Lkjasd01
Posts: 3
Joined: Wed Jul 17, 2019 4:30 am

First layer on raft MUCH higher than first layer height setting

Wed Jul 17, 2019 5:19 am

I'm using the following settings:-

nozzle 0.6mm
primary layer height 0.15mm
First layer height 120%

Raft:-
top layers 3
base layers 1

When I prepare print in S3D, I notice the first layer height is 0.9mm!! this is 600% of primary layer height - where did this come from? (shouldn't this be 0.15x120% = 0.18mm?) I noticed this after I tried printing something in ABS and the bead barely touched this build plate and eventually stopped extruding as it overloaded the extruder and ground the filament to a halt.
The next x3 layers are 0.333mm (this is 222% of the primary layer height - again where did this come?)
The first layer above the raft is 0.15mm as expected.

Is there some setting that I don't know about (I'm a relatively new user) which affects the raft height layers?

Thanks in advance,

A.

Kazuma
Posts: 1
Joined: Thu Jul 18, 2019 5:05 am

Re: First layer on raft MUCH higher than first layer height setting

Thu Jul 18, 2019 5:07 am

i have exactly the same problem been looking all over the internet but have not found anything usefull yet

S3D-Alex
Posts: 281
Joined: Thu Aug 30, 2018 1:23 pm

Re: First layer on raft MUCH higher than first layer height setting

Thu Jul 18, 2019 10:04 am

Hey thanks for posting! So I can see how this can be confusing but the Raft Base Layer Height works a bit different than just a standard first layer. The whole point in these base layers is to print them as fat and tall as possible to help with leveling an unlevel surface.

The height is determined using the following settings.

The nozzle diameter multiplied by 1.25 is your standard Raft Base Layer. In your case this would be .6 * 1.25 = .75. You then add the First Layer Height modifier you are using so we have .75 * 1.2 which gives us the .9mm number you are seeing.

I would suggest using 100% or less for your First Layer Height to make sure this layer is printable for your machine but please let me know if you have any more questions.

Lkjasd01
Posts: 3
Joined: Wed Jul 17, 2019 4:30 am

Re: First layer on raft MUCH higher than first layer height setting

Fri Jul 19, 2019 7:05 am

S3D-Alex,

Excellent reply, I should be able to control this now you've explained the 'secret' multiplier.

One other thing, which I sort of mentioned but maybe wasn't my first concern:- the subsequent raft layer heights were 0.333mm. Is there another multiplier used for these raft layers?

I do think 3DS should have a text note on the raft parameter box to advise users of this multiplier, as the first layer height percentage control can really increase the raft height beyond a printers capability to extrude (as I found out on a +20k printer). Obviously there is more than me who has encountered this issue, but like Kazuma, couldn't find any advice elsewhere.

Many thanks again,

A.

dtwrv6
Posts: 16
Joined: Tue Jan 28, 2014 8:34 pm

Re: First layer on raft MUCH higher than first layer height setting

Sat Nov 23, 2019 2:40 pm

I've just discovered this feature about raft heights, and I'd prefer to have my own control over the height. With a 0.6mm nozzle, I'm using a first layer height of 0.48 to get the right amount of adhesion for ABS. When using a raft, this gets set to 1.2mm, and there is no adhesion at all. For now, I'm manually putting an offset into the machine when I need a raft, but this isn't an optimal way to run the printer and slicer.

Don

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