Flow rate in ironing  

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prusanewuser
(@prusanewuser)
Honorable Member

Hi, sometimes even when ironing is on, the top surface shows some holes. If I used larger flow rate, sometimes burnt stuffs showed up on the top surface. So there is no single value that will work well for all prints and I have to do trial and error? It is annoying that after spending 10 hours on a print, ironing did not do a good job at the end and left one or a few holes on the top surface. 

Also, sometimes after ironing, the top surface showed parallel lines. I guess those were created when the nozzle moved along the top surface. Is there any way to prevent that from happening? Basically, I want beautiful looking flat surfaces.

Posted : 01/05/2021 9:02 pm
RedDawg
(@reddawg)
Estimable Member

Instead of allowing a 10 hour print go to the end only to be disappointed in the last few layers, why not just cut the model maybe 1 or 2mm down from the top, delete the bottom portion and try your flow rates and other parameters on just the top portion until you have an acceptable result? Saves a lot of time and filament.

1. "Creativity is the sudden cessation of stupidity." and "Any problem can be solved with the materials in the room." -Edwin Land, inventor of the Polaroid Land Camera. 2. "If I can't fix it, it isn't broken." -Me....
Posted : 01/05/2021 11:04 pm
Dan Rogers
(@dan-rogers)
Prominent Member

First - I'm thinking you don't have enough perimeters on the top - if ironing is burning holes, don't use ironing.  If you want to use ironing, I'd think 3 top layers min at .3mm, 7 top layers a .2mm  and 9 at .1 mm.

If you want very smooth finish - get some sand paper - 150 grit, 280, 400, 800, 1200 and then steel wool.  It'll shine like a mirror.

Ironing is not a short cut to "finished part".

Posted : 02/05/2021 12:25 am
prusanewuser
(@prusanewuser)
Honorable Member
Posted by: @reddawg

Instead of allowing a 10 hour print go to the end only to be disappointed in the last few layers, why not just cut the model maybe 1 or 2mm down from the top, delete the bottom portion and try your flow rates and other parameters on just the top portion until you have an acceptable result? Saves a lot of time and filament.

Tried this approach a few times already. Doesn't work. Sometimes I could made the top portion worked but when I printed the entire things, they looked differently. 

Posted : 02/05/2021 12:38 am
prusanewuser
(@prusanewuser)
Honorable Member

@dan-rogers

Could you please clarify what you mean by "3 top layers min at .3mm, 7 top layers a .2mm  and 9 at .1 mm."? I just have 5 as the number of top layers. 

Shall we consider Ironing just a way to shorten the process of sanding? One thing I don't like about sanding is discoloring. 

Posted : 02/05/2021 12:43 am
Dan Rogers
(@dan-rogers)
Prominent Member

Slicer settings in prusa slicer.  Layers and Perimeters.

You haven't talked about what your layer height is (I didn't see it) - so you don't seem to be aware of layer height such as .3mm, .2mm, .1mm ... the number of top layers matters for print integrity - you are using ironing - which is draggin the hot head across your top layers slowly with very slow extrusion.

Ironing is no substitute for finishing.  It's just a lazy "maybe it will look smoother than top layer infill"

 

Posted : 02/05/2021 1:32 am
prusanewuser
(@prusanewuser)
Honorable Member

@dan-rogers

It was 0.15mm.

So those parallel lines across the flat surface are traces of the nozzle? Sometimes they showed up but sometimes they didn't. Hard to predict.

Posted : 02/05/2021 3:36 am
Dan Rogers
(@dan-rogers)
Prominent Member

Not much to go on ... no pictures (add media button above the typing box) and no .3mf settings file (saved as file/save-project from prusa slicer) - to upload the .3mf, zip it up (add to compressed folder) and send us that compressed folder here so we can see what's going on.

Your reference to the lines on the top surface - not sure, I didn't find any pictures on this thread.

typically a top surface is a top infill pattern (you can choose what it is) - and then ironing is a pass over the final layer with the nozzle rubbing at the same level just printed - extruding much lower rate - to reheat the last layer and smoosh more plastic between the lines.  If your nozzle is gobbed up, it can make a mess.  But the lines in the top surface are probably either the top layer fill pattern, or the underlying infill showing through a very thin top layer.

At .15mm layer height, you should expect default to be 7 to 9 top layers.  If you reduce that to say 1, the infill will show through as some kind of distortion.  It's important to have the top layer be thick enough before the final "faux finish" that ironing can do to have a chance to work.

Posted : 02/05/2021 8:57 am
prusanewuser
(@prusanewuser)
Honorable Member
Posted by: @prusanewuser
Posted by: @reddawg

Instead of allowing a 10 hour print go to the end only to be disappointed in the last few layers, why not just cut the model maybe 1 or 2mm down from the top, delete the bottom portion and try your flow rates and other parameters on just the top portion until you have an acceptable result? Saves a lot of time and filament.

Tried this approach a few times already. Doesn't work. Sometimes I could made the top portion worked but when I printed the entire things, they looked differently. 

Anybody knows why there is such an inconsistency in results between fully and partially printed portion of the same thing? This has happened a few times on different objects already.

This post was modified 1 month ago by prusanewuser
Posted : 02/05/2021 2:19 pm
Dan Rogers
(@dan-rogers)
Prominent Member

No pictures yet.  How can we help you friend?

Posted : 02/05/2021 2:20 pm
RedDawg
(@reddawg)
Estimable Member

@prusanewuser

If the "atmospherics" for each partial print are the same, I can't imagine why there would be any substantial difference between them.

1. "Creativity is the sudden cessation of stupidity." and "Any problem can be solved with the materials in the room." -Edwin Land, inventor of the Polaroid Land Camera. 2. "If I can't fix it, it isn't broken." -Me....
Posted : 02/05/2021 6:22 pm
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