After fusing a couple of meter of ABS, I started gathering some interesting information related to the printing of such material on the Vertex.
245°C is definitely the proper setting for ABS on the Vertex, although this point is quite higher than on other ones with different extruder designs.
The set point is achieved in quite a short time so that it does not take ages before the print starts: good point. And the parameters on the PID look like they do the job quite well without the least overshoot and still a fast rising temperature: an other goo point (BTW, ou may check this series of posts on PID http://goo.gl/CulBi
And now the issue: after printing for a few seconds, the temperature decreases although the heater is in a steady ON state (confirmed by plots from the Repetier interface) Under these conditions, the actual temperature drops down to 230°C and even lower. This worsens when I switch the layer height from 0.1 to 0.2 mm which looks logical but drives to incomplete fusing and poor print quality. I also checked the power supply which is 15 V (P = U x U / R, checking U makes sense!). Room temperature is 24°C. For sake of safety I took the extruder apart and checked the sensor’s position (quick and dirty: remove insulating sleeve, measure wire length, replace sleeve, mark position and reinstall)
Maybe the power of the heater is to low. I think it is 30W and if the LED for the heater is constantly on it means that the heater is on and can’t supply enough energy when the melt energy is sucking heat. I changed my to a 40W and that was an improvement. Later on I replaced the nozzles with E3Dv6.
Best Regards
Swapping the heater cartridge is a reasonable option, but I did not expect to replace a part 1 week after buying a new product ! There might be other options that I want to investigate first. And I want Velleman to support a swap with a resistor featuring lower resistance and thus higher current. Also, the PID is setup for a typical thermal profile. How the heater will behave at lower temperatures ? (e.g. PLA)
Anyway, thanks for helping
I ran some tests after setting the power supply output voltage to 16V: it helps a little.
As this change did not bring significant improvement, I switched back to 15V and I used various cooling fan speeds: it help a lot ! On the other hand the cooling of the printed layers will be degraded :-s
Thus the need for a fan duct in order to concentrate the air flow down to the nozzle tip…
The needed temperature to print ABS is highly depending on the way your thermistor is making contact with the heater block. Usually the contact is quite poor (big hole, isolating sleeve…) and the actual temperature is a lot higher than the displayed one (I’m printing ABS at 210 - 220°). ABS doesn’t need cooling. So I’ve lowered the fan speed in the Start G-code to 80 and set the small fan horizontally (BTW this allowed me to get back 2 more cm on the Y axis). That way it works like a charm and my ABS prints are perfect.
I carefully check that. Earlier, I dismantled the print head in order to make sure that the bulb was in place (on not just the “bump” in the insulating sleeve). I found no error there.
Very true: I installed a very thin thermocouple next to the thermistor (Yes, there is quite a gap!) and measured a difference of up to 20°C between the set point and the print head ! I will try to think about a simple upgrade. Having in mind that filling the gap with thermal grease will not suffice as the insulating sleeve acts as … a thermal insulator
Interesting. So far I am running tests on PLA, but I am eager to try the ABS (I am in fact more familiar with ABS that I use a lot at work).
Are you using a heated bed ? Which one ? Any hint for the Vertex ?
Thanks for the constructive help
I first used an MK3 and now Marlak’s heated bed (check the “Your printer creations…” topic). I’m printing directly on the bed coated with a 3D adhesive spray at 100°. To use a bed you’ll need a new PSU and a power expander (or DC-DC SSR).
I see. I ordered a MK3, additional PSU and I plan to use a simple P-channel MOSFET transistor. My idea however is to print on glass (as I do on other printers). I’ll let you know.
