Hotend heating fast

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mac56_2100
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3D Printer(s): Hictop 3DP-17

Hotend heating fast

Post by mac56_2100 » December 11th, 2017, 11:32 am

Hi
I have replaced my hotend to a hictop stock hotend, now the temperature rapidly reaches about 50-60 over temp (ie 180 for pla) before slowly cooling

If I try ABS of 230 it goes past the 270 limit, thereby giving me a heating failure

Does anybody have any ideas why this is happening. I have changed the temperature sensor and the hotend wires on the board and have tried a number of different hotends and temperature sensors

The original hotend did not overshoot by around 5 degrees, surely it does not supposed to shoot up so high

Many thanks

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Roberts_Clif
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3D Printer(s): Hictop 3DP11/12

Re: Hotend heating fast

Post by Roberts_Clif » December 11th, 2017, 1:53 pm

How about some history of the machine, Is this a Stock Hictop 3DP17.

Measure the resistance of the Hot-end and Thermistor (please note temperature with thermistor reading).
Electronics Technician / Computer Programmer

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MTVDNA
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Re: Hotend heating fast

Post by MTVDNA » December 11th, 2017, 2:23 pm

You probably need to adjust the PID settings of your hotend.
See http://reprap.org/wiki/PID_Tuning.

mac56_2100
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Re: Hotend heating fast

Post by mac56_2100 » December 12th, 2017, 12:39 pm

Hi
Thanks for your replies, I haven't had chance to have a good look at it today, however I did notice that the Earth and Neutral to the power supply were incorrect way around from the diagram in the manual.
I will let you know again tomorrow on how i have got on

mac56_2100
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Re: Hotend heating fast

Post by mac56_2100 » December 13th, 2017, 5:55 pm

Hi
Just fitted a new hotend. Problem doesn't seem as bad as before. I have managed to do a successful print with PLA at 180 degrees. The hotend still heats up fast levelling out about 230 before cooling down to a steady 180 which i think there is still a problem there, as it shouldn't go that high.
At the moment i don't want to risk using ABS as it will go over the 270 limit when heating,
I tried a PID autotune at 180 but it failed and my electronic knowledge is limited so cant carry out measuring resistance of the thermister and hotend.
However i have reseated all the connections on the board and changed the leads to the power correctly. I think the diagram in the manual is wrong so be aware. And now the printer seems more stable now.
It is a Stock Hictop 3DP17 using the supplied firmware

Any suggestions?

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Roberts_Clif
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Re: Hotend heating fast

Post by Roberts_Clif » December 13th, 2017, 6:49 pm

I had the Stock firmware on my 3DP11 and 3DP12 for so short of a time cannot remember how it even worked.

I upgraded right off to Marlin-RC8BF-HICi3.zip this was posted by shocksofmighty. After using this firmware for almost a year continued my firmware update to Marlin 1.1.5 an currently still using. With Filament Run-out Sensor, Menu Baby stepping for Axis X,Y and Z, Menu Individual Home Axis X,Y and Z, Auto Bi-linear Bed Leveling.
And the Ultimaker PID
// Ultimaker
#define DEFAULT_Kp 22.2
#define DEFAULT_Ki 1.08
#define DEFAULT_Kd 114

I do know that your original firmware Hex file is on Hictop firmware web page

An this Marlin_3DP17_398.zip posted by Conundrum. After a quick look at it 3DP17 It appears to be very similar to my 3DP11 and 3DP12
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MTVDNA
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Re: Hotend heating fast

Post by MTVDNA » December 14th, 2017, 8:36 am

The PID settings are exactly what regulates how much power is sent to the heater, depending on the current temperature of the hotend (proportional -> P), how the temperature developed in the past (integrative -> I), and how fast it is changing right now (derivative -> D).

The influence of each of these is weighted with their own constant (Kp, Ki and Kp), as you can see in Roberts post, but these values differ for each individual machine, so using his may not work for you.

The autotune should heat up and cool down your hotend a few times, and then calculate the right PID values for your printer from the results.

If you set them perfectly, you could theoretically heat the hotend up to 180 degrees without any overshoot at all, but in practice this can be hard. Different temperatures also require different 'perfect' PID settings anyways, so I wouldn't put too much effort into it.

An overshoot of 50 degrees is way too much though, this really should not be more than 10 degrees, ideally less.

Can you show what error you got?

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Roberts_Clif
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Re: Hotend heating fast

Post by Roberts_Clif » December 14th, 2017, 10:13 am

They may not be perfect numbers, but they are numbers that are proven to work as a starting point.
I Have setup many Hictops with these Ultimaker PID numbers, and very few individuals have changed these stock numbers.

Here are the Others individuas PID numbers who have auto-tuned their 3D Printers.
I have a few of the working Stock Hictop PID numbers.
//PID numbers for Individuals I work with to get there Hictops working.

// Micron Tiger (fast PWM)
#define DEFAULT_Kp 36.15
#define DEFAULT_Ki 3.47
#define DEFAULT_Kd 94.04

//Hic 3DP-12
#define DEFAULT_Kp 17.22
#define DEFAULT_Ki 0.89
#define DEFAULT_Kd 83.25

//Hic 3DP-08
#define DEFAULT_Kp 20.84
#define DEFAULT_Ki 1.16
#define DEFAULT_Kd 93.21

// Hictop 3DP11 Factory numbers
//#define DEFAULT_Kp 17.22
//#define DEFAULT_Ki 0.92
//#define DEFAULT_Kd 80.43

//these numbers are my Auto-tune and did not work for me. Returned to Ultimaker default PID default numbers
// Hictop 3DP11
//#define DEFAULT_Kp 15.63
//#define DEFAULT_Ki 1.04
//#define DEFAULT_Kd 58.79

The numbers he is using and throwing the 3D Printer Nozzle 50C above what is set are defiantly not to be trusted.
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