Troubleshooting
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Troubleshooting |
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Note: please add any problems you may be experiencing, so Ultimaker and fellow Ultimaker users can help out!
Contents
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Problems by observation
Printing in material A worked fine, now material B doesn't print well!
See the section on Polymers and "Troubleshooting: Solving flow related problems".
Brown sludge forms on the extruder head
If your printer came with an ABS Fix Kit (a piece of ABS filament), running this through the extruder will seal up any small leaks around the printer head. If for some reason you did not get this kit, any piece of 3mm ABS filament will do.
Plastic comes out of extruder head in a flowing state
If you turn the big extruder wheel manually, the plastic exiting the extruder head should form a thin line of plastic that hangs from the extruder head. If however the plastic does not form this thin line, but rather forms a droplet at the extruder head, you are heating the plastic too much.
Be careful. Too high temperatures can cause the plastic to burn and form a plug. In general, start at 215C for PLA plastic and 225 for ABS plastic.
The extruder stops extruding
There are several possible causes for this:
- You are trying to extrude when the extruder is still cold. There is a pre-build function in Marlin that prevents cold extrusion. It could also be because of a failure. Please check the warning log.
- You're trying to extrude too much material in a small volume. Try to print a really thin walled object. If these objects work well, but a large infill doesn't, it shows you that the extrusion rate is too high.
- The temperature at which you're extruding material needs to be high enough. If you've just switched materials, e.g. from ABS to PLA, you need to extrude at the ABS temperatures to flush out the ABS. This may take quite some printing to get the last remains of ABS out of the extruder. Using temperatures that are normally suitable for PLA might jam the extruder if remains of ABS try to work their way through the nozzle. PLA can be printed at temperatures between 190 and 260 degrees C. At 250 degrees it will flow fairly easily. Above this temperature it might become too liquid and the nozzle might ooze too much.
- You're trying to extrude too fast. Try to lower the feed rate. PLA in general flows more easily than ABS. ABS will start to degrade when you heat it up too much, and might block the nozzle's orifice when it sits in the extruder for a long period of time. Heating it to a higher temperature in general allows you to print at the higher speeds.
- Possibly, liquid PLA is pushed upward in the extruder to a section where no heating is applied. When this solidifies, it causes the extruder to jam. Especially if there is a small gap between the PFA/PTFE tube and the brass part of the extruder, this will cause the plastic to be very hard to push through. Normally, the (low friction) bowden tube has such a low friction that you can still push out the solidified PLA with some force.
- When the extruder has jammed, the material-feed mechanism may continue to push material into the extruder. When that is blocked it will apply a large force on the bowden tube, causing it to come loose from the metal part of the extruder. After a while it will pull the connectors from the thermocouple board. Soon afterwards the extruder will overheat as the temperature feedback has been severed. Immediately disconnect the power when the bowden tube comes loose.
Apart from these hints, it's always good to heat up the extruder, and to try to push the filament in by hand. It should be possible to push it in with reasonable force. First see if the temperature you're setting it to is appropriate for the material that you're using. PLA becomes fairly liquid at around 250 degrees. Below this temperature it is still pretty viscous and becomes more difficult to extrude.
See also:
- Solving flow related problems
- How to remove PLA when blocked and hack the PTFT cable
The first layer doesn't stick!
This is a common problem because all thermoplastics vary. Even if you're using PLA, one color of thermoplastic may stick perfectly while another color does not stick at all: this is because the colorants affect the melting point, also shift the recommended print temperatures.
If you have trouble getting the first layer to stick, you can do several things:
- Make sure the print head is almost touching the platform for the first layer. This helps because the plastic is really pushed into the texture of the blue tape. This will also help with the pressure build up before you print. Don't hesitate to do a small adjustment by turning the Z-leadscrew by hand just after your print has started. If this works better, you can make this permanent by changing the height of the Z-limit switch at the back of the machine (the top one).
- Just when the print starts, you can turn the extruder-drive's gear a little to get increase the material flow for the first layer. This helps for the same reasons mentioned above. Don't worry, you will not damage the motor by pushing it through its steps, it will just skip a few steps which is totally harmless!
- If you're printing directly onto the acrylic platform, sanding and/or scratching the acrylic will help to create a stronger bond.
- Try raising your extrusion temp a few degrees, even bumping the print temp by 5 degrees or so can really make a difference.
- Ensure that the bed is level. If it isn't level, this will create a good bond in one place, but the head will be too high in the other.
- For the first layer, during printing you can increase the 'flow rate' through the Real Time Tuning feature (by clicking the icon with the sliders). Slide it back to 100% when the first layer has finished.
- Sometimes the tape is greasy, this makes it hard for the PLA to stick on it. Cleaning it with some rubbing alcohol removes the grease and makes the PLA stick easier.
My 3D prints do not look good!
- Analyzing your first print (a great post by Florian on his blog)
- Check if the fan (near the print head) turns on after the first layer has printed. If you can turn it on with the control panel, it's wired up correctly. If not, check the wiring. Also check your Skeinforge profile's "Cool section". If an M107 code is in the G-Code, this means that the fan SHOULD turn on.
Problem: layers aren't stacked very well on top of each other
- Solution 1: make sure your long belts are tight enough (see this instruction video).
- Solution 2: check if the short belts are tight, if not, slide down the motor in its slots and re-tighten them. You probably need washers to tighten it all the way.
- Solution 3: if too much plastic is extruded, it will try to find its way out of the extruder where it shouldn't be. Lower the extrusion rate.
- Solution 4: if too little plastic is extruded it will take shortcuts, the following layers may not stick to the layer below, because parts of that layer aren't where they're supposed to be. Increase the extrusion rate.
- Solution 5: check if your object has enough time to cool before the next layer. If you print an object with a thin cross section very fast, it will not have time to cool. Slow down your print speed. You can force a layer to always take a certain amount of time, this is done in the "Cool" section of your Skeinforge profile. Also, ensure that the "Turn fan on" checkbox is ticked there and that the fan indeed turns on!
Problem: the object looks sparse, there are holes in them! (see picture on the right)
The causes and solutions are discussed in: Troubleshooting: Solving flow related problems.
Mechanical problems
X/Y axis
The extruder head stops moving during a print, or doesnt move at all (even in manual mode). Also a stuttering or grinding noise can be heard from the stepper motors.
This is caused by a stepper motor driver that is too cold or overheating. Try to tune the stepper motor driver to a more ideal setting. You can find a manual about the stepper motor driver in the Electronics build guide.
There is a lot of friction when I move the extruder head around by hand. What can I do?
When moving the head by hand, do it by pushing the wooden blocks in ends of the rods. Pushing directly on the print head assembly twists the bushings and causes them to jam. This might give the illusion that there is more friction than there actually is.
The important thing to keep in mind is that all angles need to be orthogonal (90 degrees), not 95 or 85 degrees... The best way to achieve that the crossing rods are orthogonal is to loosen pairs of pulleys. You don't need to open the jaws of the blocks where the timing belt passes through, this is too tedious and the same result is achieved by loosening the pulleys.
Usually it is easier to ensure they are orthogonal by putting an axis (X or Y) near its end, and to compare the distance between the blocks. For the X axis (left to right if you stand in front of the machine), it is important to keep both blocks at about the same distance.
Very rarely, it seems that it runs slightly more smoothly when it's not orthogonal, but both crossing rods have an odd angle but exactly to same extent. This would lead to slightly trapezoid prints which are no good for prints that need to be mechanically accurate. Perhaps it's good to loosen the bolts of the wooden extruder housing and tighten them with the extruder housing after it has been installed in the machine.
Don't grease the rods! All bearing in the Ultimaker are self-lubricating! Use the teflon-based grease ONLY for the Z spindle. That's where it belongs.
When a layer is printed, the perimiters and infill of the object do not or barely touch. How can I fix this?
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Ensure that the motors have cooled down before you press on the motor, otherwise you risk getting burns. |
This could have a mechanical and a software cause. The software should ensure that the perimeter and infill overlap slightly. This part is about the mechanics: One thing that could cause this (a bit) would be too loosened motor timing belts (the two short belts). If the X axis has this problem, you'll see gaps at the left and right side between the perimiter and infill. If the Y axis has this problem, it will happen at the front and back of your print (when looking at the front of the machine). To fix this problem, loosen the four bolts, push the motor down firmly and hold it that way while fastening the motor bolts. Make sure you wait a while for the motors to cool down.
This problem can also be caused by loose belts, especially the short ones. For the long belts, see this instruction video.
Z-axis
The object doesn't have the correct height
If the object is longer or shorter, the Z-axis may have too much friction.
- Observation A: The height is exactly twice as big/small
- Check the jumper configuration correspond with the intended settings in the guide (for those with the 1.5 PCB version. If you don't have jumpers on your electronics, this isn't the problem).
- Observation B: sometimes the platform lowers less than it should
- Solution 1: lubricate the leadscrew (along its entire operating length), if that doesn't help, increase power to the z-motor.
- Solution 2: If that doesn't help, see if the Z-axis is trying to move too quickly. You can set a limit in your Skeinforge profile (under Limits).
- Solution 3: Check if the top end-stop is being triggered at random intervals by electromagnetic interference (EMI). How? If the problem is gone with the top Z-home limit-switch detatched, it was EMI. Twist the wires or (still not enought?!) shield the wires if this is causing it.
The object seems to have ripples in the Z-axis
The machine is depositing plastic, so it will always have ripples. However, there are several cases that can cause irregular behavior:
- If the printhead is not levelled out correctly, the print will deposit more on one side then the other, causing it to ripple or even warp prematurely.
- If the printhead is level but the print looks shakey, it can be caused by several problems:
- The Z-axis rod may have bent during shipping.
- The Z-axis rod is not correctly seated in the aluminium holder.
- The print is warping while printing, or has come loose on several parts.
External links
- "Analyzing Your First Print" blog post on Techwall.net
- The official Ultimaker forums