reprap prusa i3 need help

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Fr0z7y
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Joined: September 24th, 2019, 10:08 am
3D Printer(s): prusa i3

reprap prusa i3 need help

Post by Fr0z7y »

okay, i have a problem, that's probably covered or known but asking someone that would know might be easier.

i have ran autotune so many times now it's hilarious, which i have found that using that will also clear out the excess pla that may have been in there if i accidentally clogged it. however, the question is, since i keep my house like 21c and the hotend looks like the e3d with a fan blowing across it, would this be causing the temperature fluctuations? the cooling and heating is very rapid. it shuts off right at 200c, will hit 203c, then drop to 194c sometimes only 197ish, that's also when i turn it so there is less airflow across the extruder heatsink for the material shaft thing. yeah i know it's really late for me and im forgetting the names of things. ive wrapped some tinfoil around it, that seemed to help a little, i guess i may be trying to confirm this. i literally am starting to go a little nuts with this thing considering the first heating element (that red wire thing) was bad, and several times i had to take it apart and put it back together because of this being my first time with this kind of thing.

also, it is ramps and atmega 2560 , it says marlin 1.1.6 on startup (i have read several hours ago in some forum that 1.1.6 marlin caused some really weird wild autotune readings that kept the temperatures changing rapidly).

oh, i must also point out, i had the "original" style k8 extruder/hotend thing on there and it didn't have this problem not but 2 days ago, where i started having the problem was i clogged it and like any newb, wanted the cooler looking one and wanted it on there instead. also didnt want to wait for the tools to unclog it. thus my problem. either way, with the new style hotend, wouldn't it be better to keep heat creep off the pla, as well as better termperature control, assuming i ever get this under control?
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GrueMaster
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3D Printer(s): Hictop 3DP-17, Hictop CR-10S

Re: reprap prusa i3 need help

Post by GrueMaster »

It sounds like you may have a thermistor going bad. I have two printers, and the only time I had issues similar to that was when the thermistor was broken (still worked but as soon as I tried to adjust it, it shattered and came apart).
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Roberts_Clif
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3D Printer(s): Hictop 3DP11/12

Re: reprap prusa i3 need help

Post by Roberts_Clif »

DO NOT take your eyes off the temperature reading during PID tuning process.

"P" controls the re-activeness. It is called "proportion", think of it as "power"
"I" fine-tunes the result you get from P, will also make the temperature oscillation more "peaky.
"D" smooths out the result. Increase this to take the "wobble" out of the temperature

In addition to the P, I, and D variables, you can set the maximum current.
You may want to limit the current to hot-end, if you're using 12V heater(s) on a 24V system


Additional Information for PID auto-tuning that may help
https://mattshub.com/2017/04/26/pid-tuning/
cathpeta50
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Re: reprap prusa i3 need help

Post by cathpeta50 »

GrueMaster wrote: September 25th, 2019, 10:01 am It sounds like you may have a thermistor going bad. I have two printers, and the only time I had issues similar to that was when the thermistor was broken (still worked but as soon as I tried to adjust it, it shattered and came apart).
Yes, it's always a hassle when you no longer have this thing operational.
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