The Pursuit of Hotter:

General rules for pushing your printer further

So you've mastered the PLA that came with your printer, and your ready to go forth and use more advanced materials. You look online, and everyone says you need new hotend, or a glass bed, or a silicone heater pad in order to do the things you want to do. Why? Says who? What if you don't do that?

Long story into a short answer, it's bad if you don't. The hardware that shipped with your printer is very good at what it is intended to do, part of the reason why the Mk8 Teflon lined hotend has become the de facto standard for hotends on consumer machines. This is even more evident on budget machines, such as the ever-present Creality line of 3D printers. The Teflon lined hotends are objectively better than their fancier counterparts when printing within the safe range of the hardware, and it is much easier to use than the all-metal alternatives. What it is not so good for though, is pushing the envelope past the safe point. Even once you buy, install, and configure your brand new hotend you can't just go crazy with it. Your Thermistor will fail. Your bed heater will fail. Eventually you can reach printing temperatures that structurally weaken the aluminum heat block on the hotend, bordering on melting it. Every part on the machine has a failure point, and you do not need to change them all. It is not a good idea to gut your 3D printer just to "make it better", rather you should let the needs and desires material-wise guide the modifications made to the machine. It is important, however, to know where those safe limits are. Knowing your limits make it eaiser to operate the machine in a safe way, and arms you with knowledge that is helpful for when it is time to exceed those limits.



  • PLA
  • PETG
  • TPU

Next Step…..

All Metal Hotends

First stop, is Teflon really that bad?

As mentioned earlier, no. Teflon is awesome as long as you play by Teflon's rules. It is a great thermal isolator, is the closest thing to a frictionless surface you can reasonably get, and is resistant to relatively high temperatures. Relatively is the key word there, in that the hotend of a 3D printer is really REALLY hot by definition. How hot is too hot for teflon? The simple answer is 245-250c. Probably.

Probably? Probably. Teflon is generally accepted to be used in temperatures up to 260c, however it is important to consider inherent inaccuracies in the printing process. Most importantly, the fact that the thermistor reading are relatively and extremely difficult to verify independently. This means it is not unreasonable to expect the temperature readings to have a margin of error, requiring the inclusion of a "safety net". (Read as, up to 260 at your own risk).

It is noteworthy that there is a source that claims much lower safe temperature maximums called the Enviromental Working Group, however this is likely to not be a representative source for safety information.

Why not just cook it? Teflon fumes can make you sick, refered to as polymer fume fever or "Teflon Flu" in an acute setting. PFOA, which is a chemical used in the production of PTFE, is considered a possible human carcinogen. This led to PFOA being banned in the use of Teflon in the United States, however I cannot find any evidence of a similiar policy in China (Where your white stock PTFE tubing was probably manufactured).

All Metal

  • Polycarbonate Blends
  • Most Nylons
  • ABS

Next Step…..

High Temperature Thermistor and Heat Block

My All Metal hotend breaks down when?

Getting rid of the teflon in the hotend really open up your horizons. But it's not infinitely capable. The next failure point on your shiny all metal hotend is, by a narrow margin, the stock thermistor. The standard thermistor that is packaged with 3D printers only maintain some sembalance of accuracy up to 285c. It is important to appreciate that the low-cost thermistors (think, NTC100K thermistors you buy in packs of 5-10 on amazon) are much more accurrate at reporting temperatures at lower temperatures. This is directly antithetical to purpose built high temperature thermistors, which are able to acccurately report temperatures from about 100c to up to 500c putting any printable plastic currently avaliable within the functional range of the thermistor. These are more expesive than the lower temperature alternatives, however not by much. a high temperature 500c thermistor can be gotten for under 20USD.

Another option to prevent overheating the thermistor is the thermocouple, which can measure extremely high temperatures with very high accuracy. These have been almost completely replaced with the priorly mentioned high temperature thermistors since the user experience with HT Thermistors is simply so much better. When using a thermocouple, additional electronics are required and generally speaking standard 3D printer controlled boards are not compatible with the hardware required to utilize a thermocouple. A HT Thermistor however can be plugged directly into the thermistor point like the OEM, and the only modifications required is reflashing the firmware to a version of firmware that has support for them (such as Marlin 2.x).

Since the failure point is so close together, I'll add the heatblock in here. The maximum temperature for a standard aluminum heatblock is 295c, and it should never exceed this temperature. At that temperature the aluminum the heatblock is made out of becomes soft and structurally unsound for printing. This part should be replaced with a block made of a different material. Common alternative high temperature materials for heatblocks include copper, brass, and less commonly stainless steel. They all provide strutural integrity up to the 500c point, allowing compatibility with every modern printable thermoplastics.

High Temperature Block and Thermistor

  • PEI 9085
  • Lexan Polycarbonate
  • HT-Nylon
  • Everything Else

Next Step…..

You Win

Heated Bed

PCB Heatbed

  • PLA
  • ABS
  • PETG
  • Nylon

Next Step…..

Silicone Heatbed

The heatbed that comes equipped on most budget printers is a PCB heatbed with two wires leading to the board which acts as a reisistor. The inherent issue here is that there is not enough power (measured in watts) and the heating process is very slow. Timing the heating process from room temperature to 115c on a noninsulated heated bed powered by the standard PCB heatbed 220w heat bed yields a result of almost 15 minutes. Pushing the temperature past this number will not cause the machine to fall apart or explode, however it is unreasonable to wait othe preheat times required to heat the bed to the temperatures required for high temperature materials like Lexan Polycarbonate. Insulating the heatbed is an effective way to mitigate this issue, however using a dedicated nichrome/silicone heater pad is a much better decision.

Remember if you decide to insulate your heatbed, resist the tempation to use cork, cardboard, or anything else that has a high flashpoint but is simultaneously very flammable. It is a safety risk. Use a silicone pad, precured (slapmat variety) or RTV. The effectiveness can be improved by also insualting the top of the heatbed during the preheat phase of your print job.

Silicone Heatbed

  • Lexan Polycarbonate (Sticker)
  • Everything Else (Secured)

Next Step…..

Securing the Bed

The next step up from the standard heatbed is a silicone-nichrome heatpad that is affixed to the bottom of the aluminum plate. The operating temperatures of both silicone and nichrome wire is way higher than you would reasonably want to heat a 3D printer bed to, so the only failure point left is the adhesive generally used to affix the heater pad. Quality heater pads generally ship with 3M Brand 468MP adhesive, which has been tested by 3M to be safe for long term usage (days to weeks) for up to 149C. It is unwise to continuously use a product at its failure point, so a soft cap of 140c is reasonable.

If the heater pad is secured using a different method, such as a metal plate sandwiching it to the aluminum heatbed, allows unreasonably high bed temperatures limited only by the materials surrounding it. If all nonmetals are removed from the system, temperatures can be reached high enough to print any currently avaliable thermoplastic. A general rule of thumb in regards to choosing a heater pad is that each square centimeter o f bed should use 0.5 watts of power.

Consideration should be taken as to the method of heating you use (AC or DC). Remember that while alternating current allows for much faster heatup times and higher temperatures, it deserves respect. Alternating current is dangerous, and it can kill you or burn down your house if done incorrectly. Use of a inline thermal fuse is highly recommended, as a failsafe to a situation in which the SSR fails in the open position.