Makerfarm Prusa I3V nozzle temp issue...

[huntleybill]

My printer was working as it should. During a recent print using PLA with a nozzle temp of 215, bed temp 80. Shortly after the first layer was printed the nozzle temp drops to 190 for no obvious reason. The only firmware change I made recently was re-calibrating the e-steps. Even if I go into the display and re-enter the temp to 215, the temp never goes back up. The display will read 190/215. I thought it might be the firmware got corrupt. I reinstalled the firmware and that did not fix the issue. I checked all my connections and do not see anything wrong. Everything is plugged in. I made sure that I did not inadvertently set something wrong in Slic3r, all was ok. I DO have a part cooling fan but that is turned off.

Can anyone tell me why this is happening?
Thank you for your time.
Bill

[printbus]

I'd include info on exactly what you're using for firmware. Are you using a MakerFarm baseline or a newer version from the Marlin github?

EDIT: One of your other threads says the setpoint inexplicably changes away from the initial 215. Is that true? If so, post a copy of a gcode file where that happens to pastebin, dropbox, or somewhere so we can look at it to confirm there's nothing in the gcode to explain it.

If the setpoint isn't inexplicably changing, don't rule out a hardware problem...

Is the heater clamped tight in the hot end? If it is loose it can't heat the hot end properly. Or maybe the hot end heater is failing.

How securely is the thermistor attached to the hot end? If it is a bit loose, the thermistor will likely read a lower temperature than actual. Depending on how bad the thermal connection is, the hot end could appear to never reach temperature when it is actually running way over temperature.

How are the wires from the hot end heater and thermistor bundled and routed? Are they tied in any way that keeps the wires from shifting at the heater and thermistor as the x-carriage raises up during a print? Wires tugging on the hot end would aggravate issues with a loose heater or thermistor.

How much faith do you have in your power supply? Printing with the heated bed is going to put a hefty load on the power supply. Have you measured the power supply voltage during a print or at least when you're having the hot end temperature issue to make sure it is still outputting what it should? I seem to recall a thread from a few months ago where the power supply died while we were troubleshooting a similar setpoint issue with either the hot end or the heated bed.

[huntleybill]

Thank you Printbus. Let me answer your questions first.
Marlin firmware V1.1.0 It has been working with no issues.
Yes, the temp the setpoint inexplicably changes away from the initial 215. That is my issue. I sent a copy of the G-code to Colin and he found no issues there.
I checked the heater and thermister for looseness or shorted wires or loose plugs and did not find anything (that does not mean there isn't any issue there).
The thought of a bad or going bad power supply never occurred to me. I will check that and see if that is the issue. Thinking about that, it would make sense with respect to the symptoms.
I have the wiring zip tied to hold the bundles in place the minimize/prevent movement.

[printbus]

One more idea - are you printing from the SD card or via host software? If host software, what does it show as the setpoint temperature when the printer lowers the temp setting?

[huntleybill]

I am printing from an SD card.

[huntleybill]

Update
I put a meter on the hotend heater wires where they plug into the Ramps and it reads 11.6 VDC. I started a print from the SD card. While the bed was heating up, the voltage at the hotend heater stayed at 11.6 VDC (of course). When the bed heating was done, with the ABL process started the hotend starts it heating process. At this point I observed the voltage would fluctuate from 2.9VDC to 9VDC (note: while this was going on, the display kept showing a steady increase of heat to the hotend no matter what the voltage dropped to).

I noticed that when the bed heater kicked on (I have the bed relay upgrade) to maintain the bed temp while waiting on the hotend to reach temp, the hotend voltage would drop. So, I'm thinking I may have found my issue BUT...... here is where I thought things got weird. After the hot end heated up to 215 and the bed was at it's temp the print started and the hotend temp maintained 215 degrees UNTIL the printer finished the first layer. When the second layer started the hotend temp started dropping and leveled off at about 183. it would then fluctuate from 183 to around 194 degrees but as you might imagine the filament wasn't going through as needed.

So...power supply???? I would have thought so but I don't see a correlation between the first layer temp being stable and then dropping from the second layer on.

Your thoughts?

[printbus]

One important point is don't try to measure the voltage at the hot end heater. Once the hot end is at temperature, Marlin will start toggling the power on and off fairly quickly to maintain temperature. What you measure for DC voltage will depend on the rate Marlin toggles the output, as well as your meter and things like the sample rate and how it averages over multiple readings. For more valuable info, measure the output of the power supply or the 12V input at RAMPS.

A power supply problem might explain the hot end not reaching a set point, but would likely not explain the setpoint changing by itself. Roxy or some other Marlin expert would need to chime in, but in the 2+ years I've been monitoring the MakerFarm subforum, I don't recall anyone ever having an issue with the printer changing the temp setpoint by itself. Knowing that the temp stays stable until the end of the first layer sounds more and more like it is your slicer setup that is changing the setpoint after layer 1 and the printer is doing what it is being told to do. Are you *sure* the "other layers" filament temperature setting is set to the same as the "first layer" setting in Slic3r? Similarly, are the bed temp settings the same for layer 1 and other layers?

[huntleybill]

I just looked at Slic3r again. I have the first layer set to 215. The "other layer" is also set to 215. The heat bed first layer is set to 80 and the "other layer" is set to 80. Is there another place

[huntleybill]

UPDATE:

I tried a couple of things that I hope are helpful.
I took out and loaded another roll of PLA that has a lower extruder temp requirement. So, I set the Slic3r print to make the hotend 185 and the bed 80. It printed the part completely without any drop in hotend temp. The hotend remained stable at 185 through-out the print job.

Then, I went back into Slic3r and loaded my PLA settings for printing with a hotend setting of 185. I then changed JUST the filament temp from 185 to 210 and created the stl file. I loaded it on the SD card, and started the printer. As soon as the second layer started, the hotend temp dropped from 210 to 185.

While all this was going on, I monitored the voltage coming out of the power supply and it NEVER wavered from 12.4 VDC.

So....I have NO idea what to do from here!!