525,612 active members*
2,462 visitors online*
Register for free
Login
IndustryArena Forum > WoodWorking Machines > DIY CNC Router Table Machines > Flat Machined Dovetails (related to Gerry's thread)
Page 1 of 2 12
Results 1 to 20 of 30
  1. #1
    Registered
    Join Date
    Aug 2011
    Posts
    980

    Flat Machined Dovetails (related to Gerry's thread)

    I was already going to post a reply to Gerry's dovetail thread but did not want to highjack it with a sidetrack idea.

    I would love to use Gerry's software but unfortunately my machine does not allow for overhang machining of a vertical piece.

    But this got me thinking and I spent some CAD time this morning figuring out how to cut a dovetail joint practically with flat machining only. This does not require a dovetail bit but a 30-degree V-bit (like Amana In-Groove) and a small endmill, e.g. 1/8".

    The one in the rendering and video below is "half-blind" but can be done as well fully blind or fully visible. The V-bit path for the one side of the joint would need something like VCarvePro to generate. I guess it would be difficult to do a similar custom program like Gerry's for that? Anyway, I will probably do an experiment sometimes.

    I hope the pic and video give an idea what I mean.
    [ame="http://www.youtube.com/watch?v=B3jzjyr3Lk0"]video[/ame]


  2. #2
    Gold Member
    Join Date
    Apr 2009
    Posts
    5516
    I've actually done a thread on this in the woodworking section about a year or so ago. It requires both a 30 and 150 degree bit to execute, as well a flipping over the part. The crv files are also posted wither there or the Vectric site.

  3. #3
    Registered
    Join Date
    Apr 2006
    Posts
    17
    Nice idea. Remember seeing something similar on youtube seemed to work fine

  4. #4
    Gold Member
    Join Date
    Apr 2009
    Posts
    5516
    Videos here... The descriptions has the links and other info.

    [ame=http://www.youtube.com/watch?v=ocNqwCRo4xE]Cutting THROUGH DOVETAILS on the FLAT with a 3-Axis CNC, part 1 - YouTube[/ame]
    [ame=http://www.youtube.com/watch?v=u0BtiJka6uM]Cutting THROUGH DOVETAILS on the FLAT with a 3-Axis CNC, part 2 - YouTube[/ame]
    [ame=http://www.youtube.com/watch?v=YtZrZPBdwi0]Cutting THROUGH DOVETAILS on the FLAT with a 3-Axis CNC, part 3 - YouTube[/ame]
    [ame=http://www.youtube.com/watch?v=00oG0S9UMcI]Cutting THROUGH DOVETAILS on the FLAT with a 3-Axis CNC, part 4 - YouTube[/ame]

  5. #5
    Gold Member
    Join Date
    Apr 2009
    Posts
    5516

  6. #6
    Registered
    Join Date
    Aug 2011
    Posts
    980
    Thanks, that is excellent! Looks like this is actually possible. More food for thought.

    I have to look over your pictures and video again. I am a bit confused why this needs 2-sided machining and a 150 degree bit. The concept I was thinking about only needs one-sided machining, however to achieve a single 15-degree beveled cut I was thinking of a fixture to hold the board at this angle and then still use an endmill.

    In the meantime I worked out some interferences and the concept looks like the following pics (fully visible and blind dovetails).


  7. #7
    Community Moderator ger21's Avatar
    Join Date
    Mar 2003
    Posts
    35012
    Thermwood sells "cnc dovetail" bits for cutting dovetails on the flat. There e-cabinet systems software can do the programming.
    Thermwood Online Store - Great prices on CNC Router Supplies!
    Gerry

    UCCNC 2017 Screenset
    http://www.thecncwoodworker.com/2017.html

    Mach3 2010 Screenset
    http://www.thecncwoodworker.com/2010.html

    JointCAM - CNC Dovetails & Box Joints
    http://www.g-forcecnc.com/jointcam.html

    (Note: The opinions expressed in this post are my own and are not necessarily those of CNCzone and its management)

  8. #8
    Gold Member
    Join Date
    Apr 2009
    Posts
    5516
    Quote Originally Posted by ger21 View Post
    Thermwood sells "cnc dovetail" bits for cutting dovetails on the flat. There e-cabinet systems software can do the programming.
    Thermwood Online Store - Great prices on CNC Router Supplies!
    If I'm not mistaken, they don't make "traditional" dovetails as the tails are rounded? It almost looks like a Leigh Isoloc joint.

  9. #9
    Gold Member
    Join Date
    Apr 2009
    Posts
    5516
    Quote Originally Posted by JerryBurks View Post
    Thanks, that is excellent! Looks like this is actually possible. More food for thought.

    I have to look over your pictures and video again. I am a bit confused why this needs 2-sided machining and a 150 degree bit. The concept I was thinking about only needs one-sided machining, however to achieve a single 15-degree beveled cut I was thinking of a fixture to hold the board at this angle and then still use an endmill.

    In the meantime I worked out some interferences and the concept looks like the following pics (fully visible and blind dovetails).

    Having the bevel go the other way, eliminates needing to make a fixture to "tilt" the boards; all the boards could be lined up and beveled at the same time. Also the "notches" for interference are hidden from view.

    Interestingly, I designed and drew the joint using only 2D and some quick trig.

    I don't think you can just use an endmill for the bevel as tilting the board will require you making an "undercut", necessitating a 15 deg. dovetail bit.

    If you look how my sample is assembled in the video you'll see the bevel. It cannot be cut in one setup because the 30 deg. bit leave a "draft" on the walls between the tails, which have to be "mimicked" on the tenon end. In fact even the tails have a "draft" on the walls, which makes the joint somewhat non-self-locking in one direction, but there actually is more surface area for glueing. If I "squared" the bottoms of the tail end then it would ruin the look of the dovetail, unless I stopped short and whittled the rest, which to me defeats the purpose of doing it this way.

  10. #10
    Gold Member
    Join Date
    Apr 2009
    Posts
    5516
    I didn't see the small flat (shoulder) at first, though I think that just adds another setup and complicates things a bit.

  11. #11
    Registered
    Join Date
    Apr 2007
    Posts
    1915
    I like the blind joints. It is a great way to hide that you are using laminated pieces of ply instead of real wood.

  12. #12
    Community Moderator ger21's Avatar
    Join Date
    Mar 2003
    Posts
    35012
    Quote Originally Posted by louieatienza View Post
    If I'm not mistaken, they don't make "traditional" dovetails as the tails are rounded? It almost looks like a Leigh Isoloc joint.
    These aren't actually "traditional" either. Given the choice, I'd probably go with the thermwood type, as there are no visible clearance gaps.
    Gerry

    UCCNC 2017 Screenset
    http://www.thecncwoodworker.com/2017.html

    Mach3 2010 Screenset
    http://www.thecncwoodworker.com/2010.html

    JointCAM - CNC Dovetails & Box Joints
    http://www.g-forcecnc.com/jointcam.html

    (Note: The opinions expressed in this post are my own and are not necessarily those of CNCzone and its management)

  13. #13
    Registered
    Join Date
    Aug 2011
    Posts
    980
    Quote Originally Posted by louieatienza View Post
    If I'm not mistaken, they don't make "traditional" dovetails as the tails are rounded? It almost looks like a Leigh Isoloc joint.
    I have been experimenting with Isoloc style joints a while ago (did not know the name though). They are pretty and functional but so far I did not come up with an idea to machine a 90-degree joint of that style with both parts flat. That is why I picked up on the more traditional style dovetails.

    But I made an experiment with an inline joint (or butt joint) of 3/4" plywood. After the glue set I whacked it with a mallet in a vise and it broke right next to the joint. The joint itself held up, seems to be a really strong connection.


  14. #14
    Gold Member
    Join Date
    Apr 2009
    Posts
    5516
    Quote Originally Posted by ger21 View Post
    These aren't actually "traditional" either. Given the choice, I'd probably go with the thermwood type, as there are no visible clearance gaps.
    Mine do not have clearance gaps (other than layout error) either...

  15. #15
    Registered
    Join Date
    Apr 2007
    Posts
    663
    JerryBurks stated:

    I would love to use Gerry's software but unfortunately my machine does not allow for overhang machining of a vertical piece.

    Here are some ideas on how to accomplish a vertical mount by going through the table/spoil board.


    Legacy method

    [ame=http://www.youtube.com/watch?v=WKu6OC47Qv8]Legacy CNC through dovetails.mp4 - YouTube[/ame]


    Hole though spoil board

    [ame=http://www.youtube.com/watch?v=ccS2W2O9CJY]Cutting Dovetails on a Joes Hybrid 4x4 1/2 - YouTube[/ame]


    Mount router head horizontal? [This is timber framing, but shows idea}

    [ame="http://www.youtube.com/watch?v=7RNo0ESFsl4"]Arunda dovetail assembly system - YouTube[/ame]


    Ancillary thought: It would be great fun to get you high level creators and problems solvers in one room and see what you would accomplish. :cheers:

  16. #16
    Community Moderator ger21's Avatar
    Join Date
    Mar 2003
    Posts
    35012
    We are in one big room.
    Gerry

    UCCNC 2017 Screenset
    http://www.thecncwoodworker.com/2017.html

    Mach3 2010 Screenset
    http://www.thecncwoodworker.com/2010.html

    JointCAM - CNC Dovetails & Box Joints
    http://www.g-forcecnc.com/jointcam.html

    (Note: The opinions expressed in this post are my own and are not necessarily those of CNCzone and its management)

  17. #17
    Gold Member
    Join Date
    Apr 2009
    Posts
    5516
    I have actually mulled over ideas and techniques for doing dovetails on the flat. It seems most would either require rotating the spindle (possibly requiring large Z axis clearance,) 3D movements (requiring expensive CAM or tough hand-coding,) or leaving visible "defects" (which would be unacceptable for a through dovetail.)

    With my method, everything can be done in 2D CAM with readily availabe tools (the 30 degree and 150 degree bit can be purchasedd at ToolsToday relatively cheaply.) You won't be able to make a blind dovetail with this method, as having the corners butted up as in a manual dovetail jig would probably be the best way.

    There is a company that sells a jig called a WoodRat or something like that, and they sell dovetail bits that have a very narrow tail ends which mimics hand cut dovetails better. They also have an interesting take on carbide vs. HSS.

  18. #18
    Registered
    Join Date
    Apr 2007
    Posts
    663
    Dovetail Wizard CNC

    Dovetail Wizard CNC

    found this, did not read much, but its a lead.

  19. #19
    Registered
    Join Date
    Apr 2007
    Posts
    663

    Cambium Machines youtube video of cutting dovetails.

    Cambium Machines youtube video of cutting dovetails. Works with SketchUp.

    [ame=http://www.youtube.com/watch?v=2gT5icRbjc8]Introduction to Dovetails - YouTube[/ame]


    https://www.cambiummachines.com/home.html

  20. #20
    Registered
    Join Date
    Aug 2011
    Posts
    980
    I continued some design over the holidays (traveling and no access to the shop for some real useful stuff). It occurred to me that the "classic" dovetails are shaped to accommodate manual cutting and not really optimized for CNC machines. Therefore I simplified the shape so that it should be possible to machine this flat with an end mill and a small roundover bit. I think I will give this a try once I am done with a few other projects in the pipeline.


Page 1 of 2 12

Similar Threads

  1. LouieAtienza's "Dovetails on the Flat" Technique, take 1
    By louieatienza in forum General WoodWorking
    Replies: 38
    Last Post: 07-27-2020, 08:16 PM
  2. Replies: 0
    Last Post: 08-26-2013, 05:41 PM
  3. Reference Flat for Scraping Dovetails
    By Ed from NY in forum Uncategorised MetalWorking Machines
    Replies: 3
    Last Post: 08-21-2009, 05:47 AM
  4. screw thread mounting without machined ends
    By Action-KAT in forum Linear and Rotary Motion
    Replies: 9
    Last Post: 08-19-2008, 11:57 PM
  5. Help with a flat thread
    By shawn in forum G-Code Programing
    Replies: 8
    Last Post: 07-15-2005, 06:24 PM

Tags for this Thread

Posting Permissions

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