#Problem with bed heater

31 messages · Page 1 of 1 (latest)

shut crown
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My new-ish (about 120 print hours) 350mm machine is having a problem with the bed heater. It now will typically shut down while heating the bed with the error that it's not heating at the expected rate. I restart the machine, and then I can typically continue.

The heater I am using is a Keenovo Fermio style, 750 watt. I have it set to a max of 80%. Initially, it would heat up with no issue. Now, it seems to strugle. It will get to 110° in about 20-25 minutes, and it requires about 50% to maintain this. I need the 110° to keep the ASA adhered to the bed; 105° and they can pop off.

I have the Ellis bed fan mod, which really helps with chamber heating. I did not retune the bed after adding these (because I didn't think to) but when looking at the error, it doesn't seem like something tuning would impact. The temperature of the bed is just not changing rapidly enough.

I read on Keenovo's site that they don't really recommend using it over 100° as it will shorten the life of the heater. I'm not sure why this would be, but, there it is.

Is this a common issue? Is there a better bed heater that would handle the 110° better?

torpid fog
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Could you show us the graph of it trying to heat?

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The error absolutely something that can be impacted by pid tuning though. You definitely need to redo your pid tuning, if you're trying to heat the bed with the fans running

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That being said, I'd also suggest not starting your bed fans until the bed has reached temp

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@shut crown

shut crown
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@torpid fog thanks for the info. Next time I heat it (it’s printing now) I’ll first tune and then capture a graph. I don’t think that’s kept in printer history.

torpid fog
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It kinda is. You can take the klipper log, and then graph it with klippylyzer.github.io, but sounds good. See if the tuning fixes it, then we'll go from there.

shut crown
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@torpid fog Ah! I somehow did not know about the analyzer! So I learned something today. Thank you! Here is the graph, zoomed in to the relevant area. The down dip is where the machine shutdown & I restarted

torpid fog
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bed fans running, or no?

shut crown
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No, this was before.

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I'm still waiting for the bed to cool to ambient to tune.

torpid fog
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I don't personally think you need to cool all the way to ambient

shut crown
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355mmx355mmx9mm takes a bit to cool.

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Ah.

torpid fog
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all the stuff tuning is interested in happens fairly close to the high end

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if you're starting from like 50 or 60c, Id expect it to be fine

shut crown
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Ya, it's 33° now.

torpid fog
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that'll be fine

shut crown
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Should I use the default of 60°?

torpid fog
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no, I'd tune up around 100 or 110. whatever your high end temp is going to be

shut crown
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Running now. Does the ~20 minutes seem unreasonable for going from 18° to 110° at 80% of 750 watt?

torpid fog
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it's a little long, but not crazily so

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are you in 120v land or 240v land?

shut crown
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120v.

shut crown
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Well, I don't know how to interpret the numbers, but they changed a good deal. I'll give these a try and see what happens.

distant girder
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Did you try some external thermometer to see if it's not giving you false temp?

steep cliff
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I assume you've got the heater bed issue sorted at this point - you might want to consider the use of printing glue to help adhesion (in addition to dialing in temp + z offset, etc). I found that glue gives you a lot of margin and it can help if your bed is cooler than you'd like.

shut crown
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I have the shutdown issue resolved; but, it still seems to take a good deal of time. And now about 50%-55% to keep it at 110°. And I do use an infrared thermomater to check the bed top temp.

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One of the premium bed makers has the top machined to accept a sensor; I wish I'd got that one. My Mandala Roseworks right now - trying to get PETG to print - is at 80° on the bottom, and even after a 10 minute heat soak is only 67° on the printing plate.