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How do i fix a ridge appearing on a loft that is supposed to be smooth?

pavel_maňásekpavel_maňásek Member Posts: 6

https://cad.onshape.com/documents/7b729b678209fe13403e7fce/w/6280530c7ebb748c87e46a9d/e/b8fc1bfb0e204f1d94736962?renderMode=0&uiState=68489b4cb4d8bd6a38a43e3f

I am recreating a watering can from a picture and i want to 3d print it. This is the picture:

Untitled Image

I got stuck at the tube part where the water comes from. I made 3 profiles on 3 separate planes all angled differently, I connected them with a loft and set the end condition as normal to profile with a magnitude of 1. I used match connections, tried making the connections in multiple ways but all attempts resulted in a ridge (or what should i call it) on the tube, which prevents me from shelling it to make water go through. I can kinda see what the issue is when i turned on isocurves but I have no idea how to fix such a problem.

obrazek.png

This is what it looks like from a section view from the end of the tube:

obrazek.png

This is not the first time I am having an issue with lofts, is there a set of general rules to follow when using lofts to prevent issues?

The printing itself will be really challenging but that is a problem for future me :D

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Best Answer

  • jelte_steur814jelte_steur814 Member Posts: 490 PRO
    Answer ✓

    Hi Pavel,

    Notice how the profiles in the iso curves get these strange "S" shapes:

    image.png

    that's no good.

    When you try your loft with two profiles rather than three, in whatever combination, that issue is solved. and your surface looks cleaner.
    But when skipping the middle profile, the top profile curve is lost obviously. so instead of forcing that curve in through the middle profile, try adding a guide curve. make sure the guide curve satisfies the same constraints you're applying to the loft (normal to face at the exit end of the spout).

    With the middle profile, you're adding too much control to the loft.

    Less control -.> better surface quality…

    like this:

    https://cad.onshape.com/documents/b23fbf49d9bfafa0b5d6a941/w/75ae99bf22dd88bb58802e96/e/9069913c431bcc8eccd9b677?renderMode=0&uiState=68493b5ca99e1d63a71cda3f

    image.png

Answers

  • jelte_steur814jelte_steur814 Member Posts: 490 PRO
    Answer ✓

    Hi Pavel,

    Notice how the profiles in the iso curves get these strange "S" shapes:

    image.png

    that's no good.

    When you try your loft with two profiles rather than three, in whatever combination, that issue is solved. and your surface looks cleaner.
    But when skipping the middle profile, the top profile curve is lost obviously. so instead of forcing that curve in through the middle profile, try adding a guide curve. make sure the guide curve satisfies the same constraints you're applying to the loft (normal to face at the exit end of the spout).

    With the middle profile, you're adding too much control to the loft.

    Less control -.> better surface quality…

    like this:

    https://cad.onshape.com/documents/b23fbf49d9bfafa0b5d6a941/w/75ae99bf22dd88bb58802e96/e/9069913c431bcc8eccd9b677?renderMode=0&uiState=68493b5ca99e1d63a71cda3f

    image.png
  • glen_dewsburyglen_dewsbury Member Posts: 1,057 PRO

    I was toying with this myself trying to get a decent spout with out the squish. While thinking this through I also practiced some of my preferred surfacing methods. If it won't thicken then go back and adjust the surface. It's a bit hinkey in the circled area but it's quite adjustable.

    https://cad.onshape.com/documents/69dd864d75019d37a008b37b/w/3df19d71d40cd156b72b0358/e/5cdacc36354e45e78428c065

    image.png
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