Preheat ABS Bed Heats bed but the Hotend stops at 25 C.

[3dguy 0]

Hello,

I just finished building my heated bed and putting my new build platform on my UM 1 and upgraded my firmware and the bed heats up fine. I noticed an issue though when I go to the option to Preheat ABS, "ABS Bed", the Fan comes on at full (255) right from the start and the bed starts to heat steadily, however the Hot-End stalls at 25 C. If I choose ABS 1 under the preheat option both the Hot-End and the Bed heat together.

Is it a known issue or just an issue with the firmware the builder made for me. Should I rebuild the firmware?

I have a print going now and is seems to be printing fine.

Thanks

 

[Dim3nsioneer 557]

That's exactly what the fw is supposed to do. The option 'preheat ABS Bed' means to preheat the bed only without preheating any hotend.

Its background is the fact that some heated beds take quite some time to reach target temperature. The hotend might be leaking all the time and at the time the bed is finally heated up, the hotend is empty enough to cause serious underextrusion. Or even worse, the filament is very sensitive and is burned to a brownish slack during the heat-up time of the bed and might cause a clog.

[3dguy 0]

Ok, I was thinking it was the other way around. That makes total sense though.So it is working perfectly then, boy do I feel stupid. Thanks for the information.

 

[Dim3nsioneer 557]

The question wasn't stupid at all. Actually it would be better if 'Preheat ABS Bed' could be 'Preheat ABS Bed Only' but there is not enough space on the display. There is even a bigger problem with the number of digits in other languages than English (Marlin comes in 13 languages up to now).

But there is another issue related to the 'Preheat PLA/ABS Bed' options. When you select a preheat option including a hotend and select the bed only option afterwards, the hotend is still on. I think, it should then switch off the hotend. What do you (or others!) think?

 

[3dguy 0]

I totally agree. When the ABS Bed choice is made it should completely turn off the hot-end. It makes sense that the ABS 1 choice does not turn off the bed since you want the bed hot before the hot-end.