To raft... or not to raft. That is the question

[Polo708]

BRAND NEW at this 3D printing thing. Got it for my son, but im trying to learn so that i can teach him how to use it. (Who are we kidding... I said it was for the boy so my wife would let me buy it, haha) Anyways...

Do I need to use a Raft, Brim, Skirt if I have a heated printbed? What situations would call for these options?

[johnlsmithhart]

No matter what your printing Extreme Elmer's glue on top of a glass bed is a solid solution to many first layer adhesion problems (while your still getting a feel for that first layer height). I've never used a raft after week 1 of printing. I did not like added print time and many times my prints would warp right off the raft due to a multitude of newbie mistakes (IE layer height, printing to fast, etc). As for a brim I use it on larger prints and filaments that are prone to warping (it helps slot with abs). Happy printing

[mikep]

I use raft for extremely large prints. Raft for extremely small ones that are also tall.
Raft can alsi be used to cover up several peinter setting faults like initial layer height etc. while you are still figuring out your other settings.

[mikep]

Wow I fat fingered that..
Brim for small prints that are tall.
My bad.

[Rebekah_harper]

There are many reasons to use a raft.
But some differ depending on material.

a raft can help when you are having adhesion issues. Creating a platform which sticks well and has a nice thick lines to plant it self on the build plate.
If you want to print with a high resolution like 0.05mm then a raft is handy it levelling the build plate isn't going well. It effectively over comes the slight differences in hieght and creates a level build area.

A brim rim is also good for adhesion. Most materials have a little shrinkage which causes the part to peel of the build plate. But when you have many layers each cooling at different stages then you'll find that although the first layer may have stopped shrinking the other layers on top of that will be at different stages of shrinking and there for each will continue to pull on the layer below.
using a 1 or 2 layer brim will help with this. 5 lines out from part is decent. With only the one or two layers it will generally not have enough shrinking force to peel of the bed it self. With the distance from part at 0 (so it's attached to the part) it will hold onto the first layer long enough to counter the peeling of it can cool before it lifts off the plate. This isn't full proof but does help.

I use ABS for post processing (it sands better) and suffer a lot for the risk of peeling of the build plate but with the above I manage to avoid it most of the time.

i also use PrintByte which is a build plate cover that works very well with adhesion. I just don't like adding glue, hairspray and other stuff to achieve adhesion. There is also BuildTak but you'll need to get the system and not just the build covering as it's really good. (Raft is the only one if using the latter build covering)

hope this helps

[Marchie]

Check out PEI. I'ts a plastic polymer that comes in sheet form and is being used by a few printer manufacturers.
I've been using it for over 6 months and the results are great. no need for rafts or glues or tapes.
Buildtak is good but only lasts a short while, depending on number of prints you do.