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Thread: Math Question - What Difference Does 1 Degree Make?

  1. #1
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    Math Question - What Difference Does 1 Degree Make?

    Ok, I'm asking here because I KNOW there's a lot of smart people here.

    Table base leg set - X shaped for farm style table.
    Leg Overall height - 27.5"
    Leg Overall width - 34"
    Leg Intersection where both X pieces cross to for the "X" - 20" from the end of the long point of the leg-lower-section

    Measuring the cross-section with 2 boards, I get about 91º for the cross section angle. If I changed that to 90º, what does that do to my "width" of he leg base? Design is 34" wide....
    What is the difference 1º makes over the height of 27.5" and width of 34"???
    farm_table_legs.jpg
    Thanks & Happy Wood Chips,
    Dennis -
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  2. #2
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    Check your measurements again. I get about 87° and hence 93° for your supplemental angles. As the angle may be off the easiest measurement you could give us is the width of the leg members, then we don’t need to mess with the angles.
    Comments made here are my own and, according to my children, do not reflect the opinions of any other person... anywhere, anytime.

  3. #3
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    Where the legs cross, there is a smaller pair of angles and a larger pair of angles. From the vertical dimension of 27 35/64 inches and the 20 inch sections of the legs, I get that the larger pair of angles should be about 93 degrees each. Do you want to reduce the larger pair of angles to 90 degrees each?

    Is this a design for a new table? Or are you modifying an existing table, in which case you'd want to re-saw the bevels at the ends of the legs.

  4. #4
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    Above the "x" the short dimension is 16 15/32". Below it is 16 13/32". Is that throwing things off?

  5. #5
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    Edit to my previous.
    If you want to maintain the 34” table top, and about 27.5” from floor to bottom of table, the base from inside edge to inside edge will be 21”, and from outside edge to outside would be 21”+(2*(2^.5)*w). w being the width of your leg members.
    Comments made here are my own and, according to my children, do not reflect the opinions of any other person... anywhere, anytime.

  6. #6
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    Leg member width is 3.5" wide

    In short.....the width at the TOP of the leg section is 34" wide.
    The width at the BOTTOM of the leg section is 34".
    The height of the leg section from the floor to the top of the "X" is 27.5"
    Cross members are 3.5" wide x 3" thick

    I included the drawing to give a visual of what I'm designing for.
    Last edited by Dennis Peacock; 11-14-2019 at 12:49 PM.
    Thanks & Happy Wood Chips,
    Dennis -
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  7. #7
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    With the width 3.5, the outside edge to outside edge of your base is 30.899”, height floor to bottom of the table is 27.5”, width at the top of the cross members from outside edge to outside edge is 34”
    Comments made here are my own and, according to my children, do not reflect the opinions of any other person... anywhere, anytime.

  8. #8
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    Labeled the vertices, added a couple of midpoints (F & G).
    given: AB = 34: point F is midpoint and bisect angle ACB; segFB = 17”
    triangle ABC is right isosceles. =>

    Triangle FBC is also right isosceles; =>
    segFB = segFC = 17.
    segFC + segCG = 27.5 => segCG = 10.5

    triangles DCE, DCG, GCE are all right isosceles =>
    CG = DG =GE = 10.5
    DG + GE = 21

    Your cut off at the bottom is also a 45°, forming a right isosceles triangle.
    The cut along the floor is the hypotenuse.
    So the length is 3.5” x (square root of 2) ~4.949;
    and there are two of them ~ 9.899
    plus the 21 = 30.899”

    edit, I like making all 45° cuts. If you want to keep the base at 34” consider changing your leg widths to 4.596”... or 4 5/8ths just a tad longer, but you could hit it with a couple extra swipes of the plane. If 4 5/8” is too massive for your design, consider starting with a 4 5/8” piece and do some scroll work in the middle 2/3 to reduce mass.
    Attached Images Attached Images
    Last edited by Charlie Velasquez; 11-14-2019 at 3:03 PM.
    Comments made here are my own and, according to my children, do not reflect the opinions of any other person... anywhere, anytime.

  9. #9
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    A rule of thumb is 0.0175" / inch.
    "Anything seems possible when you don't know what you're doing."

  10. #10
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    Quote Originally Posted by andy bessette View Post
    A rule of thumb is 0.0175" / inch.
    This makes a lot of sense to me! Thank you!
    Thanks & Happy Wood Chips,
    Dennis -
    Get the Benefits of Being an SMC Contributor..!
    ....DEBT is nothing more than yesterday's spending taken from tomorrow's income.

  11. #11
    I'm not all that bright with angles so I cheat and use graphics programs

    this is my reverse engineered version-- I drew a 27.5 x 34 inch box and made the legs fit, then took measurements-- then I changed the angles of the legs to 45 and then took more measurements...

    tbl.jpg
    the right-most graphics are the 'to fit' layouts, the left is legs at 45...

    Whenever I'm dumbfounded on angles and measurements, I just let Corel do it!
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  12. #12
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    Dennis, I'm going to suggest you don't have the leg setup the same width as the table top, however..."IMHO", it's best to have the top slightly larger, both for appearance and comfort.
    --

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

  13. #13
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    Dennis, I would get a large piece of paper and draw a full scale drawing of the end view of your table legs and take your angles from that. If necessary, lay the leg pieces on your drawing and mark your angles from that.
    Joe

  14. #14
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    I'm with Jim.

    I plugged a few options into cad with similar geometries maintaining 90° to see how it looks, I have attached sketches below.

    if you go to 90 degree crossin

    I would tale the 27.5 and give some allowable .5 inch variation, and see how it looks. I prefer the look of the 36 inch top at 27.5ish with a 90 degree crossing. it has a nice round leg length for practical measurements as well. 34 works as well but insetting the legs a touch further looks better to me. =]

    original

    table 2.jpg

    90 ° crossing, new height
    Picture4.jpg
    90 degree crossing, original height
    table 1.jpg

    90 degree crossing 36 inch top
    table 3.jpg

  15. #15
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    I vote for #4: 90 degree crossing 36 inch top. I think it looks better with more of an overhang.
    David

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