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Thread: Do you burnish your scraper?

  1. #16
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    Quote Originally Posted by Edward Weber View Post
    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
    Just compare the grinder burr to the burnished burr under a microscope. The grinder burr looks like a ragged and fragile edge while the burnished burr looks more like a smooth knife edge.

    I've used both and almost always take the few extra seconds to hone off the grinder burr and add a burnished burr. The times I used the grinder burr I used CBN wheels from 80 to 600. 600 worked the best for me but none lasted as long as the burnished burr. The two do have a bit different "feel" in use.

    Also, don't remember if I mentioned this earlier but when a burnished burr starts to get dull, I generally refresh it at least once with the diamond hone and burnisher before returning for a pass on the 600 grit CBN wheel.

    JKJ

  2. #17
    Quote Originally Posted by John K Jordan View Post
    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.

    Attachment 465482

    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
    You turned me on to that one and it works great!20211012_130508.jpg

  3. #18
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    Quote Originally Posted by Allen Mattsen View Post
    You turned me on to that one and it works great!20211012_130508.jpg
    I'm glad you like it.
    While searching for Arno recently I came across their knife sharpener which is made just like the burnisher except for different carbide inserts - one for removing metal from the knife edge and the other for smoothing the edge. I find it works great when I'm in a hurry and don't want to get out the sharpening machine!

    https://www.amazon.com/Arno-Carbcut-.../dp/B07J17DMKS

    JKJ

  4. #19
    Agate burnishers were used by many old timers and considered the best. Dulled carbide laminate bits also work well.

  5. #20
    Quote Originally Posted by John K Jordan View Post
    Just compare the grinder burr to the burnished burr under a microscope. The grinder burr looks like a ragged and fragile edge while the burnished burr looks more like a smooth knife edge.

    I've used both and almost always take the few extra seconds to hone off the grinder burr and add a burnished burr. The times I used the grinder burr I used CBN wheels from 80 to 600. 600 worked the best for me but none lasted as long as the burnished burr. The two do have a bit different "feel" in use.

    Also, don't remember if I mentioned this earlier but when a burnished burr starts to get dull, I generally refresh it at least once with the diamond hone and burnisher before returning for a pass on the 600 grit CBN wheel.

    JKJ
    You prefer the 600 grit wheel for your scrapers? I've mainly been using my 180 grit for flat style tools and the 600 for gouges, in part just to leave them set up for most common tasks...

  6. #21
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    Setting grinding angles

    Quote Originally Posted by Allen Mattsen View Post
    You prefer the 600 grit wheel for your scrapers? I've mainly been using my 180 grit for flat style tools and the 600 for gouges, in part just to leave them set up for most common tasks...
    Yes, and I made some gages from plexiglas to very quickly set the wolverine platform for my most common angles for NRS, skew, hand scraper, etc.

    _scrapers_IMG_7811.jpg

    Since this picture, I started spray painting all of these on one side to make them easier to see and read. This one is for grinding a thin hand scraper at 90-deg. The 3rd pic is honing the edge flat before burnishing.

    template_angle_IMG_7898.jpg scraper_CBN_IMG_7894.jpg scraper_honing_1_IMG_7884.jpg

    This one is for my curved NRS ground at 60-deg, usable either left or right depending on which side I burnish the burr.

    NRS_IMG_7907.jpg NRS_IMG_7778.jpg NRS_IMG_7515.jpg

    I use a wolverine varigrind (not varigrind 2) for the bowl gouges, the tormek 1200grit CBN for the spindle gouges.

    JKJ

  7. #22
    Quote Originally Posted by John K Jordan View Post
    Yes, and I made some gages from plexiglas to very quickly set the wolverine platform for my most common angles for NRS, skew, hand scraper, etc.

    _scrapers_IMG_7811.jpg

    Since this picture, I started spray painting all of these on one side to make them easier to see and read. This one is for grinding a thin hand scraper at 90-deg. The 3rd pic is honing the edge flat before burnishing.

    template_angle_IMG_7898.jpg scraper_CBN_IMG_7894.jpg scraper_honing_1_IMG_7884.jpg

    This one is for my curved NRS ground at 60-deg, usable either left or right depending on which side I burnish the burr.

    NRS_IMG_7907.jpg NRS_IMG_7778.jpg NRS_IMG_7515.jpg

    I use a wolverine varigrind (not varigrind 2) for the bowl gouges, the tormek 1200grit CBN for the spindle gouges.

    JKJ
    Great idea w/ the plexiglass. I have some and so far been using a paper gauge that came w/ my NRS from D-Way tools. Do you just scribe a line or how do you form the gauge - surely not by grinding it down in the wheel, I imagine? I have plexi ready to use, this sounds like a good project.
    A friend made me a 3-D printed setup gauge for 40° which is kinda cool. Maybe down the line...

  8. #23
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    Thanks! I did shape the curve with the CBN wheel but only removed a TINY bit pf plastic!

    - Set the tool rest platform on the grinder to the desired angle.
    - Held a straight edge of a piece of plexiglas on the platform and tight against the flat side of the CBN wheel.
    - Used a xfine sharpie to trace the curve of the wheel on the plastic.
    - Carefully cut along the curved line with the bandsaw; cut a wide relief notch in the middle for a “two-point” contact (wide “points”!)
    - With the flat held firmly and perpendicular against the platform, turned the grinder on then off and with wheel turning slowly gently
    touched the gage to the wheel, refining and smoothing the two contact points. A fine grit CBN wheel may melt the plastic
    a bit instead of cleanly grinding so I cleaned up the edges as needed with a sharp knife.
    - Mark the angle and tool on the gage.

    When I use one to set the angle of the platform I’m careful to hold the gage perpendicular to the platform AND the front of the wheel or the grind angle might be off a bit. These would be a bit easier to use if made from thicker material, say 1/4” or so but more effort to make. I might try making them from aluminum or steel and use two much narrower “points” to contact the wheel.

    I do have a 3D printer so that might be a good option but would have to be careful to get the shape right for a specific tool angle since the tool thickness is much smaller than the two-point contact distance on the curve of the wheel. By making the gage to match a given tool grind that I like I don’t even have to know the angle! The important thing is the gage sets the platform so the grind is precisely repeatable so a clean grind on even a very thick tool only takes seconds and no extra tool steel has to be ground away.

    I wouldn’t use these on conventional grinding wheels since the radius changes as they wear.

    BTW, for most platform sharpening I prefer to use the mini platform instead of the larger one that comes with the Wolverine. I bought a couple of these through Amazon when they were $32.

    JKJ

    Quote Originally Posted by Allen Mattsen View Post
    Great idea w/ the plexiglass. I have some and so far been using a paper gauge that came w/ my NRS from D-Way tools. Do you just scribe a line or how do you form the gauge - surely not by grinding it down in the wheel, I imagine? I have plexi ready to use, this sounds like a good project.
    A friend made me a 3-D printed setup gauge for 40° which is kinda cool. Maybe down the line...

  9. #24
    Great info, working on gauges from plexi now .

    Question about your NRS's: I use one like those, straight on one side, and it makes me wonder why not just rounded all the way around? Is it just harder to raise a consistent burr if it was round nose in shape? There must be a reason for several with inside/outside or left/right orientation?

  10. #25
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    Quote Originally Posted by Allen Mattsen View Post
    Great info, working on gauges from plexi now .

    Question about your NRS's: I use one like those, straight on one side, and it makes me wonder why not just rounded all the way around? Is it just harder to raise a consistent burr if it was round nose in shape? There must be a reason for several with inside/outside or left/right orientation?
    _scrapers_IMG_7778.jpg

    Do you mean these?

    I don't find it difficult to burnish a burr a scraper that is rounded all the way around.

    I use a variety of negative rake scrapers and some are in face rounded around the top and part way down the other side, but not very far down the other side. In fact, I've seen pro turners at symposiums use such NRS and have seen some for sale. You can certainly grind it far down both sides but unless you use a very wide scraper it would tend to have a fairly sharp radius on the tip. This can be handy at times - I ground one with a narrow tip radius for a special purpose, to use on a small platter with a raised foot that had a smoothly curved and fairly deep cove "waist". I made the tool just to fit nicely into this tight area. (Sorry, I don't see that I took a picture of that NRS.)

    However, if you look at the three above note they all have a short straight or almost straight tip. I've never seen anyone grind one that way (until after they saw some of mine) but I did it this way on purpose for a special reason. If I'm making a small squarish platter like this with square or almost square wings...

    penta_maple_ellis_c_IMG_5435.jpg

    ... I can use the end to smooth flat areas and areas with very shallow curves. It even works very well on the wings themselves (used gently, of course). I've had people tell me you can't use scrapers on wings but perhaps they didn't thing of grinding one like this. If the NRS was curved on the end I don't think it would be as useful for general work.

    I think the flat tip on the end makes it a little easier to control the tool, moving it back and forth gently (with the tool horizontal and held firmly flat against the tool rest, supported with the left hand close to and sliding against the back of the tool rest, thumb on top, left forefinger below).

    I occasionally use the 90-deg corner at the end of the short flat has another purpose - smoothing right up to shoulder or bead, sometimes difficult to do another way.

    I guess I could grind a very wide NRS with long curves down both sides and a flat tip but it might be massive and difficult to sharpen.

    The first photo below shows using the flat tip to smooth the wings. I make the tops of most of these with shallow curves so on those I can use the flat end all the way from the edge to the center. Having a flat takes out more of the small variations typically left by the finish cut with a gouge.

    NRS_IMG_7515.jpg

    The bottom side of the piece, however, has tighter radii towards the foot so the long curve on the side is perfect for smoothing that. Also good for the insides of a bowl. The flat tip works well towards a flattened center of a bowl or a flat platter.

    NRS_curved.jpg

    Note that one huge goal (for me) for these scrapers is to eliminate power sanding with relatively coarse paper. Power sanding with coarse rotating disks has a number of serious problems. For years now I have not ONCE power sanded with a rotating disk such as on a drill. (My nice angle drill gets used for drilling holes in tight places!)

    If I follow the finish gouge cut with the NRS and follow that with hand scrapers, I can almost always start sanding with 320 or sometimes finer paper. The hand scrapers can get the surface so smooth I often do all or most of the sanding by hand. If I use power sanding, it's always with VERY gentle random orbital action from a pneumatic ROS with 2" or 3" paper, usually 600 grit.

    grex_ROS.jpg sanding_IMG_20171212_094330_319.jpg

    If I made a lot of platters that were perfectly flat I'd probably grind one NRS, maybe a 3/4", that was straight (or almost straight) all the way across the end but with a slight radius on each corner to keep it from digging into the wood.

    Using these tools for smoothing (after both initially shaping and making finish cuts with a Hunter Hercules tool), a relatively inexperienced student made this one as her first "real" project, a present for her sister. Previous to this she had a spindle lesson and few simple spindle practice projects, and completed very nice small bowl in her second lesson. Then she wanted something more challenging!

    Kristina_platter_finished_comp3.jpg

    You might not be able to tell by the photos but the surface was SO good, perfect, top and bottom. I finally found someone pickier than me!

    BTW, I've done a number of turning club demos on all these techniques. When it's safe enough again I might be talked into doing some more.

    There I go again, writing too much!

    JKJ

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