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Create the scraper model

alex_vestasalex_vestas Member Posts: 65
edited October 11 in General

How to create the scraper model? (two sine waves)

https://cad.onshape.com/documents/97899b570ed9828912f7b2e0/w/e2552ebc049e4f7b4df64a3f/e/099f1d49faf9b5874b6c02a4?renderMode=0&uiState=67098286255bf5097f521894

I created the drawing:

Comments

  • alex_vestasalex_vestas Member Posts: 65
    edited October 13

    /

  • alex_vestasalex_vestas Member Posts: 65
    edited October 14

    I tried to create Drawing of Sketch1, but it only create the partial rectangle, without the sine wave.

    https://cad.onshape.com/documents/0e2220d7304c16fab02e3a58/w/39bf2ecdd729d81fffbc015d/e/937807009368d52ba1d66bfe

    How to solve this?

  • alex_vestasalex_vestas Member Posts: 65

    Can anyone help me with this?

  • steve_shubinsteve_shubin Member Posts: 1,096 ✭✭✭✭
    edited October 16

    To use the sine wave within Sketch 1, click on it with the USE tool.

    Consider taking a number of the courses offered below.

    https://learn.onshape.com

    https://cad.onshape.com/documents/003d9b6b596809cd61db2abd/w/33dd046e26089319bc23d443/e/000aeacec8fd992e0e7a621b

  • alex_vestasalex_vestas Member Posts: 65

    Thank you!

    Can you clarify two points: what mean blue minus sign on Sketch1 Features menu: "Sketch 1 is not fully defined"? How should I solve this? Second, should I specify the radius of the sine wave for CNC cutting or it's not required for this model? As I assume, the amplitude of a sine wave equal to the radius of a circle?(in trigonometry?)

  • steve_shubinsteve_shubin Member Posts: 1,096 ✭✭✭✭
    edited October 17

    what mean blue minus sign on Sketch1 Features menu: "Sketch 1 is not fully defined"?

    In essence, it means that it is not fully locked down. It means you could possibly move something in the sketch if your aren't paying attention. And you could tell that it is not fully constrained by the long BLUE horizontal line. BLUE indicating that it is not fully constrained. So the easiest way to fully constrain the sketch was to put a FIX constraint on the dashed construction line, as it has a type of relation to that blue line.

    should I specify the radius … As I assume, the amplitude of a sine wave equal to the radius of a circle?

    https://www.reddit.com/r/todayilearned/comments/bb87k/til_that_sine_and_cosine_are_merely_2d_orthogonal/?rdt=53657

    MORE ABOUT SINE WAVE FROM WIKIPEDIA —-

    https://en.wikipedia.org/wiki/Sine_wave#:~:text=A%20sine%20wave%2C%20sinusoidal%20wave,corresponds%20to%20uniform%20circular%20motion.

    should I specify the radius of the sine wave for CNC cutting or it's not required for this model?

    Only CNC work I've had done is by giving a machinist some drawings. Others in the forum here could tell you better along these lines. But I would guess that if you were to forward or share this DOCUMENT with a machinist that uses Onshape, well, that machinist would have no problem spitting out this part.

    So maybe ask your machine shop if they work with Onshape. If so, share this document with them. They should be able to tell you right away if they can work with this document.

  • alex_vestasalex_vestas Member Posts: 65

    How to explicitly specify radius of sine wave? I tried do this on drawing, but this not work.

  • steve_shubinsteve_shubin Member Posts: 1,096 ✭✭✭✭
    edited October 17

    I honestly don't know what you're asking for when you're talking about a radius on a sine, in which the sine is obviously constantly changing from a tighter curve at the peaks, to more or less, a flat at the 180° phase location. Maybe someone else could help me to understand what it is you are asking for.

    The only radius I employed to make the sine was the radius of the helix. So if you feel you need to indicate a radius, then make a note that says that the amplitude was derived from a projected helix with a radius of 20mm.

    But since you said this was going to be CNC’d, I have to figure that the machinist has a way of taking the Onshape document or exported file, IN WHICH THE OS DOC. OR EXPORTED FILE HAS AN ACCURATE DEFINITION OF THAT CURVE BUILT IN, of which the machinist can use for converting into G code to run the CNC machine.

    Now it might be a good idea to have a drawing showing the length and amplitude and number of cycles if the shop is using something other than Onshape. But if they are using Onshape, I see no need for even this as they could simply look at the sketch.

    But again, as for the exact definition of the curve, I would rely completely on the OS DOC. or exported file to convey that info to the machinist.

    By chance - If you are not going to be using CNC, but rather using something like polycarbonate to make your scraper, then I would probably make a full scale print, then use some 3M Super 77 or something along those lines to glue the print to the polycarbonate, then some strong double stick tape to glue the polycarbonate to a wooden top work bench, where I would use a hand held router to rough in the curve. From there I would use something like an oscillating spindle sander to dial in the curve, and some type of table mounted belt sander on the straight sections of the scraper.

  • alex_vestasalex_vestas Member Posts: 65

    Yes, I'm leaning towards cutting it out with a coping saw. (its plastic)

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