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Official 3DP Thread

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  • #61
    Just trying to help.

    One more thing about design considerations that i mentioned before is that your X & Y resolution is .4 mm and your Z is whatever layer height is(usually .2 mm). Where possible, all dimensions in should be divisible by these numbers. It keeps the slicer from having to make a compromise that you might not like. Most of the time there wont be a problem if you break the rule.


    • #62
      Another relatively short subject is what can go wrong after you press "Print". These things can happen anywhere in the print but Murphy's law says it will be when the part is almost done.

      1. Filament will break while coming off the spool.

      PLA absorbs moisture and comes vacuum packed, but i have seen brand new rolls break on the first print. When you go to reload it, you will find a small section after the break that is very brittle. Break off the brittle part and reload. I have not seen this happen with ABS, but i don't print enough with ABS to say it won't happen.

      2. Loop of filament gets trapped.

      Sometimes when they wind the spool, one loop of filament gets trapped under another and the extruder motor can't pull it free so the nozzle starves. after freeing the loop, a lot of times you have to clean the drive gear because the printer doesn't know the filament is jammed and keeps turning, filing the gear with shavings from the stuck filament. If you don't clean it, you are asking for trouble on your next prints.

      3. The print starts lifting off of the bed.

      This doesn't usually happen until later in the print and happens more on corners and other narrow features. Sometimes this is not a complete failure. it could be in an area that you don't care about. The next subject will probably be how to get your part to stick. from an aesthetic point of view, i hate it when that happens and will probably scrap the part.

      4. Nozzle will clog

      This happens more frequently than you would think. There is no apparent reason for this to happen and i can guarantee you won't be around to see it. I have seen on some spools where it looks like a splice was done between two segments. if there is a bulge at the splice point, it may not make it to the extruder. again, here you need to clean the drive gear.

      5. Motor skip

      There have been times when went to check on the part and there had been a big shift in X or Y. Since there is no position feedback, the printer does not know that the motor stalled and did not move during one of the fast moves. It just starts printing in a new location. Since it happens rarely and i have never been there to see it, it's hard to come to a conclusion as to what happened. It might be that the parts started to lift off of the bed and the extruder hit it.

      6. Sometimes the slicer can do some strange things. I bought Simplify3D and on rare occasions, it will add a solid layer right in the middle of an empty space for no apparent reason. This will show up on the preview so you can check for it. Cura will do this as well. Simplify tech support said it was a inconsistency with the STL file. Other times, the extruder will stop extruding plastic and you can see the drive motor going back and forth making a clicking sound. This is in the gecode produced by the slicer. I can print on another printer with the same file and it will do the same thing. Microsoft has free STL upload service that will analyze the STL file fix any triangle issues and give it back to you repaired in the new 3MF file format.

      These are the main ones that come to mind.


      • #63
        Here is a quick example of setting up a part on the platter in the slicer software:

        1. Whole part in One-Shot:
        depending on the complexity and size, this is usually the way to go. But, when you start making larger and taller parts it becomes a bit more challenging.

        As the print goes taller, the center of gravity of the parts go higher.
        The higher the center of gravity of the parts, the greater the lever arm to the build plate.
        The smaller the contact area on the build plate, the easier for the part to come lose and fail the print

        2. Multiple Sections
        If you are modeling the part in a CAD software, you can easily break the part into sections to ease the printing.

        I usually locate these splits at locations that the seams will be hidden. I also model in notches and lips to the parts for more secure fitment and alignment.

        3. Things to consider
        -Orient the part to be low to the build plate and more surface area. An issue with this might be that the print layers are now oriented in a way that will make the part weaker. Printing parts creates a "grain" similar to wood. The part will be stronger in one direction vs the perpendicular.
        -Orientation of the part will impact the appearance, and might make the part look too "rough" in certain cases. I usually have any cylinder object oriented upward for the smoothest appearance.
        -Orientation of the part will also impact how much support material is needed. Minimizing overhang by smartly orienting parts can help reduce total material used as well as print time.
        -If the part has a small contact area to the build plate, consider adding a "brim". This is a single layer print that traces around the contour of the part outward by a user-defined distance and greatly increasing the contact area. This peels off easily from the part and requires minimal finishing.

        **Click the pictures for descriptions**


        • #64
          Thanks bandit and DD for the good information. I know that once I get my printer I will have plenty of questions.
          Flying or RTF - Freewing 64mm P.15, 70mm Hawk, 80mm A-4's "Green Knights" and Blue Angels #6, F-86, Mig-21, Twin 80mm A-10, Twin 90mm A-10, 90mm F-15C on 8S; FMS Fox 2320mm glider, FHX-800 Trainer (FPV), 90mm Super Scorpion; Eflight 1200mm Spitfire Mk XIV; Twisted Hobbies Clik R2; LX 64mm F-117 Nighthawk on 4S; Strix Nano Goblin.
          Coming soon - Freewing 90mm F-4 Phantom, Scratch built indoor Eurofighter


          • #65
            I might be a good time to talk about what slicer to use. If someone is already printing with one and getting decent results, they should probably stay with it since everything is all tuned. if you are starting from scratch t i think the best ones out there are Cura and Simplify3D. Cura is free and Simplify is 149.00. i mentioned earlier that Cura was geared more to just press print. They had a normal mode and an expert mode. Normal just allowed you change a few things and expert allowed you to customize a lot more. Its been a while since i used Cura so i installed the latest version. They still have the "Recommended Mode " and the "Custom Mode", but in the custom mode they have now made available all of the same types of customization that Simplify offers. As a matter of fact, going through the list of things you can change, i think the are more than Simplify. This can be good and bad. Having too many knobs to turn can cause you to get lost. I still like the software interface of Simplify better and their preview feature lets you do a simulated print on the screen at high speed and watch your part being built. When you are ready to start, i would try both. You can use Simplify for 30 days for free.


            • #66
              Now, for the most important step in getting a good print. Getting your first layer to stick. If you don't get this right, your chances of getting a good part, especially when it is tall is very low. The following assumes you have leveled your bed to a knats ass.

              1. Print gap.

              I mentioned before that the print gap should be about .005 in. Assuming that you have calibrated the nozzle to put out the right amount of plastic, the filament will come out and get smushed "that's a technical term" to about .4 mm. You will know if you got the gap right when the two perimeter layers go down. If there is a gap between them, then your print gap is too much. If they completely flow together, the the gap is too narrow. They should touch at the build plate, but you should still be able to see the individual strands (barely) from the top.

              2. Extruder Temp.

              I generally print PLA at 200C, but i put the first layer down at 220C. The higher temp lets it flow better and helps with the adhesion. Having different temps for different layers is easy in Simplify, but I've never tried in Cura so i don't know if that's available. This is not a major issue, it just helps.

              3. Bed Temp.

              I do the same this for the bed. For PLA i set the bed to 80C for the first three layers and drop it to 50C.

              4. Glue.

              No matter what your build platform is made of, you need glue. People used to use Aqua Net Extra Hold Hair Spray. Now it seems the glue of choice is Elmers Extra Hold Glue Stick. I'm sure there other materials you can get as well.

              5. Adhesion Mat.

              One of the best things that have come out in the last year or so is an adhesive backed adhesion mat from a company called BuildTak. you can get them on Amazon and they work great. Your part sticks so well that i have to use Elmer's glue to keep it from sticking so well you cant get your part off. They come in various sizes to fit your build plate.

              6. Slicer options.

              When you have nailed all of the above and you still have issues on some parts, there are some options in the slicer. There for adhesion options as follows

              A. None "self explanatory"

              B. Brim/Skirt

              This will add a programmable amount of material outside the perimeter starting on the first layer but connected loosely to your part. Most of the time i use a Skirt 1 layer thick and two perimeter layers 4 mm outside the part and not touching. The non touching skirt is not so much an adhesion promoter as a head primer as it gets the head extruding evenly.

              C. Raft.

              This one this the most aggressive. I lays down a multi layer raft under the entire part that extends out past the perimeter a programmable distance. The raft is separated a small vertical distance from the part, like support structures such that when the part is complete you can peel the raft off the bottom.


              • #67
                Ok, question for you experts. Got my printer this weekend and tried printing some items. Using Simplify 3D and printing a part that requires some support structures. What is happening is that parts of the object are coming loose from the supports during printing. What could likely be the cause and is there a parameter(s) that could be changed in Simply 3D to help the part stick better to the supports? Printer is an Anet A8.
                Flying or RTF - Freewing 64mm P.15, 70mm Hawk, 80mm A-4's "Green Knights" and Blue Angels #6, F-86, Mig-21, Twin 80mm A-10, Twin 90mm A-10, 90mm F-15C on 8S; FMS Fox 2320mm glider, FHX-800 Trainer (FPV), 90mm Super Scorpion; Eflight 1200mm Spitfire Mk XIV; Twisted Hobbies Clik R2; LX 64mm F-117 Nighthawk on 4S; Strix Nano Goblin.
                Coming soon - Freewing 90mm F-4 Phantom, Scratch built indoor Eurofighter


                • #68

                  In simplify, under the support tab, there is a section called "separation from part". Normally its set to 1 layer for top and bottom. If yours is set at 1 and you are still having adhesion problems, you might not be extruding enough plastic. Did you do a calibration of your extruder. Under the extruder tab, what is your extruder multiplier set to and nozzle diameter.

                  To do a calibration of your extruder, design or find on thingverse a cube. print it with 3 solid bottom layers, 3 solid top and two perimeter layers. when done, look at the top layer under a magnifying glass. each of the strands should touch and be melted together but you should still see slight grooves and make out each strand. after calibrating mine, i set the multiplier to 1.06


                  • #69
                    Also, print the cube with 30% infill.


                    • #70
                      I did print the calibration cube. I will double check the settings. But I know the separation from part top and bottom settings are set to 1 currently.
                      Flying or RTF - Freewing 64mm P.15, 70mm Hawk, 80mm A-4's "Green Knights" and Blue Angels #6, F-86, Mig-21, Twin 80mm A-10, Twin 90mm A-10, 90mm F-15C on 8S; FMS Fox 2320mm glider, FHX-800 Trainer (FPV), 90mm Super Scorpion; Eflight 1200mm Spitfire Mk XIV; Twisted Hobbies Clik R2; LX 64mm F-117 Nighthawk on 4S; Strix Nano Goblin.
                      Coming soon - Freewing 90mm F-4 Phantom, Scratch built indoor Eurofighter