Page 6 of 7 FirstFirst ... 234567 LastLast
Results 76 to 90 of 105

Thread: Clearance in BD plane

  1. #76
    Join Date
    Oct 2010
    Location
    Australia
    Posts
    2,534
    Quote Originally Posted by Normand Leblanc View Post
    Haha!
    The geometry is quite simple. All those irons have been sharpened with a 3 degree backbevel. I think that by doing this I rapidly remove the wear bevel.

    As for "dykem", english being a second language for me, I presume that it means like coloring/painting. If it's the case, I doubt that it would show anything but, having more test to do I'll give it a try and let you know.

    Good night
    Thanks for the update Normand. Makes perfect sense now. Excellent work.

    Stewie;

  2. #77
    Join Date
    Dec 2015
    Location
    Dublin, CA
    Posts
    4,119
    Quote Originally Posted by Jim Koepke View Post
    It seems Normand has test results which indicate the 10º clearance angle will have diminishing effectiveness sooner than a 20º clearance angle. Are you saying you may have to hone the blade more often but each time is removing less metal than those of us with bevels starting with more clearance?
    There is effectlively a "race" between two failure modes: Ordinary edge failure modfes like dulling and chipping, and loss of clearance due to wear behind the edge. I think that in with all else (bedding/cutting angle etc) equal it's fair to say that clearance represents a tradeoff between these modes.

    As I've said a couple times I think that high clearance probably slows the formation of the flat wear spot a bit, so in that sense it mitigates loss of clearance a bit. Conversely, high clearance means a thinner edge and therefore higher vulnerability to more conventional failure modes.

    I think that Normand's later work after he switched to rigid sharpening media is a terrific contribution too this discussion (and am ashamed not to have said so yet - my hat is off, Normand). He shows that in the specific case he tested (zero-vertical-force, cut-by-pull) relief significantly impacts useful life. The next question is of course: How does that translate to real human use, where the woodworker can generally sense the behavior of the blade and adjust accordingly, for example by applying a big of vertical force to start the cut. That was really Warren's point a few posts back.

    So to recap we have the following:

    1. Everybody agrees that you need some amount of overall clearance to deal with compression/expansion of the wood
    2. We have micrograph evidence showing that wear causes formation of a "land" of zero clearance behind the edge rather than simple reduction of clearance
    3. Normand shows that In the absence of vertical pressure the initial clearance angle has a significant impact on how long the plane cuts
    4. Real users who do apply pressure (me, Warren, Derek) report MUCH longer blade lives than Normand's data suggest at fairly low clearance angles (~10 deg). I personally find that my blades become dull long before clearance becomes an issue

    Taking all 4 together my guess is that the vertical pressure that we apply when using our planes "holds" the wood under the flat wear patch in compression until it reaches the relief bevel behind the wear patch. That allows real users (as in 4) to experience good performance with much worse wear than is tolerable for Normand's setup in (2). That in turn shifts the balance in favor of low relief. Just my $0.02 fwiw.
    Last edited by Patrick Chase; 05-26-2016 at 12:23 AM.

  3. #78
    Join Date
    Oct 2010
    Location
    Australia
    Posts
    2,534
    Patrick; correct me if I am wrong. Normand's tests indicate that an included angle of 28* (25* primary + 3* secondary) is the ideal target to aim for with regards longevity of the cutting edge; your suggesting 30* is the ideal target. Their is only a minor discrepancy of 2* between both opposing views. As to the issue of wear angles; it should be remembered that you are starting with a bed angle of 40* ; whereas Normand is working with 45*. Clearly your commencing wear angle is going to remain 5* less than Normand's recommendation. From a personal judgement; given the choice between your starting point of a 10* wear angle, and Normand's 17*, I would opt for the latter as it offers me greater scope between periodical regrinding. As to the question on what I would deem as a minimal wear angle to work with; it would be close to 10 degrees. As someone who freehand sharpens, its difficult to give an exact no.

    Stewie;
    Last edited by Stewie Simpson; 05-26-2016 at 6:34 AM.

  4. #79
    Join Date
    Aug 2010
    Location
    USA
    Posts
    5,582
    Quote Originally Posted by Steve Voigt View Post
    I think what's really going on is that these people feel threatened by data that contradicts their entrenched outlook. Oh well, too bad for them.
    I don't see anyone being threatened by this in the least. Only speaking for myself though, the question in my mind is WHY the results are as presented. I'd like to understand this better personally because the key to improvement is understanding the root cause of the issue. Normand has presented som fascinating results that seem to buck traditional understanding and I'd like to understand why.
    Quote Originally Posted by Steve Voigt View Post
    My one caveat is that you are taking thin shavings in softwood; I wonder if the results would be the same with harder woods and/or thicker shavings. I suspect not, but I don't really know.
    What angles do you use in your own wooden bodied planes Steve? Have you ever experimented with different angles? Would you make the angle of your own planes different if a customer was telling you up front that they were concerned with planing hardwoods?

  5. #80
    Quote Originally Posted by Normand Leblanc View Post
    Haha!
    The geometry is quite simple. All those irons have been sharpened with a 3 degree backbevel. I think that by doing this I rapidly remove the wear bevel.
    Am I reading this right? The angles presented to the wood in the experiment are really 28, 31, 34, 37, and 40? The 3 degree back bevel makes these tests equivalent to one with a 48 degree bed. I can't think that a 40 degree angle would not have trouble starting a cut without any pressure other than the weight of the plane. Dulling or not.

    Consider these two situations: 1) a plane bedded at 48 with a 37 degree bevel. 2) a planed bedded at 41 with a 30 degree bevel. Both of these would have an 11 degree clearance angle, but I would expect these to give rather different results especially with the way your test is designed having initial penetration as the great factor.

    It has been more than 40 years since I have used any angle other than 30 degrees or a backbevel. All but one of your tests exceed 30 degrees. I have used a plane with a 45 degree bed and a 30 degree bevel along side a plane with a 42 degree bed and 30 degree bevel since 1982. It is barely noticeable that the 42 bedding yields a better surface. I would question the suggestion that the iron bedded at 45 had longer edge life. I think your tests are measuring the bluntness of your angle (40 degrees!) as much as clearance.
    Last edited by Warren Mickley; 05-26-2016 at 9:29 AM.

  6. #81
    Join Date
    Sep 2007
    Location
    Longview WA
    Posts
    27,347
    Blog Entries
    1
    Quote Originally Posted by Stewie Simpson View Post
    Patrick; correct me if I am wrong. Normand's tests indicate that an included angle of 28* (25* primary + 3* secondary) is the ideal target to aim for with regards longevity of the cutting edge; your suggesting 30* is the ideal target. Their is only a minor discrepancy of 2* between both opposing views. As to the issue of wear angles; it should be remembered that you are starting with a bed angle of 40* ; whereas Normand is working with 45*. Clearly your commencing wear angle is going to remain 5* less than Normand's recommendation. From a personal judgement; given the choice between your starting point of a 10* wear angle, and Normand's 17*, I would opt for the latter as it offers me greater scope between periodical regrinding. As to the question on what I would deem as a minimal wear angle to work with; it would be close to 10 degrees. As someone who freehand sharpens, its difficult to give an exact no.

    Stewie;
    Okay, you noticed the difference in the bed angle. My understanding is Normand didn't use a secondary bevel. He used a 3º back bevel.

    The lowest angle I know of for a clearance angle is 8º on Stanley and Lie Nielsen side rabbet planes.

    jtk
    "A pessimist sees the difficulty in every opportunity; an optimist sees the opportunity in every difficulty."
    - Sir Winston Churchill (1874-1965)

  7. #82
    Join Date
    Dec 2012
    Location
    Ste-Julienne, Qc, Canada
    Posts
    194
    Quote Originally Posted by Warren Mickley View Post
    Am I reading this right? The angles presented to the wood in the experiment are really 28, 31, 34, 37, and 40? The 3 degree back bevel makes these tests equivalent to one with a 48 degree bed. I can't think that a 40 degree angle would not have trouble starting a cut without any pressure other than the weight of the plane. Dulling or not.

    Consider these two situations: 1) a plane bedded at 48 with a 37 degree bevel. 2) a planed bedded at 41 with a 30 degree bevel. Both of these would have an 11 degree clearance angle, but I would expect these to give rather different results especially with the way your test is designed having initial penetration as the great factor.

    It has been more than 40 years since I have used any angle other than 30 degrees or a backbevel. All but one of your tests exceed 30 degrees. I have used a plane with a 45 degree bed and a 30 degree bevel along side a plane with a 42 degree bed and 30 degree bevel since 1982. It is barely noticeable that the 42 bedding yields a better surface. I would question the suggestion that the iron bedded at 45 had longer edge life. I think your tests are measuring the bluntness of your angle (40 degrees!) as much as clearance.
    Warren,
    As I can see this 3 degree backbevel wasn't clear. In my french blog, where all this started, the readers are very well aware that this is my standard sharpening technique. I've updated the blogs to clarify this. I have a video showing my technique (in french but no need to understand, just look)
    https://www.youtube.com/watch?v=5XLB...ature=youtu.be

    So you're right, it's like if those tests were done with a 48 degree bedded plane. If this makes a large difference (compared to 45) then all those people using 50 and 55 degree should see a much large blunting effect. My opinion (nothing scientific here) is that the difference is minimal between 45 and 48.

    As I said before, I've decided to do some testing after getting a new LN 4-1/2 that was giving me so many more shaving than the 3 BU planes that I own, sharpened at 30-35 degree. With the bed angle of 12, this gives 42 to 48 degree which is close to a standard BD. What was going wrong? That's why I came to the conclusion that it had to do with the relief angle and I began testing this right away. I'm far from being completed with those test but, using softwood, a Record blade and 48 degree frog, a 25 degree (+3 = 28) sharpening angle is much better than all the other steeper angles.

    If I was to use a 41 degree bedded plane, I believe that I would be getting more shavings than a 45 degree plane if both had the same relief angle. This is just an opinion, I haven't tested that. That would be a very nice test to do and, if I'm right, would give LV an edge to LN. Derek Cohen seems to be getting very good results with a lower bed.

    That being said, I've been hand sharpening my blades for 5 years with an angle of 30-35. If the test with hardwood gives the same kind of results I'll have to change my method or live with a poorer result.

    Have a good day

  8. #83
    Join Date
    Dec 2012
    Location
    Ste-Julienne, Qc, Canada
    Posts
    194
    Thank you Patrick for your contribution convincing me that I should not strop.

    "There is effectlively a "race" between two failure modes: Ordinary edge failure modfes like dulling and chipping, and loss of clearance due to wear behind the edge. I think that in with all else (bedding/cutting angle etc) equal it's fair to say that clearance represents a tradeoff between these modes.

    As I've said a couple times I think that high clearance probably slows the formation of the flat wear spot a bit, so in that sense it mitigates loss of clearance a bit. Conversely, high clearance means a thinner edge and therefore higher vulnerability to more conventional failure modes. "

    I agree entirely with the above.

    Where I disagree now. I believe that edge failure is less important than the formation of a flat. At this stage I've tested softwood. When I'll do hardwood we will have more information to answer this question.

    The technique I'm using is, a given mass (the plane) applied to an area (flat under the blade) and a dull blade, taken together, is able or not to take a shaving. If you add vertical force (like point 4) you will be able to use it for a longer period but IMO it will be close to proportional to the test results.

    Hum...What do you think?

  9. unfortunately the three angles- cutting angle (set by the frog), clearance angle and bevel angle are inseparably linked. even if you built a variable angle frog to do the tests with you would not be able to isolate 1 angle as a variable.

    and yes, measuring the grab with just the weight of the plane isn't relevant to actual use.



    Quote Originally Posted by Warren Mickley View Post
    One of the problems with the test is that both the clearance angle and the bevel angle were varied simultaneously. It is difficult to separate which was the dominant factor. And in addition the test was done without the normal downward pressure; it tested only the irons ability to grab hold of the board and take a shaving. I think this would tend to bias the results toward a more acute honing angle, regardless of the clearance angle.

  10. #85
    Quote Originally Posted by bridger berdel View Post
    unfortunately the three angles- cutting angle (set by the frog), clearance angle and bevel angle are inseparably linked. even if you built a variable angle frog to do the tests with you would not be able to isolate 1 angle as a variable.

    and yes, measuring the grab with just the weight of the plane isn't relevant to actual use.
    Indeed not relevant to the actual use, but it is not ment as such. It is used as an indication for the size of the wear bevel. We could quible of course if it is a good indicator.

    BTW, I read somewhere in this thread that the wear bevel at the clearance side would be flat. But it isn't. The wearbevel is a bulge. The edge is raised higher and higher above the lowest point of this bulge. This is a gradual proces. When researchers measure the vertical force, this is very clear, the vertical force changes gradually too with distance planed. This is universally recognised to be a good wear indicator in the wood cutting science area.

  11. #86
    Join Date
    Dec 2012
    Location
    Ste-Julienne, Qc, Canada
    Posts
    194
    The flat/bulge seems to vary depending on grain direction. From Kato and Kawaii:

    http://planetuning.infillplane.com/h...ron_study.html

    I'm planing with the grain with an grain angle anywhere between 0 and +7. I can see that the shaving thickness is getting smaller but it's hardly measurable with a regular micrometer.
    Last edited by Normand Leblanc; 05-27-2016 at 7:49 AM. Reason: wrong link

  12. #87
    Join Date
    Aug 2010
    Location
    USA
    Posts
    5,582
    Quote Originally Posted by Kees Heiden View Post
    Indeed not relevant to the actual use, but it is not ment as such. It is used as an indication for the size of the wear bevel. We could quible of course if it is a good indicator.

    BTW, I read somewhere in this thread that the wear bevel at the clearance side would be flat. But it isn't. The wearbevel is a bulge. The edge is raised higher and higher above the lowest point of this bulge. This is a gradual proces. When researchers measure the vertical force, this is very clear, the vertical force changes gradually too with distance planed. This is universally recognised to be a good wear indicator in the wood cutting science area.
    Kees, I really think the pictures on your webpage are now so much more relevant to me (after all of the above discussion). As was mentioned previously, as the edge becomes eroded after planing lumber, the downforce required to overcome the wear effects becomes more significant. Looking back at your pictures this alll makes perfect sense. I see now that Normans work does a great job of tabulating that effect. For me personally, one that doesn't enjoy the sharpening process all that much, I can see the merits of using the more acute bevel angles. I wonder now if perhaps going to an angle even less than 25 degrees might not be a bad idea. Thoughts?

  13. #88
    Just to be sure, those are not my pictures! I only pointed out where they are. It's the work from Steve Elliot, who was also so kind to give room on his website for my articles about chipbreakers.

  14. #89
    I tried Normand's experiment this morning with two of my planes:

    Plane 1) #3 Bailey c1915, 47 ounces, 45 degree bed, 15 degree clearance
    Plane 2) #4 Stanley Handyman 1973, 50 ounces, bed altered to 42 degrees, 12 degree clearance

    Both planes had century old Stanley irons, sharpened full flat bevel on Arkansas stones and stropped on clean leather. I used a 30 degree angle bevel; no back bevel.

    Both planes passed the test even after 200 strokes on white pine (Pinus strobus). In both cases I felt the urge to sharpen the irons somewhere in the 120-150 range, but kept going for the sake of the experiment. I don't like to abuse an iron by running it into the ground.

    Four of Normand's tests were done with higher sharpening angles (bevel plus back bevel) than mine, which I think is a significant factor. And all of Normand's tests were done with higher cutting angles (bed angle pus back bevel) than mine, which I think also plays a role.

    I don't recommend micro bevels, secondary bevels, tertiary bevels, back bevels or ruler tricks. And I don't recommend planing above 45 degrees.

  15. #90
    Join Date
    Dec 2012
    Location
    Ste-Julienne, Qc, Canada
    Posts
    194
    Warren,
    If you're right about the high angles that means our BU planes do have a problem when sharpened at 50, 55 and 60 degrees.

    The test that I'm doing are called completed when the plane with his own weight, pushed by the rear part of the sole, do not engage a full cut. How did you called your test completed? Same as me or another method?

    The Stanley blade that I'm using is just stamped Stanley. I believe it's a newer one than yours.

Posting Permissions

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