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Thread: Angle Setting Jigs

  1. #1

    Angle Setting Jigs

    I am preparing to make a new set of angle setting jigs (as in attached photo) for my 6" bench grinder. The idea is that I grind to an angle and then hone a micro bevel.

    I have only just realised that if I grind say, a 25 degree angle such that when I place the chisel (or whatever) on the oilstone so that the front and back of the concave grind are both touching the stone then the actual bevel angle is less than 25 degrees. The difference is 2 to 4 degrees depending on the angle and the thickness of the steel.

    Consistency is probably more important that the actual numbers but I would appreciate people's opinion as to whether one should aim for the stated angle at the cutting edge or when the front and back of the bevel are both in contact with the stone.

    Thanks for any input.
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  2. #2
    Join Date
    Feb 2010
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    Philadelphia, PA
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    3,632
    My preference is to grind so that the (approximate) desired angle is achieved when honing directly on the bevel (front and back of hollow touching stone)

    2 reasons for this:

    1. Repeatability from honing to honing for the angle that I most often want the tool at.

    2. If I desire to raise the angle a little for a specific reason. Its easy enough to raise the angle a few degrees by simply lifting from the hollow. For example, I typically keep my bench chisels at around 28 degrees. Last week I was chopping a bunch of rather large blind dovetails in hard maple and was having problems with edge failure. To remedy this, I just went over to my stones and eyeballed a lift of a few degrees. The bevel is small enough when you do this that you can actually get a few honings at that approximate angle even though it seems that such a micro bevel would not be repeatable. When I'm done with this project its easy enough to go back to the grinder and return my chisels to my base angle with minimal grinding.

    And yes 25 degrees for thick plane blades and chisels is not the same setting as 2 degrees for an old Stanley blade. Once I get each tool about where I want it I use the tool itself as an angle setting jig from there on out. I have a little jig I made for initial angle setting, but I am able to deal with the thickness issue by simply setting things a little steeper than the jig for thick blades and a little lower for thin. I can usually get within a degree or so doing this and that's good enough for me.
    Last edited by Chris Griggs; 02-07-2013 at 6:08 AM.
    Woodworking is terrific for keeping in shape, but it's also a deadly serious killing system...

  3. #3
    Join Date
    Jun 2010
    Location
    Warner Robins, Georgia
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    49
    What works for me is to grind the blade 5 degrees less than wanted for the edge. Grind no closer than 1/16 of an inch from the edge. Then hone edge at desired angle. The back of the concave grind never touches stone.

  4. #4
    Here is a jig I built:

    http://www.inthewoodshop.com/Woodwor...ryGrinder.html

    Regards from Perth

    Derek

  5. #5
    Join Date
    May 2007
    Location
    Ventura, CA
    Posts
    474
    Quote Originally Posted by Derek Cohen View Post
    Here is a jig I built:

    http://www.inthewoodshop.com/Woodwor...ryGrinder.html

    Regards from Perth

    Derek
    <slaps forehead>

    Great idea! Why didn't I think of that eons ago?

  6. #6
    Derek, I never thought of including the blade itself in the setup!

    However it won't work for woodturning gouges so I'm considering spacers to clip onto the jig.

    What I would like to make is a single tool which adjusts for angle, blade thickness and wheel diameter but this may be OTT.

    Thanks to all for the inputs.

  7. #7
    Derek has awesome ideas. I personally like to do a lot of my sharpening freehand, so the initial hollow grind is usually 25 degrees between the cutting edge and opposite side of the bevel, if that makes sense.

  8. #8
    Join Date
    Apr 2007
    Location
    SE Indiana
    Posts
    203
    Derek, That is a wonderful idea. I first thought of the Tormek jig when I read it. Just to be sure, you do use the grinder to grind the wood to shape? I guess that you could pre-cut it on a bandsaw or a fretsaw. Jim

  9. #9
    Hi Jim

    It was 5 years ago. I would have removed most of the waste with a coping saw, then ground the final shape on the wheel.

    The idea was just an adaption/combination of a few ideas that have been floating around for many years. The idea of the type of jig to set the angle is old as the hills. It is worth looking at the LV site for their angle jig, which influenced my thought at the time. My jig is simply taking theirs one step further ..

    http://www.leevalley.com/US/shopping...s.aspx?p=43212

    If you wish to duplicate the existing angle on a blade, you can use the gauge to check this in one of two ways. On the shallow side of the gauge, there is a circular depression in the center; you can place the chisel face on the reference edges running into the circle and check it against each of the four angles that are marked (Figure 1). Alternatively, for more registration, you can place the gauge on a flat surface and check the blade under each angular face with the bevel butted up to the gauge (Figure 2).

    You also need to know how thick the blade is to properly set the Grinder Tool Rest to your wheel. Place the blade on a reference edge running into the center circle, and note how many lines thick the blade is; most plane blades will be about one line thick, and most chisels will be less than two. This height is important because the angle gauge must touch the stone at 1/2 of the thickness of the blade in order to correctly set the angle (Figure 3).

    Regards from Perth

    Derek

  10. #10
    Join Date
    Apr 2007
    Location
    SE Indiana
    Posts
    203
    Thanks Derek,

    I guess one needs to write on the jig the thickness of the steel that you are grinding. I was messing with some old Hollows and Rounds. I am trying to get to the point of making my own. I had just made some jigs like Larry Williams used in his making hollows and rounds video. To make those jigs you cut a stick to the thickness of the tool stock, and then cut what ever angle on the end of that stick. You could take it one step further and grind it for easier (no light showing) setting. Any way, I have learned from the experience.

    The LV jig looks to be an adaptation of their hand-stone jig. Always clever that LV.

    Many Thanks,

    Jim

  11. #11
    Join Date
    Sep 2007
    Location
    Longview WA
    Posts
    9,809
    I would appreciate people's opinion as to whether one should aim for the stated angle at the cutting edge or when the front and back of the bevel are both in contact with the stone.
    For me this provokes an answer paraphrased from the teachings of Zen, "when the butterfly's wings are hidden it is poised to take flight... "

    Maybe if there was a grinder in my shop the bevel angle on my blades would be more important. Most of the time they are just in a range of low or high angle. Being a few degrees off hasn't been a problem.

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

  12. #12
    My grinder setting jig is a stick sawed off at the angle I want. I put it on the tool rest and line it up to the wheel.

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