Printing Small Holes

[ssashton 2]

Hi Everyone!

 

I'm trying to print a PCB test jig which has a number of 1.75mm though-holes.

 

Cura keeps wanting to print the (Red) small inside shell of the holes first which means they have minimal bed adhesion and half of them come off before the wall (Green) and solid infill (Yellow) bottom layer are filled in.

 

Is there a way to print the (Green) walls of the holes first, then move to the smaller (Red) inside shell?

 

Alternatively print the solid infill first before printing the walls and shell?

 

I tried 'infill before walls' option but it doesn't seem to affect bottom solid layers.

 

 

 

Edited May 1, 2019 by ssashton

[MechDesigner 3]

What type of bed adhesion are you using?

 

I have the same problem with small holes, I create a thin material that fills the hole in and drill them out.

 

[Smithy 1,144]

You can try to change the setting "Outer before inner walls" but it is normally not checked, which means the inner wall (green) is printed first. But not sure how it behaves with the holes, so give it a try.

 

But anyway, your first layer should not come off, regardless of what is printed first. So you should check your nozzle distance to the bed, maybe it is too far away. Additionally, as MechDesiner already mentioned check your bed adhesion.

[ssashton 2]

Thanks for the replies.

 

I'm using a Brim.

 

However, I've just found that in Cura 4:

 

Brim selected, Red shell is printed first, then Green walls. This is regardless of the 'outer before inner walls' setting.

Raft, skirt or none selected, I get the Green walls first, then Red shell which is what I wanted. The 'outer before inner walls' setting now does have an affect too, and when selected it prints Red shell first like it keeps doing using the Brim method.

 

Could this be a bug that the bed adhesion setting affects the wall printing order?

[Smithy 1,144]

No, I think when brim is selected, the outer wall have to be printed first, because the brim line connects to it. So, in my opinion, it works as designed.

[MechDesigner 3]

For adhesion, I meant  what do you put on your glass to make the material stick to the glass?

 

I use 3d Lac from Amazon, works to good sometimes,

https://www.amazon.com/3d-lac-3D-Lac/dp/B075D7T664/ref=sr_1_1?keywords=3d+lac&qid=1556744460&s=gateway&sr=8-1

 

you can also try to slow the printer down while it prints the small holes, then speed it up after,

 

[ssashton 2]

4 hours ago, Smithy said:

No, I think when brim is selected, the outer wall have to be printed first, because the brim line connects to it. So, in my opinion, it works as designed.

That makes sense now you point it out. Indeed it works that way if I have selected 'optimise wall printing order' - it prints the outside most shell directly after the brim.

 

However, if I have not ticked the 'optimise wall printing order' setting (which I think is default unchecked?) it actually makes a travel move after the brim and goes to print the inner hole shells first.

 

MechDesigner, I simply use the buildtak like print surface that came with the CR10S Pro. I've tried PEI sheet, masking tape, hairspray and glue stick but the build-tak stuff sticks the best by a large margin.

 

Edited May 1, 2019 by ssashton

[burtoogle 513]

Hello @ssashton, if you are using Cura on Linux or Windows, you may wish to try one of my builds that has extra settings for slowing down the printing of walls when the length of the feature is small (i.e. like a small diameter hole). The builds also contain many other bug fixes and improvements that have still not been incorporated into Ultimaker's releases. They can be installed alongside the Ultimaker releases. If you are interested, take a look at https://www.dropbox.com/sh/s43vqzmi4d2bqe2/AAADdYdSu9iwcKa0Knqgurm4a?dl=0

 

Edited May 2, 2019 by burtoogle