Rafting Along

[Pridanc 4]

Folks, 

After successfully printing some smaller PP parts, I decided to step up to printing a larger part out of PP as well. At first I found the warping of this larger part to be a bit pesky but after some messing around, I've reduced the warping to an almost imperceptible level which leaves me with a question about adjusting the connection between a raft and the part.

 

If you look at the picture of the raft pulled from the most recent part, you will see 4 red circles. If you look even closer, you will notice that inside each red circle is a white mark (spot?) at the juncture of two straight lines.  Interestingly, three of the white marks are nearly identical with one being a lone wolf as it were.

 

This oddity (the lone wolf) is the only corner of the part that remained 100% stuck to the raft, with the other three having pulled away from  the raft the smallest amount.  No question, the part is perfectly usable with only the slightest indication of warping seen at those three corners when looking. The imperfections are hard to even notice at a glance.

 

My question is this:  How do I adjust the settings in CURA to make the contact between the raft and the part stronger?  

 

• CURA 5.5.0-beta.1  (let me know if you feel I'm silly not to upgrade. So far, very happy)

 

Many thanks and as always, all suggestions are welcome.

Sincerely, PDC

[Slashee_the_Cow 479]

8 hours ago, Pridanc said:

CURA 5.5.0-beta.1  (let me know if you feel I'm silly not to upgrade. So far, very happy)

You're silly not to upgrade. At the very least use the release version of 5.5 if you don't want to use the latest version.

 

Rafts aren't used much these days (relic from a bygone era when proper bed adhesion was nigh impossible) but if your build plate always warps, that's a fair enough reason.

 

The main setting for a stronger connection would be Build Plate Adhesion > Raft Air Gap. Normally it puts a layer (at least) of space between your print and the raft to make it easier to remove (i.e. it just does an empty layer then starts doing your print... sounds wrong but hey, it works, like there's an air gap by default between support interface and a model).

Initial Layer Z Overlap lowers the layers of your model (except the first one above the raft) a little bit to sort of force your model to squish onto the raft but you don't want to set that too high (like, one layer height, tops, but it's not something I've tested so I don't know what's ideal, I think the default is half a layer).

[Pridanc 4]

Slash, 

OK many thanks as I will look into it. 

 

I've yet to find a solution to some of the larger ABS or PP part prints I've done / I do staying successfully down on the build plate without a raft regardless of what is used between the part and the plate. 

 

Without question, rafts have done the best job of helping me reach success.

 

I'll keep you informed when I try the PP print next.  I'm close....

 

As always, TYVM   PDC

[Slashee_the_Cow 479]

3 hours ago, Pridanc said:

I've yet to find a solution to some of the larger ABS or PP part prints I've done / I do staying successfully down on the build plate without a raft regardless of what is used between the part and the plate. 

Never tried PP myself, but ABS has the adhesive properties of a piece of sticky tape which has been trodden around an office on different peoples' shoes for a week than left ignored next to the water cooler for two weeks. It's something you pretty much need an enclosure (not a printer with an enclosed chamber, just a tent or something) for because it'll warp if you give it an icy stare, or even a warm smile, and to make sure you have a hot bed for it to go down on. An enclosure is also a great idea because the fumes are poisonous 🙂

 

People use it because the common belief is that's stronger than PLA - it isn't really, just less brittle. You can bump a thin bit of it and it's less likely to crack than PLA but for structural purposes it's about the same. About the only other difference is that (once it's properly set) it can stand warmer temperatures than PLA (don't leave your PLA in the car when you park it in the sun on a hot day, kids) but for both of those weaknesses I'd use PETG instead - it is a bit flexible, fairly flexible if you design it to be (I've deliberately made bendable parts) so it can withstand a knock and it survives warmer temperatures than PLA. And it's a hell of a lot easier to print than ABS.