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Thread: Need advice on Tenon vs. Mortise

  1. #1

    Need advice on Tenon vs. Mortise

    I just received a 14" X 5" Walnut blank. I am going to chuck it up to turn a large salad bowl. This is a heavy piece of wood and I have #2 One Way Jaws. I usually prefer a recess, but am a little worried about going that route here due to size and weight, and the fact the jaws are not dovetailed.

    I am looking for advice on whether to mount it with a Tenon (I don't usually prefer them) or whether a mortise should be sufficiently stable.

    Thanks for any advice.

    Jon

  2. #2
    Everyone has their favorite way....I prefer a tenon over a recess everytime.. I think it holds better and I've never had one come loose while turning.

  3. #3
    Join Date
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    I looked up the #2 jaws on-line and it appears that when fully contracted they will fit into a 2" recess or compress a 1-5/8 tenon. Both seem a little small for a heavy 14" diameter bowl. Maybe this is the justification for picking up a #3 set of jaws.

    I prefer a recess or mortise. I have dovetail jaws and have torn off the tenon on a couple of bowls. I haven't had those issues with a recess. When I've used a tenon (especially a small one like 1-5/8") I end up turning off the tenon at the end. I prefer a recess as I don't waste that tiny bit of extra wood. I often will remove the dovetail portion of the recess when I'm finished just because it looks a little nicer.

    But the argument of the mortise versus tenon is kind of a personal one with no "right' answer.

  4. #4
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    Go for a larger set of jaws.. You won't regret it. I prefer a tenon. But recess for some things.
    C&C WELCOME

  5. #5
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    Quote Originally Posted by Jon Kurtz View Post
    I just received a 14" X 5" Walnut blank. I am going to chuck it up to turn a large salad bowl. This is a heavy piece of wood and I have #2 One Way Jaws. I usually prefer a recess, but am a little worried about going that route here due to size and weight, and the fact the jaws are not dovetailed.I am looking for advice on whether to mount it with a Tenon (I don't usually prefer them) or whether a mortise should be sufficiently stable.Thanks for any advice.Jon
    The #2 jaws are not large enough for that size blank, I would go with a faceplate, first to round the blank and shape the outside, then glue a waste piece on it, turn it flat and then screw a faceplate to it again, flip the piece over and hollow the piece out.I would use the faceplate for the first shaping even though I do have the #3 fawn for my Stronghold, only after that would I use the Chuck to hold it in a recess and hollow it.

    Used a recess on this 15” Walnut bowl, but used the faceplate to round and shape the outside first.
    recess in 15%22 Walnut.jpg
    Last edited by Leo Van Der Loo; 08-24-2017 at 10:39 PM.
    Have fun and take care

  6. #6
    Join Date
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    agree that #2 jaws (assuming you're talking about stronghold chuck) are too small. I've used #3 smooth dovetailed jaws grippig a tenon on 95% of what I turn almost exclusively with blanks up to 20" for several years without loosing a tenon. a well cut tenon with a smooth step that rides securely on the face of the jaws provides a very strong grip without having to tighten the chuck to the point where it could compromise the tenon. Don't let the tenon bottom out in the jaws.
    I switched all my oneway chucks (stronghols and talons) to smooth dovetail jaws after loosing a piece to the profiled, serrated jaws. Haven't lost one since.

  7. #7
    This is a video clip I did a while back that explains a bunch. I regularly turn bowls in that size range with a recess 2 5/8 inch diameter. Having a larger set of jaws would not be mandatory for that size of a blank. Anything under that size is easy. I prefer a recess...

    https://www.youtube.com/watch?v=5KHkkws9lWA

    robo hippy

  8. #8
    Join Date
    Feb 2008
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    Quote Originally Posted by Reed Gray View Post
    This is a video clip I did a while back that explains a bunch. I regularly turn bowls in that size range with a recess 2 5/8 inch diameter. Having a larger set of jaws would not be mandatory for that size of a blank. Anything under that size is easy. I prefer a recess...

    https://www.youtube.com/watch?v=5KHkkws9lWA

    robo hippy
    I also prefer a recess. It may be stronger depending on how much wood you have around the mounting point - a tenon may have less area subject to splitting away when a side force is applied to the blank. Note the Nova guidelines for many jaw sets "allow" a larger blank with a recess than a tenon. For example, the 5" Nova Titan powergrip jaws are recommended for a 29"x6" workpiece in when expanding into a recess but 14"x14" for compressing on endgrain and just 8"x8" for crossgrain.

    For some bowl/platter designs the recess wastes less wood than a tenon, unless using a glue block of course. I often leave the recess in the bowl or platter and make it a design element. For example:

    bottom_IMG_4687.jpg bottom_IMG_4749.jpg bottom_PC012804_e.jpg

    Note the recess on the last (18") platter is just the inside curved parts of the three little triangles, maybe 1/8"-3/16" deep. It is plenty enough to hold. I learned this from Frank Penta.

    One additional reason to use a recess: a Forstner bit makes a quick recess. I use a 2-1/6" carbide bit for the 50mm Nova jaws.

    BTW, for a 14"x5" blank I too would use bigger jaws.

    JKJ

  9. #9
    Thank you everyone for sharing your knowledge. Most helpful and very much appreciated!

  10. #10
    Quote Originally Posted by Reed Gray View Post
    This is a video clip I did a while back that explains a bunch. I regularly turn bowls in that size range with a recess 2 5/8 inch diameter. Having a larger set of jaws would not be mandatory for that size of a blank. Anything under that size is easy. I prefer a recess...

    https://www.youtube.com/watch?v=5KHkkws9lWA

    robo hippy
    I really appreciate your reply. Quick question, do you use a dovetail chuck or a straight serated one a la One Way?

  11. #11
    John, how did you carve the pattern on the rightside picture. That looks amazing!

  12. #12
    Join Date
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    Quote Originally Posted by Jon Kurtz View Post
    John, how did you carve the pattern on the rightside picture. That looks amazing!
    Thanks, It is interesting - makes a person do a double take when they turn it over!

    It's not my idea, I learned that technique from turner Frank Penta. http://www.frankpenta.com/ It is done by mounting the platter blank on four different centers using a screw chuck, one in the center and three equally space a short distance from the center. You cut a recess in the center then then turn overlapping rings to create a pattern. You can vary what you cut away to change what the base looks like (best to draw everything out first). It is surprising how little offset is needed for the three off-axis centers due to the size of the decorative rings. I tried something a bit different than Frank but the principle is the same. I made the bottoms of the recess and all the rings in one plane which was a bit tricky to get perfectly smooth!

    Remember that you have to turn, sand, and finish the entire bottom side of the platter before you turn it around and mount it in the recess.

    Frank has a document on his web site showing how to set this up; look at the Platter doc at the bottom of this page: http://www.frankpenta.com/index.php/...rojects/detail, part III, Turning a Multi-Axis Base. Frank does teach classes on platters and other things but be forewarned: if you hang out with Frank you'd better have a texturing tool at hand!

    The one in the picture was my first try, made from a 2" thick sapele blank. We auctioned this one to benefit two little girls who lost their mother to cancer. The friend holding the platter gives some idea of the size:



    JKJ

  13. #13
    Jon, I use Vicmark chucks which have about a 7 degree dove tail. Maybe a 1/8 inch recess. The dove tail is a 'locking wedged' joint and holds better than straight jaws. The taller serrated type jaws do a good job on spindle blanks, or a square blank you are turning round. I still prefer the dove tail for my spindle turnings. Just old habit now...

    robo hippy

  14. #14
    Quote Originally Posted by Reed Gray View Post
    Jon, I use Vicmark chucks which have about a 7 degree dove tail. Maybe a 1/8 inch recess. The dove tail is a 'locking wedged' joint and holds better than straight jaws. The taller serrated type jaws do a good job on spindle blanks, or a square blank you are turning round. I still prefer the dove tail for my spindle turnings. Just old habit now...

    robo hippy
    Thanks!! Great tip.

  15. #15
    Quote Originally Posted by John K Jordan View Post
    Thanks, It is interesting - makes a person do a double take when they turn it over!

    It's not my idea, I learned that technique from turner Frank Penta. http://www.frankpenta.com/ It is done by mounting the platter blank on four different centers using a screw chuck, one in the center and three equally space a short distance from the center. You cut a recess in the center then then turn overlapping rings to create a pattern. You can vary what you cut away to change what the base looks like (best to draw everything out first). It is surprising how little offset is needed for the three off-axis centers due to the size of the decorative rings. I tried something a bit different than Frank but the principle is the same. I made the bottoms of the recess and all the rings in one plane which was a bit tricky to get perfectly smooth!

    Remember that you have to turn, sand, and finish the entire bottom side of the platter before you turn it around and mount it in the recess.

    Frank has a document on his web site showing how to set this up; look at the Platter doc at the bottom of this page: http://www.frankpenta.com/index.php/...rojects/detail, part III, Turning a Multi-Axis Base. Frank does teach classes on platters and other things but be forewarned: if you hang out with Frank you'd better have a texturing tool at hand!

    The one in the picture was my first try, made from a 2" thick sapele blank. We auctioned this one to benefit two little girls who lost their mother to cancer. The friend holding the platter gives some idea of the size:



    JKJ
    It give a great look to the bowl!

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