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Thread: Anxious to try a new tip tool

  1. #16
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    Quote Originally Posted by Bill Jobe View Post
    Well John, how did I do?
    Not much of an edge on it yet. Wasn't sure how sharp you grind them.
    I realize it ain't as pretty as yours but I just have a cheep HF grinder and did it freehand.
    What I did do was try to get the curve as smooth as possible. And, I dipped it in water after every 2 or 3 seconds so I would not damage the hardness of the steel.
    The only thing that matters is how well it works.

    I grind mine freehand sitting flat on a grinder tool platform rest. I ground a bevel on one side, the flipped the tool over and ground the other side to the same angle and the same bevel width, although that probably doesn't matter. This makes a negative rake scraper that can be used either "left-handed" or "right-handed", depending on which way I burnish the "burr" for use inside or outside or depending on the profile of the piece. (Raise the burr on the upper side by burnishing the underside.

    I don't know the grinding angle but I can check the next time I get to the shop.

    I raise the cutting burr not by grinding as most do but with a carbide burnishing rod. A HSS tool shaft will work too. The diameter of the shaft doesn't much matter. It doesn't take much pressure.

    burnisher_IMG_6767.jpg

    JKJ
    Last edited by John K Jordan; 02-11-2018 at 8:56 PM. Reason: type

  2. #17
    Ok, so it ain't perfect. But it does a better job than anything else I have. Had to round back the righthand side so it would transition from bottom to side better.
    All I can think of is that it needs to be sharper.
    Not once did it even hint at grabbing, a problem I had with the tool in its original form.
    Attached Images Attached Images

  3. #18
    I was typing when your post came in.

  4. #19
    I see the problem.
    No bevel on the bottom equals no burr.
    Bet I look silly with what I made.
    It will get the bottom bevel first thing tomorrow.
    Amazing how well it cuts without it.
    John, you pics gave me a distorted idea of how you grind yours. The 2 bigger tools look like they are flat on the bottom clear to the edge.

  5. #20
    Do you think this hone would work in creating a burr?
    If not the honing surface, will the edges of it make burrs?
    It was a gift from a friend when he was getting me going on carving and it is diamond impregnated on the side used to sharpen my knife. The remainder of the piece is smooth.
    Would either surfaces create a good burr?
    Attached Images Attached Images

  6. #21
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    Quote Originally Posted by Bill Jobe
    John, you pics gave me a distorted idea of how you grind yours. The 2 bigger tools look like they are flat on the bottom clear to the edge.
    The bottom bevel shouldn't matter much. I haven't tried one ground like that but you could probably just burnish a bevel on your existing grind and it should work fine. In fact it may work better than what I use. I sometimes use spindle gouges upside down for fine scraping in coves - similar in cross section to your scraper grind.
    scraper_gouge3.jpg

    All three of these are ground the same way. The differences are one is ground from a skew chisel and one is wider than the others.
    scrapers_neg_rake.jpg


    The bottom bevel does not have to match the top bevel. The wood doesn't care. However, it does let me use the tool identically when flipped over and a new burr applied. I make other negative rake scrapers with a large and large angle bevel on the bottom and a small but sharper angle bevel on the top. Here are some very small ones made this way - they give a glass-smooth surface on end grain in good wood:

    scrapers_small_thompson.jpg

    Quote Originally Posted by Bill Jobe View Post
    Do you think this hone would work in creating a burr?
    If not the honing surface, will the edges of it make burrs?
    There are several ways I know and have used to make a burr.

    • One way is to grinding on the bottom bevel last. This will deform and curl up a ragged burr which will cut very well for a short time. The size of the burr depends somewhat on the grit and pressure used in that final grind. You can easily feel the size of the burr with your finger. Many people use this method and replenish the burr often, sometimes after just one or two scrapes. If you look at the burr under a microscope you might see why - the burr looks like a jagged mountain range and it's easy to imagine the peaks wearing off quickly.
    • Another way is to use a ceramic or diamond hone and hone the bottom bevel/edge, usually not flat on the bevel but at an angle. This will raise a burr the same way but it will be much the same as the grinder burr except smaller. This is a good way to raise small burr for a very fine and delicate scrape. It also doesn't last long.
    • The third way is to use a burnisher. You hold the burnisher so it is not flat against the bottom bevel but forms an angle with the the bottom bevel. Apply some pressure and slide the burnisher along the entire scraping edge. The amount of angle, the diameter of the burnishing rod, and the amount of pressure determine the size an shape of the burr. The metal is actually deformed at the edge and curled upwards. If you look at it under the microscope the burnished burr might look like a smooth, polished cutting edge instead a ragged row of teeth. A burnished burr can be very gentle or quite aggressive. It can even be curled too much and won't even cut without holding the tool at a downward angle instead of horizontal as you would otherwise.


    It is my experience that a burnished burr can last a lot longer than a burr from the grinder. I will typically grind the scraper, use a diamond or ceramic hone flat on the bevel to remove any grinder burr, then polish the edge by stropping on leather or some polishing compound spread on a piece of mdf or wood. After the edge is polished I raise the burr with the burnisher. When that burr wears away, I may re-hone, polish, and burnish several times before going back to the grinder.

    Burnishing the cutting edge is the way hand and cabinet scrapers have been prepared for ages. I use the carbide burnisher on scrapers such as these, prepared and sharpened the traditional way used by cabinet and instrument makers:

    scrapers_.jpg


    Besides the hand burnisher I showed, Veritas also makes a scraper burnisher you fasten to the workbench. I used to use this on large scrapers. With this it is easy to put too much burr on large scrapers and make them way too aggressive.

    burnisher-veritas.jpg

    As mentioned, you can burnish with a carbide rod, a HSS steel rod (even the shaft of a tool) or almost any piece of steel in a pinch. The smooth end of an old HSS steel drill bit is perfect, especially if it is hardened all the way to the end (some are not). It helps if the burnisher is the same hardness or harder than the burnished tool so I prefer to use carbide. You need less pressure with a smaller diameter rod but a larger rod works fine - I have a larger carbide burnisher and used it for everything for years.

    (sorry, in a big rush this morning - no time to proofread this, hope it's not too bad)

    JKJ

  7. #22
    Quote Originally Posted by John K Jordan View Post
    The bottom bevel shouldn't matter much. I haven't tried one ground like that but you could probably just burnish a bevel on your existing grind and it should work fine. In fact it may work better than what I use. I sometimes use spindle gouges upside down for fine scraping in coves - similar in cross section to your scraper grind.
    scraper_gouge3.jpg

    All three of these are ground the same way. The differences are one is ground from a skew chisel and one is wider than the others.
    scrapers_neg_rake.jpg


    The bottom bevel does not have to match the top bevel. The wood doesn't care. However, it does let me use the tool identically when flipped over and a new burr applied. I make other negative rake scrapers with a large and large angle bevel on the bottom and a small but sharper angle bevel on the top. Here are some very small ones made this way - they give a glass-smooth surface on end grain in good wood:

    scrapers_small_thompson.jpg



    There are several ways I know and have used to make a burr.

    • One way is to grinding on the bottom bevel last. This will deform and curl up a ragged burr which will cut very well for a short time. The size of the burr depends somewhat on the grit and pressure used in that final grind. You can easily feel the size of the burr with your finger. Many people use this method and replenish the burr often, sometimes after just one or two scrapes. If you look at the burr under a microscope you might see why - the burr looks like a jagged mountain range and it's easy to imagine the peaks wearing off quickly.
    • Another way is to use a ceramic or diamond hone and hone the bottom bevel/edge, usually not flat on the bevel but at an angle. This will raise a burr the same way but it will be much the same as the grinder burr except smaller. This is a good way to raise small burr for a very fine and delicate scrape. It also doesn't last long.
    • The third way is to use a burnisher. You hold the burnisher so it is not flat against the bottom bevel but forms an angle with the the bottom bevel. Apply some pressure and slide the burnisher along the entire scraping edge. The amount of angle, the diameter of the burnishing rod, and the amount of pressure determine the size an shape of the burr. The metal is actually deformed at the edge and curled upwards. If you look at it under the microscope the burnished burr might look like a smooth, polished cutting edge instead a ragged row of teeth. A burnished burr can be very gentle or quite aggressive. It can even be curled too much and won't even cut without holding the tool at a downward angle instead of horizontal as you would otherwise.


    It is my experience that a burnished burr can last a lot longer than a burr from the grinder. I will typically grind the scraper, use a diamond or ceramic hone flat on the bevel to remove any grinder burr, then polish the edge by stropping on leather or some polishing compound spread on a piece of mdf or wood. After the edge is polished I raise the burr with the burnisher. When that burr wears away, I may re-hone, polish, and burnish several times before going back to the grinder.

    Burnishing the cutting edge is the way hand and cabinet scrapers have been prepared for ages. I use the carbide burnisher on scrapers such as these, prepared and sharpened the traditional way used by cabinet and instrument makers:

    scrapers_.jpg


    Besides the hand burnisher I showed, Veritas also makes a scraper burnisher you fasten to the workbench. I used to use this on large scrapers. With this it is easy to put too much burr on large scrapers and make them way too aggressive.

    burnisher-veritas.jpg

    As mentioned, you can burnish with a carbide rod, a HSS steel rod (even the shaft of a tool) or almost any piece of steel in a pinch. The smooth end of an old HSS steel drill bit is perfect, especially if it is hardened all the way to the end (some are not). It helps if the burnisher is the same hardness or harder than the burnished tool so I prefer to use carbide. You need less pressure with a smaller diameter rod but a larger rod works fine - I have a larger carbide burnisher and used it for everything for years.

    (sorry, in a big rush this morning - no time to proofread this, hope it's not too bad)

    JKJ
    Thank you very much for the info. I think I'll try grinding a very narrow bevel on the bottom and go from there. If it doesn't work out I won't lose much of the tool length.

  8. #23
    The little hand scrapers...do you ever use them on the lathe with it running?

  9. #24
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    working with hand scrapers

    Quote Originally Posted by Bill Jobe View Post
    The little hand scrapers...do you ever use them on the lathe with it running?
    I use these hand scrapers and others several ways.

    • With the lathe running I use these hand-held in the "air", no tool rest, angled significantly, lathe running very slowly. I use them on the outside and inside of bowls, vessels, etc. I'll use them on the bottoms of a bowl or platter but not in the center. If used inside a vessel with a large enough opening to reach inside I use a small curved scraper, small enough that if I drop it it goes harmlessly to the outside wall. I've never use one like one gentleman did - he used a large scraper inside a tight space and when he dropped it it turned into a food processor. After scraping with the lathe running I almost always go back over the surface with the lathe off, scraping gently with the grain.

    • When the lathe off I use them more with the lathe off. I pick one with a shallow curve to removing the nub in the middle of the inside or bottom of a piece. After using these you will never again look at a finished piece in the light and see circular tool ripples/undulations in the bottom of a bowl or platter. When I turn a piece with "wings" such as one of the squarish platters I like to make (pics below) it is almost impossible to avoid took marks where you are cutting air. I use hand scrapers to remove all tool marks before sanding. When scraping, I scrape with the grain and scrape downhill. With the hand scrapers there is rarely a need for power sanding - I haven't used my angle drill for sanding for years. I keep one of the small squarish platters to use as an example - after scraping the top and bottom and wings the only sandpaper I used on it was 600 grit.


    Here are some of the squarish dished platters I smoothed mostly with scrapers instead of sandpaper:

    penta_plates_comp_small.jpg penta_maple_ellis_IMG_5435.jpg

    This is one from Olive wood with scraping in progress with one cabinet scraper and two StewMac scrapers, no sanding yet. Please believe me that I'm not trying to brag but several people have commented on how perfect the surface is on the finished piece - the scrapers make it easy. Below is another picture of this one which shows it mounted on the carving stand.

    scrapers_platter_IMG_20171111_161724_603.jpg

    I've occasionally used the small scrapers with the lathe running to smooth thin spindles as well when I ran into a problem.

    F01_scraper_IMG_5033.jpg

    I grind new curves on hand scrapers as needed. Some small scrapers I've bought in sets from Highland Hardware and Woodcraft. Some I've ground from new and used cabinet scrapers with high quality steel. (When grinding these keep them cool since they are not HSS and bluing will destroy the hardness.) The thicker cabinet scrapers from high-end tool companies are best.

    I've been using scrapers like this for more than 15 years. More recently, I've started making good use of the thicker StewMac scrapers, marketed to people who make violins and guitars. These are sharpened in a different way and are not burnished.

    SCRAPERS_StewMac_IMG_20171019_081858_098.jpg

    It is amazing how perfect you can get even a large surface by scraping instead of sanding.

    One more thing. When scraping, sanding, or otherwise working on a piece with the lathe off I usually take the chuck off the lathe and mount it on an articulating carving post held the the lathe's banjo. This makes it SO much easier to work on - no bending over, far easier to see and remove defects.

    I use this stand from Best Wood Tools which has some significant advantages to some of the others: http://bestwoodtools.stores.yahoo.net/arcaandfipow.html One huge advantage is by loosening the top lever you can rotate the chuck and work 360 degrees to work on different areas. Some of the other post use two locking angles instead of one angle and a rotating pivot and require you to use two hands to juggle the piece into a new position. With a heavy piece you almost need three hands when loosening the levers to keep from smashing the piece into the lathe. The rotating method is far better.

    carving_stand_IMG_20171111_162052_024.jpg

    JKJ

  10. #25
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    NRS grind angle

    Quote Originally Posted by Bill Jobe View Post
    I think I'll try grinding a very narrow bevel on the bottom and go from there.
    I measured the included angle on the curved negative rake scrapers I showed. They are 56 degrees. I didn't make the angles 56 degrees on purpose, I just ground them so they looked right to me. They work well on bowls and platters.

    I don't think the angle matters too much unless it is too large. I've heard people say to keep the angle reasonably less then 90 degrees but I think what you use the scraper for and the type of wood makes a difference. For example, I have some over 90 degrees and they work extremely well on end grain in hard wood, such as the bottom or lid of an ebony box.

    JKJ

  11. #26
    John, I did as you said. Ground the bevel where I wanted it, then with my hone I removed the burr. Then, using a drill bit, I pushed up a burr that was very small but uniform.
    It worked well except for one thing...it would chatter when I go into the transition between side and bottom. Most chatter I could eliminate with slowing the rpm.
    I got it smooth enough that just a little wet sanding gave me a nice smooth finish.
    I've since ground more clearance on the right side and now I will hone it smooth, hone away any burr, then push up a new burr.

    I've learned a tremendous amount about grinding by reading your posts as well as others and I very much appreciate the advice and suggestions from all of you.
    Thank you very much,John, for going into such detail. I am going to start using scrapers more. And (a big plus) it's something I can do indoors when I get some hand scrapers.
    Robo, I watched you turn a bowl using just scrapers and it was done seemingly in a matter of seconds. Man, you don't fool around, do you? Very nice work. I watched several of your videos.
    Thank you to all who posted.

  12. #27
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    Quote Originally Posted by Bill Jobe View Post
    ...It worked well except for one thing...it would chatter when I go into the transition between side and bottom. Most chatter I could eliminate with slowing the rpm....
    If it chatters I'm guessing you have too much of the edge touching too much of the curve at one time. It might be trying to take a shaving off a too wide of an area at once, just at the point where the tool may be extended a fairly long distance over the tool rest.

    There should just be a very narrow part of the edge scraping at any one time. If the radius of a transition is too sharp it might be worth grinding a second one with a sharper curve. Just a thought. (A thicker scraper might also help - and can't hurt!) When working deeper inside a bowl or box I also sometimes use a special box rest (from Best Wood Tools) with a 1" wide flat top - it is made to extend deep into a box.

    Also experiment with raising or lowering the tool rest a little while keeping the tool horizontal and flat on the rest. Another thing that SOMETIMES helps with certain types of chatter is consciously pressing down on the tool right where it is supported by the rest, I've had this help occasionally with other tools besides scrapers

    JKJ

  13. #28
    slant scraper.jpgI'm adding a shear scraper variation I made a few weeks ago, just to toss it into the conversation and see what you guys think. It's a Sorby cutting head mounted on 1/2" shaft at about 45 degrees. The goal is to be able to shear scrape while keeping the tool handle level

    I made it for two situations - finishing a shear scrape when the head or tail stock would block the handle from swinging through, also to smooth the interior of vessels when it's too unwieldy to get the tool rest and tool at the right angle.

    It seems to be working pretty well although it's odd to use. You can't sharpen it while mounted on the rod of course, so that's not convenient. It's got my brain working quite a bit while using it - there is an extra variable in presentation regarding the roll of the tool. Feedback from the tool is directed straight back up the shaft so you can really feel the quality of the cut as the tool rotates or the wall curves.

    I tried it out today on a faceturned birch bowl in the lower third where I would typically be moving to a bottom feeder and was able to produce some angel hair shavings although not to take it all the way to the nib. It won't replace my heavier shear scrapers with broader edges but it seems like it might get a spot in the rotation.

  14. #29
    John and George, thank you for posting.
    I made abother scraper, 1/2 width.
    I don't have the bevel quite right, but was able to finish a small bowl where I put a radious far beyond the width of its rim.
    I think I might buy a couple scraper so I can get a better understanding of just exactly how these things are ground. Then perhaps beginning to make my own.
    Anyone know whether or not stainless steel can be used. I have a fair amount on hand and was considering trying it.
    One more thing....I bought an old toolbox at Habitat and it contained a round tapered diamond impregnated knife hone. Any reason not to use it on scrapers?
    The hone has a very nice relief near the handle that is smooth and considerably smaller in diameter than the whole. Good for raising up a burr?

  15. #30
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    Quote Originally Posted by Bill Jobe View Post
    ....I bought an old toolbox at Habitat and it contained a round tapered diamond impregnated knife hone. Any reason not to use it on scrapers?
    The hone has a very nice relief near the handle that is smooth and considerably smaller in diameter than the whole. Good for raising up a burr?
    My observation: A burr raised with a hone of any sort is quite small and delicate. A burr raised from a grinding wheel is rough and weak. A burr raised with a burnishing rod is smooth and stronger. You should probably try each way and make your own observations, see how they work and how they hold up.

    JKJ

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