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Why preheat bed to unload filament?  

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Lensdigital
(@lensdigital)
Active Member
Why preheat bed to unload filament?

So when unloading filament from control panel it asks to preheat hotend. Makes sense.  But why it preheats the bed as well?

 

Best Answer by rmm200:

The assumption seems to be you are unloading to change filament and print.

I wish it did not. Heating the bed on filament load makes more sense.

But then I also wish it turned off hot end and bed after unload.

Posted : 23/09/2019 8:47 pm
rmm200
(@rmm200)
Noble Member
RE: Why preheat bed to unload filament?

The assumption seems to be you are unloading to change filament and print.

I wish it did not. Heating the bed on filament load makes more sense.

But then I also wish it turned off hot end and bed after unload.

Posted : 23/09/2019 9:55 pm
Nikolai
(@nikolai)
Noble Member
RE: Why preheat bed to unload filament?
Posted by: @robert-rmm200

But then I also wish it turned off hot end and bed after unload.

I think the assumption is that you want to load a new filament and continue printing 😉

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Posted : 23/09/2019 10:09 pm
Sembazuru
(@sembazuru)
Prominent Member
RE: Why preheat bed to unload filament?

I've noticed the same thing and either modified my behavior to manually heat the hotend (either from the control panel, or another interface like Pronterface), or modified my attitude and decided not to care that the bed was being heated up.

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PrusaPrinters - https://www.prusaprinters.org/social/1448-sembazuru/prints
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Posted : 24/09/2019 2:10 am
Lensdigital
(@lensdigital)
Active Member
Topic starter answered:
RE: Why preheat bed to unload filament?
Posted by: @sembazuru

I've noticed the same thing and either modified my behavior to manually heat the hotend (either from the control panel, or another interface like Pronterface), or modified my attitude and decided not to care that the bed was being heated up.

Yeah good point. I usually heat up my nozzle from OctoPrint to 180 and retract, this way it pulls out most of the filament out of nozzle while it's still semi-solid. That's why I was surprised that menu option wants to not only preheat nozzle to full extrusion temp, but also heat up bed.  Oh well..

Posted : 24/09/2019 2:14 am
BillC
(@billc)
Reputable Member
RE: Why preheat bed to unload filament?

LCD menu Settings | Temperature | Nozzle , set temp, wait, unload filament, Setting | Temperature | Nozzle - back to 0.

 

Bill
Tagaytay City, Philippines
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Posted : 24/09/2019 11:15 am
Lensdigital
(@lensdigital)
Active Member
Topic starter answered:
RE: Why preheat bed to unload filament?
Posted by: @billcampbell

LCD menu Settings | Temperature | Nozzle , set temp, wait, unload filament, Setting | Temperature | Nozzle - back to 0.

 

That completely defies the purpose of quick convenience of easy load/unload menu option...

Posted : 24/09/2019 11:37 am
gnat
 gnat
(@gnat)
Noble Member
RE: Why preheat bed to unload filament?
Posted by: @leonid-k
Posted by: @billcampbell

LCD menu Settings | Temperature | Nozzle , set temp, wait, unload filament, Setting | Temperature | Nozzle - back to 0.

 

That completely defies the purpose of quick convenience of easy load/unload menu option...

I think the convenience option is there and configured as such because the expectation is that most of the time you are unloading so that you can change filament and then start printing. If it just simply heated the nozzle then I expect more people would be irritated by having to remember to also heat up the bed or waste more time waiting for the bed to warm after they start their print.

What I would like is a timer on the pre-heat option so that if a print is not started in a given period of time, it automatically turns the heaters off. I've forgotten to turn the heaters back off after a simple unload and come back to find things had been hot for 8 hours ☹ 

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Posted : 24/09/2019 4:14 pm
Nikolai
(@nikolai)
Noble Member
RE: Why preheat bed to unload filament?

@gnat

The thing is that people are using their printer in a very different way. Once you set a time limit there will be people complaining because they are using the preheat option to really preheat the enclosure/printer. So they let it stand for couple hours in this state.

I don't see any easy ideal solution for this problem.

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Posted : 24/09/2019 4:25 pm
Bunny Science
(@bunny-science)
Noble Member
RE: Why preheat bed to unload filament?

If it REALLY bugs you, it is fairly trivial to alter the firmware to avoid heating the print bed during pre-heat.

Change the HBP temps in Configuration_prusa.h to zero. For instance....

/*-----------------------------------
PREHEAT SETTINGS
*------------------------------------*/

#define FARM_PREHEAT_HOTEND_TEMP 250
#define FARM_PREHEAT_HPB_TEMP 80

#define PLA_PREHEAT_HOTEND_TEMP 215
#define PLA_PREHEAT_HPB_TEMP 0 //no bed preheat for PLA by changing to zero

 

Posted : 24/09/2019 4:32 pm
Nikolai
(@nikolai)
Noble Member
RE: Why preheat bed to unload filament?

@guy-k2

But then you have to compile it every time new release is available.

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Posted : 24/09/2019 4:48 pm
gnat
 gnat
(@gnat)
Noble Member
RE: Why preheat bed to unload filament?
Posted by: @nikolai-r

@gnat

The thing is that people are using their printer in a very different way. Once you set a time limit there will be people complaining because they are using the preheat option to really preheat the enclosure/printer. So they let it stand for couple hours in this state.

I don't see any easy ideal solution for this problem.

Ewww. That seems painfully inefficient and expensive. Seems like a separate heater would be much faster and more efficient for that.

I agree though that we all do things slightly differently so such changes have to be carefully thought out. Was just saying it would be nice is all. I'm lucky enough to have my printer in an out of the way place so that I have little concern about fire or injury risks from such a situation, so it's just the irritation of something slipping my mind and the associated waste of energy that bugs me 😉 

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Posted : 24/09/2019 4:51 pm
Bunny Science
(@bunny-science)
Noble Member
RE: Why preheat bed to unload filament?

But then you have to compile it every time new release is available

Not much effort actually. I'm readjusting and tweaking firmware a lot more frequently than most. The compile and flash process is not much effort once you learn the first time. Not for the less technical forum members, but it is THE way to get things behaving as you wish.

I wanted a polycarbonate preheat preset. So I added one. 

Posted : 24/09/2019 5:10 pm
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