It is important to maintain your printer to avoid it malfunctioning or producing poor quality prints. We show you how.
3D printers are complex machines that rely on many individual components to be functioning optimally to work effectively. Despite this complexity, they are also fairly low maintenance. However, they are certainly not maintenance free. There are many procedures that the home hobbyist and maker can perform that will keep their printer running optimally, and thus producing the best possible quality prints. In this issue, we are going to guide you through some basic maintenance tasks that you should be doing periodically on your 3D printer.
Changing the PEI Sheet
Most modern 3D printers now come standard with a Polyetherimide (PEI) sheet. This sheet is marketed as a maintenance free build surface, but it isn’t the case. The maintenance free claim comes from the fact that the sheet itself needs just a little cleaning before each print, usually with some Isopropyl alcohol. This is a great improvement from the previous commonly used build surfaces, such as masking tape and Kapton tape, which needed replacing, and in some cases, before EVERY print. However, these PEI sheets also need replacing, albeit significantly less regularly.
Over time with normal use, the areas used most (usually the centre of the build platform) will lose the build surface texture. This texture is part of the reason PEI sheets have superior first layer adhesion. The texture creates a higher surface area that the filament binds to during the printing process.
This means over time, through normal use, the PEI sheet loses its superior adhesion properties, resulting in reduced first layer adhesion and the increased possibility of failed prints.
This effect is greatly increased with abnormal use, such as an incorrectly levelled bed. If you incorrectly level your bed, which results in the nozzle coming into contact with the PEI sheet, this will damage the PEI texture. This will result in visible differences in the surface of future prints on that sheet. This can be seen in some of our recent projects printed on our Flashforge Creator Pro, such as the Camera Trap project from Issue 030, the low battery device from Issue 029 and even the data logger in this month’s issue. In all of the enclosures for these projects, a ring is visible on the surface of the print that comes into contact with the build platform.
This is the result of a nozzle coming slightly into contact with the PEI sheet while printing an object, and can’t easily be repaired. This means the sheet must be replaced to remove the undesired effect.
Another common way to damage the PEI sheet and requiring its replacement, is by using a scraper on the bed to remove the finished print. We recommend that makers refrain from using a scraper to remove 3D printed parts from their build platforms. Not only does it significantly increase the chances of injury, it also increases the chances of damaging your 3D printer. The risk of this is obviously increased if the scraper is metal and/or sharp. Using a scraper on your PEI sheet reduces the adhesion by significantly wearing the sheet’s textured surface, and could very easily dig into the sheet. Any gouges made in the sheet can easily show up on the surface of your 3D prints.
Of course, in this case, the best solution is to ensure that your bed is correctly leveled, and you don’t use a metal scraper to remove prints, thus you don’t damage your sheet. Accidents do happen though, so replacing the PEI sheet becomes a normal part of EVERY 3D printer’s regular maintenance procedure. However, it is also potentially one of the trickiest, or at the very least, the most time consuming maintenance procedures. Generally speaking, the PEI sheet is mounted to different 3D printer models in much the same fashion. It is normally secured to the build platform using a very sticky adhesive that can tolerate high heat. However, there can still be differences between printers that will require the user to take a different approach.
Take, for example, the two printers discussed here. On one hand, the Flashforge PEI sheet is attached to the borosilicate glass build platform, the other printer, the Cocoon Create (a rebrand of the Wanhao Duplicator i3), the PEI sheet is attached directly to the aluminium build plate from factory.
Note: Our Cocoon Create has an aftermarket glass bed attached to the aluminium build surface.
If your PEI sheet attaches directly to the build platform, as with standard Cocoon Create / Wanhao i3 printers, etc., you MUST NOT use a metal scraper to remove the PEI sheet. Doing so can permanently damage the aluminium build plate, which may also include the build surface heating element.
A scraper is much less likely to damage the borosilicate glass build platform, provided that care is taken.
The first step in replacing the PEI sheet on any printer is to heat the build plate up to about 90°C. This will help to soften the adhesive and allow you to carefully remove the sheet. It will also significantly reduce the amount of adhesive that will stay stuck to the build plate, speeding up the replacement process. Naturally, working with a very hot build plate adds the possibility of burns, and as such, you should be wearing gloves and taking care to avoid touching the build plate.
Start by very carefully and slightly lifting a corner of the PEI sheet. Just enough to grab with a pair of pliers (using a pair of pliers will significantly reduce the chances of burns).
Pull the PEI sheet backward, curling the sheet back over itself. This will reduce the stress on the build platform mounting hardware and springs.
As you’re removing the PEI sheet, do it nice and slowly. As you lift, pay attention to any glue that is being left behind, and gently use a razor blade, hobby knife or similar to cut the adhesive. Cut as close as possible to the bed so that it does not continue to pull off the PEI sheet. This will reduce the amount of effort needed to remove the adhesive in the next step. If you have a glass bed, you can also use a scraper or knife to remove as much of the adhesive residue as possible while you work.
Once the PEI sheet is removed, you need to let the build platform cool back down to room temperature so you can remove the adhesive that remains on the platform. To do this, we use a product called Solvit, which you can find at Autobarn, Officeworks, Supercheap Auto, etc.
Simply spray the citrus scented liquid onto the adhesive residue and let it sit for a few minutes. This product dissolves the adhesive, allowing you to easily remove the leftover goop just with a paper towel or tissue.
NOTE: We have used this product on glass and aluminum beds and can confirm it's safe to use with both. If you’re using this product on any other surface, read the instructions and make sure it wont damage the surface. Perhaps, test a small area first to be sure. Do not let this substance come into contact with the new PEI sheet because it may reduce its adhesion properties.
After removing the adhesive residue, thoroughly clean and dry the build platform using Isopropyl alcohol. This will help to ensure that there is no residue left from the Solvit solvent. During this process, run your hand over the build surface to feel for any imperfections or lumps of residue that may possibly remain.
You need to make sure that the build plate is perfectly flat. Imperfections will likely cause the new PEI sheet to have a high spot that could cause the PEI sheet and nozzle to make contact during the printing process. Once you’re satisfied the surface is clean, give it one more wipe down with isopropyl alcohol and set the bed to heat back up to 90°C. When the build platform has reached 90°C, you can remove the backing from the new PEI sheet and carefully align and attach it to the platform.
It’s important to have the build platform up to temperature. This will allow you to easily lift the sheet back up if you get a bubble or incorrectly place the new sheet. We start by placing the PEI sheet on the front first. We use a ruler (placed lengthways) on top of the platform to help spread the sheet evenly, and to prevent any bubbles appearing. That’s it! Your new PEI sheet is installed. However, it’s very important that you re-level your bed before you attempt to print anything as the process of replacing the PEI sheet is likely to have altered the beds' level.
WHEN TO PERFORM THIS MAINTENANCE
This procedure should be done on an as needed basis. If you notice that your prints have obvious markings across their surface, or your prints just don’t seem to adhere to the bed as well as they should, then you should consider if your PEI sheet needs replacing.
Cleaning & Lubricating
This may be an obvious maintenance procedure for most people, but it is very important to keep your smooth rods clean and lubricated. Failure to do this can cause the linear bearings to become impregnated with debris, which over time, will prematurely wear the bearing and the smooth rod.
We find the best way to clean these rods is to first use a stiff bristled brush (an old toothbrush works well) to remove the dust and debris from around the bearing. We then use a tissue to thoroughly clean the linear rods. You may need to gently move the extruder and carriage manually (see important note below) to clean the full length of the rod.
Don’t use any solvents to clean the rods because you don’t want to strip any lubricant away from the surface. All we need to do here is remove the build-up of dust.
IMPORTANT NOTE: When manually moving a 3D printer’s carriage, you cause the stepper motors to turn. This can produce voltages that are sufficient enough to potentially damage components. To minimise the risk, move the carriage very slowly to reduce the energy generated. If your printer’s LCD screen illuminates whilst moving the carriage, you’re moving too fast, for example.
Once the area around the bearings and rods have been cleaned, it's time to lubricate them. The type of lubricant you use will depend on the linear bearings you have installed on your printer. In most cases, your linear bearings will be metal like the ones shown here, however, some 3D printer manufacturers are now using PTFE linear bearings.
For metal bearings and bushes, we recommend the use of a fine grade mineral oil, which will easily wick into the bearing. Its low viscosity means that the oil easily coats the bearing internal surfaces, and will also lubricate the smooth rods.
IMPORTANT NOTE: You only need to apply just a little oil. Applying too much oil may cause it to drip onto your build surface and result in bed adhesion problems. We recommend you cover your printer’s bed prior to oiling any bearings above it.
With the bed covered, drip a small amount of the oil onto the area where the bearing makes contact with the smooth rod. You then gently move the carriage manually so that the bearing moves over the oil, spreading it evenly across the rod and into the bearing. Repeat this procedure for both sides of each bearing until all bearings are lubricated.
Remember to keep the movement of the carriage slow so you are not generating enough voltage on the stepper motor that could damage parts of your printer.
Note: We don’t recommend that you use WD40 on your bearings or smooth rods. This product, whilst designed as a lubricant, isn’t ideal for 3D printers. The blend of lubricants inside WD40 contains a hydrocarbon based, kerosene-like oil which will react with Amorphous / Thermoplastics like ABS / PLA, and damage them over time.
If your bearings are the PTFE material type, we recommend using a silicone based lubricant. Silicone wont eat into the PTFE like some oils.
WHEN TO PERFORM THIS MAINTENANCE
We recommend you inspect and clean any dust from the smooth rods about every 50 hours of operation or more regularly depending on where your printer is located. You don’t need to lubricate the bearings as often, as the bearings tend to keep the oil inside them. We tend to oil the bearings only once a year on our machines and they receive quite heavy use. PTFE bearings will need to be lubricated much more regularly compared to metal bearings.
Cleaning Printer Fans
The fans on a 3D printer’s extruder ensure that the heat generated in the heater block is confined (as much as practical) to the heater block. If this fan isn’t working optimally, it can lead to an increased risk of jamming in your extruder. This effect is caused by something called heat creep. The extruder on most 3D printers consists of a hot end and cold end.
The hot end has the heater cartridge, heater block and the nozzle, which as its name suggests, is the area of the extruder where temperatures are higher than the melting point of the material being extruded. The cold end, on the other hand, needs to be much lower than the hot end’s temperature so that the material being fed into the hot end maintains its rigidity. If the fan and heatsink on the extruder is unable to keep the cold end sufficiently cool, the heat will creep up from the hotend via the heatbreak / guide tube. If this heat rises to the melting point of the material being extruded, the material loses its rigidity and the material begins to jam inside the heatbreak / guide tube.
2. Heater block / Hot end
3. Heater cartridge
4. Heatbreak / Guide tube
5. Upper bar mount / Cold end
With the material having lost its rigidity, it's then unable to push the molten material through the nozzle and the printer will stop printing. The material in the molten state fills up any void in the guide tube, oozing between the PTFE liner and possibly the guide tube. This jam is quite difficult to rectify and often requires the replacement of the PTFE liner inside the heatbreak / guide tube. Naturally, this requires a complete disassembly of the hot and cold side of the extruder. Take it from us, this is not a job you want to spend your weekend doing, so it's much better to keep your fan clean.
To clean the fan to negate the potential for this issue, we just use the same rigid brush we used earlier to clean the dust off of the linear bearing mounts.
Carefully brush the dust away from the fan shroud, while attempting to stop the fan from spinning with a thin screwdriver. If a brush isn’t effective, another method is to use a can of compressed air, also known as air duster.
You’ll need to carefully use a screwdriver or similar to stop the fan blades from spinning as you blow the compressed air into the fan.
WHEN TO PERFORM THIS MAINTENANCE
This maintenance should be done on an as needed basis, however, we recommend that you inspect the fan every 50 hours of operation or so. Inspect more frequently if your printer is used in a dirty environment, such as a garage, for example.
You can always get into a habit of inspecting the printer whenever you're waiting for that print job to finally finish.
Changing the Nozzle
The single part that has the biggest impact on the quality of your 3D prints is quite possibly the smallest. The nozzle on your printer is what guides and steps down the thickness of your filament from the usual 1.75mm to 0.4mm by working as a die. Over time, this die becomes worn and the diameter of the nozzle increases.
The image above shows two nozzles for our Flashforge Creator Pro. The left is a brass nozzle after about 400 hours of printing standard PLA and intermittently specialty filaments like glow in the dark and aluminium. The right shows a brand-new nozzle. Notice the larger diameter of the old nozzle and uneven wear pattern.
The time it takes your nozzle to wear depends heavily on many different factors, most notably the material the nozzle is made from. Most printers come standard with brass nozzles which conduct heat very well but are quite soft and wear quickly.
An upgrade from the standard brass nozzle is a stainless-steel nozzle. These nozzles wear significantly slower, however, they don’t conduct heat nearly as well. This means you have to increase the extruder temperature quite significantly. For example, with a stainless-steel nozzle, we print PLA at 230°C to get the material to flow correctly, compared to around 195°C using a brass nozzle.
Another key factor in nozzle wear is the filament you’re using. Filaments often have materials inside of them designed to increase specific properties and even colours. This material can be abrasive and promote nozzle wear. Some are quite obvious and others not as much. For example, we would likely all expect carbon fibre filament to be abrasive, as the filament is impregnated with carbon strands, but so is white PLA and glow in the dark filament.
White PLA can include a Titanium dioxide to create the white pigment. This Titanium is many times harder than Brass and will easily erode a nozzle over time. Likewise, glow in the dark filaments use Strontium Aluminate to give its characteristic phosphorescence. This material will rapidly degrade your nozzle.
There are a number of specialty nozzle options such as hardened steel, and even a very unique brass nozzle with a manufactured ruby press fit into it for users who print highly abrasive materials, such as these. If you’re noticing constant nozzle wear, you may want to investigate these options.
No doubt you’re wondering how to tell if your nozzle needs replacing? Unfortunately, it's not usually something you can just inspect and decide if replacement is needed. You need to monitor the quality of your prints. The degradation happens slowly, therefore, over time the quality of your prints degrades with it.
A worn nozzle will generally have a larger diameter die. This will greatly increase the amount of oozing from the nozzle, requiring longer retractions. Therefore, excessive stringing is often one of the first signs, informing us that our nozzle is starting to wear but it isn’t alone. Look for a degradation in the quality of overhangs and dimensional stability, and generally speaking, the printer’s ability to translate detail.
If you’re noticing a persistent degradation of the quality of your prints in general, your nozzle is often the first place you should look. To replace your nozzle, you will likely need to consult your 3D printer’s manufacturer. Whilst all printers are very similar in construction, your specific printer may very well have a mandatory step that is unique to your printer.
Note: You usually need to remove the nozzle while the machine is at temperature because the melted filament holds the nozzle tight, almost as if it’s glued in place. Thus, you will strip the nozzle and/or destroy the heater block and possibly the entire hot end if you attempt to remove it cold. Working on the printer at temperature means you need to take EXTREME care to avoid burns. Consider using leather gloves and get assistance from an adult if you are a young maker.
For our Flashforge and Cocoon Create, we heat the extruder up to the melting point of the material currently in the extruder. i.e. 190°C for PLA and 230°C for ABS.
Once the machine is up to temperature, we turn it off and unplug the printer. We use a shifter to hold the heater block in position, being very careful not to damage the heater cartridge or thermistor. We then use a 3/8” socket that fits the nozzle and ratchet to remove the hot nozzle.
Note: You MUST keep the heater block in position and not let it rotate. Doing so can damage the thermistor and heater cartridge.
Once the old nozzle is removed, allow the machine to cool down completely before attaching the new nozzle. When tightening the new nozzle, just nip it up with the ratchet. Do not overtighten as you can easily damage the aluminium heater block.
WHEN TO PERFORM THIS MAINTENANCE
This is quite possibly the hardest of all maintenance tasks to suggest a timeframe for inspection as it is so specific to use cases. For us, we are usually printing parametric non-organic designs in standard PLA, such as enclosures that generally use straight lines. Thus, our designs don’t generally have significant surface detail features that someone printing organic high detailed models like sculptures would. This means, we are less likely to notice the print quality degradation and can usually use a worn nozzle for longer.
With that said, we replace our nozzles approximately every four months, which for us, translates to around 400 hours of printing (25 hrs a week). In this period, the nozzles become quite worn and start to change their shape.