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Thread: Do you burnish your scraper?

  1. #1
    Join Date
    Sep 2006
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    L.A. (Lower Alabama)
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    Do you burnish your scraper?

    I have seen this Lee Valley scraper burnisher as well as some homemade tools for this purpose.

    I would like to know if any of you take the time to burnish your turning scrapers.

    I suspect you need to hone the top of the scraper and then burnish a hook. Burnishing one fresh off the grinder without honing the top may produce a hook that is so rolled over it is less effective.

    Interested in your experiences.

    Capture.JPG

  2. #2
    The main scraper I use for bowl roughing is the Big Ugly tool, which has tantung silver soldered onto the end of some bar stock. It gets a great burr from the grinder and doesn't need burnishing, though this material can be burnished. My more standard scrapers that I use for shear scraping, most of which are M42 HSS or V 10 (D Way and Thompson) I am still experimenting. Frequently the burr off of the grinder does a good job. I use wheels from 80 to 600 grit for my burrs. It can be turned down and burnished back up a couple of times, but presently, I am thinking that returned burr is not as sharp. I seldom go to the trouble of honing off the grinder burr. I have done that, and then burnished on a fresh burr, and it cuts very well, but not positive that it is a better edge. I have been turning some big leaf maple that has been problematic. For reasons unknown, I am getting tear out in one quadrant only, and nothing seems to take it out, including NRSs, 600 grit gouge grinds, and any type of burr for shear scraping. Standard tear out is in 2 quadrants, always... With the older M2 HSS scrapers, a burnished burr seems to work better for durability, but not sure if it provides a better cutting edge for shear scraping, haven't used them in years for that. I am currently experimenting with hand honing with a diamond card to raise the burr, going across the bevel rather than up or down. Mixed results, but most of it has been with this strange big leaf maple.

    I do prefer to burnish NRSs (negative rake scrapers). I use a hand held tool with a 3/16 carbide rod in it. Hand pressure only. I also use it on my card scrapers. After much experimenting, I have settled on a 60/25 grind for my NRSs. The skew chisel types, in the 30/30 range have too acute of an angle to take a burnished edge, at least for me. I tried a 40/40, and a 45/45, and didn't care for them. I am thinking that you need a certain amount of metal under the burr to support it for longer cutting action and sharpness. The edge can be burnished down and back up again a couple of times.

    As for the Lee Valley burnisher, it does have carbide rods. It is intended to be bolted down to your work bench. I never considered getting one. Main reason is that I have many different angles that I use, and it seems to be set for one specific angle. Another problem with it is that you can over burnish. By that I mean that it is easy to put too much pressure on the rod and scraper which yields a burr that is too heavy, and some times they can curl back too far which is not the best edge for cutting with. I prefer the hand held. My first one was a 1/8 inch carbide drill bit. You can burnish with the standard burnishing tools for card scrapers on M2 HSS. The triangle one works best. For the M42 and V 10, you pretty much need carbide.

    robo hippy

  3. #3
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    Sep 2006
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    L.A. (Lower Alabama)
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    Thanks for the insightful reply Reed!

    I have successfully avoided spending the money on the Veritas tool. It is too limited in application and therefore the 60+ bucks to get it in hand doesn't make sense to me. Guess I will make me a tool or use a Veritas handheld that I have already for some testing. I have some carbide milling bits that I have wrecked in the mill that could serve the purpose.

    I have tried the skew chisels with a hook but the edge is just way too fragile for me and I decided not to repurpose a good tool (Dway) for that.

    Your advice on the NRS of 60/25 is appreciated. I may buy some stock for that and grind my own. Do you have an opinion on the steel to use? M42 or PM10V? Thompson's blanks are attractive to me for grinding myself but I like the Dway stuff as well.

  4. #4
    Join Date
    Jan 2013
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    sykesville, maryland
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    I burnish my scrapers sometimes. I bought a 5/16" dia carbide rod that is short and put a handle on it. I think it was about 3" long before I put the handle on it. Sticks out about 2" which is plenty for burnishing. Works good and didn't cost much. But you can only burnish a few times before the burr is too weak. Then you have to go back to the grinder for a second or two.

  5. #5
    Join Date
    Feb 2008
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    E TN, near Knoxville
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    I bought one of those burnishers years ago. I used it on a variety of scrapers including some that were very large.

    That burnishing tool can be very aggressive because of the leverage the pin at the rear gives you. It can easily create a burr that is much too large to be useful. When used gently, it's fine.

    I quit using the thing at least 10 years ago and instead use burnish with hand tools. I started with a fairly large diameter carbide rod then went to a smaller rod. I like the small one better.

    _scrapers_IMG_7784.jpg

    My favorite burnisher now is made by Arno, has a round rod on one side and a triangle on the other side. The triangle actually as a small radius on the working edge rather than a sharp edge so it really works like a small diameter rod. The triangle is more aggressive than the round rod. Sorry, I can't find a pic of the Arno.

    I use the hand burnishers for scrapers, negative rake scrapers, and hand scrapers.

    JKJ




    Quote Originally Posted by Alan Heffernan View Post
    I have seen this Lee Valley scraper burnisher as well as some homemade tools for this purpose.

    I would like to know if any of you take the time to burnish your turning scrapers.

    I suspect you need to hone the top of the scraper and then burnish a hook. Burnishing one fresh off the grinder without honing the top may produce a hook that is so rolled over it is less effective.

    Interested in your experiences.

    Capture.JPG

  6. #6
    Join Date
    Sep 2013
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    Wayland, MA
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    I burnish with a carbide rod-- Alan Lacer sells a nice kit with the rod and ferrule, you make your own handle to suit. You can also use the butt end of an old solid carbide router bit or other carbide tooling if you want to make one for near free. I had the Veritas jig years ago, it makes far too aggressive a hook for me. A light pass by hand is plenty to turn a burr for light duty scraping like cleaning up the inside of a bowl. I polish the top flat with a diamond teardrop card (also from Alan) then pull the burr. My scrapers go a very long time between trips to the grinder; the raised burr is smaller, more consistent and longer lasting than the burr off the grinder.

  7. #7
    Join Date
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    Northern Illinois
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    I love the Veritas burnisher. For me it works well although I also have burnished my scrapers with a carbide pin mounted in a small handle. Both work well.

  8. #8
    Join Date
    Nov 2009
    Location
    Peoria, IL
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    I prefer the burr off the grinding wheel. Just a super light pass completely restores it.

  9. #9
    As for tool steel, I can't see any difference between the V10/Thompson and the M42 from D Way. I have a friend who is mostly retired now and he turned myrtle wood trays for the tourist shops for 30 or so years. He didn't notice any difference either. Funny thing about the M42, it comes in 1/4 inch, then 5/32, then jumps to 3/8. I use 1 inch wide ones. Just because I guess. You don't need a heavy tool for a NRS. The cuts you do are feather light, and if you have to push at all to get it to cut, then it is dull. I got a bunch of blanks from D Way so I could 'experiment'.... Smaller width ones are good for the insides of boxes.

    robo hippy

  10. #10
    Well this question feels like a poll, so I'll add in my answer that I don't burnish my scrapers. They get sharpened on the 80 grit wheel but normally are touched up with a hand hone.

  11. #11
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    L.A. (Lower Alabama)
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    Quote Originally Posted by David M Peters View Post
    Well this question feels like a poll, so I'll add in my answer that I don't burnish my scrapers. They get sharpened on the 80 grit wheel but normally are touched up with a hand hone.
    Thanks for participating in the poll David. Your response generated another question!

    Have you compared the edge you get on the 80 grit vs. something finer? I have always wondered about that but have never taken the time to really investigate it deeply enough in the shop.

  12. #12
    I have sharpened and raised burrs with 80, 180, 320, 600, and 1000 grit CBN wheels. I settled on the 180 grit wheel. The burr I get from it seems to be every bit as durable as the 80 grit burr, and just as sharp. The finer wheels do leave a nice burr, but I don't think they are quite as durable. Part of the burr raising that can make a difference is how hard you push into the wheel. I have some times thought that if you grind hard, rather than just brushing the bevel against the wheel, you get a more aggressive burr, but not necessarily a better burr. For my McNaughton blades, Kel tole me to use a coarse/220 grit diamond hone to raise the burr. With those, I will hone across the bevel rather than up the bevel. This does seem to raise a better burr than the fine hone cards.

    Side note, Jimmy Clewes is one who sharpens his scrapers up side down. He said this produces a finer/sharper burr. I tried it a few times, but didn't notice any real difference. I will say that I did not give this method a heavy duty work out, so maybe I need to play with it some more. I don't have a negative 70 degree setting on my grinder platform. I do have one that I can do at about 80 degrees.

    robo hippy

  13. #13
    Keep in mind that the burr created by the grinder is weaker than the burr created by burnishing.
    A burnished burr is considered to be work hardened and therefore much stronger.
    A burr created by the grinder is much quicker to create/restore and is usually turners need.
    YMMV

  14. #14
    Join Date
    Aug 2011
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    Lummi Island, WA
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    594
    I've gotten in the habit of hand burshing scrapers when needed - I sharpen scrapers on an older 80 grit cbn wheel (probably closer to the 180 when it was new. When going for a final sheer scrape, I grab a 3/4" D-Way skew and use the rounded edge to quickly burnish a nice burr. The M42 steel seems to turn a nicely hooked burr that lasts a little longer, and the skew was handy..
    Got in the habit because I'm too lazy - and way too cheap - to go back to the grinder too often.

  15. #15
    Quote Originally Posted by Alan Heffernan View Post

    Have you compared the edge you get on the 80 grit vs. something finer? I have always wondered about that but have never taken the time to really investigate it deeply enough in the shop.
    I have 80/350 CBN wheels. Scrapers off the 80 grit wheel just seem to cut better for me.

    But then I'm contradicting myself by stating that I hand-hone them when they're dull, that's like a 600 grit finish. If scraper no longer feels sharp to my thumb (i.e. the burr is gone and the corner is a bit rounded off) then I'll hand hone it.

    I'll also add that scrapers are not my primary tool, I'm trying to improve my gouge skills to get finish cuts from them. Listen to Reed if you want scraper expertise :-)

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