All Metal Hotends A Guide & TroublshootingJune 3, 2020
What is an All Metal Hotend?
Are you need to 3D Printing and just looking to buy your first printer. Or have you had your stock printer for a while and are now itching to make all of the improvements you’ve heard about on the chat forums, but don’t know where to start? Or have you bought an All Metal Hotend and now your printer wont work?
Well you’ve come to the right place. Here we will explain what an All Metal Hotend is and give you troubleshooting tips on how to make one work with your 3D Printer.
The Basic Components of a Hotend.
The Basic Hotend can be broken down into 5 distinct parts>
1 The Heat Sink: The heat sink or also referred to as the radiator is where the excess heat generated by the hotend is expelled, The fins of a radiator allow airflow driven normally by a fan to be expelled into the air and reduce the risk of fire or printer failure. A good rule of thumb is the more fins on a radiator, the more surface from which to radiate the heat and the cooler it is.
2 Heater Block: The active area of the hotend, the metal of the heater block is heated up by the heater cartridge inserted in it, which in turns heats the nozzle which then melts the plastic filament into a semi-liquid like state and then extrudes that onto the build bed and the print. Heater Blocks are commonly made of Aluminum. Higher quality ones are made of copper coated in a protective metal, like stainless steel.
3 Nozzle: Made usually of Brass, the nozzle is screwed into the Heater Block and is where the plastic filament is heated to a liquid state and pushed through. Nozzles have a varying diameter hole through which the molten plastic is extruded to the print or print bed. The most common sizes are 0.2mm, 0.3mm, 0.4mm, 0.6mm, 0.8mm, 1.0mm, 1.2mm, with o.4mm being the most commonly used size and what most 3D printers include as stock.
4 Heat Break (Throat): The Heat Break is the connecting tube between the heater block and the heat sink. It can also be referred to as the “throat” of the hotend. Heat Breaks come in two designs, PTFE lined also called Teflon, or All Metal. Yes this is the little piece of the hotend that makes it All Metal Hotend.
A PTFE lined heat break is made of a stainless steel outer shell, which screws or inserts into the heatsink and screws into the heater block. This PTFE tube can be the bowden tube inserted all the way down the heat sink and into the heatbreak terminating at the top of the hotend\’s nozzle. Or it’s a a small tube, the length of the heatbreak built in.
Heat Breaks labeled as metal or Titanium (TC4), eliminate the PTFE liner and the plastic filament follows the path of metal down through the heat break into the nozzle.
Other Parts: Pneumatic connectors, fan mounts or fan shrouds and a fan can also be part of a hotend.
What is an all metal hotend?
We hinted at it with the parts description of a hotend. But here it is: The standard stock hotend which ships with most 3D printers have heat breaks (throats) lined with PTFE (Teflon) tubing. e3d hotends, CR-10 Hotends and J-head hotends all come standard with a PTFE lined heatbreak. It\’s the cheapest version of a hotend and what most hotend manufacturers sell as the cheapest version of their hotends.
The problem with PTFE lined hotends, where the PTFE abuts the top of the nozzles is heat. PTFE at lower temperatures is a fantastic pathway for the filament to pass through till it reaches the nozzle where it needs to be turned molten. PTFE (Teflon) tubing is non-stick and self lubricating. But when the common version of PTFE tubing is heated above 240 degrees celsius it begins to break down, outgasing toxic chemicals and burning. Making it only sutiable for lower temperature plastic filaments like PLA, ABS and some versions PETg. (Recommend using higher temp PTFE tubing like Britch Blue or Capricorn for long term PETg printing.)
(NOTE: Capricorn and our own Britech Blue tubing can reach higher temperatures of around 275 and for short time periods 290 degrees celsius.)
But PTFE has another problem, it doesn’t wear well when used with abrasive plastic filaments like Glow-in-the-Dark or Carbon Fiber filaments. Their abrasive nature will eat quickly away at the PTFE liner of standard heat breaks.
An all metal hotends are designed to eliminate that internal PTFE liner in the standard heat break and replace it with an all metal path through to the nozzle. The stainless steel or titanium construction of a metal heat break can be heated beyond the 240 degree celsius failing point of most PTFE tubing. Thus making All Metal Hotends ideal for printing plastic filaments like Nylon, HDPE, Polycarbonate. Stainless Steel or Titanium also wears far better than PTFE tubing making all metal hotends ideal for use with PLA, ABS or PETg that are infused with glow in the dark particles or carbon fiber.
But All Metal Hotends are difficult to use, I’ve read.
Yes the internet forums are awash in complaints of nightmare stories of someone who has just switched from their stock PTFE lined hotends to a new all metal hotend. Outside of build plate adhesion of the print, they are the most common complain/problem you will find.
All metal hotends are no more difficult to use, than say as a neophyte, getting your print to adhere to your build plate and not fail. All metal hotends are different from using the standard ptfe lined stock hotends but they are not hard if you know what you are doing and experiment some. Which is why this is was written.
PTFE tubes in heatbreak have one major benefit, they are self lubricating and have a smooth inner diameter finish that allows the plastic filament to push through easily. It allows for higher retraction, since even if the filament cools inside the ptfe liner it will most likely not stick to the self lubricating walls.
There is also one major drawback to PTFE lined heatbreaks (throats) is the temperature restriction. The max for most PTFE tubes is 240C before the PTFE tube or liner breaks down, losing it\’s self lubricating features while outgassing toxic fumes leading to damaging the hotend. (Capricorn and Britech Blue PTFE tubes can go higher to 290) So you can not use PTFE lined heatbreaks with plastic filaments that require high temperatures! When overheated PTFE if fine for PLA, PETG, ABS but anything that requires temps above those plastics, you should really use an all metal hotend of stainless steel or titanium (TC4).
Additional problem with PTFE lined heatbreaks is that it is quickly destroyed by popular but abrasive filaments, like glow in the dark or carbon fiber laced filaments. These abrasive filaments are going to quickly eat away the lining and cause your hotend to clog.
The benefits of all metal hotends summed up are:
Printing High Temperature filaments. Use the highest temperature filmanet you can find, you\’ll melt your aluminum heater block before the stainless steel or titanium heat break starts to fail. (Please not higher temps will require an upgraded heater cartridge and use of thermocuoples like the PT100 instead of the glass bead thermistor.
Print without worries “abrasive” filaments like carbon fiber and glow in the dark. Keep in mind that your brass nozzles will quickly be consumed by these filaments and you should switch to stainless steel or hardened steel nozzles.
Longer life of the heat break.
Lower retraction of the filament.
But which should I choose, stainless steel or titanium? Booth are very good options for your 3D printer\’s hotend, but titanium winds hands down in our book. Why?
Stainless steel is a very good conductor of heat and because of this can cause heat creep up into the heatsink causing a clog. It is true that that PTFE lined hotends are made of stainless steel, however the self lubricating and insulating properties of the PTFE liner minimizes the problem with heat creep to some degree, up into the heatsink. This causes your 3D printer to work harder and run the heater cartridge longer as the heater block is losing heat as it’s drawn up to the heatsink. The cooling fan for the hotend have to work harder to keep heatsink dissipating the creeping heat.
All metal stainless steel hotends are great, with millions of printers out there using them. But we love all mental titanium hotends even better! Why? Because Titanium unlike stainless steel is not a good conductor of heat! This means the heatsink stays cooler and the more of the heat remains down where it belongs in the heater block allowing the heater cartridge to work less and saves you energy.
All metal hotends using a titanium heatbreak are the best addition to your 3D printer and their cost have dropped significantly.
Whether you have stainless steel, titanium or e3d, CR-10 or J-head hotends, they don’t “act” the same as a hotend with a ptfe throat liner so there are things you need to be aware of when setting up and printing with an all-metal hotend have a successful and good looking prints.
Setup & Troubleshooting All Metal Hotends
Users new to all metal hotends immediately notice the most common problem hotends with these types of throats have, jamming. Jamming is where the filament, when it is retracted away from the nozzle and into the heatbreak quickly cools causing a clog. Like stated above, this is rare in PTFE lined hotends as the PTFE is self lubricated and doesn’t stick to the filament, as long as the PTFE is in good shape.
PLA especially has this problem because it is a corn starch based product. The PLA filament retracts into the all metal heat break and while it quickly cools the starch in it binds with the metal sticking in place. Instant filament jam.
What causes this type of jam in all metal heat breaks.
Primary reason too much retraction. As stated PTFE is self lubricating and non-stick. Retraction with PTFE liners isn’t that big a deal. The filament retracts form the nozzle area, into the ptfe and cools as it goes up but does not stick to the liner or tubing when it’s ptfe. When the extruder reverses and pushes the filament back into the nozzle, it just slides through the ptfe no problem.
But with stainless steel or titanium heatbreaks if you retract into them too much, instant jam. Think of it like cooking in a frying pan without oil or liquid. Within seconds the hot pan will burn your food onto it’s surface causing a hard to remove surface. Something similar is happening here with the plastic filament as it touches the all metal heatbreak in a fluid state.
Change your Retraction.
With standard PTFE tubing a retraction of 3-4mm is good. We’ve noticed that CR-10 machines will come set as high as 6m. Leave them there if it isn’t causing problems.
If you have our Britech Blue high temp Bowden tubing a setting of 2-3mm on retraction is usually good.
With an all mental stainless steel or titanium heatbreak your settings may be 3 to as low as 1. Most printers seem to work fine with around 3 to 2, but we’ve had feedback on the titanium that some people got the best results with 1. Experiment and find the best balance between print quality and risk of jamming for your machine. Above 3 risk of jamming increases.