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Thread: Base Mount for Upright Really Big Lights

  1. #11
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    Default Re: Base Mount for Upright Really Big Lights

    Maybe. I well tuned printer yes. Most printers will do 45deg angle


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  2. #12
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    Default Re: Base Mount for Upright Really Big Lights

    The angle that can be printed varies with printer as well as print settings.

    When the printer is doing its thing, its extruding a semi-liquid plastic string out of the nozzle. This string is round at the point it exits the nozzle. For the fist later, its pressed against a rigid bed and flattens out much wider and thinner to form the first layer bonding layer.

    Subsequent layers are printed so that they are slightly oval to a flattened oval depending on the print settings. This bonds the fresh semi-liquid new layer extrusion to the previous layer which has likely already solidified to be mostly rigid but not fully. The layer height and extrusion multiplier have the biggest effect on the shape of the layer extrusion. Layer height controls the distance the head (nozzle) moves in the Z axis with each layer move. The extrusion multiplier controls the flow of plastic through the nozzle, the more it extrudes the fatter and harder the new layer is pressed into the old. As stated, it also enlarges (horizontally) the layer which can cause dimensional changes in the printed part (meaning its either bigger or smaller than designed).

    Perimeter shell count (the actual title of the setting varies with the slicer) determines the thickness of the walls of the printed part in the form of how many outlines the printer prints. Most slicers print perimeter shell paths from the inside out, meaning it prints the inside path, then a middle path then the outer path (example of 3 shell count).

    Ok, where is this leading you ask? And whats it got to do with your print? Well here we go.

    A vertical wall ends up printing a round shape on top of a round shape. Think stacking a round PVC pipe on top of a round PVC pipe. Except that the pipes are malleable and the extrusion of the new layer presses it into the previous one slightly. This pressing bonds them together. This is the maximum bonding strength since the highest point of the prior layer aligns with the lowest point of the new layer extrusion.

    When a wall expands or grows outward as height increases, the extrusion of the new layer no longer aligns directly on top of the prior layer's highest point. The print head still is at the same height relative to the platform. It still extrudes the same amount of plastic. However, it no longer is pressing directly on top of the highest point of the prior layer. This produces a weaker bond between the layers. And the further off of center the new layer extrusion is, the less bond and contact area there is. At some point the offset distance becomes too much for the new layer to adequately bond to the prior layer extrusion and you start getting sagging, delamination and ultimately, failure of the print. Because it is extruding generally round on top of round, you can see that the extremity is generally at 45 degrees.

    This failure angle can be tweaked by increasing the extrusion multiplier to a certain point. By extruding more plastic, the width of the prior extrusion is wider than the nozzle diameter and provides enough contact area for the wider new layer to bond to. But as I sad, it can affect dimensional accuracy of the print.

    In addition to the new layer bonding to the prior layer, it also bonds to itself. This is where the perimeter shells comes into play. The first (inner) extrusion is laid down first. The second (middle) is laid down next and both bonds to the layer below it but also to the prior shell because of the oval nature of the extrusion itself. This provides additional support for the increasing angles of a print. Since the inner shell could be extruded on top of the middle or outer shell of the prior layer and each subsequent shell can adhere to the prior shell as well as the layer below it forming multiple bonds, the print angle can possibly exceed 45.

    Print speed also affects bonding and sagging however the settings I listed above affect the ability to print overhangs more than print speed. And there are other settings of digressing relativity.

    In the end, unless a part has supports on both ends of a horizontal extrusion (known as bridging), it can't print it. Period. Thats why the original tab can't be printed without supports. The bottom of the horizontal section would be extruded in mid air with nothing to hold it up. And why the 45 degree edge you suggest as an alternative can probably be printed as each prior layer forms the support for the new layer above it.

    And believe it or not, there are times when you purposefully leverage this knowledge. 99% of the time we go out of our way to print without significant overhangs which would form stringing, sagging and failed prints or print with supports to correct that issue. However, you can print fuzzy things by thinking things through and understanding how your printer actually works.



    So, back to your design. Curious about the interior. I am wondering if a "plug" would be a better option and would circumvent the need for the tabs. Could you photograph the interior?

    See, the thing I am worried about is the strength of the tabs. As designed I would be wary they could break off if the base piece you are making is anchored firmly to PVC (or other pipe) and the RBL is hit. What I am thinking is make a flange bigger than the hole in the RBL with the body of your part the diameter of the hole with protrusions that match the slots (to prevent twisting). That piece inserts from the inside out.

    Or could you make the base with the tabs above it rather than sticking up something like how i designed the pumpkin mount for pixabulbs?

  3. #13
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    Default Re: Base Mount for Upright Really Big Lights

    Lots of great info! Here's a pic of the interior. I'm not sure how I'd secure it if it went in from the top?

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  4. #14
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    Default Re: Base Mount for Upright Really Big Lights

    Ok, thats absolutely perfect!

    I would approach this from the inside out. See that recess in the bottom? Measure the diameter and depth of that.

    RBL1.jpg

    Sorry, don't have 3D design software at work. But thats a crude vector cross section representing the right half of the part. Now, yes, it has an overhang. However, that overhang is not several inches above the bed eating up tons of print time and material, its only the thickness of the plastic RBL base so support material is at a bare minimum. Its present but negligible as far as print time or material use. Three little pieces you can easily remove with needle nose pliers. You would insert this from the inside and give it a twist to lock in place. The interior base offers a much larger diameter and will key into the ring that I see in the photo on the interior.

    The illustration is the orientation I would print it. You have a nice flat base to bond to the platform. You have mostly vertical walls for the best strength. You have only 3 minor overhangs (the three tabs presumably at 120 deg increments). Minimal support needed. Lots of base material for strength.

    Obviously you need to facilitate wires with via openings but being round holes, those tend to print fine (see bridging explanation) as would the screw hole (horizontal) in the base for the screw to lock the PVC pipe in place.

    And, obviously my scales are off as I was doing that freehand with absolutely no measurements of actual dimensions. But its enough to convey the idea. Whether you use it, well thats up to you. You can, of course, do your own thing or even a combination if this and your own thing. Play with the thought and see what you make of it.

  5. #15
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    Default Re: Base Mount for Upright Really Big Lights

    That's a great idea, makes sense. I'll see if I can get some time to draw something up this evening.

  6. #16
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    Default Re: Base Mount for Upright Really Big Lights

    I don't get the engagement, but when the printed part is shown and screwed in I will get the orientation there. I get the concept I think that you are just hitting that sort of lock in back down there deep with a piece that will hang over and engage it?

  7. #17
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    Default Re: Base Mount for Upright Really Big Lights

    Here we go. I think this just might work.
    Attached Images Attached Images

  8. #18
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    Default Re: Base Mount for Upright Really Big Lights

    With the right setup and settings, printing those tabs in the original design should be doable although possibly not ideal. If you post the stl to it, I'll give it a go at printing this weekend.

  9. #19
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    Default Re: Base Mount for Upright Really Big Lights

    Quote Originally Posted by didjareally View Post
    With the right setup and settings, printing those tabs in the original design should be doable although possibly not ideal. If you post the stl to it, I'll give it a go at printing this weekend.
    You could attach this to your bulb mounts and have an awesome setup


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  10. #20
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    Default Re: Base Mount for Upright Really Big Lights

    Quote Originally Posted by didjareally View Post
    With the right setup and settings, printing those tabs in the original design should be doable although possibly not ideal. If you post the stl to it, I'll give it a go at printing this weekend.
    That would be great, thanks! I'll post it tomorrow.

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