Adjusting Bed Temp values on Monoprice/Wanhao I3 (Repetier Firmware)

Jason Clark
  • Adjusting Bed Temp values on Monoprice/Wanhao I3 (Repetier Firmware) Jason Clark

    I have a Monoprice Maker Select, which is a rebranded Wanhao Duplicator I3 V2 (Prusa clone). I've found that the heated bed temperature values on the LCD are incorrect. The heater works, and the controller maintains the bed temp just fine, but the temperature reported isn't the true temperature. When using the PLA preset, with the bed set for 60°C, once the temperature stabilizes at 60°C on the display, I can measure it with a laser thermometer and get a consistent 54°C across the buildplate. With the ABS preset of 90°C, I read 80°C. And with the bed set for the maximum value of 120°C, I'm only reading 102-104°C.

    I've checked these values with the bare aluminum build plate, and I've allowed the temps to stabilize for at least 10 minutes to ensure that I have consistent readings. I believe the the firmware is using the wrong temperature curve for the thermistor in my device.

    I had hoped that there was a simple scaling constant that I could adjust, but that doesn't seem to be the case. I've researched enough to learn that my device is running Repetier 0.91 firmware, and this page on temperature control on the Repetier wiki says that each type of thermistor needs a custom voltage->temp lookup table, and talks about building a custom table in "configuration.h". I've tried to follow this line of research but I feel like I'm going around in circles. It sounds like I could build a custom version of the firmware to install on my printer, and in doing so I could potentially specify a better conversion table. This gives me pause for several reasons:

    1. I haven't found any online reference to other people installing a custom Repetier build on a Wanhao I3.
    2. I have no idea what values to use for the temp conversion table.
    3. I can't even find anyone else reporting my issue.
    4. I'm fairly new to this; I rather not brick my printer, and I haven't found any good guides to installing firmware on the device either.
    5. I'm not convinced this is the right option. Should I be looking at replacing the thermistor instead? And if so, what's the correct part?

    I've also looked into the Melzi board inside the printer hoping for a variable resistor to tweak the thermistor voltage divider, but no such luck, at least in the schematics.

    I could just live with it; I've been using a 67°C setting to achieve a true 60°C bed temp for PLA, but I'm starting to work with ABS and I'd like the option to get above 100°C bed temp. Am I on the right track? Suggestions? I'm still pretty new to the device and 3D printing in general, so I may have overlooked something obvious.

    Update: additional question in light of Tom's answer: what is the expected max actual bed temp achievable on a Wanhao/Monoprice I3? I'm measuring 100°C with an LCD reading of 120°C, but I'd like to get to 110°C if possible.

  • It is completely normal for the surface of the bed to be cooler than the indicated temperature. The thermistor goes on the underside of the bed, near the heating traces. The top of the bed (which is further away from the heating traces) will naturally be cooler.

    It would be possible, though a lot of work, to build a custom thermistor table that more accurately reflects the surface of the bed, though that means your thermistor table will no longer reflect the characteristics of your thermistor, but instead reflect the particular circumstances under which you build your custom table (which would be affected by ambient temperature, any drafts, ...).

    The accuracy of an infrared laser thermometer depends on the characteristics of the surface you're measuring for, so unless you adjusted the thermometer specifically to measure the aluminium surface of the bed, it's possible your thermometer is off as well.

    The exact temperature of your bed doesn't matter anyways (you just need it approximately in the right ballpark) so I would suggest to just live with it. The 60C/90C figures are not supposed to be for the surface of the bed. They're meant to reflect the temperature reported by the printer. That said, 90C is a bit low for printing ABS (but the bed/power supply on your printer might not be powerful enough to get any higher).

Tags
prusa-i3 heated-bed repetier
Related questions and answers
  • Background: I just successfully installed a RepRapDiscount Full Graphic Display on my Prusa i3; and in doing so, I've upgraded all of the firmware to the latest version of Marlin, 1.1.0-RC7. With my.... For the record, maybe I'm missing something obvious, so please let me know. I measured the voltage on my A4988 stepper drivers on the RAMPS 1.4 board, sitting on the Arduino Mega2560 R3, and it is reading... point me in the right direction, I would really appreciate it. I'm getting desperate with this new firmware version. It has all these conditional tabs that didn't exist in my other one, and I can't quite

  • of those last holes but I have to think that maxing out S3D's outline overlap setting to just barely make the print work means I haven't found or addressed the true root cause... .../stringing issue that I didn't think was but perhaps could be related). The screw hole mounts seem well-designed to me: No 90 degree transitions - I would think this would be the least of my problems. But last night they had serious problems: I haven't seen a problem like that before. Extrusion rate seems basically perfect - why does it look like it just stopped extruding around

  • :-inf /nan T:25.2076 /nan I have not connected bed thermistor yet. pins.h #define TEMP_0_PIN 1 // Extruder / Analog pin numbering #define TEMP_BED_PIN 0 // Bed / Analog pin...I have a RAMPS 1.4 and an Arduino Mega 2560. The problem is with 100k NTC thermistor. I've tested it with a multimeter, it results in ~122kΩ. I am using Marlin 1.0.2 (latest stable). I am using an MK8 extruder and do not receive temperature readings from the thermo-sensor - no matter how I connect it. However, on APrinter firmware it works flawlessly. In configuration.h, I have tried most

  • . I am keen to buy an aluminium PCB heatbed for my P3Steel v.4 printer, which has a larger build area of 200 mm x 300 mm. So, after some searching, I found this MK2A: MK2A 300x200mm Aluminum Heated Bed Hot Bed for RepRap 3D Printer 12V + Wiring + NTC 3950 Thermistor - Upgrade you Prusa i3 for LARGE Printsize, or this cheaper MK3, Anycubic Dual Power MK3 Heatbed 300*200*3mm Aluminum Heat Bed 12V/24V Perfect for Prusa i3 3D Printer. Note: this is not a shopping question, I am merely providing a background to my questions. While the RepRap wiki is full of information, the information can

  • (resistance value around ~200 kΩ at room temperature). Which leads me to believe that I may have damaged the control board. What do I do? Note: This is not a firmware problem as the printer was getting correct temperature readings before that. Also, I have a second extruder thermistor port that is unused. If I did damage my board, could I edit pins.h and configuration.h to use this port...I just got my HICTOP Prusa i3 Aluminium frame printer and finished putting it together. After setting it to preheat, I realized the bed was not level - I adjusted it and accidentally caused the head

  • I have Sainsmart Mechanical End Stops, and I'm building a Prusa i3 Rework. I've recently gotten the x-axis to move, but it needs to stop when it gets to the end and it does not do that; I end up having to pull the plug. From what I understand, there are two ways to wire ends stops in general, but you have to change the settings in the firmware to make it work right. There are 3 connectors on the board: S (signal) - (ground) + (VCC) My Sainsmart Mechanical End Stops have 4 connectors!!! According to their website, left to right with the white connector facing you, they are as follows

  • on my computer. I have been able to print the test object that came on the SD with ok quality but when I switch to using the computer it just doesn't work at all. It starts up and heats the bed and extruder then zeros out the axis. After coming to temp which I set to 192c for the PLA plastic and bed temp of 60-65c it tries to print. Now comes my problem. It acts as if not enough plastic is being... with the settings in Repetier-Host to see what I could come up with. In printer settings I got everything set up besides the Max Volume Per Sec. How do I figure this number out? I also messed with the settings

  • to prevent the issue. Here is the one that I am using now: http://www.thingiverse.com/thing:620627 I am running a Printrbot Simple Metal with a heated bed and have not been able to get my fan to run... settings, ensuring that fan operation is selected (starting at 0.6 mm) and that it is being told to run at 100%. I have also sent 'M106 S255' from Proterface UI (this, from what I have researched, should turn the fan on at 100%). This command had no results. The firmware is stock (Marlin), all exposed cables seem intact and without damage, and the plug to the control board seems to be fine. Maybe I

  • I have a Folgertech Prusa i3, on a Ramps 1.4 with Marlin and I use Repetier-Host to control it. I am attempting to convert it to a dual extruder Bowden setup, and I can't seem to get the second extruder to work, although the first works just fine. This is my problem: I am not getting a reading in Repetier-Host for the thermistor of the second extruder. It is at a constant 100C. When I turn... is indicated under the 'manual controls' tab. This is what I have double checked: I confirmed the second thermistor works because it indicates a proper temperature reading when plugging it in both T0

Data information