Hey there, I just finished constructing a Prusa Mendel i2, I’m using RAMPS 1.4 with the latest marlin firmware from github.
Everything moves fine, no hang ups, it’s all smooth moving and beautiful. Now here’s the issue, when I did the PID auto tune, it ran fine, and the temperature held at 200 perfectly. But when I do the 20mm cube calibration print it starts out great, I have good base layer adhesion, and it extrudes well. But after a couple layers into the build the temperature drops off, slowly but constantly, and won’t start heating again until 170, but then back up to 200 perfectly. I tried this with and without filament, same situation. I’ve poured over code, and though I’m a novice I couldn’t find anything. Of anyone could help me with a fix, this is killing me.
Contact me with any information you need from me to help.
I remember seeing a setting to change the time between checking temp. Maybe the delay is too long? BTW I’m a novice still.
What hotend are you using?
I bought the Aurora i3 off of Amazon. I’m using the default it came with. It says K type extruder?
Okay next questions. Does it say specifically what thermister it came with? Which one do you have selected in the firmware? It looks like it has a heater block so it shouldn’t have any issues heating up fast. What PID settings are you currently using?
200? So you are probably using PLA, and a fan aimed at the hotend. So if you had no fan on while auto-tuning, there is a good chance your PID setting are probably way off.
Another reason I only print ABS. I’ll look at the files this afternoon but tuning with the fan on definitely makes sense if you did not before. It would cool down the hot end much faster than expected by the settings used without it so it won’t recover fast enough.
@Shawn_Nguyen I saw the setting, in my marlin it’s based off of a formula, which I tracked down and I even commented that out and put the interval at 0.168, same issue.
@Ryan_Hescock_Stanos I have a full metal hot end I got from Folger http://tech.com. I don’t recall it having a name per se
@Ryan_Hescock_Stanos I actually had that same thought on my drive into work today, I haven’t had time to test it, but it’s the only thing that really make sense to me. I am going to check again online to see if it says specifically which thermistor, of not I will send emails. Worst case I will get a known type thermistor and put that into the firmware.
Most common is going to be the Epcos 100k, give that a try. If you have something to take a reading you can compare the actual temp to the reading you get from the firmware and confirm that you have the right table. You may also want to give the standard E3D settings a try just to see if they work since that looks like a bit of a clone of their system.
UPDATE: Thank you all for the help! I finally had some time to play with it and rather than sorting through lines of code, I made notes of my values and erased my current firmware version, got the zip from github again, and put my values in, then uploaded. Now it stays hot perfectly! I don’t know what the issue was, but that’s behind me now thank goodness. Now I’m working on calibration prints, but the mechanics of the extrusion system seem to be flawed in some way. Several times now the filament breaks off and won’t feed, I’m thinking an alignment issue and when I have time I will look closer into that issue. Thanks again!