    Join Date
    Dec 2013
    Location
    San Antonio, Texas, USA
    Posts
    3,070

    Default

    When considering these data some important procedural and technical points must be borne in mind.

    Hardness testers such as the one used for these measurements require that the force applied to the indenter diamond be 'normal' or perpendicular to the surface of the object being tested. Given the variability in positioning of the files, their triangular cross sections and the fact that the v-block anvil on this tester is a 90o type it is likely that at least some measurements will have been made with the surface of the file skewed.

    The v-block anvil only supported the opposite edge of many of the files during testing. If the opposite edge or the anvil supporting the edge distorted under load the HRC values reported would be lower than the actual hardnesses of the files.

    Surface roughness causes negative deviations in HRC measurements, the rougher the surface the lower the measured hardness and the higher the error.

    Measurements at the tips of the files are more problematic because of the perpendicularity issue discussed above.

    Bends, even imperceptible bends, that arch the body of the test article above the anvil a the test point will cause strong positive deviations in measured hardness values relative to the true hardness.

    Thin materials also show negative deviations in measured values due to plastic flow under load. This problem is the reason that the N and T scales were developed.
    Innovations are those useful things that, by dint of chance, manage to survive the stupidity and destructive tendencies inherent in human nature.

  11. #25
    Join Date
    May 2008
    Location
    Australia
    Posts
    2,357

    Default

    Hi Rob. Considering the front 1/2" of the file edge is rarely touched during the saw sharpening process; its possible to exclude readings within this area as well.

    regards Stewie

  12. #26
    Join Date
    Dec 2013
    Location
    San Antonio, Texas, USA
    Posts
    3,070

    Default

    Quote Originally Posted by planemaker View Post
    Hi Rob. Considering the front 1/2" of the file edge is rarely touched during the saw sharpening process; its possible to exclude readings within this area as well.

    regards Stewie

    Hi Stewie,

    My plan is to first do HRN45 testing on this batch of files in the same way that the HRC testing was done. Next I'll grind away a two inch long segment of teeth from the middle section of each file on one face and repeat the HRC and HRN testing there. Finally I'll cryo-treat the files and repeat the HRC and HRN45 testing.

    Given that cryotreating is known to increase the abrasion resistance of ferrous alloys and further that the process works on both martensitic and non-martensitic alloys I think that an abrasion type tool such as a file may benefit greatly. Plus it's easy for me to do because I have all of the equipment to perform the treatment and measure the results.

    Rob
    Innovations are those useful things that, by dint of chance, manage to survive the stupidity and destructive tendencies inherent in human nature.

  13. #27
    Join Date
    Dec 2013
    Location
    San Antonio, Texas, USA
    Posts
    3,070

    Default

    citric acid treatment of saw files analysis 041815a.jpg

    Citric acid decreases both measured hardness (roughness effect) and user ratings but the differences are not statistically significant.
    Innovations are those useful things that, by dint of chance, manage to survive the stupidity and destructive tendencies inherent in human nature.

  14. #28
    FenceFurniture's Avatar
    FenceFurniture is offline The prize lies beneath - hidden in full view
    Join Date
    Oct 2010
    Location
    1017m up in Katoomba, NSW
    Posts
    10,651

    Default

    Quote Originally Posted by BobL View Post
    Good idea. I'd leave the tang data out altogether.

    Are all the testers filing the same materials?
    Yes Bob. Not just the same material but the same piece. In the report you can see pics of the plate that they used, and there are three sets of toothing. Furthermore, the three testers were all using the same file - one corner each. Even then there were inconsistencies within the same file - some of the results were wildly divergent within the same file.

    It was all blind testing - all identifying marks on the files were ground off, and even ones that didn't have a mark were ground as these would have been known by their lack of mark as Liogiers.
    Regards, FenceFurniture

    COLT DRILLS GROUP BUY
    Jan-Feb 2019 Click to send me an email

  15. #29
    FenceFurniture's Avatar
    FenceFurniture is offline The prize lies beneath - hidden in full view
    Join Date
    Oct 2010
    Location
    1017m up in Katoomba, NSW
    Posts
    10,651

    Default

    Quote Originally Posted by rob streeper View Post
    Finally I'll cryo-treat the files and repeat the HRC and HRN45 testing.

    Given that cryotreating is known to increase the abrasion resistance of ferrous alloys and further that the process works on both martensitic and non-martensitic alloys I think that an abrasion type tool such as a file may benefit greatly. Plus it's easy for me to do because I have all of the equipment to perform the treatment and measure the results.
    Rob, I guess you're trying to see if you can increase the performance (hardness?) of them? Don't forget that these files are knackered now and performance increase (or not) won't be able to be measured.

    EDIT: However, it would be very interesting to treat about 4-5 new files and compare them against untreated.
    Regards, FenceFurniture

    COLT DRILLS GROUP BUY
    Jan-Feb 2019 Click to send me an email

  16. #30
    FenceFurniture's Avatar
    FenceFurniture is offline The prize lies beneath - hidden in full view
    Join Date
    Oct 2010
    Location
    1017m up in Katoomba, NSW
    Posts
    10,651

    Default

    Quote Originally Posted by rob streeper View Post
    Citric acid decreases both measured hardness (roughness effect) and user ratings but the differences are not statistically significant.
    I was looking for a pattern there but three are up and three are down which doesn't really prove much. Surely the Japanese file (citric) is an aberration - I can't see the graph whilst replying but the drop in hardness is something like 30 Rc - can't see an acid bath doing that.
    Regards, FenceFurniture

    COLT DRILLS GROUP BUY
    Jan-Feb 2019 Click to send me an email

Page 2 of 10 FirstFirst 1234567 ... LastLast

Similar Threads

  1. 4140 HARDNESS
    By morrisman in forum METALWORK FORUM
    Replies: 15
    Last Post: 6th March 2015, 08:01 PM
  2. Hardness testing of saw plates
    By rob streeper in forum Saws- handmade
    Replies: 2
    Last Post: 18th February 2014, 05:30 PM
  3. Fun with a hardness tester
    By .RC. in forum METALWORK FORUM
    Replies: 5
    Last Post: 19th August 2012, 07:52 PM
  4. sheraton bed hardness
    By morrisman in forum METALWORK FORUM
    Replies: 4
    Last Post: 14th November 2011, 08:04 PM
  5. Timber Hardness ?
    By Burfodus in forum TIMBER
    Replies: 11
    Last Post: 28th July 2010, 05:15 PM

Tags for this Thread

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •