Results 1 to 15 of 15

Thread: Entry hall table for a niece: Part 8

  1. #1
    Join Date
    Feb 2004
    Location
    Perth, Australia
    Posts
    7,076

    Entry hall table for a niece: Part 8

    It would be nice to have some discussion, guys.

    Following hot on the heels of the last post, where we created the male or tail section of the tapered sliding dovetail, now comes the female or pin socket to house the base for the legs.





    These are the bases. This post will focus on the socket for the one closest the camera.





    The base is positioned exactly 3 1/4" from the side. The tapered side is on the inside, with the outside face square to the front and rear of the case ...





    This process is essentially the same as transferring marks from the tail- to the pin board with drawers.


    The base tapers towards the toe, that is, the sliding dovetail will tighten up as the base is pushed into the socket.


    The first step is to register the far end of the base in such a way that the position is repeatable. This is done by placing a long board along the "square" side. The position for the end of the board is marked ...





    Now the base can be stood up to mark inside the tail with a scratch awl. You can make out the mark aligning the baseline of the tail ...





    Look carefully for the dots.





    This is repeated at the other end.





    The dots are now joined up ...





    The plan is to saw the socket sides, as if sawing dovetails in a drawer. The angle ratio is 1:6, as it was with the base. Since the socket is blind or stopped, the saw needs to have space in which to begin the cut. An area at the toe is excavated with a router.


    The depth of the cut is set using a 7.0mm drill bit. I am aware that the actual depth is 7.5mm, but this will be a second pass. I intend to clear the waste with the router - this Jarrah is bloody hard, and I am not a masochist!








    Using an angled saw guide, the end is chopped to the line ..





    Now this is space to register the azebiki saw ...





    I have roughly marked a depth to aim for ...



  2. #2
    Join Date
    Feb 2004
    Location
    Perth, Australia
    Posts
    7,076
    Both sides have been sawn ...





    The waste is removed with the router, leaving a few mm close to the sides ...





    This is chopped away with a chisel in two passes, and then cleaned up with a hand router ...





    The side rebate #79/dovetail plane is used to clean any rough sections ..





    The power router drops a 0.5mm to 7.5mm and this is cleaned up ...





    Amazingly, the base slides in and tightens up about 1/4" from the end. It will need a tap to be fully secure.





    That's it for now.


    Regards from Perth


    Derek

  3. #3
    Join Date
    Aug 2012
    Location
    Missouri
    Posts
    1,572
    Derek, Is using hand work to finish the sockets a mater of accuracy? I was wondering why you didnít just set up to cut the whole socket with a straight and then dovetail bit?

  4. #4
    Join Date
    Mar 2006
    Location
    Austin Texas
    Posts
    1,704
    Very stupid question - What happens if you make the azebiki cuts without the end cavity? I have always figured one would just make the side cuts on a stopped dado while making sure that the saw did not cut past the end line. I can see that it does no harm at all to create the end cavity, just wondering if it is essential or just preferable. Another question - did you describe the base section as having a "square side" and also mention that the base is only tapered on one side? Or did I mis read it? I thought that the taper should be applied to both sides (equally) of the sliding piece of the joint. As always, thanks for the photos and description Derek.
    David

  5. #5
    Join Date
    Feb 2004
    Location
    Perth, Australia
    Posts
    7,076
    Quote Originally Posted by James Pallas View Post
    Derek, Is using hand work to finish the sockets a mater of accuracy? I was wondering why you didn’t just set up to cut the whole socket with a straight and then dovetail bit?
    James, firstly I do not have the appropriate dovetail bits, which would need to have 9.5 degree slopes (1:6 ratio). And secondly, and most relevantly, I feel more secure that I can be more accurate using hand tools ... they allow me to make my mistakes at a slower speed!

    Regards from Perth

    Derek

  6. #6
    Join Date
    Feb 2004
    Location
    Perth, Australia
    Posts
    7,076
    Quote Originally Posted by David Eisenhauer View Post
    Very stupid question - What happens if you make the azebiki cuts without the end cavity? I have always figured one would just make the side cuts on a stopped dado while making sure that the saw did not cut past the end line. I can see that it does no harm at all to create the end cavity, just wondering if it is essential or just preferable. Another question - did you describe the base section as having a "square side" and also mention that the base is only tapered on one side? Or did I mis read it? I thought that the taper should be applied to both sides (equally) of the sliding piece of the joint. As always, thanks for the photos and description Derek.
    Not silly at all, David. The cavity is essential for Western saws, where a place is necessary for sawdust to be lodged rather than remain in the gullets. I was intending to use a Western saw at the start. The azebiki benefits from the cavity as a place to start the cut as it is lower. Otherwise it will leave a arched cut and this will require more chiseling.

    Both sides of the base are dovetailed, but only one side needs to have a taper. The base still ends up tapered. This is also a better way since setting it up to transfer marks is more reliable when there is one square, predictable side.

    Regards from Perth

    Derek

  7. #7
    Join Date
    Jan 2019
    Location
    Fairbanks AK
    Posts
    224
    Derek,

    I am happy to discuss, but you are today a better woodworker, a more sophisticated craftsman, than I could hope to become before I die if I retired tomorrow and my arthritis went away.

    With that caveat aside, why not just cut all the way through the case bottom, front to back, use a parallel sided sliding dovetail with a bit of glue, and a trapezoidal rather than inverted keystone shape for the crosspiece your legs are mortised in to?

    I can see that using a stopped dado hides the sliding dovetail on the front of the finished piece. But you are still going to have a dark line where the cross piece with the legs meets the bottom of the cabinet if someone is laying on the floor with a strong flashlight inspecting your work; and the sliding dovetail will still show on the back, so why? Are you maybe going to shape the front end grain of the sliding bit so it vanishes under the table?

    I am happy to incorporate some of your smooth moves into my eventual builds, like stopping the dado behind the front of the casework above. On the other hand if your crosspiece was trapezoidal you could use the sides of the crosspiece as your saw guide, I think.

    I am only asking because you fished for input. You are so many levels of experience and sophistication above my minimal skills that I find my self trying to figure out why you did a thing, because there must be a good reason I am too inexperienced to fathom.

    I can honestly say I hope to finish a thing someday and think to myself "Derek Cohen would be OK with this completed thing." Like my next bench for instance. Or anything ever really. The table looks great. Mid century modern is not my thing, but you are executing the bejezus out of it.

  8. #8
    Join Date
    Dec 2016
    Location
    South West Ontario
    Posts
    988
    Derek, as the leg support is narrow compared to the leg width and the leg force is not into the grain but opening the grain, are you worried the support may split on the lower face? If the leg support grain was rotated 90 degrees to match the bottom grain of the carcass it would seem to resist the force far better.
    ​You can do a lot with very little! You can do a little more with a lot!

  9. #9
    Join Date
    Nov 2015
    Location
    Freiburg, Germany
    Posts
    185
    Quote Originally Posted by Derek Cohen View Post
    Not silly at all, David. The cavity is essential for Western saws, where a place is necessary for sawdust to be lodged rather than remain in the gullets. I was intending to use a Western saw at the start. The azebiki benefits from the cavity as a place to start the cut as it is lower. Otherwise it will leave a arched cut and this will require more chiseling.

    Both sides of the base are dovetailed, but only one side needs to have a taper. The base still ends up tapered. This is also a better way since setting it up to transfer marks is more reliable when there is one square, predictable side.

    Regards from Perth

    Derek
    David: there might be one more virtue of tapering only one side of the sliding dovetail. If one only has one dovetail plane (say righthanded) for cutting the male part then tapering both sides means planing against the grain on one side. Tapering one side only one has the possibility for planing straight grain on one side, and slightly downhill grain on the other. Although, for very small tapers the natural grain variation might cancel this.

  10. #10
    Join Date
    Feb 2004
    Location
    Perth, Australia
    Posts
    7,076
    Quote Originally Posted by Scott Winners View Post
    .....why not just cut all the way through the case bottom, front to back, use a parallel sided sliding dovetail with a bit of glue, and a trapezoidal rather than inverted keystone shape for the crosspiece your legs are mortised in to?

    The "inverted keystone shape" has a beauty shoulder which not only allows for a cleaner look (not that anyone will ever see that), but the shoulder adds to the strength of the joint by increasing the wedging.

    I can see that using a stopped dado hides the sliding dovetail on the front of the finished piece. But you are still going to have a dark line where the cross piece with the legs meets the bottom of the cabinet if someone is laying on the floor with a strong flashlight inspecting your work; and the sliding dovetail will still show on the back, so why? Are you maybe going to shape the front end grain of the sliding bit so it vanishes under the table?

    Now Scott, whom is going to crawl on the floor with a flashlight?

    I do plan to shape the front - and sides - of the base.


    [snip]

    I can honestly say I hope to finish a thing someday and think to myself "Derek Cohen would be OK with this completed thing." Like my next bench for instance. Or anything ever really. The table looks great. Mid century modern is not my thing, but you are executing the bejezus out of it.

    Thanks. That is very kind. "Executing the bejesus" is exactly how I see it, although I believe what I am doing is simply what is needed to be done for this design to work.
    Regards from Perth

    Derek

  11. #11
    Join Date
    Feb 2004
    Location
    Perth, Australia
    Posts
    7,076
    Quote Originally Posted by William Fretwell View Post
    Derek, as the leg support is narrow compared to the leg width and the leg force is not into the grain but opening the grain, are you worried the support may split on the lower face? If the leg support grain was rotated 90 degrees to match the bottom grain of the carcass it would seem to resist the force far better.
    Hi William

    The base may be narrow, but it is very securely locked into the case via the double sliding dovetails (one on each side). The alternative to this design, one that is commonly used with shelves, but also I have seen some do with legs, is to have the dovetail on one side and a flat side on the other. The wedging action would be compromised by this design. Also, I believe that the joint would be weakened if the should was small. The shoulders here are about 3/8" across, and this is quite substantial.

    Placing the socket across the grain (as done here) is stronger than placing the socket with the grain (as you suggest). The latter invites the case to split. The base for the leg is wedged but will only be glued at the toe. This leaves the rear free to move and expand with the environment. Strain is taken off the socket.

    Regards from Perth

    Derek

  12. #12
    Join Date
    Feb 2004
    Location
    Perth, Australia
    Posts
    7,076
    Quote Originally Posted by Oskar Sedell View Post
    David: there might be one more virtue of tapering only one side of the sliding dovetail. If one only has one dovetail plane (say righthanded) for cutting the male part then tapering both sides means planing against the grain on one side. Tapering one side only one has the possibility for planing straight grain on one side, and slightly downhill grain on the other. Although, for very small tapers the natural grain variation might cancel this.
    Oskar, the dovetail plane (the Stanley #79) is double ended, which means it can plane both ways. Grain direction is not a limitation. I actually planed in the other direction with a test piece.

    As I mention before, there is no virtue here in dovetailing one side and leaving the other flat. The legs splay, and there are forces pulling across the socket. If one side was flat, it would possibly cause an edge to break out.

    Regards from Perth

    Derek

  13. #13
    Join Date
    Dec 2016
    Location
    South West Ontario
    Posts
    988
    Quote Originally Posted by Derek Cohen View Post

    Placing the socket across the grain (as done here) is stronger than placing the socket with the grain (as you suggest). The latter invites the case to split. The base for the leg is wedged but will only be glued at the toe. This leaves the rear free to move and expand with the environment. Strain is taken off the socket.
    Derek, I have to disagree, the dovetail shoulder is about 1/4 of the rail. The splayed legs want to twist the grain open. If the grain was turned 90 degrees the leg end would be pushing into end grain. When the lower part of the rail splits due to itís small size that will be more likely to split the carcass, however the carcass grain runs the correct way so that is unlikely.
    I have had a similar experience many years ago in some directors chairs.

    Yes glueing just the end in an opposing grain scenario is a good idea.

    Your carcass is not that small, the area and length of the leg joint is small, as is the rail.
    ​You can do a lot with very little! You can do a little more with a lot!

  14. #14
    Join Date
    Apr 2013
    Location
    Stone Mountain, GA
    Posts
    530
    It's looking great as usual Derek, and I agree with your construction decisions. My only comment is that if you are going to use a router anyways, you can make a jig similar to an adjustable dado jig, with one side fixed and the other movable to set the socket width and taper. Then fine tune the taper of the male end with your plane. Currently you are trying to match the female socket taper to a pre-existing male taper, which seems like doing it the hard way. I suppose you are limited by the fact that the angle on your dovetail plane fence does not match your router bit. IMO this orientation of sliding dovetail, with a cross grain socket and long grain tenon (I call them batten dovetails), benefits from a larger than usual angle. 14 degrees is the largest angle I have found for readily available router bits, so were it me I'd get one of those and set up a dovetail plane to match.

    This is not intended as criticism, you obviously know what you are doing, it's just offered for conversation really. And thanks for sharing.

  15. #15
    Join Date
    Nov 2015
    Location
    Freiburg, Germany
    Posts
    185
    yes Derek, your right. My dovetail plane goes only one way

    I didnīt write clear enough, my bad. I meant that there is "dovetail rabbets" on both sides, but when tapering only noe side one might arrange for planing one side perfectly along the grain, for the other the plane works downhill. I fully agree that both sides need the dovetail profile.


    Quote Originally Posted by Derek Cohen View Post
    Oskar, the dovetail plane (the Stanley #79) is double ended, which means it can plane both ways. Grain direction is not a limitation. I actually planed in the other direction with a test piece.

    As I mention before, there is no virtue here in dovetailing one side and leaving the other flat. The legs splay, and there are forces pulling across the socket. If one side was flat, it would possibly cause an edge to break out.

    Regards from Perth

    Derek

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •