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  1. #1

    Screw holes for self-tapping screws

    Hi,

    Essentially, I want to print a block/spacer to raise the level of a doorbell button. The block would affix onto the wall where the button was, and the button would then be screwed onto the block.

    The problem I'm envisaging is the infill of the block will not be substantial enough for self tapping screws to bite securely into. Is there a way to print internal areas more solid?

    I have attached an image to illustrate what I'm trying to get at. The block on the left is what I think a regular 3D print would look like; Four big holes running all the way through for the screws that affix the block to the wall, and a hole (or holes) fix the doorbell button to the block. All of the internal area would be infill. Looking at the block on the right, is it possible to have a "halo" of solid print around the single hole?

    The illustration is over-simplified just to help get at what I'm after.

    I am using Cura 4.71 and my printer is AnyCubic i3 Mega S.

    Many thanks in advance for your help.
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  2. #2
    If your slicer supports multiple profile definitions in a single print, it should be possible. Simplify3D slicer would allow me to specify number of walls, layer thickness, infill percentage for a profile that would print, for example, from the bottom to the underside of the center hole. At that point, I'd define an increased number of walls and/or increased infill for the remaining levels. This would provide for nearly the exact build in the image you have provided.

    I found a YouTube video that covers a more elaborate application of this concept. It requires that the model be cut into pieces. The video creator used Fusion 360 but for a simple plane cut, Meshmixer will work well.
    Later in the same video, a different approach is used. It requires a second shape with the new settings be merged with the first.

    I attempted to perform the steps in 4.7 Cura on my machine, but the program crashed. With the newer version, many of the features are hidden and in different locations from the video, but with a little experimentation and fewer crashes, you should be able to accomplish your goal.

  3. #3
    The number of perimeters also called shells will determine how thick the hole wall is. Also for something small like that you can print it with high infill rates so there is lots of meat.
    However, most door bell buttons are screwed to the surface with 2 screws or they are mounted with mounting tape. Why not build your riser to match the button and just get longer screws that pass through the block and into the surface.. Or use mounting tape for riser to wall and button to riser. You are in control of the entire process so experiment and find out what works, that is the beauty of fast prototyping with a 3d printer.

  4. #4
    Quote Originally Posted by fred_dot_u View Post
    If your slicer supports multiple profile definitions in a single print, it should be possible. Simplify3D slicer would allow me to specify number of walls, layer thickness, infill percentage for a profile that would print, for example, from the bottom to the underside of the center hole. At that point, I'd define an increased number of walls and/or increased infill for the remaining levels. This would provide for nearly the exact build in the image you have provided.

    I found a YouTube video that covers a more elaborate application of this concept. It requires that the model be cut into pieces. The video creator used Fusion 360 but for a simple plane cut, Meshmixer will work well.
    Later in the same video, a different approach is used. It requires a second shape with the new settings be merged with the first.

    I attempted to perform the steps in 4.7 Cura on my machine, but the program crashed. With the newer version, many of the features are hidden and in different locations from the video, but with a little experimentation and fewer crashes, you should be able to accomplish your goal.
    Thanks for the video link. I searched all manner of terms, but not "differnet infills cura". Doh! I'll try this to see how V4.71 copes. As I said, this is all new to me. Cura is what was supplied with the printer. If you recommend different freeware, I'd welcome the suggestion.

    Cheers.

  5. #5
    It's quite a bit different from other slicers in the way it works, but Prusa Slicer v2 is a great program. There's a rather comprehensive instructional web site specifically for your printer and configuration for Prusa Slicer v2. I've used the program and taught other users in the makerspace how to use it. Happy results all around. It supports variable infill and layer specific settings and so many other features.

  6. #6
    Quote Originally Posted by airscapes View Post
    The number of perimeters also called shells will determine how thick the hole wall is. Also for something small like that you can print it with high infill rates so there is lots of meat.
    However, most door bell buttons are screwed to the surface with 2 screws or they are mounted with mounting tape. Why not build your riser to match the button and just get longer screws that pass through the block and into the surface.. Or use mounting tape for riser to wall and button to riser. You are in control of the entire process so experiment and find out what works, that is the beauty of fast prototyping with a 3d printer.
    Thanks for the infill suggestion. I am hoping not to waste too much unused material though.

    As I said, my example was over-simplified. The full spec is to make a 25° downward-facing wedge that is to be affixed onto an aluminium doorframe (using the existing screwholes) and then the backplate of an IP doorbell (Ring) fixed onto the wedge. At the moment there is way too much sky in the displayed video, and I get a motion notification every time car passes by.

    Cheers
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  7. #7
    Plastic is cheap.. make a prototype and test it out..

  8. #8
    Super Moderator curious aardvark's Avatar
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    I do this a lot - it's all about the perimeters. Slicers apply perimeters to the shell of a model but also put them round any holes/voids in the model.

    so with three perimetyers on a 0.4mm nozzle - you will automatically get 1.2 mm of solid plastic on the outside of any screw holes.
    Absolutely no need to use a lot of infill.

  9. #9
    Quote Originally Posted by curious aardvark View Post
    I do this a lot - it's all about the perimeters. Slicers apply perimeters to the shell of a model but also put them round any holes/voids in the model.

    so with three perimetyers on a 0.4mm nozzle - you will automatically get 1.2 mm of solid plastic on the outside of any screw holes.
    Absolutely no need to use a lot of infill.
    Thanks.

    I solved my problem by adding two 2mm-wall tubes as a separate entity into Prusaslice, and setting them to print with a 2mm shell. I'm not sure that it's a textbook solution, but it worked.

    Printed perfectly .

    Thanks for all the input.
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  10. #10
    You know what's important in all this maker stuff is to find tools that work for you, use those tools and accomplish your objective. You did that.

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