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Thread: Why does aggressive chisel prep make such a big difference?

  1. #16
    Quote Originally Posted by Derek Cohen View Post
    I don't think that others here are getting what you are trying to say, that is, by grinding back the chisel back, the steel that remains is harder than the outer surface that was removed. And that this enables the edge retention to significantly improve. Is that correct? Will you say why?
    All I am saying is that all of them cut better when they got past some "threshold" of chisel prep... It was very noticable - both on the stones and on wood...

    As to the cause of it... I am not convinced it is specifically decarb... For several reasons... Patrick makes good points in the other thread about alloys used to reduce decarb problems... I noticed the same thing as he mentioned in my backyard chisel experiments... There was no noticable decarb layer to deal that persisted beyond simple adequate flattening and sharpening... I had no decarb problems even with a Mapp gas torch..

    And I am not convinced it is from "Flattening" the back.... I think flattening the back has a side effect on whatever was hurting edge durability.. But I doubt "Flat" is the cause of better performance....

    What I did notice last night is that when I re-honed the bevel on my Worksharp - the problem came back when chopping mahogany and eucalyptus - though not when paring mahogany, spruce, or eucalyptus end grain.....

    Although it's nowhere near the extent of previous - it still feels like I went backwards somewhere.. It could just be my expectations, though.....

    Do you guys prep separate chisels for chopping? If so - how? Is it possible that a finely honed and polished edge performs worse chopping than a fairly coarse edge?
    Last edited by John C Cox; 02-24-2018 at 10:48 AM.

  2. #17
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    Might be be more to do with the angle of the bevel....chopping takes about..30-35 degrees, paring is around 20...and 20 is not good for chopping..too thin.

  3. #18
    Quote Originally Posted by John C Cox View Post
    All I am saying is that all of them cut better when they got past some "threshold" of chisel prep... It was very noticable - both on the stones and on wood...

    As to the cause of it... I am not convinced it is specifically decarb... For several reasons... Patrick makes good points in the other thread about alloys used to reduce decarb problems... I noticed the same thing as he mentioned in my backyard chisel experiments... There was no noticable decarb layer to deal that persisted beyond simple adequate flattening and sharpening... I had no decarb problems even with a Mapp gas torch..

    And I am not convinced it is from "Flattening" the back.... I think flattening the back has a side effect on whatever was hurting edge durability.. But I doubt "Flat" is the cause of better performance....

    What I did notice last night is that when I re-honed the bevel on my Worksharp - the problem came back when chopping mahogany and eucalyptus - though not when paring mahogany, spruce, or eucalyptus end grain.....

    Although it's nowhere near the extent of previous - it still feels like I went backwards somewhere.. It could just be my expectations, though.....

    Do you guys prep separate chisels for chopping? If so - how? Is it possible that a finely honed and polished edge performs worse chopping than a fairly coarse edge?
    Would be interessting to know how you sharpen and with what, Benchstones or just a Grinder/Beltsander? Strop yes or no? Could be for whatever reason you might've ever so slightly rounded over the back at the very edge and simply ground it down to flat again, just a thought.

    And yes it is possible for a Polished edge to performe worse then a "coarse" edge with, more or less, micro. serrations, kinda like how a Breadknife bites easier into a Loaf then a mirror polished edge.

  4. #19
    Quote Originally Posted by Philipp Jaindl View Post
    Would be interessting to know how you sharpen and with what, Benchstones or just a Grinder/Beltsander? Strop yes or no? Could be for whatever reason you might've ever so slightly rounded over the back at the very edge and simply ground it down to flat again, just a thought.

    And yes it is possible for a Polished edge to performe worse then a "coarse" edge with, more or less, micro. serrations, kinda like how a Breadknife bites easier into a Loaf then a mirror polished edge.
    My typical routine was to use diamond stones for backs and a Worksharp 3000 thru 1000 grit for bevels and then strop the bevel with green chrome. Primary bevel at about 25. Microbevel at 30.

    In this go round - I went at the backs with 100 grit PSA on my surface plate. If there was a burr on the bevel - I touched it with the Worksharp.

    After I was done - I went back up to 325 grit PSA on the backs. It wasn't till I resharpened the bevel that they quit chopping...

  5. #20
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    Quote Originally Posted by John C Cox View Post
    Do you guys prep separate chisels for chopping? If so - how? Is it possible that a finely honed and polished edge performs worse chopping than a fairly coarse edge?
    It would be more accurate to say "separate chisels for paring vs mortises vs everything else", but the answer is basically yes. My paring chisels have lower tip angles than my general-purpose ones and (particularly) my mortise chisels. The specifics vary by width, since I also use higher angles on narrower chisels than wide ones, due to the inevitably higher edge pressures in the former.

    I think that for cutting wood a fine and polished edge will always last at least as long as a more coarse one, and often longer. A lot depends on the steel, since coarse-grained, high-carbide steels like D2 and HSS are designed to "run rough". By this I mean that the martensite matrix around the carbides has to "wear back" a bit to expose the carbides and allow them to shoulder the load. That happens all its own, so you won't improve life by starting the edge in a coarse state. By the same token it's also a waste of time to refine such a chisel to a perfect edge, but that's not the same thing as saying that refinement actually reduces edge life.

    In contrast homogeneous, fine-grained steels like HCS and white will last longer when honed as sharp as possible. There are no "hard chunks" in those steels to take up the load as the edge recedes, and a duller edge causes higher cutting forces and therefore more wear. Whereas D2 will wear a bit and then stabilize, for the homogeneous steels it's just a vicious cycle as dullness begets higher forces begets more dullness. Your best strategy with those steels is to hone frequently and thereby avoid the serious and more time-consuming damage that comes from chopping on a dull edge.
    Last edited by Patrick Chase; 02-24-2018 at 4:58 PM.

  6. #21
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    Shape before sharp.

    I used to get a bit lazy when sharpening and would try to get by with honing... and more honing. When I finally got back to grinding, I rediscovered "sharp". Exploring it a bit, I think it gets back to the basics we all know. I was not refreshing the bevel and creating a wire edge. I think the honing was adding some convex curving to the edge, both top and bottom. Who knows? In any case, this came to mind as I read the OP. In summary, I learned to not don't get lazy.

    Now I take some metal off to get the proper shape, then sharp.

  7. #22
    So it honestly sounds like the folks here are drawing a blank here like I am....

    Whatever happened - I want to figure out how I can "turn it on and off".... Once they crossed this mystery threshold - the chisels became quite well behaved on the work - Chopping and end grain paring... It would be very convenient to be able to use cheap miscellaneous chisels for this sort of duty... That will take more experiments - and I am now out of 100 grit PSA..

    I have 3 guitars that need binding and the necks carved.. Sharpening and fettling chisels isn't my hobby, more a means to an end.... I need to put this to bed and get back to working on actual wood... .

    For now - Stanley Fat Max long blade chisels (from the UK) set up with a 35 degree microbevel in my current process seem to do quite well.. (The regular US market fodder Fat Max were just too short..) And so that's probably the logical stopping point for chopping duty for the time being.... They are nominally designed for optimum transmission of shock from "Sledge to Edge" after all aren't they....

    The other cheap chisels will pare end grain spruce nicely at 30 degrees... Which is fine... This all started because my edges wouldn't hold up when trimming guitar brace ends - which are spruce...
    Last edited by John C Cox; 02-26-2018 at 11:37 AM.

  8. #23
    So I decided to torture an Aldi chisel just to see where it ended up... This is what happened.....

    Sharpened at 25 with a 30 microbevel.

    1" mahogany end grain and a nice heavy 4lb deadblow mallet....,.
    whack! Cut 1/2" deep and about a 0.040" thick shaving.
    lightly rolled edge.
    Wiped the rolled edge off the back with my X fine diamond and go again...
    whack! Cut 3/4" deep and about a 0.040" thick shaving.
    Wiped the rolled edge off the back again, stropped the bevel and go again..
    whack! Cut all the way through with the same thickness...

    After 1/2" of chopping - the micro-roll bevel kinda stabilized... I switched to chopping Lyptus flavored Eucalyptus.. Same thing with initial rolling the edge, flattening the burr on the back, stropping, and it seemed to go fine... All it takes is a light stropping to shave...

    So... What's the microbevel now? Who knows... Above 35 degrees.... Convex... I have no way to measure the effects of honing off the rolled burr on the back and going back at it... I chopped a 3/4" square hole in the Lyptus.... The edge holds up fine at wherever....

    And so at the end of the day -- It seems like I have arrived at this massive, earth shattering point:
    John, buddy - You were way over thinking it... The angles don't matter - cutting wood is what matters.... And it cuts fine. Flatten the back, strop the bevel wherever it ends up and bang away... If it gets bad - grind it back to 35 degrees and off you go...

    Save a different chisel for fine paring work..
    Last edited by John C Cox; 02-26-2018 at 11:00 PM.

  9. #24
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    I like this approach. Not the repeated rolled edges ( that only shows the steel is too soft) not the incessant stopping (only necessary to deal with too-soft steel) microbevels (difficult to measure/repeat), or 4lb maul (abusive of the poor innocent chisel) but the testing, examination, analysis, conclusions, adjustment, and repetition. Sound methodology.

    You should do a similar analysis of your tools in use on the wood you actually cut. In the end, you will find the best angle. 30 degrees is usually a good place to start for striking chisels, but only you can decide.

    Stan

  10. #25
    I am not exactly drawing a blank. I think you are getting the performance you are asking for. Everything seems careless and haphazard. You sharpen with some kind of machine. Then you use harsh and coarse abrasives to hone. Then you "whack" on the chisel with a four pound mallet, maybe a maul. People who get high performance from chisels do not treat them like crap.


    The angles don't matter - cutting wood is what matters.... And it cuts fine. Flatten the back, strop the bevel wherever it ends up and bang away... If it gets bad - grind it back to 35 degrees and off you go..


    This is a recipe for poor performance.

  11. #26
    Obviously a case of letting the tool know who the boss is. Treating the chisel like the Snowflake Princess of tools just breeds that millennial attitude that we see everywhere else...pampered, entitled, and clueless. Before you know it, the blade goes full triggered mode when faced with modern abrasives for honing or - indeed - any sort of work to be done.

    A little tough love in the form of aggressive prep and a whack or two that the neighbors can hear sets things right and lets a tool know where it fits in the grand scheme of things. Don't surrender to the PC (Prep Correctness) crowd with that nonsense about '...just enough prep to make the tool feel special' - - make that blade EARN the privilege of residing in your shop.
    Last edited by Todd Stock; 02-27-2018 at 8:07 AM.

  12. #27
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    Nah...sounds more like the OP was doing a Stress Test on that type/brand of chisel...to see how well an edge will stand up.

  13. #28
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    Quote Originally Posted by Todd Stock View Post
    Obviously a case of letting the tool know who the boss is. Treating the chisel like a special snowflake princess just breeds that millennial attitude that we see everywhere else...pampered, entitled, and clueless. Before you know it, the blade goes full triggered mode when faced with modern abrasives for honing or - indeed - any sort of work to be done.

    A little tough love in the form of aggressive prep and a whack or two that the neighbors can hear sets things right and lets a tool know where it fits in the grand scheme of things. Don't surrender to the PC (Prep Correctness) crowd...make that blade earn the privilege of residing in your shop.
    This one needs some mood music to go with it! Superfly or something similar.

  14. #29
    Quote Originally Posted by Warren Mickley View Post
    I am not exactly drawing a blank. I think you are getting the performance you are asking for. Everything seems careless and haphazard. You sharpen with some kind of machine. Then you use harsh and coarse abrasives to hone. Then you "whack" on the chisel with a four pound mallet, maybe a maul. People who get high performance from chisels do not treat them like crap.

    This is a recipe for poor performance.
    Care to share how you get high performance out of your Aldi chisels?

  15. #30
    Lol Todd.... I now have the solution when the Kids start playing their music too loud... Get out the Chisels and the BFH and go chop some Oak Mortise and Tenon joints in the house... And if that doesn't do it - I can drag the Drum Sander and Dust Collector inside. Maybe resaw some 9" thick Rosewood!

    Quote Originally Posted by Todd Stock View Post
    Obviously a case of letting the tool know who the boss is. Treating the chisel like the Snowflake Princess of tools just breeds that millennial attitude that we see everywhere else...pampered, entitled, and clueless. Before you know it, the blade goes full triggered mode when faced with modern abrasives for honing or - indeed - any sort of work to be done.

    A little tough love in the form of aggressive prep and a whack or two that the neighbors can hear sets things right and lets a tool know where it fits in the grand scheme of things. Don't surrender to the PC (Prep Correctness) crowd with that nonsense about '...just enough prep to make the tool feel special' - - make that blade EARN the privilege of residing in your shop.

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