Print not starting -> extruder Temperture

[coolm8 0]

I downloaded cura 2.1 and wanted to print with colofabb xt so i chose the CPE material.

Now the printer does not start printing beacuse the extruder temperature always fluctuates between 240°C to 258°C back and forth. I tried to modify the machine settings extruder_heatup_speed and extruder_cooldown_speed, but this did not help.

Note that i upgraded  my Ultimaker Original shortly with the E3D V6 with the PT100 and yesterday with an aluminium heatbed. Before the heatbed and with the old curra i could print even though then it was fluctaing as well.

What could be the issue here?

Edited June 12, 2016 by Guest

[Torgeir 212]

Hi coolm8,

When it fluctuated "before", did you have the old thermocouple as a temperature sensor, or did you use the same PT100 sensor there as well?

Does your PT100 thermistor have a loose fit before you lock it?

What happen if you print without the heating on the bed?

If you have a loose fit of the PT100, then this prevent proper thermal conductance between the aluminum block and the stainless steel housing of the PT100.

This will create such fluctuation, because the thermal properties between the aluminum block and the stainless steel housing of the PT100 is not like what the firmware is tuned for.

To cure this, you may use “copper paste”, the one that can stand 1100 deg. Celsius! Check the properties of the one you find before buying/using it!

This stuff is used on cars, for brake pads, exhaust pipes and spark plug. Etc.

It has very good thermal conductance and prevent parts to burn stuck.

One of the best thing with this copper paste is, that the thermal properties is best around (200-300) deg. Celsius.

One thing more, when adding copper paste, add it to the hole's in the aluminum block (yes it can be used for the heater as well). Don't overdue it, you should just fill the open space around the PT100/heater. Have a rag ready to wipe off any excess copper paste. Also, when doing this be very careful and do not bend/straiten out those wire going into this two elements. They are to easy to break...

Note: When you heat this up first time, you sould be able to see the two “elements”, cause it will oze out some exsess of the copper paste here and smoke a litlle, so have good ventilation. Rise the temperature slowly and use this rag. When you reach max, temperature and there is no oze or smoke, -you are ready.

And yes, this was one of the first thing I did on my 3D printer.

This setup require a power supply that's delivering enough power without any fluctuating voltage during any part of 3D printing. Should be able to deliver about 30% more amps than needed.

Good luck.

Thanks.

Torgeir.

[coolm8 0]

Hi Torgeir,

Thanks for the info, i^ll gonna check that. For now I've set the wait time for M109 from 10 to 5 and it works so far.

The only issue now is that it prints half the intended size. The steps per units are correctly configured, but somehow the printer does not print the object in the center where it should be and as i said in half the size.