Hot end slowly losing heat over print
Hey guys,
I got my prusa i3 a couple months ago and I love it! I've been able to figure out most of the basic tweaks and repairs I've needed to take care of, but I've run into a little problem that I can't quite figure out how to troubleshoot.
My hot end nozzle will heat up to the right temperature, then over the course of the print it'll slowly drop down a few degrees. It's nothing too much, and I've been able to do a little workaround so far by just setting the temp to a few degrees higher. I'm kinda at a loss on how to even go about checking to see what's wrong. the heater connector on the rambo board is nice and tight, and I replaced the nozzle in case there was some kind of clogging that could have been causing the temp to drop. Could anyone give me some help on how to figure out what's going on? I know this is minor but I'm a little worried it might get worse as time goes on.
Twitter: @firr
Re: Hot end slowly losing heat over print
Hi Will
This can be caused by an user-powered heater cartridge. They are supposed to be 30W, but some are being shipped from E3D as low as 24W, which makes a whole load of difference when the part fan turns on.
Easiest way to check is to disconnect the extruder heater at the RAMBo ens and put a multimeter across the screws terminals of the connector. Let us know the resistance.
Peter
Please note: I do not have any affiliation with Prusa Research. Any advices given are offered in good faith. It is your responsibility to ensure that by following my advice you do not suffer or cause injury, damage…
Re: Hot end slowly losing heat over print
I had the exact same problem. I had to turn my fan down to 55% for it to stay around 210 degrees when the fan started spinning (though it usually dropped to around 206-207 anyway). As Peter said, this is due to some bad tolerances and quality control from E3D (which I found strange and pretty lousy, given that the 3D printed community are composed of technically capable people and was bound to find out about this).
Contact support and they will send you a new one. I did this, and my current one actually acts just like the heat bed; It might reach 211 degrees, in which the board will turn off the power for a short while until it drops to 209, even with my fan now going on full speed.
Short time sollution: Turn your fan down to around 60% - Long time sollution: Do as Peter says, read the resistance over the cartridge. If it's high (like 6-6,5 ohms or so) get a new through support. They're supposed to be around 4,8-5 ohms.
/Sascha