Raft Settings

[bagel-orb 61]

Currently the raft options are being abandoned because the rafts produced are unsatisfactory. I think this is a shame.

I will implement better rafts which focus on the ease of removal from the model.

However, I haven't gotten the rafts to work at all. They just won't come loose!

I've tested with bed temp, interface thickness, line width and air gap with no avail.

Does anyone know of settings which do produce rafts which you can remove with little effort and little scars?

It would be helpful to get some community knowledge before blindly implementing what i think should work.

PS: My goal is to improve rafts, so please don't come with alternatives to rafts ^^

 

[3poro 9]

I've been relatively satisfied with Cura's raft - I'm printing ABS. Here are my current settings:

Number of surface layers is an overkill - normally I have used 3 (which I think is the default). Now I was printing an object which was surprisingly stubbornly trying to lift its corners up...

For me it was important to increase the extra margin and to reduce line spacing - otherwise the raft didn't stick to the glass strongly enough in some occasions.

Depending on object, I may need to use knife to remove the raft. For me that's not a big issue, but naturally I would welcome an improvement

 

[Titus 170]

I always experienced objects being stuck to the raft. I tried increasing the airgap to like .5 which worked, but did result in low quality first layers.

 

[Daid 298]

New RC has a few extra raft settings that might help tuning the settings more to perfection:

http://software.ultimaker.com/Cura_closed_beta/

 

[bagel-orb 61]

I've gotten the raft perfected such that it breaks off with a finger snap - yay! This is by using the above mentioned beta version.

-edit2: see post below for better settings!

I will be tweaking the settings further so that printing the raft doesn't take extraordinarily long.

Elaboration:

Structure: (top to bottom)

[ ..... model ]

[ second model layer ]

the negative of the first layer airgap

[ first layer ]

first layer airgap +

airgap

[ multiple surface layers ]

[ single interface layer ]

[ base layer ]

I set the surface layer thickness extremely low so that the nozzle effectively smoothes the layers below. The interface layer has a thickness and spacing in between as to bridge the large difference between the base and the surface.

I will be posting soon with more and better results.

-edit: remember to turn off the heated bed!

-edit2: see post below for better settings!

 

[jweaver 2]

Does the RC version fix the problem with raft, where top of the model is missing from the layer view?

So if you start with a model that has 100 layers.. And then use 10 layers of raft (just an example).. The model is still 100 layers and the top 10 lines is missing from the view (still havn't tested that it will actually print)

Jon

 

[bagel-orb 61]

@jweaver: no, the raft settings have been extended. Layer view mode is as before.

 

[jweaver 2]

@jweaver: no, the raft settings have been extended. Layer view mode is as before.

 

Cheers.. Thinking about it.. I should/could have just tried this myself.. Rather than asking.

At some point I need to do a test to prove that by adding a Raft and having an incorrect layer view, the GCODE output is still OK.. Infact I will do it now.

Jon

 

[jweaver 2]

Cheers.. Thinking about it.. I should/could have just tried this myself.. Rather than asking.

At some point I need to do a test to prove that by adding a Raft and having an incorrect layer view, the GCODE output is still OK.. Infact I will do it now.

Jon

 

I just tested this and don't like what I am seeing

I started with an object which was 100 layers.. I then added 20 layers of Raft, so the entire creation is now 120 layers

I looking at the Layer view its still shows 100 layers and the top of the mode has been cropped off.. So I saved the GCODE and its only got 100 layers.

So surely this means that by adding RAFT, you are loosing the top layers of the model? What am I missing??

 

[bagel-orb 61]

So surely this means that by adding RAFT, you are loosing the top layers of the model? What am I missing??

 

No the raft layers are classified as -1; they don't add to the counter of the layers in the Gcode.

Please don't get off topic. The topic is on the optimal raft settings, not the layer view.

 

[Daid 298]

So surely this means that by adding RAFT, you are loosing the top layers of the model? What am I missing??

 

NO. This is purely a visual bug. The layer view of Cura does not display all layers, the model is printed fine.

 

[jweaver 2]

No the raft layers are classified as -1; they don't add to the counter of the layers in the Gcode.

Please don't get off topic. The topic is on the optimal raft settings, not the layer view.

 

Ahh.. OK. Sorry.. I am a novice at GCODE, and didn't even realise that you could have "minus" layers.. Sorry.. Lets get back on topic, as this is a really interesting thread, details of which I will certainly use.

 

[bagel-orb 61]

I've done some more optimization and the resulting Raft settings are as such:

I've printed this with standard settings on the UM2, except that the heated bed was disabled and I've pumped up the bottom layer speed to 50mm/s.

Hope this helps you guys!

 

 

[bagel-orb 61]

My crappy cam shows these results:

"10" is without heated bed, "10H" is with heated bed

The underside of the prints (10x10x3 mm) is shown and highlighted with a black marker.

Both undersides are garbled, though 10 seems less garbled than 10H.

In both cases the raft was easily removed by hand.

notes:

standard silver PLA on 210 degrees.

All non-raft settings were standard, except bottom layer speed=50mm/s.

 

[kenzu 0]

See my post here for my settings and a video. http://umforum.ultimaker.com/index.php?/topic/8506-anyone-got-any-tips-for-printing-when-the-first-layer-has-lots-of-tiny-part/?p=86450