Just like any other mechanical product, the A8 has a number of components that are going to need replacing at various stages. Fortunately the items that I would say needed to be replaced most often are very reasonably priced, especially if you get organised. You should always keep a stock of components in your tool box just in case you need to swap something out. I find that for me I need to replace certain parts often solely because I’m quite heavy handed. The following is a list of the components I like to keep stocked up:
- Heater Blocks
- Heat Breaks
- PTFE Tubing
With the standard issue and recommended starting point being a 0.4mm brass it’s a nice all round nozzle that gets used by the majority. Buy in a stock of 0.4mm nozzles as typical deals ranging from £1 – £6 for 1, 2, 5 or 10 pcs means the price per unit is relatively low. Stocking up when you don’t need them means you can search for the best deals and not be pressured by delivery time. Nozzles purchased on sites like eBay or banggood have an excellent cost per unit but will no doubt be shipped from China and could take a month to arrive. Remember to have a look at the sellers estimated delivery date before rushing in to purchase.
Once you have started to get the hang of 3D Printing with a 0.4mm nozzle there are a couple of options you could begin to look at if you’re up for expanding your experience. The two main features to focus on with nozzles are diameter and material. The diameter of a nozzle ranges from 0.1 to 1+ mm and typically goes up in 0.1mm increments. There is an abundant amount of information on the World Wide Web with regard to user experience of varying diameters so I won’t go into that here. The general rule of thumb is >0.4mm will yield quicker but less detailed prints and <0.4mm will give slower but higher resolution prints. Which ever one you choose, be sure to check it has an M6 thread (matching the thread on your heat block)
The material of a nozzle only really needs to be considered if you intend on using more abrasive filaments that contain metal particles. The next step from brass is steel which is available as stainless or hardened. These are more expensive then brass but will last a lot longer when printing with abrasives. E3D are considered the best in hot end development and have various types of nozzles available but come with a higher price tag.
The image above shows the two most common shapes of nozzle for 3D printing. Personally I haven’t seen any difference in printing quality.
The heater block on the A8 sits just below the extruder motor housing and typically consists of an aluminium block that measures 20x20x10mm. Connected to the heater block is the nozzle, heat break, heater cartridge and thermistor. On a standard heater block, the threaded through hole is an M6 and holds the nozzle on one side and the heat break on the opposite, screwed in until they meet tightly. The heater cartridge attaches from the side via the unthreaded M6 hole and is secured in place by an adjacent M3 x 3mm grub screw.
Similar to the nozzles, the price of these blocks can vary depending on where you source them and how many you buy in a pack. Likely to also be shipped from abroad, its worth buying in a couple of aluminium heat blocks to have at your disposal. There is considerably less variety of blocks available making this process much simpler but if you really want to experiment with the really high end filaments there are alternatives available.
Heat breaks; also referred to as throats, connect the heat block to the extruder motor housing. They consist of a 30mm long section of M6 threaded bar with a hole running directly through its centre. Typically this hole is lined with PTFE tubing which acts as a barrier to enable your filament to travel from the extruder to the nozzle without it melting prematurely. On the A8, the heat break is screwed into the heater block on one end and an aluminium cuboid on the other. This cuboid is then fixed within the extruder motor housing directly beneath the feed zone ready to receive the filament. This is held in place by an M6 nut. Take care when tightening this nut as it is very easy to snap the heat break, its walls are only 1mm thick.
Having a PTFE lined heat break works brilliantly for filament that requires an extruder temperature of less than 250 degrees Celsius. Any higher than this and the PTFE will begin to melt and cause a blockage. If you are hoping to print filament that requires a higher temperature you will need to swap out the whole heat break for an all metal one. These are distinguishable by the gap in the thread around a quarter of the way up.
It’s unlikely you will need to buy this in separately unless you plan on upgrading to a Bowden extruder (for flexi filament). On the other hand, buying the heat breaks above from cheaper suppliers can result in poor quality tubing with a misaligned through-hole. This is bad. The PTFE tubing sits inside the length of the heat break and allows the filament to travel through without prematurely heating up and becoming soft. If this happens it will not extrude sufficiently and will begin to block. If the hole is misaligned then the heat resistant properties will not be as effective.
For the Anet A8 it uses a 1.75mm diameter filament and the heat break is an M6 x 30mm. This means the specs for the PTFE tube are an outer diameter of 4mm, internal diameter of 2mm and a length of 30mm to match the heat break.