wirlybird
Posts: 1100
Joined: Sun Jul 17, 2016 12:32 pm

Is a 90% First Layer Pointless Now?

Sun Mar 24, 2019 7:26 am

It setting the first layer height at 90% kind of pointless now since the extrusion multiplier no longer stays at 100% of the set value when below a first layer height of 100?
It used to be that for a first layer height below 100% the extrusion multiplier would stay at the set value essentially causing a slight over extrusion for the first layer. My understanding is it no longer works this way.

S3D-Jake
Posts: 516
Joined: Wed Jun 20, 2018 11:45 am

Re: Is a 90% First Layer Pointless Now?

Tue Mar 26, 2019 12:48 pm

You're correct it no longer works that way. 90% first layer height will print the correctly scaled amount of filament for a 90% first layer height. If you wish to use the formerly popular "squish" method you can set to 100% first layer height and use the global G-Code offsets settings in the G-code tab to lower the entire build by an absolute amount.
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wirlybird
Posts: 1100
Joined: Sun Jul 17, 2016 12:32 pm

Re: Is a 90% First Layer Pointless Now?

Tue Mar 26, 2019 1:19 pm

It really boggles the mind why you took yet another item that worked fine and complicated the whole thing.

So instead of just setting it a 90% and leaving it for most all prints I now have to jump to another tab and calculate how much to lower the Z offset based on my layer height and do this for every print that has a layer height change from the last print.

Wasted time and effort.

airscapes
Posts: 261
Joined: Tue Mar 06, 2018 10:35 am
Location: Philadelphia PA Area

Re: Is a 90% First Layer Pointless Now?

Tue Mar 26, 2019 1:30 pm

Sounds like a developer that doesn't use a 3d printer looked at that as a bug..

wirlybird
Posts: 1100
Joined: Sun Jul 17, 2016 12:32 pm

Re: Is a 90% First Layer Pointless Now?

Tue Mar 26, 2019 1:46 pm

Yea, and at the rate they are going they will put themselves right out of business.
Too much competition now that is free.

horst.w
Posts: 769
Joined: Fri Oct 17, 2014 4:00 pm

Re: Is a 90% First Layer Pointless Now?

Tue Mar 26, 2019 5:39 pm

It was mentioned in the changing log of V 4.0 or 4.1.

Before user have grumbled about it because they haven't understood why it is the best solution and now others are grumbling about the changes. But sure, there is someone who doesn't know what he is doing. That is the difference between practice and design.

To use the former solution someone must know that it is possible to reduce the layer height below the 100% (of general layer height) but holding automatically the extrusion amount to 100%.
The new solution I find more intuitive for beginners. Also other slicers they are coming from, don't know such a solution and beginners don't looked for it. So they merge 2 functions together without knowing why the result is bad.

horst.w
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dkightley
Posts: 1960
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Re: Is a 90% First Layer Pointless Now?

Tue Mar 26, 2019 6:29 pm

I am also quite puzzled as to why this change has been made. Why make changes that upset the existing and correct slicing behaviour of the software that give the overall impression that an upgrade has broken more things that it has mended!

It was exactly the same as the changes made to top layers. Top layers worked very nicely before an upgrade....and then a change is made that cocks many existing prints up. Why?

I would really appreciate that changes are only made that IMPROVE printing overall....and please always provide a reason for making changes...not just change the way the software works...and hope users like what you've done.
Doug Kightley
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horst.w
Posts: 769
Joined: Fri Oct 17, 2014 4:00 pm

Re: Is a 90% First Layer Pointless Now?

Wed Mar 27, 2019 3:08 am

dkightley wrote:
Tue Mar 26, 2019 6:29 pm
...
Why make changes that upset the existing and correct slicing behaviour ...
... and it would be so easy to change it better, when the user has a drop-down menue where he can choose all values he needs.
All automatical solutions, depending of unknown situations (i.e. distance heatbed to nozzle) are pure luck but better than nothing.
To cancel this function was not great. Using instead the - negative - Z-Offset needs a intimate knowledge.

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Ayres3D
Posts: 79
Joined: Mon Aug 14, 2017 12:15 pm

Re: Is a 90% First Layer Pointless Now?

Thu Mar 28, 2019 10:03 am

I didn't realise this had changed either. That does seem like a backward step to me too.

SteveYYC
Posts: 7
Joined: Sat Jun 16, 2018 4:01 pm

Re: Is a 90% First Layer Pointless Now?

Wed Apr 10, 2019 11:39 am

Thanks all for pointing this out and enumerating how the new version changes the first-layer/bed-layer.

Since I really don't like messing with global offsets, I added the following post-processing instructions to my S3D process instead to use the GCode M221 instruction to alter the extrusion factor for layer 1. Posting here in case it helps someone else.

{REPLACE "; layer 1," "M221 S135\n; layer 1,"} ; use f/w to overextrude layer 1 @ 135%
{REPLACE "; layer 2," "M221 S100\n; layer 2,"} ; reset f/w extrusion to 100% for layers 2-n

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