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Extruder heater temperature swing

davejones

Extruder heater temperature swing
July 30, 2011 12:54AM

Registered: 12 years ago
Posts: 35

My extruder heat swings +/- 4c from the set temperature i.e. when set for 210c it ranges between 206c and 214c when not extruding. Is this ok or can it be improved? I'm using Sanguinolou running sprinter and my hot end is basicaly Adrian's push fit.
Dave

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kdrummer

Re: Extruder heater temperature swing
July 31, 2011 11:43AM

Registered: 12 years ago
Posts: 12

What kind of temperature swing do you get at lower temperatures?

Is there any possibility that the leads on your thermistor are touching one another (not properly insulated)? I would measure the resistance with a meter when it is hot to see if the resistance is varying a lot.

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NelsonRap

Re: Extruder heater temperature swing
July 31, 2011 07:56PM

Registered: 13 years ago
Posts: 862

Mine does that but it doesn't seem to affect print quality so I ignore it

__________________________________________________________________________
Experimenting in 3D in New Zealand

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davejones

Re: Extruder heater temperature swing
July 31, 2011 10:59PM

Registered: 12 years ago
Posts: 35

NelsonRap Wrote:
-------------------------------------------------------
> Mine does that but it doesn't seem to affect print
> quality so I ignore it

That's the kind of answer I like! I can't print yet as my stepper drivers seem to have disappeared into a postal black hole.
I guess that if the temp swing does affect my prints, I could look at insulating the hot end.

Edited 2 time(s). Last edit at 07/31/2011 11:00PM by davejones.

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DeuxVis

Re: Extruder heater temperature swing
August 01, 2011 03:40AM

Admin
Registered: 12 years ago
Posts: 2,569

I believe what you see is an artifact of the way the temperature is controlled, switching heat on when under target minus a threshold and switching off when over target plus threshold.

See nophead's blog entry about bang-bang temperature control.

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nophead

Re: Extruder heater temperature swing
August 01, 2011 04:58AM

Admin
Registered: 17 years ago
Posts: 7,879

I get about +/- 2 or 3C with aluminium heater blocks and +/-5C with a brass one.

[www.hydraraptor.blogspot.com]

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davejones

Re: Extruder heater temperature swing
August 01, 2011 05:47AM

Registered: 12 years ago
Posts: 35

The heater block I'm using IS brass. I'll knock up an aluminium one and give that a go. Thanks