I’ve been printing with my Vertex for a while, and generally it works well, but I’ve noticed for a while that the nozzle struggles to maintain temperature during a print, often dropping up to ten degrees below the target temperature, whereas I believe it shouldn’t deviate more than a couple of degrees (is this correct?). This is at PLA temps so shouldn’t be a problem at all for the printer (printing at 195, actual temp during print is often around 185-190).
For single nozzle prints this doesn’t seem to cause too much of an issue, but recently I’ve been doing a lot of dual nozzle prints and here it is causing a problem. After printing a layer or two, the printer parks the head at the side while it heats the first nozzle back up. This can take a while during which time it oozes material which then gets smeared all over the print, or it melts the prime/wipe tower.
I’ve tried using the PID tuning but it doesn’t seem to have helped much. I have a spare heater cartridge which I can try to install to see if the cartridge is the cause, as one nozzle is slightly worse than the other. Other than that the problem seems to be made worse by the small fan blowing on the nozzle. Am I right in thinking that setting the fan speed options in Cura only controls the larger radial fan? I know the small fan needs to cool the PEEK isolator, but is there a way I can turn it down a bit? The other option I’m considering is to try to find a different way of mounting the small fan so it doesn’t blow on the nozzle so much while still maintaining cooling to the PEEK, or some sort of shield for the nozzle.
I print ABS at 220 but lately I have real issues with it for the same reason that the nozzle struggles to get to the right temperature and then cools down too much while printing.
Thanks for the suggestions, I did check previously that everything seemed to be connected properly, but just to make triple sure I went back and screwed everything down as tight as I possibly could and tried another dual head print.
This one was a little better, although the nozzle did cool during printing it only dropped to 189/190 and was able to heat up reasonably quickly again between layers.
However it is still struggling to keep the nozzle at 195 which is still a fairly low temperature for a printer that should be able to print ABS. When I watch the temperature curve, I note that for the first 12 mins or so the temperature stays pretty stable, then after that it starts to drop steadily while the nozzle is printing even with the heater on full power the whole time, and then only heats back up when the printer parks the head to the side. It’s hard to judge how much this affects both nozzles as the second nozzle was only printing a relatively small amount of support material and the temperature curve in Repetier only shows one nozzle (is there a way to monitor both?)
So I’m still not quite convinced it is working as it should.
As far as I can tell from feeling through the insulation the thermistor is correctly mounted with the bead within the heater block. The room is centrally heated so 19-21 degrees C, with no open windows or draughts, so I wouldn’t have thought that would be a problem.
It’s hard to verify the actual nozzle temperature, I have an IR thermometer and also a temperature probe on my multimeter but as both would be measuring the outside of the heater block the measurement would still likely be different to the interior.
It’s worth noting that the printer has always struggled to get much above 220 C from the LCD panel. I had to change the load ABS temperature in the firmware as it will only reach 240 C either by manually heating it from Repetier and turning down the fan or by putting something in the way of the airflow to shield the nozzle while it heats up.
The main problem is that the fan blows cool air to the printer head (nozzle), and you should be carefull
to lower the fan speed too low, bacause then it is not cooling the hot-end enough. the best solution is to
make a deflection plate to force the air to the hot-end and not to the printhead.
I have seen several ways to do so.
I notices the same behavior. I am sure that it nothing to do with the electronics and/or connections, since it is depending on the position of the head above the bed. Upon lowering the bed, no problem to reach the set temperature, in the “home” position it was not possible. The flow of air by the big fan reflects on the bed in the latter case, causing too much cooling. I put a provisional shield of Al-foil on top of the heaters which solved (temporarily) the problem. Will figure out a better and nicer solution. Thinking of something like is on the heat-break of the E3D-hotends.
An update on this, I finally received a replacement printhead PCB from Velleman (delays due to Christmas post, not Velleman service) and this seems to have solved my problems, the nozzle temperature is staying much much closer to target, rarely more than 1 degree +/-, and dual head prints are now working properly without the long pauses to heat up and consequent oozing everywhere. This is even with the fan speed at maximum, whereas before I was having to do all sorts of hacks to slow it down.
I haven’t tried ABS yet, that is the next thing to check, but given how much better it’s working with PLA and PETG I’m optimistic I should be able to get it to reach the right temperatures.
Thanks again Velleman for the prompt dispatch of a replacement part.