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Designing For Cura

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Posted · Designing For Cura

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@Arjan

Could you elaborate? Not sure I understand what exactly you are wanting to document. When you say "How to make corrections in CAD", are you thinking of a ,tutorial, if you will, on how to make those corrections in CAD?

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Was more thinking along the lines off a data table with offset values, for example if you need a 3.2 mm hole in your project, printing in PLA the CAD design needs a hole of 3.5 mm, in XT you'll need a hole of 3.3 mm (fictional values..) In real life it will be a combination of CURA behaviour, material, temperature etc etc... so this will be hard to get precise....

 

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Posted · Designing For Cura

Just thought I'd share this technique with some of the new guys...

I designed this part to be printed in ABS. A crucial factor for a successful print was NO WARPING. The first print I let Cura throw in some brim. It started to warp about 20 or 30 layers in. Then I tried it again with a bag over the UM2, and a plexi panel to block the door. Started to warp at layer 60 or so.

Went back to the drawing board... redesigned part with my own brim. This time, 2 layers thick, opposed to Curas 1 layer, which breaks free from the glass pretty easy on large prints like this. I think I designed in a .22mm layer brim, and in conjunction with my .1mm initial layer height and .14mm print layer height, Cura rounded off to print 2 layers....Much stiffer, adheres to the bed better, and is still very easy to remove...if not easier.

Printed again... warped towards the end.

So I decided to add the ribs at the base, one on each corner, all the same length, and all .8mm wide, for 2 passes. I put the bag back on the top, covered the door and let her cook for 12 hours or so.

Success! And by success, I mean flat as the glass she was born on.

Here's an image of the model in Cura

AR lower

 

And here it is printing

ABS print1

Here is an even more critical part, where the two halves mate together, there could be absolutely no warping, or functionality would fail.

ABS print2

here are the links in case your browser won't display the videos

 

 

 

Same methods of designing in a double brim, and ribs at corners really kept the part flat.

 

So, if you have a part that is similar and wont print flat, maybe these techniques will help you.

 

P.S. I am not a gun nut. I printed this as an advertising campaign. It is completely legal where I live to do so. Please do not go printing guns and saying Pat from SolidPrint said it was OK ... I am into archery however...PM me to see my 3D printed compound mini bows :)

 

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Posted · Designing For Cura

OK, here is another problem I'm having, not a big deal, but I'd like to know if it is a design thing ( as in, I'm the only one with this problem) or if it's a known Cura bug.

These 4 squares are built on the X,Y Plane.

When I load them into Cura, this is what I get... slice view, layer 1

 

The bottom does not touch the platform apparently, so I'm assuming it just moves on to the next layer.

 

SO, I cut off the bottom layer by .03mm and it seems to fix the issue.

 

 

No big deal, but I just ruined a print (AGAIN) becasue I forgot to check if the first layer was indeed printing. I usually always check my layer view before saving, but I forgot.

 

When it skips the first layer, is it also skipping the .2mm layer height for the first layer, and trying to print a .4mm layer with .2mm worth of filament on the 2nd layer?

 

Here are my settings

 

 

Just another thing to add to my "Watch Out For" list

 

Initial layer thickness must be set at least 0.01mm thicker than half of the layer height value otherwise Cura gonna skip the first layer (initial layer) completely.

If your layer high is for example 0.2mm then initial layer thickness must be at least 0.11mm

Layer high 0.25mm - initial layer thickness >0.13mm

Layer hight 0.1mm - initial layer thinckness >0.06mm

and so on ....

 

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Posted · Designing For Cura

Initial layer thickness must be set at least 0.01mm thicker than half of the layer height value otherwise Cura gonna skip the first layer (initial layer) completely.

If your layer high is for example 0.2mm then initial layer thickness must be at least 0.11mm

Layer high 0.25mm - initial layer thickness >0.13mm

Layer hight 0.1mm - initial layer thinckness >0.06mm

and so on ....

 

Awesome Info! Thanks for the share

 

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Posted · Designing For Cura

Another quick Cura tip:

Picture this... you bring in a very small part. You multiply the part several times. Cura lays them out in a rectangular pattern

arrange 1

You get about 80% through the print, and pieces begin to get knocked over becasue the print head is skipping over parts and hitting the tops of the little pieces.

Here's a typical path the printer takes over a rectangular pattern of parts.

arange 2

Not very optimal

Instead try to think outside the box... think circle :)

arange 3

No more parts knocked over from the print head:)

 

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Posted · Designing For Cura

Unless you have a dual extruder... :-|

But you could use the z hop feature anyway to avoid collisions...

 

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Posted · Designing For Cura

Unless you have a dual extruder... :-|

But you could use the z hop feature anyway to avoid collisions...

 

I wish :p

Besides, I don't use the Z-Hop. I don't like the wear and tear on the brass nut from thousands and thousands of short jumps up and down...unless absolutely necessary. In this case, it's not necessary.

Also, I find that sometimes the Z-hop strings a little as it lifts and moves to the next piece, whereas no hop cleans itself off as it passes along the part to the next.

Anyways, that's just me :)

 

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