After doing PID tune it look goods again but the bed is showing spikes in the graph.
Why would the bed temp show spikes? They seem false because it could change that much in that short period of time.
Bed is showing spikes in the graph
Bed is showing spikes in the graph
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- BedTemp.JPG (39.43 KiB) Viewed 10195 times
Re: Bed is showing spikes in the graph
That suggests the thermistor wires are:markb wrote:Why would the bed temp show spikes?
- making intermittent contact in the connector or
- have a break between the bead and the connector
Re: Bed is showing spikes in the graph
Thanks I will look at it when the print finishes.
Re: Bed is showing spikes in the graph
Interesting that all the spikes are downward. Most thermistors (and other conductors, for that matter) have higher resistance at higher temperatures. Now, it may be that the firmware is reading the temperature as zero when the thermistor circuit is open, and the graph is plotting a smoothed temperature trend, so you don't see the spike go all the way to zero. (Might have a look at the communications from the printer when the software is polling the temperature -- see if the number returned is zero.zero or something else....) Anyway, what I'm getting to is this: also look for some little bit of wire or other conductive stuff getting into the circuit --- a short rather than an open. Granted this is highly unlikely --- a loose or intermittent connection is most common --- but it wouldn't hurt to inspect for this other possibility...
Hope I'm wrong. But I do enough electronics projects that I get little strands of wire into places they shouldn't be when I'm not careful. Getting one in the electronics enclosure could lead to a bigger problem if you don't get it out of there!
Ask me what smoking 2-watt resistors smell like!
Dale
Hope I'm wrong. But I do enough electronics projects that I get little strands of wire into places they shouldn't be when I'm not careful. Getting one in the electronics enclosure could lead to a bigger problem if you don't get it out of there!
Ask me what smoking 2-watt resistors smell like!
Dale
Re: Bed is showing spikes in the graph
Strange after some time the spikes are gone.
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- BedTemp2.JPG (36.73 KiB) Viewed 10187 times
Re: Bed is showing spikes in the graph
Dale, we actually use NTC (negative temperature coefficient) thermistors - the resistance starts at 100kΩ(±1%) at 25°C, and drops as the temperature increases (35kΩ@50°C, 6.2kΩ@100°C, etc.). So a spike to 0 is actually an intermittent open circuit (and a short is generally read as 359.9°C).
Re: Bed is showing spikes in the graph
Thanks for all the help!
It was the thermistor connector coming apart. It was about ¼ the way apart. I put it back together and used some black elect tape to help it stay together.
I am doing a few hour print right now and it is working great again.
It was the thermistor connector coming apart. It was about ¼ the way apart. I put it back together and used some black elect tape to help it stay together.
I am doing a few hour print right now and it is working great again.