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Thread: Bontz kerfing tool and a question- why not just use this, sans saw?

  1. #16
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    [QUOTE=Robert LaPlaca;2717521]Indeed, I have a VHS (remember those) tape of Tage Frid

    Unfortunately, I have no way to play those anymore.

  2. #17
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    Interesting. I need one of these...... Sent you an email Ron.....

    I own the Tag Frigid books, but I had not seen this done. I can't wait to give it a try.

    Derek, are you using an extra thin chisel there? I don't think that I could do that with any chisel I own unless I cleared a bunch of waste first (which is how I do it now). I also use a clamp when I do this.... I mean, I did not when I first started doing this, but, after having an unwanted crack..... or two (slow learner)..... I do now. I expect that using something thinner will reduce the likelihood, since my chisel is very thick compared to a saw and the bevel will push the wood apart leaning towards a split.

  3. #18
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    Hi Andrew

    I posted a link to the article I wrote several years ago when I made my "kerfing chisel". Here it is again.

    I also made it as clear as I could that one must ALWAYS add a clamp across the board when chopping into the kerf with the tool to avoid splitting, notably at the ends ...



    The blade of my kerfing chisel is made from a stainless steel trowel. This was ground down to the thickness of the saw plate. The end is square, NOT bevelled ..



    Again .. ONLY nibble the kerf. Never try and chop the full width of the kerf. That is a recipe for splitting if the wood is dry and brittle.

    I have been using this tool for several years and had a few boards split at the start. However, they taught me a lesson, and taking the precautions mentioned here, this has not happened again.

    I did test out a wide blade several years ago but discarded that design, ending instead with the present narrow blade as (1) this offers better visibility and directionality, (2) hammering the end of a hooped chisel transmits energy more efficiently, and (3) one only wants to deepen a narrow section of the kerf, and widen it progressivey. I also expect that a hooped end will hold up better than a brass back (however there may be hardened brasses that will do so).

    Regards from Perth

    Derek

  4. #19
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    I also expect that a hooped end will hold up better than a brass back (however there may be hardened brasses that will do so).
    It may also depend on what one is using to drive the tool. A metal headed hammer will likely have more of an effect on the point of impact than a wooden mallet.

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

  5. #20
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    I find this discussion vary interesting. I have been using the SIDE of a square edge putty knife for several years. I think Derek suggest using a putty knife as an alternative but can't remember if he elaborated on how to use it. The difference is I lay the board flat on the bench and tap the knife blade in from the flat side of the board instead of from the end grain as I see in most of the pictures. My reasoning is that the saw kerf is usually longer on the flat then on the end grain therefore a longer kerf to register the knife in and the square corner of the knife kind of cuts/ brakes the the grain as it's being tapped in. It seems to work fine but all of the pictures I've seen shows the knife/chisel or whatever being tapped in from the end grain. Please tell me if I'm missing something here???
    Thanks,
    Chet

  6. #21
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    Quote Originally Posted by Derek Cohen View Post
    Hi Andrew

    I posted a link to the article I wrote several years ago when I made my "kerfing chisel". Here it is again.

    I also made it as clear as I could that one must ALWAYS add a clamp across the board when chopping into the kerf with the tool to avoid splitting, notably at the ends ...


    The blade of my kerfing chisel is made from a stainless steel trowel. This was ground down to the thickness of the saw plate. The end is square, NOT bevelled ..

    Again .. ONLY nibble the kerf. Never try and chop the full width of the kerf. That is a recipe for splitting if the wood is dry and brittle.

    I have been using this tool for several years and had a few boards split at the start. However, they taught me a lesson, and taking the precautions mentioned here, this has not happened again.

    I did test out a wide blade several years ago but discarded that design, ending instead with the present narrow blade as (1) this offers better visibility and directionality, (2) hammering the end of a hooped chisel transmits energy more efficiently, and (3) one only wants to deepen a narrow section of the kerf, and widen it progressivey. I also expect that a hooped end will hold up better than a brass back (however there may be hardened brasses that will do so).

    Regards from Perth

    Derek
    Thanks, that clears things up for me.

    I had missed that article.....

    I would not have thought to progressively work my way in, but when you say it, it sounds obvious.

    For certain I will not hit the brass back with a steel hammer, I have plenty of much softer things to use. I do not disagree that a hooped back chisel will hold up better, but, depending on what I hit it with and what wood I would use, not even sure I would need the hoop for my usage. Off hand, making one like yours sounds like a good / fun project. I have no ability to turn (no equipment), but a hard wood dowel would probably suffice, and I could probably make some other shapes myself. I would just need to then figure out how to do some of the other things such as fitting a ferrule and the hooped back.

  7. #22
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    [QUOTE=lowell holmes;2717549]
    Quote Originally Posted by Robert LaPlaca View Post
    Indeed, I have a VHS (remember those) tape of Tage Frid

    Unfortunately, I have no way to play those anymore.
    I bought hobby level equipment to convert VHS to DVD. So, if you have one that you want to convert, I can give it a go for you. The quality is not great, but it is usable. VHS copy protection is designed to degrade the signal. My Brother owned equipment to fix this, but he is no longer around (sadly). Also, I believe that VHS degrades over time.....

  8. #23
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    Quote Originally Posted by Chet R Parks View Post
    The difference is I lay the board flat on the bench and tap the knife blade in from the flat side of the board instead of from the end grain
    I would be concerned that by chopping in, it will follow the grain, no mater where you cut in. If you already have a portion of the cut existing, the will help guide the blade. Perhaps this is not as much of a problem with the blunt tip as opposed to a knife edge (wedge) because it is imply crushing the fibers, but that is uneducated speculation.

    Derek also mentioned that he had better luck when he "nibbled" his way in. In other words, he did not take a full cut at the once. As you nibble your way in, the established portion of the cut will help guide the new portion of that is crushed out of the way.

    If you think of wood as a bunch of straws, and then you thinking of cutting in along the end grain as opposed to the not end grain, is one more likely to deflect the cutting tool? No idea. I expect that a riven knife is used from the end grain because that probably has the smaller cross section, but again, I am guessing.

  9. #24
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    Quote Originally Posted by Jim Koepke View Post
    It may also depend on what one is using to drive the tool. A metal headed hammer will likely have more of an effect on the point of impact than a wooden mallet.

    jtk
    OK. My last reply. I made these to be struck with a wooden mallet, but took into consideration a 16 ounce claw hammer. We wood workers sometimes do foolish things.
    1) My tool is designed to be struck from the back or on the top of the brass, depending on your method of work.
    2) The handles, backs and internal rod are interchangeable. Although they are tight in their mortised slots. Personally I prefer to have three different tools with different wood handles to tell the difference.
    3) The plates are different thicknesses to accommodate the different kerfs of various saw makers.
    4) I wanted something that would give me another use for my gent saw handles as well.
    5) To say " It is difficult not to reach the conclusion that your tool copied Rob Cosman since he has been producing the same design for a while before yours was made public. " is insulting. Take a real hard look at my design, Mr. Cohen. The designs serve the same purpose, but are NOT the same. You posted a comment and implied I "copied" some ones tool for the world to see and you did so out of ignorance. Had you contacted me prior to making such a false statement, I could have perhaps shared some of my old designs or given you the name of the person that requested I make a tool to replace his putty knife, years ago. One of my emails, discussing this tool was dated 4 July 2014. So clearly I must have had a premonition of what the Cosman tool would look like. By the way, To this day I still use my "Red Devil" putty knives in my shop. Although I no longer strike them with my 16 oz. claw hammer. No further comment will be made and if the moderators feel this is inappropriate they are certainly welcome to close the thread or delete it. Thank you.
    IMG_3656.JPG
    Last edited by Ron Bontz; 08-15-2017 at 5:50 PM.

  10. #25
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    Quote Originally Posted by Ron Bontz View Post
    The designs serve the same purpose, but are NOT the same.
    Not exactly how I took it, not that it is not how he meant it..... He also mentioned that both are similar to the Tag Frigid design. I have seen neither.

  11. #26
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    Quote Originally Posted by Ron Bontz View Post
    OK. My last reply. I made these to be struck with a wooden mallet, but took into consideration a 16 ounce claw hammer. We wood workers sometimes do foolish things.
    1) My tool is designed to be struck from the back or on the top of the brass, depending on your method of work.
    2) The handles, backs and internal rod are interchangeable. Although they are tight in their mortised slots. Personally I prefer to have three different tools with different wood handles to tell the difference.
    3) The plates are different thicknesses to accommodate the different kerfs of various saw makers.
    4) I wanted something that would give me another use for my gent saw handles as well.
    5) To say " It is difficult not to reach the conclusion that your tool copied Rob Cosman since he has been producing the same design for a while before yours was made public. " is insulting. Take a real hard look at my design, Mr. Cohen. The designs serve the same purpose, but are NOT the same. You posted a comment and implied I "copied" some ones tool for the world to see and you did so out of ignorance. Had you contacted me prior to making such a false statement, I could have perhaps shared some of my old designs or given you the name of the person that requested I make a tool to replace his putty knife, years ago. By the way, To this day I still use my "Red Devil" putty knives in my shop. Although I no longer strike them with my 16 oz. claw hammer. No further comment will be made and if the moderators feel this is inappropriate they are certainly welcome to close the thread or delete it. Thank you.
    IMG_3656.JPG
    I don't want to start or contribute to a fight on this topic, although, if you look at the Cosman tool there are plenty of similarities. It would be a natural assumption that one was basically the genesis for the other or perhaps they both came from another similar tool posted on the web or published in a magazine or shown in a video. Perhaps Ron has his own IP and that is all well and good to me. Maybe there is no registered IP on any of these designs and that to is all well and good.

    kerftool.JPG

  12. #27
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    I want to see a picture of what Tag Frigid used....

  13. #28
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    Hi Andrew,
    I'm using the term knife in relation to a "putty knife" not a sharp edged tool and I learned the hard way that just lightly tapping the square edge into the saw kerf produces much better results than pounding. I want to thank you for your thoughts and insight. I may have to rethink my methods. Thanks again.
    Chet

  14. #29
    Andrew, Tage didn't use anything special, either a small piece of a bandsaw band or a card scraper dedicated to the purpose. IIRC the small piece of bandsaw band had the teeth ground off, the purpose was to keep from cutting oneself on the teeth. I use a card scraper dedicated to the purpose, as the top of the scraper is struck with a metal hammer, the metal hammer gives a nice audio signal when the tool has bottomed out.

    What is important, is a blunt edge, take a small bite at a time and protect the pin board with a clamp, otherwise you can split it.
    Last edited by Robert LaPlaca; 08-15-2017 at 6:17 PM.

  15. #30
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    Quote Originally Posted by Robert LaPlaca View Post
    Andrew, Tage didn't use anything special, either a small piece of a bandsaw band or a card scraper dedicated to the purpose. IIRC the small piece of bandsaw band had the teeth ground off, the purpose was to keep from cutting oneself on the teeth. I use a card scraper dedicated to the purpose, as the top of the scraper is struck with a metal hammer, the metal hammer gives a nice audio signal when the tool has bottomed out.

    What is important, is a blunt edge, take a small bite at a time and protect the pin board with a clamp, otherwise you can split it.
    You know, I probably even read that here in this thread somewhere but my brain did not connect the dots.

    Yeah, that is the embarrassed emoticon.

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