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  1. #1
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    Default A fishtail chisel in an hour

    Over the last couple of weeks I've been trying my hand at half lap dovetails. Now I know that it should be entirely possible to clear the corners with ordinary chisels, but boy, do I struggle. I was at it today, and expect to be doing more tomorrow. Now is as good a time as any too whip something up.

    I have a couple of pieces of metal that resemble a chisel given to me many moons ago by my in-laws. They never get used as they're rubbish, so thought I'd try reshaping one. If I ruined it, no real loss.



    I marked out a rough shape and set it to the grinder.



    And because the buffing wheel was already on the other end, decided to give it a bit of a polish. Then of to the sharpening stones. I guess one advantage of really soft steal is that the back flattened in no time at all.



    It seems to pear pine end grain rather well, but its real test will have to wait till tomorrow. I think dinner is nearly ready.

    But where to put it now. Back with the reject tools or my special chisels? I decided to compromise. It can sleep with my nice set, but they will remain segregated. Once I buy a lathe and make a nicer handle for it, I will allow it to associate with the others.


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  3. #2
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    Well done, an otherwise useless tool repurposed!

    I’ve been waiting for the cheap chisels to come back on special at Aldi to do the same thing; I’m planning on getting two sets so I can have matching L & R skew chisels and a fishtail or two. I have a VERY cheap and nasty trio of Chinese paint can openers to practise on beforehand.
    Nothing succeeds like a budgie without a beak.

  4. #3
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    I've modified a few cheap chisels - it's 1 thing they're particularly good for. You've made a good job of that one but after numerous sharpenings the shape will be lost. Would a skew shape have done the job?
    Cheers, Bob the labrat

    Measure once and.... the phone rings!

  5. #4
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    Default

    Quote Originally Posted by labr@ View Post
    I've modified a few cheap chisels - it's 1 thing they're particularly good for. You've made a good job of that one but after numerous sharpenings the shape will be lost. Would a skew shape have done the job?
    The "sharpening the shape out" made me cautious of the fishtail design initially, but when you consider that it is put to such light duty, it will require very infrequent sharpening I would think. Time will no doubt tell. Actually Derek uses one with Jarra, so he would certainly be able to offer an opinion on longevity.

    Yes a right and left hand skew would also work, but I'd need two dodgy chisels a similar size to do that

  6. #5
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    Lance, I have made quite a few turning tools by silver soldering pieces of machine hack saw blade to mild steel. Might be worth silver soldering some hack saw blade to your chisel??? That will give you a longer wearing tool that will hold an edge longer. If you grind a recess in the chisel for the insert, it will look even more professional.

    Jim
    Sometimes in the daily challenges that life gives us, we miss what is really important...

  7. #6
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    Quote Originally Posted by labr@ View Post
    I've modified a few cheap chisels - it's 1 thing they're particularly good for. You've made a good job of that one but after numerous sharpenings the shape will be lost. Would a skew shape have done the job?
    Bob, you can use either a skew or a fishtail.

    The advantage of a fishtail is that you only need to push it forward ..



    ... where as the skew chisel requires a slicing action, which is more work (less ergonomic) ...


    My preference is a fishtail chisel. I have made many over the years, as well as own a few from makers such as Blue Spruce ...



    and Koyamaichi ...



    Here is a recent one I made, using a prototype 1/4" Veritas O1 chisel (it was rough - for testing, before they released their chisels) ...




    Regards from Perth

    Derek
    Visit www.inthewoodshop.com for tutorials on constructing handtools, handtool reviews, and my trials and tribulations with furniture builds.

  8. #7
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    Lance, your chisel reminds me of the first one I made, about 20 years ago (inspired by Rob Cosman) ...




    Regards from Perth

    Derek
    Visit www.inthewoodshop.com for tutorials on constructing handtools, handtool reviews, and my trials and tribulations with furniture builds.

  9. #8
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    Derek, your VeriCohen one was very well executed. I realised pretty quickly that were I to make mine look nicer I would need a far better grinder support than what I was using (and more time).

    The larger the chisel that has been "Cosman'd", the more it resembles a flying dragon lizard to my eye.
    Untitled.png


    Earlier in the thread there was some discussion about fishtail chisel longevity as the shape will eventually be sharpened out. Any comment? Considering the hard woods you use, were there an issue, you would no doubt be seeing it first.

  10. #9
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    Hmmm, a fishtail has been on my 'to do' list for about 25 years, I'd better hurry up or I'm going to run out of time. I made a couple of sets of skews from some pretty decent old chisels, back in the 80s or 90s and they've been my cleaner-outers for half-laps ever since. Evey time I use them, I'm reminded that a fishtail would be so much better, only one damn chisel to find on the bench instead of two. How come it's always the wrong one that's visible, and the one you want is hiding? It defies the law of averages!......

    Cheers,
    IW

  11. #10
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    Derek, your VeriCohen one was very well executed. I realised pretty quickly that were I to make mine look nicer I would need a far better grinder support than what I was using (and more time).
    Lance, I should have mentioned that I shaped this with a small 100mm handheld Makita grinder. Light strokes and lots of water.

    Regards from Perth

    Derek
    Visit www.inthewoodshop.com for tutorials on constructing handtools, handtool reviews, and my trials and tribulations with furniture builds.

  12. #11
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    Ok, my fishtail chisel is a failure in its current form. If you compare mine to the selection Derek posted, note those "tails" are a lot longer than mine with a more gentle angle to boot.



    I think however that the issue was more due to these particular dovetails. The front board is very thin, so had shallow sockets for which I chose a more dramatic angle. Trying to get into the corners resulted in bruising the socket edges if I wasn't careful.



    I will need to ensure I do far gentler angles in future. I do try for 1:7 where depth allows, but thought, perhaps incorrectly, that the shallow sockets necessitated this more dramatic tail.

    So a couple of questions:
    1. What is the cutting edge width on your fishtail chisels?
    2. Angle/ratio of your chisels?
    3. Would a gentler angle on the shallow sockets have sufficed?

    Thanks for any thoughts.

  13. #12
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    Well, my theory is that shallow dovetails do need a good angle so that they stand out, but I don't think I ever go beyond 1:6. That works for the ~5mm thick D/Ts on a plane, for example, you don't have to squint to see they are dovetails & not just finger-joints that got a bit skewed First shavings.jpg

    Acute angles aren't too much of a problem with metal, but if you use an angle that's too acute, you are more likely to chip corners when test-fitting & working on them & if it's a crumbly sort of wood like Aust. cedar, you can have trouble at any angle....

    Cheers,
    IW

  14. #13
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    So a couple of questions:
    1. What is the cutting edge width on your fishtail chisels?
    2. Angle/ratio of your chisels?
    3. Would a gentler angle on the shallow sockets have sufficed?
    Lance, importantly, do not beat yourself up for trying something new. I constantly screw up ... and no longer get worked up as I know that there is usually a fix. Anyway, I do not think that you screwed up ... just have an interesting design

    I would say that your angles on the chisel are closer to 40 degrees than 14 degrees, which is a 1:7 ratio. I am for 1:7 on mine. Most of my dovetails these days are 1:7 for drawers and 1:6 for cases. With angles on chisels, rather make one a little steeper (as you have done) than a little shallower - the aim is to get into the corners, and yours will do this.

    The preferred width of the chisels is around 1/4" - 3/8".

    You can rework the fishtail you made if you want. That first fishtail chisel I made - shown earlier - started like as a Witherby. I used it like this for some years, and then reshaped it quite considerably. It became this ...



    I still pull it out and use it. The bevel on this one is a low 20 degrees. All my others are 30 degrees.

    Regards from Perth

    Derek
    Visit www.inthewoodshop.com for tutorials on constructing handtools, handtool reviews, and my trials and tribulations with furniture builds.

  15. #14
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    Quote Originally Posted by derekcohen View Post
    Lance, importantly, do not beat yourself up for trying something new. I constantly screw up ... and no longer get worked up as I know that there is usually a fix. Anyway, I do not think that you screwed up ... just have an interesting design
    Thanks Derek, I appreciate the thought. Despite the less than ideal outcome however, I’m far from despondent. I continue to get plenty of things wrong, and as long as they’re not silly mistakes where I should know better, I do rather enjoy the challenge of iterative improvement.

    Also, thank you for the various measurements. I was concerned that at 10 mm, my donor chisel was too narrow but your post has dispelled that.

  16. #15
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    Quote Originally Posted by IanW View Post
    Well, my theory is that shallow dovetails do need a good angle so that they stand out, but I don't think I ever go beyond 1:6. That works for the ~5mm thick D/Ts on a plane, for example, you don't have to squint to see they are dovetails & not just finger-joints that got a bit skewed ,
    I was more concerned with strength, but thinking about the strength of finger joints, that is probably unfounded. Your mention of then actually looking like dovetails never crossed my mind, but YES. In learning to make nice dovetails, I do like to show them off, even if just to myself, so absolutely do want them to look like dovetails.

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