Delaying hotend heating  

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pedja
(@pedja)
Eminent Member

PrusaSlicer starts heating both hot end and bed at the same time. Hot end gets to target temperature much quicker and cooks filament while waiting for bed to heat up.

With filaments that require higher temperatures this issue is even more evident - hot end cooks filament on higher temperature and waits longer for bed to heat up.

It would be good to have defaults set in a manner that hot end heating starts later, when bed is already at required temperature or close enough.

Even when both temperatures are reached there is still delay waiting for temperature to spread evenly on bed (which is a must for successful print of large objects).

If bed is heated first then time waiting for hot end to heat up would also serve as time for spreading temperature evenly on bed, reducing additional delay.

Users can achieve this by altering configuration in PrusaSlicer but it is advisable to have this settings as default.

This topic was modified 2 months ago by pedja
Posted : 19/06/2020 10:01 am
Tim
(@tim-m30)
Illustrious Member

Simply change your Printer Custom G-Code.  Many of us use custom code to adjust heating to suit our own needs based on local conditions.  Hot rooms need one setting, cool rooms another.  No two situations are identical.

It is always wise to get more than one opinion......
Posted : 20/06/2020 9:16 am
bobstro
(@bobstro)
Illustrious Member
Posted by: @pedja

[...] It would be good to have defaults set in a manner that hot end heating starts later, when bed is already at required temperature or close enough.

Even when both temperatures are reached there is still delay waiting for temperature to spread evenly on bed (which is a must for successful print of large objects).

If bed is heated first then time waiting for hot end to heat up would also serve as time for spreading temperature evenly on bed, reducing additional delay.

A 2-step nozzle warmup startup gcode routine will do what you're looking for. There are many variations, but I've got a documented example here that you can use as a starting point.

Interestingly, Prusa has adopted this approach for the startup gcode on the Mini. They have not yet made it the default for the Mk3, so you simply need to create a custom printer profile for PrusaSlicer. 

My notes and disclaimers on 3D printing and miscellaneous other tech projects
He is intelligent, but not experienced. His pattern indicates two dimensional thinking. -- Spock in Star Trek: The Wrath of Khan...
Posted : 20/06/2020 2:19 pm
pedja
(@pedja)
Eminent Member

@tim-m30

Procedure (and gcode) is the same for all. What is not the same it may be simply parameterized.

As this is necessity for all, it is common sense to have it systematically included in defaults.

This post was modified 2 months ago by pedja
Posted : 21/06/2020 9:11 am
pedja
(@pedja)
Eminent Member
Posted by: @bobstro

A 2-step nozzle warmup startup gcode routine will do what you're looking for. There are many variations, but I've got a documented example here that you can use as a starting point.

Interestingly, Prusa has adopted this approach for the startup gcode on the Mini. They have not yet made it the default for the Mk3, so you simply need to create a custom printer profile for PrusaSlicer. 

I learned about this from your article.

If it is already adopted for Prusa Mini then there is no reason why not to the same for all other printers. Problem is the same.

Posted : 21/06/2020 9:14 am
bobstro
(@bobstro)
Illustrious Member

There are some differences between printers to be aware of. The Mini does not have a temp sensor in the MINDA probe, so the "wait for PINDA temp" routine doesn't work. It also has a Bowden tube, so you need to consider this for any Linear Advance or retraction actions. Finally, everybody likes to tweak things, so allowing users to customize their startup gcode in the slicer is a good solution. I'd be annoyed to be locked out of making changes.

My notes and disclaimers on 3D printing and miscellaneous other tech projects
He is intelligent, but not experienced. His pattern indicates two dimensional thinking. -- Spock in Star Trek: The Wrath of Khan...
Posted : 21/06/2020 1:49 pm
pedja
(@pedja)
Eminent Member
Posted by: @bobstro

Finally, everybody likes to tweak things, so allowing users to customize their startup gcode in the slicer is a good solution. I'd be annoyed to be locked out of making changes.

I agree. This is not locking settings, just request to set defaults to what is more appropriate to prevent obvious issues.

We have default profiles that are very good and we just have to tweak them a bit. This is tweak everyone has to do. Instead of everyone tweaking it is better to have this as default.

This post was modified 2 months ago by pedja
Posted : 22/06/2020 1:38 pm
bobstro
(@bobstro)
Illustrious Member
Posted by: @pedja

[...] We have default profiles that are very good and we just have to tweak them a bit. This is tweak everyone has to do. Instead of everyone tweaking it is better to have this as default.

I'm sometimes surprised by what bothers people. There was a recent discussion on reducing the area of the bed probed during mesh bed leveling in order to drop something like 30 seconds off the startup procedure. I'm all for fast printing, but reducing 1st layer quality to save 30 seconds on a multi-hour print seems counter-productive. I can only imagine the complaints we'd hear if the PINDA warmup routing was made standard, and yet Mini users complain about lack of a PINDA temperature sensor and add in long warmup wait times. I can understand why Prusa provides baseline profiles, then allows users to customize them however they like. It will be interesting to see if the 2-step warmup makes its way from the Mini profiles to the Mk3.

 

My notes and disclaimers on 3D printing and miscellaneous other tech projects
He is intelligent, but not experienced. His pattern indicates two dimensional thinking. -- Spock in Star Trek: The Wrath of Khan...
Posted : 22/06/2020 2:45 pm
pedja
(@pedja)
Eminent Member

@bobstro

I guess you did not read my proposal with enough attention.

I do not care about time. What I am pointing out is filament leaking during unnecessary long heating and cooking filament within extruder.

Posted : 29/06/2020 8:27 am
Neophyl
(@neophyl)
Noble Member

It seems that time vs leaky nozzle is the important factor for you, the problem is that other people have different priorities. You stated that this is something that everyone should do. That is just your opinion.  No single default start up is going to satisfy every body.
It’s lucky then that Prusa allows you to set your own. I think that’s the point, if the current mk3 defaults were updated then I am sure many would be delighted.
I am just as sure that many would complain about the longer wait time before the printer actually starts printing.  

I’m also sure that like the mini owners there will be people who would cancel their prints when the temperature stops at 170 degrees thinking there was something wrong. You have made a suggestion, great, now it’s up to Prusa to see if they act on it.

Posted : 29/06/2020 10:03 am
bobstro
(@bobstro)
Illustrious Member
Posted by: @pedja

[...] I guess you did not read my proposal with enough attention.

Oh no, I read it. I think you missed the part where I responded that there are just as many people who feel strongly that even basic functions like mesh bed leveling take too long.

I do not care about time.

Good for you. I find that spending a bit more time preparing the print and heating things up properly it time well spent. No sense saving 30 seconds on a 3 hour print only to have it fail halfway.

What I am pointing out is filament leaking during unnecessary long heating and cooking filament within extruder.

There are solutions for that which you can easily configure if it's important to you.

 

 

My notes and disclaimers on 3D printing and miscellaneous other tech projects
He is intelligent, but not experienced. His pattern indicates two dimensional thinking. -- Spock in Star Trek: The Wrath of Khan...
Posted : 01/07/2020 5:53 am
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