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Tips for those interested in FDM/FFF ("hot glue gun" syle) printing...

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  • Tips for those interested in FDM/FFF ("hot glue gun" syle) printing...

    AKA, Greg's "Learn from my fail" for 3D printing...

    These tips are based on my personal experiences and opinions derived from them and my own research in the world of consumer 3D printing. Take them only as that, and nothing more. You are welcome to agree, or disagree, as your experience may differ from mine. That's OK. Please feel free to share the things YOU have learned in your journey through the world of 3D Printing.

    - Build it yourself. Unless your 3D printing budget includes paid support/maintenance, you WILL be having to fix it. Building it yourself means you're already familiar with it. For the actual building, take your time and follow any provided guide TO THE LETTER. It does not matter how much or how little you pay, or how complete the kit is. Whether you buy a complete kit like I did, or build it with off the shelf parts and a bill of materials (BOM) for making your own printer, just BUILD IT YOURSELF! That said, there is still an element of "you get what you pay for" and often times the really cheap kits are more trouble than they are worth. However, spending more will not necessarily net you a perfectly reliable printer from the start. Buy the best kit you can find within your budget. Buying a kit versus an assembled printer often means you can get more printer for your money as well. Also, be aware that some printers sold as "kits" aren't kits so much as mostly-built printers that you only have to put a couple large parts together. See if you can review the assembly guide prior to purchase. If it's only a few pages long, then I don't put it in the "kit" category, and you'll know little about how to make adjustments and effect repairs if all you did was put the Z axis on the base. Not only will building it up from a pile of parts result in a better understanding of how to repair it, but also it will build investment into the project and encourage you to resolve issues, rather than throw up your hands in frustration and bin the whole thing.

    - Keep all filament in a ziplock bag with the silica gel, or an air tight container with dessicant... even PLA, from DAY ONE! If it's not printing, store it properly in a dry bag/box. Most filament will come with a packet of silica gel for a reason, but many don't come in a resealable bag/container. One gallon Ziplock bags are big enough for most 1kg filament reels. As soon as you open a new spool, get a bag and put the silica gel packet in there in order to store that reel when you're done with it. Some people even go so far as to set up a "dry box" container with the filament spooling out the side of it. Although it seems like plastic, it's not that simple, and keeping it perfectly dry is a must. You might think your house is dry, but this stuff can be sensitive, especially cheaper filament (and we all love saving money!). Even if you do this, sometimes filament can stop printing well due to absorbed humidity, and you'll need to dry it for it to print well. Inexpensive food dehydrators are a popular way to do this, but if your oven works at very low temperatures, that will do in a pinch. Don't just put it in there, though. Get some tips online on how best to dry out whatever filament you have that's not printing well. If you need it dry fast, then get a dehydrator. If you can wait, then make a dry box and leave the roll in there for at least a week, and up to a month if it's bad. Sometimes you don't know how "wet" a spool is until you try to print with it and have all kinds of problems doing so.

    - Your first layer, and the adhesion to the build plate is EVERYTHING. I mean it. Seriously. If you don't have a good tune of the first layer, then you don't have a good foundation. There can be problems if the first layer (e.g. how close the nozzle is to the build plate for the very first layer) is too high, or if it's too low. Those problems often translate into bigger problems as the print progresses. Finding the "sweet spot" can be a challenge, and some printers make that process easier or harder. What kind of surface your build plate has (glass, PEI, whatever) also makes a big difference in how well things will stick, but if the first layer isn't going down right, chances are you'll have a failed print soon. After you get the printer assembled and calibrated, you'll want to spend some time trying to find the sweet spot for the first layer. Since every printer has its own way of setting that, you'll need to refer to the support/community for your printer for help with that. Usually searching for "first layer calibration" will get you everything you need to know. But if that doesn't work (and you actually tried), then ask someone in the printer community that supports your printer how best to set the first layer, and I'm sure you'll get help. But, it needs to be help that applies to your printer, not just any printer, since they're all different.

    - When something goes wrong, look for help before trying to solve a problem or fix a failure on your own. Just because you built it, doesn't mean you know the BEST ways to fix it. There are usually guides that will save you more headaches. You could cause more problems if you fix something the way you think it should be fixed without knowing for sure. I could have avoided some of my major down times if I had reviewed the published resolution to my issue prior to "fixing" it. Crazy, right? Specifically, I had a "blob" due to poor first layer settings. As the printer was moving around, the print came off the bed and stuck to the nozzle. There's no way for the printer to know this is happening, so it just kept going, extruding more filament into the growing mass still stuck to the nozzle. In the end, my entire hot end was enveloped in hardened filament. I did all kinds of things to clean it off, and ended up breaking wires and melting parts. The damage may have been unavoidable, but I'll never know, because I didn't do it the right way the first time. I could have had a V8 once I found out the right way to do it.

    - Keep the extruder clean. Cheap filament (especially when it hasn't been properly stored) is often the cause of MANY printing problems. As soon as you even have a HINT of problems, make sure you clean it well. This doesn't always mean jamming something up in there or cranking up the heat. If there's residue from bad/old filament up in there, it won't always work itself clear. I've found that an "atomic pull" at 90 degrees with cleaner filament is working SUPER well for me and my printer, and I do this whenever I expect to leave the printer unused for any amount of time, or right before I use it if it has been unused, and/or when I'm changing to a different color and/or brand/type of filament. Since every printer is a little different, be sure to look up the tried and true maintenance methods for the one you build.

    - Don't put (heavy) things high on your printer frame. This will depend a lot on the type of printer you have, of course, but for Prusa i3 and its clones, where there is a rigid frame that the print head moves up and down on with a sliding heated build plate, you don't want heavy things up high. This is because the motion of the print head and bed moving quickly will cause the weight up high to move and depending on the pattern of motion it can start to resonate. Sometimes nothing is wrong with the print, but sometimes you get printing fails due to knocks or layer shift. In extreme cases, whatever is up there could come crashing down. Setting your filament spool up there is super convenient, but supporting the spool elsewhere is better. Similarly, don't hang tools and other things up there. It's nice when everything is compact and portable, which is why I did it at first, but inevitably, you want reliable printing more than you need a convenient location for things.

    - Make sure your table is sturdy. If the table is not perfectly level, that's probably not a big deal, but you DO want it to be perfectly flat so that your printer doesn't tweak just by resting on it, and you want it to be sturdy so that the table can help absorb the motion and not resonate or wobble as a result. Some people use small tables and make them sturdy with a concrete paver of some kind. Weight will reduce motion, so a combination of weight and sturdiness is a good thing. The very affordable IKEA "Lack" table is quite popular. My current table was cobbled together with scrap and hardware, but the table top is a HEAVY chunk of something that's been sitting in the garage forever. I don't even remember what it ever was. Now it's a printer table.

    - Don't change too many things at once. Preferably, only change ONE thing at a time. This applies to settings for printing, as well as changes to the printer, or filament, or whatever. If you change too many things, you won't know which change caused the desired result or the undesired fail. Sticking with PLA until you're comfortable is a good idea. Play with other filament types after the initial learning curve is well and truly over. I would almost say wait for a big fail or three, but if you're lucky enough to have problem free printing, you might as well jump into the tough stuff. Sooner or later, you'll be learning new things about your printer.

    I'm sure there's more, but please don't hesitate to ask a question, or share your own tips!

  • #2
    Some great tips there, first layer is king.

    I was wary of using a socket wrench when removing a nozzle, mine was too tight from the factory so removed the hot end and put an adjustable spanner on that so I wasn't stressing the machine.

    After changing nozzle a couple of times I noticed there was slight weeping of molten PLA coming from the nozzle thread, I made a steel washer that was a tight fit over the threads of the nozzle and gave the head of the nozzle something solid to tighten to...I also put a dab of copper grease on the thread to make it easier to remove next time (like a spark plug). Since I added the steel washer it hasn't leaked molten PLA.


    • #3
      And you were removing the nozzle why?

      Also, sounds like a great application for a crush washer. Usually made of aluminum or copper. It would deform, by design, to a gas-tight seal when the nozzle is tightened.

      Ed Bianchi


      • #4
        I wanted to try 0.2mm for a body but changed my mind and went with 0.3mm which is still on.


        • #5
          I also tried a 0.2mm on some small models, and found that most of the time 0.4mm is best. I have 0.8 nozzles in my main fdm printer for quick printing. (I print large stuff).


          • #6
            Originally posted by Profoxcg View Post
            I also tried a 0.2mm on some small models, and found that most of the time 0.4mm is best. I have 0.8 nozzles in my main fdm printer for quick printing. (I print large stuff).
            I'm coming to the conclusion the 0.4 is probably better for our needs, I've been thinking of going back to that for a few days now.


            • #7
              Originally posted by Kevan View Post

              I'm coming to the conclusion the 0.4 is probably better for our needs, I've been thinking of going back to that for a few days now.
              Yes, I think the 0.4 are the best all around nozzles. Depending on the settings you printer allows you can even extrude a thinner line width to some extend it absolutely needed.


              • #8
                A leak means you did something wrong. What you did wrong depends on the machine, but I've never seen one where tossing a washer into the hot end was an appropriate remedy. Usually the problem is that the nozzle isn't properly tightened when it has been heated up. For some hot ends, that also helps seal up the butt join between the nozzle and the heat break. For others, it makes sure there is no gap between the nozzle and the PTFE. For a PTFE hot end like on the Ender series, it's not uncommon to loosen the nozzle a turn, then force the PTFE down while holding the collet up, then tighten the nozzle to lock it all in.

                Changing nozzles is how most people run into their first hot end leak, so it's a good idea to look up the proper procedure for changing the nozzle, and don't skip any steps.


                • #9
                  Maybe I'm old skool and Engineers habits die hard, for me a bolt needs a washer, much like a nitro R/C glow plug needs a copper gasket.


                  • #10
                    Well, in the end, if it works, then it's good.