Why does the filament not stick to the bed?
Please check the following
- Distance between bed and nozzle is the same at every x,y position
- Bed is degreased. Even a small fingerprint could potentially ruin your print.
- The temperature of the bed is sufficient. 60 degrees is sufficient for small prints, but 65 degC is more reliable for large
- The print speed of the first layer must be slower than the rest of the print. This will make the filament stick better to the bed.
- Is the nozzle temperature enough? Try increasing it 5 degrees.
This happens mostly to smaller parts with thin walled features
- The temperature of the filament is way too high
- Slow down the print speed.
Even though the fan-airduct, cools the filament relatively fast. It could still not be fast enough for small parts to print with reasonable quality.
- decrease temperature
- slow down speed.
- print multiple parts in the same print. Use the multiply plugin in SFACT/Skeinforge
The most common reason for this is the extruder tensioning mechanism is not tensioned enough. Increase the tension by tightening the nuts on the bolt which hold the curly washers on the extruder arm. When tightening make sure the bolt is not turning along. Fixate that with a nippers.
Recommended hot-end nozzle temperature
For small detailed parts I print as cold as possible, but for my production prints I print close to as high as possible (200-205 degC), because that increases strength of the parts.
Higher temp is possible but you will suffer from bad quality prints because you will see big blobs at the start of perimeters, if I see that I lower the temp 5 degC.
Recommended way to change filament
It is possible to change filament in the following ways.
- Retract/Replace. This is the safest way to change filament.
- Retract the old filament at a high speed, 1000mm/min for 100mm. The high speed prevents development of a long string which can potentially jam the hot-end.
- Now extrude the new filament 50mm at a time at low speed 200mm/min, until filament comes out of the nozzle.
- Feed through. In this method filament is cut off near the extruder.
- Cut the filament off as straight as possible. The new filament will push it down, and if cut of scew, the new filament will slip of the to be pushed filament resulting in a extruder jam.
- Extrude the filament long enough at a low speed 200mm/min. When the filament is just cut off above the extruder entrance, 50mm should be sufficient to push the new filament into the hot-end.
- Again extrude it 50mm to flush out the old filament.
Solving extruder jams
- Wrong feed-through of filament
- Bad filament quality. Sometimes bad filament, can have high tolerance on filament diameter. The nominal value recommended value for the filament for the printer is 1.75mm with a tolerance of 0.15mm. On a filament roll I once bought I experienced a diameter variation of 1.5mm to 2.1mm.
- Too thin filament results in that the molten filament creeps up to the hot-end barrel.
- Too thick filament will obviously not go through the nozzle barrel.
- The hot-end parts are not assembled good enough.
- When the temp is too hot. So filament can creep up the barrel.
- The three hot-end parts were not fabricated perfectly, the holes didn’t align well and caused the filament to get stuck behind the peek part.
- Contaminents inside the hot-end. They somehow create a thermal barrier and prevent heat to go into the filament fast enough. Only way to prevent it is to redrill the hole a little.
- The fan on top stopped working, This got the top part very hot and filament started melting too fast.
If for some reason a extruder jam happens, I follow the next procedure.
- Cut of the filament just under the filament guide above the extruder wheel.
- Unscrew the hot-end M8 bolt
- Slide out the hot-end.
- Try to pull out the filament, if the hot-end is cool, that probably doesn't work. The cut the filament as straight and close to the hot-end top part as possible.
Elongate the lifetime of the hot-end
The hot-end is robust, seldomely have I experienced a jam or failed operation. But when printing 24/7 I've experienced that the hot-end stopped working after 2-3 months. The reason for that is a contaminated hot-end.
Ways to prevent this from happening.
- Make sure the filament enters the hot-end is clean from dust. Do this by letting it run through a piece of sponge before it enters the hot-end. You will be surprise how much dust there will be there after a 5 hour print. That would of all entered the hot-end and form a layer of contaminent, which isolates that heat. from going into the filament
- Do not use too high temperatures. This will make the filament decompose and contaminate the inside of the nozzle.
- Do not leave the hot-end heated for hours. The filament might decompose after leaving it at high temperatures and this will leave a layer of contaminents behind in the hot-end nozzle
Minimize friction and chance of vibrations.
Vibrations in the sliding bearings are caused by the stick slip effect of the contacting elements, this effect can be amplified when the friction coefficient is higher than it supposed to be. It seems that the production process of the bearings can somethimes vary, as some sliding elements seem to have slightly more friction than others. To overcome this problem, PTFE/Teflon spray is advised by the manufacturer. It can be obtained from any bike or car store.
First clean the bearings with alcohol or some detergent. Then spray a little PTFE/Teflon on a q-tip and rub it against the rail where the rail makes contact with the sliding elements.
Note1: Do not use any oil based products, those will only work for a short time because they will catch dirt and eventually increase the friction coefficient.
Note2: Do not spray it directly on the rail it will make a big mess.
After applying this the bearing rail should move a lot smoother than before and the friction is a lot lower.
Minimize play in sliding bearing
Before the kit is sent out to the customer, the sliding bearings are tuned to have virtually no play. It might happen that it is not done correctly. It is however a relatively easy procedure to tune it yourself. See the tutorial in this post how to properly do it.
http://www.felixprinters.com/forum/view ... ?f=14&t=10
Several users have reported z-wobble, this results in banding on vertical walls of printed parts. From my experience it is because of the following causes:
1. Wrong assembly of z-spindle
2. Z-spindle is not straight
3. Too much play in z-axis bearing
To eliminate the wobble I try to find to solve the causes from 1 to 3.
-  Wrong assembly of z-spindle:
- Make sure the curved washer is mounted at the bearing on top and also underneath the bolt which is there to fix the coupling. This will compensate for any imperfections of the bolt. I experience that the top or bottom surface of the bolt is not always perfectly flat. When you tighten the bolt against the coupling you are forcing the coupling a little out of line. Don't over tighten it, because that will loose the compensation effect.
- Make sure the top part which holds the z-axis spindle is mounted firmly. Any deformation or imperfection on the top part is transmitted to the bed.
- Make sure the spindle isn't screwed in to the coupling fully. Screw it all the way to the end of the coupling en then turn it back one turn.
- Loosen the setscrew which locks the coupling slightly, do it in such a way the coupling can slide over the shaft of the coupling but when rotating the motor schaft will still turn along with the coupling
- Now when you rotate the coupling by hand, you will notice that the motor will wiggle a little bit. The goal is to reduce the wiggling to a minimum.
- keep rotating the coupling and try to reposition the z-axis motor including bracket in such a way that the shaft will get more in-line with the z-axis spindle
- Keep doing this until you think it doesn't get any better. Now carefully fix the setscrew, without forcing it out of line.
- Print the following test piece. Part sliced at 0.1mm layer height to better see banding effects Hold it against the light and if you don't see any banding you got it tuned perfectly.
Remove the spindle from the printer and roll it over a flat surface. Ideally it should look straigt, but a slight deviation of 0.1mm should be acceptable. If deviation is too much you could try to bend it back, but it is almost impossible and you need to get a replacement.
 If the z-spindle is straight (enough) and you mounted the z-axis assembly correctly than there could be too much play in z-axis bearing. During production the bearing is tuned to have no play, but it could happen that it is done not properly. You should be able to feel it if you exert some back and forth force on the big fork. If you can feel some significant play, you can do the following steps:
- Lay the printer on the wide beam of the frame.
- Remove the z-spindle and put the z-axis assembly in the middle of the guide
- Unscrew the four bolts (button-head screws) which hold the z-axis rail to the beam.
- Rotate the whole z-axis assembly in such a way, that you can slide off the z-axis guide.
- Remove the plastic sliding parts from the z-axis parts from the z-axis.
- Put some extra kapton or other thin tape on the spots where there already is some tape.
- Move the rail on the slider and check if it can still slide smoothly. Otherwise remove some tape again.
- Iteratively check to get it right. As low possible play with acceptable friction.