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  1. #1

    Print on top of finished print?

    New to 3D printing and I wanted to print a giant nut, specifically the battlebots nut so that I could copy it in silicone and remold it multiple times in pourable plastic (that's more my domain) what I didn't know is the nut needed to be printed with 100% filler and I only used 10% to save on pla, this nut is 250 mm wide X 100 mm tall. And used an entire 2kg roll of pla in 48 hours. So since it required a 100% fill the top of the nut is still open. I left it sitting on the bed untouched. If I upload my gcode is it possible there is someone that can write me a simple code to cap the top? I am at work now so I dont have the gcode with me. But I do have a picture of the nut. Thank you in advance.

    https://ibb.co/mJwXj02

  2. #2
    Engineer-in-Training
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    Jun 2014
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    Why would you need one hundred percent infill? If the top isn't enclosed, it's because your top layer settings are incorrect, not that the infill settings are incorrect.

    It would probably be difficult (but not impossible) to complete the top and it may be possible to determine the failure point from the g-code if you know the exact layer height at which it ceased to print. A complication would be if only a portion of the last layer completed as there would be either a single layer gap in part of visible section or the printer would attempt to print over existing material.

    If you've turned off the printer, there's a complication of determining bed zero and homing and I suspect that it's going to be very risky to attempt a continuation.

    It would be easier to determine where to start the print by measuring it, then cutting the original STL at that point (Meshmixer, Edit, Plane Cut) and print the remaining portion, with the correct layer settings. Sand off the irregular, partially printed layer of the big nut and glue the two together. You'd have to sand the glue joint to make casting practical, of course.

  3. #3
    Link to the gcode below, I couldnt attach it because the file was to large. So I understand It will be easier to print just the top layer then glue it and sand the edge smooth. I can manage that. I downloaded the stl from thingiverse and the only change I made was sizing it to fit my bed so I dont understand why it didnt print the top layer. So what needs done to print just the top layer at the same size? Thank you.

    https://drive.google.com/open?id=1Gl...UVt9tCytNQWEyQ

  4. #4
    Engineer-in-Training
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    The g-code is not of much value without knowing the layer at which the print failed. More useful would be the thingiverse item number or a complete link, along with the scale figure you used to enlarge it. That number should be precise as well.

    What slicer program do you use?

  5. #5
    Just the very top layer is missing and within my software parameters its set as 1.2mm so im guessing thats all thats missing. I use the software that came with my printer which is JGcreate. I took another picture last night of the unfinished nut. its just the very inner nut surface but... it still did the layer that applied the "battlebots" logo so thats what lead me to believe that the very top layer was required by fill. The size I chose was 20% of the original STL from the link below. I am 100% okay with removing the "battlebots" writing from the nut and just adding a smooth layer or whatever is easiest.

    https://www.thingiverse.com/thing:3887284 20200313_230846.jpg

  6. #6
    Engineer-in-Training
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    That's an interesting model, 1250 mm from point to point (not flat to flat). Can you measure across the points (major diameter) to confirm that yours is 250 mm now?

    It appears from the manual that the software is a version of Cura. I'm not all that familiar with Cura, but have v3.2.1 on my machine, which allows for moving the part downward through the bed. Once placed appropriately for your requirements, the slicing will generate a g-code to match.

    If your version of software allows move and you've used 20 percent as you've said, I found that moving the model downward by about -94 gets pretty close to the level of the text. The program crashed before I could get the two figures to the right of the decimal point.

    If you want to have an easier job of future prints, consider a slicer such as PrusaSlicer 2 and configure it for your specific printer. You can have both slicers on your machine and use the specifications from the old one to configure the new one. PrusaSlicer also allows for chopping a model by lowering it below the bed.

    One can use Meshmixer to accomplish the same thing, but if your slicer doesn't crash as mine did, it's a one-program task, making things easier.

    Be sure to set your top and bottom layers appropriately. There's rarely a need for 100 percent infill and despite what you'll read in places on the internet, it won't make a part stronger than a correctly configured infill. Especially for your model, you don't need structural strength and ten percent was a good choice.

    I'm going to ask the creator of the Thingiverse model if he wants numbers in his remix. It's an easy task in Fusion 360.

  7. #7
    My exact dimensions are 250x216.5x100mm I already tried moving the object below the bed and when on the printer the extruder started moving around as if it was printing from start but without printing anything because the project was below surface. I stopped the print because I didnt want it to run like this for an extended period. I was hoping there was a way to edit the code to print just the top. I have fusion 360 as well but literally just installed it a week ago and havnt learned it yet.

  8. #8
    Engineer-in-Training
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    I've attached an STL file of the orginal nut, reduced to twenty percent and chopped at the point just below the lettering. There will be a solid bottom if you have your slicer settings correct and the lettering should appear in a normal manner.

    I used Meshmixer, imported the big nut. In the import screen, I set scale to 0.20, ensured that uniform scaling was turned on and snapping is turned off.

    Zooming into the much-smaller model, I then selected Edit, Plane Cut. The settings for that is to fill the cut mesh, not many things there. Use the blue arrow to move the slicing plane up and down until it reaches the desired location. I determined that by looking at the bottom of the letters, the "base of the valley." When it disappeared, I had the plane too high, and moved a "tiny bit" downward from there. Accepting the results, exporting the model and here you have it.

    Even if you learn that oh-so-powerful Fusion 360, Meshmixer can be faster and easier for the small stuff.

    I like both of them as well as a number of other programs. Don't restrict yourself to just a couple, learn as many as possible. Even Tinkercad has value. I just realized that I could have done this in Tinkercad too!
    Attached Files Attached Files

  9. #9
    I just found out that my top layer didnt print because I bought cheap PLA. [3D Solutech] My price on Amazon was $15 to my door for 1kg. Heres what ive now learned. 80% of the spool was fine but the last 20% has brittle spots like it was over heated in production, the brittle PLA clogged my print head and my printer doesnt have a warning for this and because it was such a long print I wasnt around to notice it not printing or making a "skip noise" attempting to push the PLA. Just my luck I guess it happened on the very top layer. I am still going to try and just print the top layer and fix it that way but I am fairly upset finding out this cheap PLA wrecked my project... going to take a look at what you worked on for me now. Thanks a bunch for all of your input and advice. I dont know where you are from but if you are ever in the Akron, Oh area in OCT. there is a haunted attraction there called Ghoul Brothers. Stop in and ask for Matthais, I run the show. Ill let you and your kin in for free and if all worked well with this project you will see this giant nut on the wall in several places looking like its holding it together!

  10. #10
    Engineer-in-Training
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    Thanks for the offer, but my traveling days (from Florida) are over. I've run into failed prints due to crappy filament too, although I got a bunch at five bucks a kilo and some at zero dollars per.

    Your use of the printer is wonderful! A great idea for a functional and decorative build.

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