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Thread: Reading annotations, radius

  1. #1
    Associate Engineer
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    Confused Reading annotations, radius

    Hi!

    I am reading these blueprints of a bread toaster and I just can not figure out how to dimension a fully defined sketch out of this.

    My main issue of understanding are these radius annotations. What is the difference between R60 and R40, appart from the obvious radius difference.

    May someone shed some light on this matter? I am out of ideas.


    (Bottom view and zoom in)

    (Iso-view of bread toaster)
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    Last edited by jhg17004; 06-13-2017 at 06:55 AM.

  2. #2
    Administrator Kelly Bramble's Avatar
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    It's a complex curve composing of several radius... where each radius starts and ends is missing data.
    Tell me and I forget. Teach me and I remember. Involve me and I learn.

  3. #3
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    I was suspecting this as well but didnt dare to assume it was missing data.

    This concerns me. When I attempt to sketch with these dimensions I can not achieve a similar shape.
    I will bring this to my teacher and see whats going on.

  4. #4
    Technical Fellow jboggs's Avatar
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    You can assume the curves are tangential, else the joint would be a sharp corner. That will help you locate the centers. The center of the larger radius, the center of the smaller radius, and the tangent point will all lie on the same line.

  5. #5
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    Is that why one of the radius arrows extend all the way to the centerline?

    Still though, my biggest concern is R20, how does it connect to the others. If its center originates from the centerline, is will look like this. Please im going insane, I feel like im missing out on something fundamental.

    Look at this mess!
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    Last edited by jhg17004; 06-15-2017 at 03:02 AM.

  6. #6
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    I dont even know whats going on anymore, but this is possibly correct.

    I will have to ponder about this...

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    • File Type: png 4.png (11.9 KB, 12 views)

  7. #7
    Technical Fellow jboggs's Avatar
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    These are all good questions for a student to ask. We are limited in how much "help" we can give on homework. You are on the right track. In fact, your last diagram appears to be correct, but you are unsure why. Examine at your last diagram very carefully while you carefully re-read my statement from above: "The center of the larger radius, the center of the smaller radius, and the tangent point will all lie on the same line." I did not say the centers of the two radii would be at the same point. (The tangent point is the point where the two arcs meet.)

  8. #8
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    Thank you for the attention, also for the great compliment from jboggs.

    I believe to have solved it and I will post some results and conclusions next thing in the morning.

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