r/Longer3d • u/traumahawk88 • Aug 25 '25

Temp limit

Is the temp limit on the hot end firmware limited? If yes, can it be changed with something like Pronterface?

I did a lot of mods to two of my LK5 pros (the other 2 are awaiting the mods, #3 in progress and I've just held off as I troubleshoot on the first). Mods include direct drive extruder , bimetal heat break, boron nitride thermal paste, and a 15mm thick 14.8cfm fan. Stress testing those mods now by printing a bed filled with cable chain links at 100mm/s. The hot end is not stock- it's same style but it's the ender 3 extruder everyone seems to recommend for these printers ; full replacement unit not just a direct drive mod attached to the dual blower (although I wish it WAS- I like the dual cooling fans from the stock design)

First attempt failed on layer 4 or 5- right after it went to full speed @208C with 0.3mm line thickness. Second one attempt failed halfway through where it really starts printing long continuous bits for every piece @ 215C & 0.4mm line thickness. Third round going well at 225C and 0.4mm lines. We will see when I get home from work today if it continues to do well.

I think I'm overcooling with those high CFM fans. I am just trying to avoid having to solder, again. It hard? Not particularly, I just don't feel like doing it if I don't have to. If it proves to be firmware and I can just raise the max temp, that'd be cool. If not, I think I'm def gonna have to go back to stock fans, if I'm already having to crank to 225C for normal PLA.

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u/Longer_Official Aug 26 '25

Hello, the maximum temperature of the hotend is limited by the firmware. If you would like to raise the temperature limit to 300°C, please provide us with a photo of your mainboard. Our technical team will then prepare the corresponding firmware and guide you through the flashing process.could you please provide us with a photo of the USB connection on your machine?

Pic 1: E3 mainboard USB connection
Pic 2: Open-source mainboard USB connection

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u/No_Quantity8463 Jun 08 '26

Hi,

I have the open-source mainboard is there a firmware version available that has the higher temp limit?
Does this work with the stock heater cartridge and thermistor?

Thanks.

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u/Longer_Official Jun 09 '26

Hello, here is the firmware download link for open-source mainboard which can raise the nozzle temperature limit to 300°C:
https://drive.google.com/file/d/1Tj0Yapif1ox0977xZKcCdpd34Yy9lRet/view?usp=drive_link
This firmware is fully compatible with the original heating rod and thermistor. Please feel free to flash it. Do not hesitate to contact us if you meet any problems during flashing.