FDM 3D Printer Maintenance Practices

Try as you might, your print just refuses to get off the ground. No filament extrudes from your hot end; the possible causes for this type of 3D printing problems are numerous.FDM 3D Printer Maintenance Practices

Nothing is printing even though the model has been set and configured correctly in the slicing software. However, try as you might when repeatedly sending the print to the printer still nothing happens bar the odd spit of filament emerging from the nozzle.

Alternatively a model is part way through the print and the filament extrusion stops but the nozzle continues to print into air.

It’s an obvious problem that’s unmissable in many printers such as the PRUSA i3, where the filament reel is in full view, but on other printers such as the XYZ DaVinci, Cel Robox and Ultimaker series the issue isn’t always immediately obvious.

These and many other printers either encase the filament within the design of the printer, or the filament is hidden round the back.

Of course, some printers feature smart spools that feed back data to the software and highlight if the filament reel is close to, or out of material. However we all like to tinker and use our own tweaked firmware or third party software, and these sometimes work around such failsafes. And then there are other printers that simply don’t feature any type of failsafe at all.

In all cases, especially with Bowden style extrusion systems, you’re going to have to extract some remaining filament and then feed in fresh material.

3D PRINTING TROUBLESHOOTING TIP: CHECK THE FILAMENT REEL

Look at the filament reel and see if there’s any filament left. If not load a new reel. Easy.

Check the filament reel

Inexplicably, despite loading the filament and the print head moving without a hitch, no filament is depositing on the print bed.

Quite simply, your nozzle may be too close to the print bed. If you’ve somehow tuned your print bed to mere microns from your nozzle opening, it’s unlikely the melted filament has room to escape. At best your print will be missing its first layers, and have a higher chance of not sticking once the filament does extrude. At worst, you’ll cause a backup of melted filament in your hot end, possibly leading to a blockage.

3D PRINTING TROUBLESHOOTING TIP: Z-AXIS OFFSET

Just raising the height of the nozzle slightly can often help. Most 3D printers in their system settings will allow you to set a Z-axis offset. To raise your nozzle away from the print bed you’ll need to increase the offset into the positive value. This also works for the reverse, with a negative offset helping to address your prints not sticking to your bed.

Be careful though, too high of an offset and it won’t stick to the platform.

Alternatively if your printer allows for it, you can achieve the same effect by lowering your print bed. This is the more troublesome fix though, as it requires you to re-calibrate and level the bed for even prints.

• Z-Axis Offset
• Lower Print Bed

You initiate a print job but whatever you try, nothing comes out of the nozzle. Extracting the filament and reinserting doesn’t work.

What’s Causing the 3D Printing Problem?

A small piece of filament has been left behind in the nozzle after changing spools, often because the filament has snapped off at the end. When the new filament is loaded, the piece of old filament that is left in the nozzle doesn’t allow the new filament to be pushed through.

A little printer maintenance can go a long way to reducing the chance of problems like a blocked nozzle affecting your extrusions. In fact you’ll often find that before a clog even appears, there is old carbonized  filament sitting inside your nozzle. It can and will sit there for weeks or even months without you realizing, but there will be small signs in the quality of your prints.

The effects are often overlooked; such as small nicks in the outer walls, small flecks of dark filament or small changes in print quality between models. These defects are often simply put down to the slight variants we come to expect from 3D printers, but really there could be something a little more sinister going on. A cleaning method known as the Atomic Pull or Cold Pull (which we detail below) can clear this up.

You’ll commonly see this if you frequently switch from a PLA to ABS, for example. A small amount of PLA is left in the nozzle, and it is heated beyond its normal melting point. That can mean it will carbonize and burn.

Likewise, switch between ABS and Nylon and again you’ll witness something similar. It’s not uncommon to see a wisp of smoke appear briefly as the new filament is fed through.

If you’re lucky then unblocking can be a quick and easy process. Start by removing the filament. Then using your printer’s control panel (if it has one) select the “heat up nozzle” setting and increase to the melting point of the stuck filament. Alternatively, hook your printer up to a computer running compatible control software (such as Lulzbot, and their offshoot of Cura) and heat the nozzle using that. For PLA set the temperature to 220 C. Once the nozzle reaches the correct temperature, use a small pin to clear the hole (being careful not to burn your fingers). If your nozzle is 0.4mm then you need a pin that is smaller; an airbrush cleaning kit works perfectly.

If you find that the nozzle is still blocked then you may be able to push the filament through with another bit of filament. Start by removing the filament as before and then remove the feeder tube from the print head. Heat up the hot end to 220 C for PLA and then using another piece of filament push this through from the top to try to force the stuck filament in the nozzle out. Usually if new filament hasn’t succeeded in unblocking then the extra pressure you can exert by hand might just do the job. However don’t push to hard as you’ll risk bending the horizontal printer rods.

Once the end clears use a needle to push through the nozzle and a brush to clean any filament excess.

In extreme cases when the nozzle remains blocked, you’ll need to do a little surgery and dismantle the hot end. If you’ve never done this before then it’s a good idea to make notes and take photographs so you know where everything fits when you reassemble. Start by removing the filament, then check your printer’s manual to see exactly how to dismantle the hot end.

You can use ABS or Nylon for this, but over time we’ve found that the most consistent results come from Nylon due to its higher melting point. The filament also holds its shape far better. ABS is more common however, so we’ll use it here.

Start by removing the filament that’s already in the print head in the usual way for your printer. Then remove the Bowden tube or release the direct drive, so that when the time comes you can manually feed the filament through.

Increase the nozzle temperature to 240 degrees. We’re using ABS, but if using Nylon check the melting point temperature on the packaging. Leave it at this temperature for 5 minutes without pushing the filament through.

Slowly apply pressure to the filament until it starts to come out of the nozzle. Pull it back slightly and push it back through again until it starts to flow from the nozzle.

Reduce the temperature to 180 degrees for ABS or 140 degrees for Nylon (you’ll need to experiment a little for your filament). Leave the printer at this temperature for 5 minutes.

Pull out the filament from the head. When you look at the end you should see some black carbonized material at the end. Repeat the process until clean. If the filament won’t pull from the nozzle, increase the hot end slightly.

• Heat the nozzle and clean with a needle
• Remove the feeder tube and try pushing the filament through with another piece of filament
• Dismantle the hot end and see if you can extract the filament blockage
• Try an Cold Pull

There’s really no missing this one. At its most severe the noise will instantly alert you that something is very wrong.

When the printhead misses the bed it will usually also have reached the limit of either the X or Y position. As the head tries to travel beyond it’s furthest point noise will be generated through slipping belts, grinding cogs, or the head simply trying to rip through the side of the printer.

It’s very unlikely that your printer will succeed in producing a print in this state. And while it’s easy to fix, it’s not a problem that can be overlooked or dealt with at a later time.

Misconfiguration, wrong printer selection or worn out or broken end stops are all common issues.

If the problem starts with a new printer then the likelihood is that something is amiss with the printer’s configuration. Run through the setup process again and ensure that you have the correct firmware version for your printer.

Accidentally selecting the wrong printer from a dropdown list in your slicer program can be a common cause for this 3D printing problem. For example, trying to print using Ultimaker Go using print files configured for the Ultimaker 2.

When you set up your printer ensure that you have specified the correct print volume, again either in the printer’s firmware or through software. If the printer thinks it has a bigger print platform than it has then it’s going to try to use it, even if it’s not there.

If your printer is usually fine and then the problem occurs suddenly, start by double checking your print preparation software. Something may have reset or been altered by an update! It’s not unusual for software to either revert to the default settings or to automatically select the latest printer version, even if that not the one you’re using.

And if all else looks fine then it could be that one of your end stops in the printer has stopped working.

If this happens it can all get very messy.

Before trying anything else make sure that you have the correct printer selected in your printing software. All printers are different so even if the print bed of two printers are the same it’s highly unlikely the other dimensions and settings will match exactly.

If you’ve just purchased the printer and this issue is happening make sure you have latest version of the firmware installed. Once updated run through the setup process and double check all settings, especially around the size of the print area are correct.

This will take a little more effort to diagnose. Watch the print head move. If it tries to push past the furthest point one of its axes, check that an end stop hasn’t disconnected. If all looks fine (and none of the above steps fixed the issue for you) then replacing the end stops with new ones should be your next step.

• Check slicer for correct printer
• Update firmware
• Check end stops

The filament spool still looks full, and when you check there appears to be filament in the feed tube, but nothing’s coming out of the nozzle. This is more of an issue with Bowden feed printers than direct feed as the filament is hidden so breakages aren’t always immediately obvious.

Caused by a number of issues but primarily old or cheap filament. Although the majority of filaments such as PLA and ABS do last a long time, if they’re kept in the wrong conditions such as in direct sun light then they can become brittle. Then once fed into the printer no amount of adjustment is going to help.

Another issue is filament diameter, and this can vary through manufacturer and batch. Sometimes if the idler tensioner is too tight then some filament that still has a good amount of life left in it can snap under the pressure.

The first thing to do is to remove the filament from the printer in the usual way. In the case of the Ultimaker select Maintenance and Change Material. As the filament will usually have snapped inside the tube you’ll need to remove the tube from both the extruder and hotend. Then heat the nozzle and pull out the filament.

If after reloading the filament it happens again, use another filament to check to see if it’s not just the old brittle filament that should be disposed off.

If the new filament snaps check that the idler tensioner isn’t too tight by loosening all the way. As the print starts tighten until there is no slippage of the filament.

Check the nozzle isn’t blocked and give it a good clean.

If the problem continues check that the hot end is getting hot and to the correct temperature. Also check that the flow rate of the filament is at 100% and not higher.

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• Check the filament isn’t past its best
• Check the filament diameter
• Adjust the idler tension
• Check that the hot end is clear and reaches the correct temperature
• Set the flow rate to 100%

Stripped or slipping filament can happen at any point of the print process, and with any filament. The result is that no filament is extruded from the hot end bringing your print to an abrupt end.

Blockage, loose idler tensioner, wrong hot end temperature, these are just a few of the common causes, but all are usually easy to correct. The result of the problem is that the knurled nut or toothed gear in the extruder is unable to pull or push the filament through the printer. As the motor spins the small teeth on the gear that would usually grip and feed the filament through the system, instead wear it away until there is no longer any grip, and the gear and filament slip.

If the filament has just started to slip, you can usually tell by the noise and the appearance of plastic shavings, then apply some gentle pressure to the filament to help it through the system. This will often help to get the machine printing smoothly again.

Start by loosing the idler, feed in the filament and tighten until it stops slipping. Filaments vary in diameter so although the idler will absorb some difference in diameter some filaments will require fine adjustment.

In most cases you’ll need to remove and replace the filament and then feed it back through the system. Once the filament has been removed cut the filament below the area that shows signs of slipping and then feed back into the system. If the filament has snapped it may be passed its usable best. Try it again and if it snaps again and you find the filament appears brittle discard and use another filament.

If you have just inserted a new filament as the issue started, double check that you have the right temperature.

• Help feed the system
• Adjust the idler tension
• Remove the filament
• Check the hot end temperature

Things were looking great, but for some inexplicable reason, the print has failed. It didn’t stick to the bed, or the filament just stopped extruding — regardless, this type of 3D printing problems could be one of many things.

Sometimes, for any of a number of reasons, the hot end will stop extruding molten filament.

Typically this 3D printing problem is attributable to two parts of the printing process — either something is wrong with your filament supply, or there’s a problem with the hot end/nozzle itself. It could be as simple a case as your filament has run out. Some printers obscure the spool, so you never know! Or it could be too tight of an idler on your extruder resulting in stripped filament that isn’t being fed into the hot end.

Alternatively, you could have a blockage in your hot end, preventing any further filament from being extruded.

A little obvious, but even the best of us have momentary lapses in concentration. Many slicers now give a material estimation for your prints, and judging that against the weight of your spool of filament and how much is left on it can give you a feeling for if there’s enough filament to complete your print.

Stripped filament can be responsible for a print stopping mid-way through, and can be caused by a myriad of issues. Check out our dedicated 3D printing troubleshooting tip on how to deal with stripped filment.

A nozzle caked in old burnt filament can cause a few different print issues, one of which is blocking any new extrusions from being laid down. Check out our dedicated 3D printing troubleshooting tip on how to deal with a clogged nozzle.

An issue that mainly affects Bowden style extruder setups, snapped filament can cause a disjoin between the extruder and hot end. Thankfully, it’s easy to diagnose and fix, but it may be a sign that your filament is past its best. Check out our dedicated 3D printing troubleshooting tip on how to deal with snapped filament.

• Check You Have Enough Filament
• Check for Stripped Filament
• Check for Clogged Nozzle
• Check for Snapped Filament

Losing a print due to it not sticking to the print platform is a common issue and one that’s usually relatively easy to resolve.

Unfortunately, a 3D print can break free at almost any time, from the first layer through to the last, which is especially infuriating.

Of course it’s not always the printer’s fault and if you’ve tried to print a model that only has a small amount of contact with the platform then undoubtedly that’s going to be the issue. Imagine you’re trying to print a plane and the only contact the model has with the print platform is the wheels. It’s therefore unlikely to print without some type of build plate adhesion and brim, and that’s before you even start to look at supports.

Luckily because this problem is so common there are many easy ways to solve it.

The most common cause is simply that the print just doesn’t bond to the surface of the print platform. The filament needs a textured base in order to adhere, so to solve the issue you’ll need to create a better bonding surface.

An unlevel print platform can be another major issue. If the platform is uneven then for some parts of the print the nozzle won’t be close enough to the platform to correctly extrude and bond the first layer.

Calibration can also be a major issue, over time the distance between the nozzle and platform can increase to the point where the initial layer is dragged rather than pushed into the print platform.

In all cases you’re likely to see a spaghetti of filament appear above your half formed model, just filament spaghetti or parts of your model dotted around the print platform.

To increase the chances that filament will bond to the platform you need to add another material to add texture. The most common solution is to apply a thin layer of stick glue to the print platform, which can then be easily washed away with hot water. Another alternative for PLA is to add decorators tape. For filaments that require a heated platform of 40º and above, there are a variety of special tapes now available which are a little more heat resistant.

Every printer has a different process for print platform leveling, some like the latest Lulzbots utilize an extremely reliable auto leveling system, others such as the Ultimaker have a handy step-by-step approach that guides you through the adjustment process. Refer to your printer’s manual for how to level your print bed.

If the nozzle is too high then the filament won’t stick to the platform, too low and the nozzle will actually start to scrape the print off. Find the Z-axis offset option in your printer’s settings and make small adjustments — into the positive to raise the nozzle away from the bed, and negative to lower it closer.

If you’re printing on a material such as glass, every so often it’s a good idea to give it a good clean, especially if you frequently apply glue. The grease from your fingerprints and the excessive build up of glue deposits can all contribute to the non-stickiness of the print platform.

Some models will print fine without a brim, but smaller items and those with only a small footprint in contact with the platform will require some type of Build Plate Adhesion. These can be added in your slicer software- — look for “Brim” and “Raft”.

Brim will add a single layer of a specified number of perimeter lines radiating out from where your print makes contact with the print bed; it’s the least wasteful of the two, and in our experience is the better option, provided you don’t mind taking a knife to your print to trim the brim away.

Raft adds just that to your print. Depending on the parameters you specify, you will get a shadow of your print’s footprint, printed in thicker, better adhering layer. Your print is then printed as usual on top of this. Rafts tend to create a rough, unpleasant surface where it touches your print, and uses up more material than a brim. The benefit of a raft though, lies in being able to simply snap the part off.

As well as adding build plate adhesion, if your model has complex overhangs or extremities be sure to add supports to hold the print together during the process.

• Add Texture
• Level the Print Bed
• Adjust the Nozzle Height
• Clean the Print Platform
• Apply Build Plate Adhesion
• Add Supports

Printing complex models will require a support or two, and whilst supports can be pain to remove, they’re unfortunately an essential part of modelling.

The job of a support is simple, it supports, but on occasion they fail leaving your model unsupported.

You’ll notice that as your print is extruded parts of the support structure will look uneven, cracks may appear or they’ll just start to look stingy.

Not only are the supports failing but the additional filament is ruining your model rather than ensuring it prints correctly.

Support structures are complex things and most slicer applications will provide you with several options. It’s all too easy to stick with the default settings, but this doesn’t guarantee success with your 3D printed overhangs. An important consideration is the type of support that will keep your model steady and supported throughout the print.

Lines and zig zags are generally easy to remove after the print has finished, but offer less rigidity during the print process. Triangles and grids offer more support but can be a pain to remove.

Take a simple bridge structure with thin uprights and then think about the supports. They will have a great deal of work to do keeping the model rigid, if you’ve opted for lines or zig zags then the likelihood is the model will move during the print process, breaking the delicate supports as it goes.

A rigid structure like a grid would be a better option.

Some slicing software enables you to print supports without platform adhesion. If this is the case then the small footprint of the support will struggle to bond directly with the print platform.

Often with tall models the length of the supports can be excessive and the thin structure is simply pushed to the limit. In these cases it’s important that you look at creating a physical support such as block. Under large overhangs, these can add robust support.

Supports can be a real hassle to remove so there is a tendency to reduce the density to as low as it will go. This can of course cause issues, if supports are load bearing you will need to increase the Support Density.

Old or cheap filament can be another issue, if the filament is past it’s best then when it’s extruded you may find that the filament may not sufficiently bond layer on layer, or the extrusion is untidy and cracked, leading to broken supports.

Finally watch your printer print. If the printer is moving or vibrating more than it normally does then check the nuts and bolts and just ensure that everything is tight. Once you’ve run through all the usual checks make sure to rerun the calibration process.

Look at the type of model you’re about to print — if there are large overhangs that connect sections of the model and these have good contact with the platform, try using lines or zig zag supports. If the model has less bed contact or needs much stronger supports, use grid or triangle. supports.

Make sure you have added some type of platform adhesion, such as a brim, so that the mounts have plenty of foundation to bond to.

Try this as a last resort. Increasing the support density will offer your model a denser structure to rest on and will be less affected by any model movement, but will be much tougher to remove.

Supports that are overly tall can be susceptible to weakness. By adding a tall block as part of your print that ends just below where the supports are required, this can give the supports a solid base without the need to print tall and weak.

Filament can become brittle as it reaches the end of its usable life span, and this usually shows in the quality of the supports. Swap the filament for a fresh reel and see if the problem improves

Printer shakes and wobble can be a real issue. Give your machine the once over and make sure that everything is tight and re-calibrate if needed.

• Use Correct Support Type
• Add Platform Adhesion
• Increase Support Density
• Create In-Model supports
• Use New Filament
• Check everything is tight

Jennings A (2019) 2019 Troubleshooting Guide to Common 3D Printing Problems. In: All3DP. https://all3dp.com/1/common-3d-printing-.... Accessed 22 Aug 2019