Note: For the purposes of these discussions, I will be using either my favorite Solidoodle 4 or my FolgerTech 2020 Prusa i3 printers. Both are Cartesian style printers, but different in how each axis moves. I also use free software - Repetier Host to communicate & control the printer, and Slic3r as my go-to slicing software. Both of these programs are completely free to download and use. So, you have your 3D printer and you are all excited to print some of the amazing stuff you found on Thingiverse, or other stl sharing website… but hold up, partner! You need to do a little work first if you want truly nice prints. To start with, read the manual! Yeah, yeah, I know what you are thinking - “I don’t need no stinking manual!”, but you would be doing yourself a favor if you do read it. Some printers come with a printed manual, others you need to go online and download it - either way - read the darn thing! Learn how YOUR printer works, how to turn it on/off, how to load the filament, how to level the bed, etc. With the multitude of printer designs out there, they are all slightly different. Next, you should make sure everything is nice and snug - no sloppiness anywhere. Belts (if yours has them) are tensioned properly, all screws are tight, and so on. Loose fasteners will cause you no end of headaches. Belt tension… Sloppy belts will cause axis shift problems. Belts should be tensioned enough that they do not vibrate doing movements. On my printers I will set the carriages all the way to one end of travel and then pinch the belt about halfway between - on a Cartesian type printer they should be tight enough to just barely meet when pinched with a bit of resistance. On a Delta/Kossel, the longer run won’t give as much resistance when pinched, but they should still not vibrate while the printer is running If your printer does not have an easy way of tensioning the belts, you will probably want to look for possible upgrades that will make it easier to do so. Belts do stretch over time and will need to be adjusted occasionally. Many of the Prusa type printers tend to use springs to increase belt tension. This, in my humble opinion, is not the best way of handling the situation. A fully adjustable option is far more useful and easier. OK, we have belts tensioned properly - can we print yet? Nope, not just yet. Now we need to level the bed so we get a good 1st layer down. Just like with a building we need a good foundation for our prints. If the first layer is not put down well enough, we will have all sorts of issues with the remainder of the print. Bed Leveling…. Most Cartesian style printers have either 3 or 4 bed leveling screws. These screws help us fine tune the bed to nozzle level, or gap. Bed “leveling” can be a bit of a misnomer - we are not leveling with a bubble level to make sure it is perfectly flat and level to the ground - we are adjusting the gap between the nozzle and the bed so that it is the same across the entire build plate. There IS a difference. To start with, we need to adjust the Z axis endstop to get the nozzle close to the bed. Tighten the leveling screws to about ½ of their travel. This will vary depending on the length of the springs used. You want a fair amount of tension on those springs before you even start making adjustments. Home the printer using your host program. Then move the printhead using the manual controls so it is over the middle of the bed (make sure there is no filament sticking out of the nozzle from ooze - if there is, use a razor or exacto blade to trim it off - you want bare nozzle for this). Adjust the Z endstop so the nozzle is about 0.5mm off the bed with the printhead in this position (a piece of cardboard from a cereal box or soda carton would be very close). The exact procedure will vary depending on the printer, some have an adjustment screw, others you may need to move the endstop mount itself. If you have read your manual you will know what you need to do. You will want to preheat the bed to the desired operating temperature. We will be “leveling” with the bed warm - not cold - as the temperature will affect the gap between bed and nozzle. Typical temperatures are For PLA: 50 to 60C For ABS: about 100C You will want to repeat the process when switching between bed temps - it DOES matter! Once you have the Z endstop adjusted, move the printhead using the manual controls so it is nearly over one of the leveling screws. You don’t have to be directly over it, but close Using a piece of standard copy paper (0.1mm thick), slip it between the bed and nozzle, then adjust the screw until you can just feel a little bit of drag on the paper when you move it. There should be just a very slight resistance when moving the paper under the nozzle. You don’t want it to be digging into the paper, or tearing it. Repeat the process for each leveling screw your machine has. Be sure to check each location again after the main adjustment is completed to make sure everything is where you need it to be. Often, adjusting one location may change another slightly.
Once you have things where you think they need to be, verify in several places across the build plate to make sure the gap is consistent. If you find it is not - either too low or too high in some places, then you may have a warped bed and will need to modify to get a perfectly flat surface. Glass is a very good choice for this. Either plain window glass, or a piece of mirror, cut to the same size as your bed works beautifully. You will want something that is about 3mm thick (1/8th inch) - any less and you run the risk of it cracking in the heat/cool cycles. To hold the glass in place, go to your local drug store and pick up a can of Aqua Net Super Extra Hold hairspray (unscented - in a purple can). Spray one side of the glass - get it damp, but not runny. Set the glass on the bed and heat to 60C, turn off the heat and let it cool completely. Repeat 2 or 3 more times and the glass should be firmly fixed to the bed. Then go through the leveling process again, beginning with adjusting the Z endstop. So we now have a nice, level bed - ready to print, right? Not quite yet… Stay tuned for the next posting where we go over calibrating our feed and flow rates. Time to go melt some plastic! Leave a Reply. |
AuthorA "Jack of all trades, master of none", I have dabbled in a lot of different things, but none have held my interest like these darn 3d printers do. Archives
May 2016
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