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Thread: How do I make this cutting board curved joint?

  1. #46
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    Works the same on your curve Johnny.

    tight curve.jpg

  2. #47
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    Quote Originally Posted by johnny means View Post
    The problem here is that, mathematically speaking, there is no way to use the one side of the pattern to create a perfectly mating piece. The opposing curves will always change in varying ways depending on what part of the curve your on.
    That is actually not true, you can "mathematically make perfectly mating pieces (I am a mathematician btw and have done this).
    Suppose you have an arbitrary curve A and you want to make a mating piece B. First you use a flush trim router bit of your choice, say 1/2", and following piece A create two pieces on a template piece (say MDF). You get a perfect copy of A on one side and a piece B' that is not a perfect fit of A as it is 1/2" off set.
    Now use that piece B' with a bearing that is 1" on top of a 1/2" router bit and follow B' as a template and you create piece B. Now B will be a perfect fit of A.

  3. #48
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    I would like to throw my hat in the ring. Sometimes I make complementary curve by stacking the parts on top each other and cutting them on the bandsaw.
    I don’t need to part to fit perfectly like a cutting board does. Its a method I use to make tops for my boxes.
    Thought I share to open up possibilities that haven’t been discussed.
    Good Luck
    Aj

  4. #49
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    Quote Originally Posted by Mark Hennebury View Post
    To route two patterns to fit perfectly you have to cut on each side of the cutline.
    The small circles in the drawing below represent router bits.
    The blue router bit cuts the blue pattern.
    The brown router bit cuts the brown pattern.
    The two template guides simply move the bit from one side of the cutline to the other.
    The template guides router.
    There is no loss due to kerf or radius.

    Attachment 459638
    Exactly. This illustrates what I was describing earlier in this thread. Matched templates...one for each side of the end project material which are processed separately.
    --

    The most expensive tool is the one you buy "cheaply" and often...

  5. #50
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    Interestingly, (or frustratingly) the two templates I made with the 1/2" rabbet bit seem perfectly symmetrical, but have a tiny gap between them. I'm not sure if this will go away with clamping and gluing, or now I'm wondering about that Bondo trick on one of the patterns with the other one taped off. Another reason why this would have been SO much easier with inlay. The plan is for the final thickness of the cutting board to be 1-1/4".

    Any thoughts?

    Loving the discussion and the debate, BTW. Really shows the strength of the community here.
    - After I ask a stranger if I can pet their dog and they say yes, I like to respond, "I'll keep that in mind" and walk off
    - It's above my pay grade. Mongo only pawn in game of life.

  6. #51
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    Jim, There are no matched template.
    There is only one template, in the sketches below the template is the pink piece.
    The blue and brown are the finished pieces. they are the pieces that you are making.
    This drawing shows the the two patterns that you are cutting, these are the finished pieces of wood, not templates.
    The drawing shows where the router bits must be to cut on either side of the line for each pattern piece.
    Pattern line.jpg

    The image below shows the template overlaid on the finished matched pieces for reference, to show the position of the router bits in relation to the template and the patterns cut .

    complimentary pattern assemble1a.jpg

    The sketch below shows the relative positions of the template, the template guides ( bushing/ bearings) and the router bits to the cutline.
    You can see that changing the template guides bushings changes the position of the router bit. with the small template guide bushing the router bit is moved close to the template and cuts on one side of the cutline. When you use the large template guide bushing the router bit is moved to the other side of the cutline.

    assembly7a.jpg

    In the drawings below, you will see that the cut line in each operation is exactly the same distance from the template reference edge, and the you are cutting one pattern from one side of the cutline and the other pattern from the other side of the cutline.


    router assem for complimentary curves.jpg





    Quote Originally Posted by Jim Becker View Post
    Exactly. This illustrates what I was describing earlier in this thread. Matched templates...one for each side of the end project material which are processed separately.

  7. #52
    Quote Originally Posted by Mark Hennebury View Post
    Jim, There are no matched template.
    There is only one template, in the sketches below the template is the pink piece.
    The blue and brown are the finished pieces. they are the pieces that you are making.
    This drawing shows the the two patterns that you are cutting, these are the finished pieces of wood, not templates.
    The drawing shows where the router bits must be to cut on either side of the line for each pattern piece.
    Pattern line.jpg

    The image below shows the template overlaid on the finished matched pieces for reference, to show the position of the router bits in relation to the template and the patterns cut .

    complimentary pattern assemble1a.jpg

    The sketch below shows the relative positions of the template, the template guides ( bushing/ bearings) and the router bits to the cutline.
    You can see that changing the template guides bushings changes the position of the router bit. with the small template guide bushing the router bit is moved close to the template and cuts on one side of the cutline. When you use the large template guide bushing the router bit is moved to the other side of the cutline.

    assembly7a.jpg

    In the drawings below, you will see that the cut line in each operation is exactly the same distance from the template reference edge, and the you are cutting one pattern from one side of the cutline and the other pattern from the other side of the cutline.


    router assem for complimentary curves.jpg
    Hi, I'd like to thank you for posting the illustrations and details on your single template process.
    As I understand what I'm seeing here, the difference in guide bushings is compensating for the router bit diameter and thus resulting in coincident cut lines.
    In fact, it doesn't have to be the same router bit. Any combination of router bit/bushing that cuts to the same line will do. Clever

  8. #53
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    Hi Edwin, Thank you.
    Yes you are correct, any combination of bit and template guide that give you the correct position will work.

    If you wish to multiple pieces you can of course use the finished pieces as templates and a flushcut bit, but for a single job this is a simple, quick and accurate setup.


    Quote Originally Posted by Edwin Santos View Post
    Hi, I'd like to thank you for posting the illustrations and details on your single template process.
    As I understand what I'm seeing here, the difference in guide bushings is compensating for the router bit diameter and thus resulting in coincident cut lines.
    In fact, it doesn't have to be the same router bit. Any combination of router bit/bushing that cuts to the same line will do. Clever

  9. #54
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    Mark. I get it, looking at your pictures, then I don't get the order of doing things. In particular, how do you make the right-hand piece? Making the left-hand piece seems straightforward with a router and the appropriate matched bearing size.

    Do you put both the template and the righthand rough wood piece on another piece of wood then rout it?
    - After I ask a stranger if I can pet their dog and they say yes, I like to respond, "I'll keep that in mind" and walk off
    - It's above my pay grade. Mongo only pawn in game of life.

  10. #55
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    Hi Alan,

    You can do either piece first, but it probable makes sense to cut the lefthand (Blue) first, then use that for supporting the template (Pink)

    To make the righthand cut;

    Support the template (Pink) on a piece of wood (Blue) the same thickness as the piece that you want to cut ( Brown)
    Move the brown piece into the cut path of the router bit and clamp it in place.
    The router bit will be cutting on the edge away from the template.
    When you route following the template the bit will trim off any material that is in its path left of the cutline.

    I will see if i can do a video to demonstrate.

    Pattern Assem3b.jpg

    Quote Originally Posted by Alan Lightstone View Post
    Mark. I get it, looking at your pictures, then I don't get the order of doing things. In particular, how do you make the right-hand piece? Making the left-hand piece seems straightforward with a router and the appropriate matched bearing size.

    Do you put both the template and the righthand rough wood piece on another piece of wood then rout it?

  11. #56
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    So I went in the shop and made a quick template setup and did a sample.
    I made one of the template guides as i didn't have one the correct size.
    This setup was done with 1/4" router bit. Patterns are 1/4" hardboard.
    This is super easy to do, minimum amount of steps and as accurate as you want to make it.

    I have to go into town this afternoon and I will try to do a video this evening when i get back in the shop.


    A couple of points to keep in mind.

    1. Template guides are not as concentrically accurate as shaft mounted bearings.
    2. Router bases are not accurately mounted concentric to the shaft.
    3. Router bases are not precision fitted the the router body and move when tightened.

    So there are lots of places to lose accuracy with templates.
    So it's best is to use a bearing setup.
    It's best whatever setup you use to leave it setup until you are finished.
    Setup two router and leave them setup, or a system that you can rely on to maintain accuracy.

    One more point is that off center template guides can be used to advantage, as you can vary the cut offset by referencing a different part of the bushing.
    It's all quite fascinating stuff!


    PXL_20210617_165840641.jpgPXL_20210617_165903042.jpgPXL_20210617_165911041.jpgPXL_20210617_165924754.jpg

  12. #57
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    I was almost tempted to start a contest as to each person's methods, and comparing the results. Hmmm.....

    I glued up mine today, after using Bondo Fast Dry Filler to fill in the gap between the Final piece A and the Template B to make Template B more accurate size (note to self - never use that type of Bondo again. 3-4 minutes of working time is way too short). I then used a bearing trim router bit to trim Piece B (the Paduak) and it is being glued to the Purpleheart Final Piece A now. Tomorrow morning I'll take it out of the clamps, joint/plane/sand it again, and see how well I did.

    I'd love to see your video, Mark. As would, I'm sure, all of us. It will be very instructive.
    - After I ask a stranger if I can pet their dog and they say yes, I like to respond, "I'll keep that in mind" and walk off
    - It's above my pay grade. Mongo only pawn in game of life.

  13. #58
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    Hi Alan,

    I didn't get the video done tonight but will do it tomorrow.

    Lets do it!.
    When the flag drops the BS stops, as they say at the race track.


    Quote Originally Posted by Alan Lightstone View Post
    I was almost tempted to start a contest as to each person's methods, and comparing the results. Hmmm.....

    I glued up mine today, after using Bondo Fast Dry Filler to fill in the gap between the Final piece A and the Template B to make Template B more accurate size (note to self - never use that type of Bondo again. 3-4 minutes of working time is way too short). I then used a bearing trim router bit to trim Piece B (the Paduak) and it is being glued to the Purpleheart Final Piece A now. Tomorrow morning I'll take it out of the clamps, joint/plane/sand it again, and see how well I did.

    I'd love to see your video, Mark. As would, I'm sure, all of us. It will be very instructive.

  14. #59
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    A couple of points to keep in mind.

    1. Template guides are not as concentrically accurate as shaft mounted bearings.
    2. Router bases are not accurately mounted concentric to the shaft.
    3. Router bases are not precision fitted the the router body and move when tightened.
    This is why the sell a centering cone/pin. They do a tremendous job of eliminating (or significantly reducing) all those issues.
    My granddad always said, :As one door closes, another opens".
    Wonderful man, terrible cabinet maker...

  15. #60
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    Quote Originally Posted by Mark Hennebury View Post
    Lets do it!.
    When the flag drops the BS stops, as they say at the race track.
    OK. I'm in. Hopefully will finish up the cutting board this week, if I don't get too busy. So mine will be the rabbet / Bondo technique.

    Any other takers? Let's see some great skills and learn new techniques along the way.
    - After I ask a stranger if I can pet their dog and they say yes, I like to respond, "I'll keep that in mind" and walk off
    - It's above my pay grade. Mongo only pawn in game of life.

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