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FDM 3D Printer FAQs 

1.       No extruding when print starts

R1. Extruder not well prepared before printing

       Most extruders will leak when they are travel at high temperature. The filament is about to leak and this will lead to an empty part inside the nozzle. This empty part may occur during you first pre heating the extruder or extruder cooling down. If extruder loss some filament, it needs a few seconds for filament extruding. So we must take care of the delay before we start printing. You can add skirt in Cura (Simplify3d has same function too). The skirt will print a circle first. This enables the extruder fulfilled with filament. If you need extra filament, you could add skirt numbers. Someone likes to pre-extrude with touch screen.

R2.  Nozzle too close to print bed

         Nozzle will be stocked by printed bed if too close. The first few layers not build, but since then it starts extrude, that would be this reason. Slightly raise nozzle can solve the problem. G-code label in simplify3d settings can adjust the G-code.

R3. Feeding gear scratches the filament badly

       Most FDM 3D printer feeds the filament by little gears. Feeding gear will grab the filament and control its movement accurately. But if you see lots of plastic shavings or filament is stripped, that might be this reason. Once filament is scratched badly, gear can’t grab the filament and then no extruding. Please check filament damage for reference.

R4. Nozzle jammed

       If up-mentioned advices didn’t solve the problem, then check the nozzle. It might be some shaves blocked in nozzle, or filament melting in nozzle when it is no needed.

2.       Print doesn’t stick to build platform

R1. Bad platform leveling

       Most 3d printers have a heated bed which is adjustable by its screws or rotator. If one side is too close to bed, the other size is too far from bed, the build platform is not level. Simplify3D has a useful leveling guide by Tools-Bed leveling Wizard and do as it guides.

R2. Nozzle too far from print bed

       Nozzle should be set a fine position before start printing. Slightly press the print bed would be good. Some 3d printers have “Z axis zero fine tune” function. For example, set -0.05mm, nozzle will get 0.05mm closer to bed.  Simplify3D can help too. Click “Edit Process Settings”, then G-code label, you could change Z axis G-code to adjust the nozzle position.

R3. Print too fast for first layer

       First layer should stick to build platform before continue printing. Filament cannot stick to platform if print speed is too fast. Lower it and give more time for sticking. Cura: advanced setting—first layer printing speed, reduce it. In Simplify3D, you can adjust by Edit Process Settings—Layer—First Layer Speed. For example, set 50% first layer print speed and the real printing speed will be 50% of normal layers.

R4. Temperature

      Heated bed is a great thing for printing. Set 60-70 degrees C for PLA and 100-120 degrees C for ABS filament. In Cura, set it by basic—heated bed temperature. In Simlify3D,  set it by Edit Process Settings—Temperature.

R5. Cooling fan

       Shut down cooling fan when printing first layers and make sure they stick to print bed tightly. You can set by Advanced settings—professional settings and adjust Fan Full on Height. For example, you could set fan start working after Z axis lift 0.05mm height. If print with ABS, you could shut down the cooling fan whole time by Advanced settings—Cooling fan. In Simplify3D, Edit Process Settings—Cooling, Layer1 at 01% cooling speed, Layer 5 at 100% cooling speed. Set Layer 1 at 0% cooling speed if you don’t need cooling whole printing.

R6. Print bed surface

       Blue painter’s tape is a good stick tape for PLA. ABS sticks to Kapton (Polyimide film) better. Solid glue, spray, hair glue are helpful too. We suggest PVP solid glue, works for PLA and ABS. Glass bed is a good choice too!

R7. Brims and Rafts

       Very small model has no enough area to stick on bed. Cura has a function “brim” which can print a circle around the model to add sticking area. You can add it by Basic—Adhesive bed. Adding a Raft also can large the area.  In Simplify3D, we can add Use Skirt/Brim in Additions.

3.       No enough extrusion

R1. Filament diameter

       Check the filament diameter. By Basic—Filament diameter, you can see the printing setting. Make sure the two are same. The common filament diameter is 1.75mm and 2.85mm. In Simplify3D, you can find Filament diameter in Edit Process Settings—Other.

R2. Higher extrusion rate

If filament diameter is right, then check the extrusion rate. Flow rate is a very useful parameter in Cura. It allows you to change the filament flow amount. You can see it in Basic-Flow setting. Every extruder has its own extruding rate. Usually, we set 90% rate for PLA and 100% for ABS. For example, the original rate is 100%, adjust it to 105%. The extruder will extrude 5% more filament. We suggest printing with 5% extra extruding rate and check the printing result. In Simplify3D, you can find Extrusion by Edit Process Settings—Extruder.

4.       Extrude too much filament

Please refer to No enough extrusion about Cura. Just on contrary, reduce the extruding rate.

5.       Gaps on top

R1. Top solid layer thickness is not enough

       Filament attends to fall in hollows when print top solid layers. In order to get a fine solid layer, you must print a few more layers. Rule of thumb: print at least 0.6mm thickness, if not enough, try 1.0mm. Extra solid layers won’t add the print size. Find Basic and adjust in Bottom/Top layers thickness. In Simplify3D, you can set by Edit Process Settings—Layer.

R2. Low fill density

       Fills are basis of upper layers. There will be many gaps in fills. For 10% fill density, 90% are hollows in print. And this leads to gaps on top layers. Rising fill density form 30% to 50% can offer a better basis for solid top layer.

R3. No enough extrusion

Check the up-mentioned No enough extrusion solution.

6.       Strings and leaks

R1. Retraction distance

      The most important setting in Retraction is retraction distance. This decides how many filaments are retracted in nozzle. Usually, more retracted filament, less leaks. Most direct extruders need 0.5-2.0mm retraction distance. While Bowden extruder needs 15mm due to longer distance between extruder and nozzle. Change Retraction distance by 1mm in Cura.

R2. Retraction speed

       20-100mm/s are good retraction speed for most filaments. Different filament may differ. Too slow, filament will leak from nozzle before nozzle move to destination. Too fast, filament will apart with melting ones. And sometimes, feeding gear may scratch the filament.

R3. Temperature too high

       Filament leaks if nozzle temperature is too high. Try 5-10 degrees C lower, changing by Cura, Basic—print temperature. In Simplify3D, change by Edit Process Settings—Temperature.

R4. Long distance travel movement (Only for Simplify3D)

       Simplify3D has a useful setting to reduce the suspend travel. It can automatically adjust the travel routine and make sure nozzle travel at least. Set by Advanced—Avoid crossing outline for travel movement.

7.       Temperature too high

R1. Not cooling enough

       Filament didn’t cooling down timely. And it distorted. If your printer has cooling fans, try higher power consumption. In Cura, Advanced settings—open professions setting window, type the fan speed in Max fan speed. If no, add one by yourself or use a handed fan. In Simplify3D, Edit Process Settings—cooling, click and edit fan speed as your needs.

R2. Print temperature too high

       Try 5-10 degrees C lower, changing by Cura, Basic—print temperature. In Simplify3D, change by Edit Process Settings—Temperature.

R3. Print too fast

       Too fast print speed can’t guarantee the cooling time, especially for small prints. In Cura, reduce print speed in Advanced—Minimal layer time. For example, Minimal layer time is 15s. Cura will automatically slow down the print speed when print time is less than 15s.  In Simplify3D, click Edit Process Settings—Cooling—Speed Overrides.

R4. Print a few objects at a time

       When nozzle moves to another position and print, this gives more time for prints to cool down.

8.       Print leans where it shouldn’t

R1. Nozzle moves too fast

       Basic settings—Print speed, Advanced settings—Travel speed, infill speed, top/bottom speed, outer shell print speed, inner shell speed. If one of these speeds is too fast, the print will have offset. In Simplify3D, Edit Process Settings—Other, adjust Default Printing Speed and X/Y Axis Movement Speed. Default Printing Speed controls all real speed of extruding.

X/Y Axis Movement Speed controls the speed when no extruding.

R2. Mechanical problem

       Bowden tie is loose or too tight. Bowden tie is moved by a gear installed in stepper motor and fixed by a screw. If anything wrong with them, the nozzle won’t work correctly. Please check all the screws and Bowden tie.

R3. Electric problem

       There are some electric problems will lead to stepper motor fails. For example, stepper motor can’t work well if it has no enough current. Motor will stop working when temperature of driver is too high. 

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