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  1. #1
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    Default PlsHlp change axis on complex angle star project segments

    You might remember this:

    Help requested going from Sketchup to build on small but complex tight angles project


    Bamboo Start Shped Bowl

    Star_Orig.jpg
    https://www.woodworkforums.com/attach...5&d=1421484345

    I did finish the project is mdf.

    Star MDF.jpg

    But threw it out to force myself to try again.






    Star 5 Points 12.7mm SKP8.jpg
    Star 5 Points 12.7mm SKP8.skp


    Seperated.jpg
    Star Single Point Left and Right3 seperated SKPv8.skp


    The Left and Right segments of the top point of my star will make up my project.
    Cutting five of the left and five of the right.

    I've been trying to figure out how to calculate the angles.
    And failing for a few hours.

    I want to knock these two segments over onto their backs but can't figure out how.

    I'm hoping there is a way to simple change the axis on each one and go from there.
    But, again, can't work it out.

    I've tried moving flipping etc. etc.
    Drivin' me mad!

    Any help would be greatly appreciated.

    Thanks in advance.
    Thanks,
    Barry G. Sumpter
    May Yesterdays Tears Quench the Thirst for Tomorrows Revenge

  2. #2
    Join Date
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    Location
    Caroline Springs, VIC
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  3. #3
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    Default

    I'll be using my new Dewalt DWE4791-XE.
    With my new Incra 1290 Mitre Guide.

    DW745-Side-View-4.jpg


    Incra V120.jpg

    The dewalt only bevels left to 48°
    But the Incra mitres left 60° and right to 60°.

    I already checked them both for accuracy.
    Thanks,
    Barry G. Sumpter
    May Yesterdays Tears Quench the Thirst for Tomorrows Revenge

  4. #4
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    Oct 2014
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    Caroline Springs, VIC
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    Default

    I laid over one of the pieces. I don't know an easy way, and I don't understand how the change axes thing works so I just farted around measuring angles and rotating until I got the back dead flat. I would tell you exactly how I did it, but it would be 1000 pages long. You can measure the angles now. I think one of the angles is 17.8° but I may have misclicked when I was placing construction lines.

    Star Single Point Left and Right3 seperated SKPv8.skp

  5. #5
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    Default

    Champion!

    Many thanks!


    I knew it was something to do with axis.


    I build a box on the bottom of mine.

    Started lines extending the edges
    1.jpg



    points joined to make a plane.
    2.jpg



    Then pulled down to make the box.
    3.jpg


    Then used the bottom corner of the box to set the axis.
    4.jpg

    Like you I mucked about with the axis until it looked right.



    Deleted the box.
    5.jpg


    Then exploded and exploded again.
    Then made group.

    Then moved the bottom corner to the axis point.
    6.jpg



    Many thanks.
    Thanks,
    Barry G. Sumpter
    May Yesterdays Tears Quench the Thirst for Tomorrows Revenge

  6. #6
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    Default

    Actually what I have done isn't 100% perfect. It is because sketchup sux for accuracy. It literally gives angle measurements as ~71.7° instead of 71.7°, so the angle should actually be something like 71.757843484° or whatever it is as a million decimal places. That segment I flattened is out by a bit. damn sketchup.

  7. #7
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    Default

    I found the culprit. Your pieces aren't an equal thickness across its width. varys by 1mm. 12.3mm -> 11.3mm. Throws in a massive curve ball for the manufacture of the item.

  8. #8
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    Default

    Yeah. That accuracy happens with the tape measure as well.

    The incra v120 is only by 1° increments.
    Don't know what Im going to do with the .7 up or down.

    That x.57 should be rounded to a x.6 which I'll round up.
    hope that works
    Thanks,
    Barry G. Sumpter
    May Yesterdays Tears Quench the Thirst for Tomorrows Revenge

  9. #9
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    Blast!

    Mucked about so much I forgot what I was going to do once I got the backs flat.

    build another box along the edges then measure angle?

    Tomorrow ....
    Thanks,
    Barry G. Sumpter
    May Yesterdays Tears Quench the Thirst for Tomorrows Revenge

  10. #10
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    Default

    Barry
    what you can do is approach the problem as though you were cutting crown molding.

    Make yourself a wedge that corresponds to the angle of the tray sides and attach this to the face of your miter gauge.
    Then when the sides are presented to the saw blade they will be at the correct "spring angle" for the cut without any difficult maths.

    look at this jig KregĀ® Crown Molding Mitering Fixture - Lee Valley Tools If you can sort of "turn your head upside down", imagine the miter saw's blade as being your table saw's blade and the jig as being a wedge attached to your miter gauge, then with the saw blade at 90 degrees to the table, and the work piece inclined at the required angle, the saw will cut a trapezoid with the correct angles on the end.
    regards from Canada

    ian

  11. #11
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    Thanks Ian,
    Too hard for my simple mind.
    Thanks,
    Barry G. Sumpter
    May Yesterdays Tears Quench the Thirst for Tomorrows Revenge

  12. #12
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    Default

    grab a piece of thin wood (or your smart phone)
    pretend that your right hand is a table saw blade
    cock your wrist so that your little finger is on the table and your right palm is vertical.
    Now, using your left hand, hold your smart phone at 90 degrees to your right palm and the table -- every angle is 90 degrees
    now turn the phone so that it makes an angle of about 45 degrees with your right palm -- the vertical angle is still 90 degrees, but you would be cutting a bevel at 45 degrees across the thicness of the phone.
    now lay the phone back at an angle of about 45 degrees to the table -- now your right hand would be cutting a compound angle

    If you attach a wedge to your miter gauge it will allow the sides to lay back at the splay angle you need. I'm guessing you want an angle somewhere between 40 and 45 degrees.
    If you then angle the miter gauge to the plane angle you require, the saw blade will cut the compound angle you need. The sides will be wider at the top than at the bottom and the bevels should line up.
    regards from Canada

    ian

  13. #13
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    Default

    Thanks,
    Barry G. Sumpter
    May Yesterdays Tears Quench the Thirst for Tomorrows Revenge

  14. #14
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    That previous question should be a statement.

    I'm sure there's a smart way to do this.

    Like adding up all the angles and divide by 6?
    Thanks,
    Barry G. Sumpter
    May Yesterdays Tears Quench the Thirst for Tomorrows Revenge

  15. #15
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