Raft settings

[thomas-roager 0]

Hello folks

I just installed cura 14.10 RC2

And for the first time im trying to use the raft functions. Im having kind of a hard job to get the raft off. Im getting Nice and beautiful prints but its stuck with the raft.

Can somebody tell What the settings means?

I tried changing the airgap to 0.27 instead of 0.22 but that didnt help :(

- TRoager

[Daid 306]

What material are you printing with? This really matters for the raft.

Also, most people prefer a brim instead of a raft these days.

 

[thomas-roager 0]

What material are you printing with? This really matters for the raft.

Also, most people prefer a brim instead of a raft these days.

 

Im printing with Black Colorfabb PLA, i changed the airgap to alittle more, something around 0.33 this helped but the object is now "white" on that side i took of the raft.

i havent tried with ABS as i dont want to mix up my E3D hotend with 2 materials. But if its ABS then it needs to be closer to the raft?

i like the raft feature cause it looks like im not getting any warp at all

 

[Daid 306]

You might just need to print a bit cooler then. I have no experience with colorfabb PLA. But it's quite temperature critical from what I've heard.

 

[gr5 2,172]

Raft is an older technology. It still is used by a few people but you don't really need it anymore. Instead we have learned to get parts to "stick like hell".

For your non-heated bed printer, I recommend blue tape and here's the key: clean the blue tape with isopropyl alcohol. This removes the waxy surface that keeps the tape from sticking to itself before you unroll it.

There are other tricks - you need to print the first layer slower and hotter and squish it a bit into the tape so you might need to level slightly lower. Also a brim makes a huge difference and is much easier and cleaner to remove than a raft. In summary:

- clean with rubbing alcohol (only once when you put down new tape)

- if tape is lifting off bed use wider tape

- First layer 240C (optional - this is for very large difficult prints)

- First layer 40mm/sec max speed .3mm thick

- use brim

Once you do that you will be annoyed how hard it is to get the parts off so you can *not* do some of these tricks with smaller prints. For example skip the 240C or brim.

Isopropyl (aka rubbing) alcohol can be found anywhere bandages are sold:

 

[thomas-roager 0]

Well im using heatedbed at 70c and hotend at 220c printing with e3d v5 on glass but it seems like printing on clean glass is a No go. Then theres hairspray and that doesnt work. Im using glue stick now and its Worning but still some kind of warping on larger prints, but using a raft work wonders.

Ill try and lower the temp alittle on hotend to see if that works.

[pm_dude 27]

I use colorfabb black pla on heated bed at 50-60C and it's always holding good. Maybe your leveling is not close enough.

I print the first layer with:

- 0.2mm thickness

- 20mm/s speed

- 200mm/s for travel but I have reduce the acceleration to 1000 instead of the 3000 by default.

I print at 200C for slow prints (20-30mm/s) and up to 220C for fast prints (60mm/s).

You can try glue stick if the printed filament doesnt stick well or I have been switching to 3DLac (3dlac.com) recently and I'm pretty impressed even on cold bed.

With 3dLac:

 

[gr5 2,172]

You have heated bed and you want to try blue tape? glass is better!

I agree you probably aren't squishing the first layer enough. Don't use the leveling procedure. Instead watch the brim go down and if it should be 3x wider than it is tall. If it's not that fat then twist the nearest leveling screw a 1/4 turn to get the glass closer to the nozzle until it's squished a little as it puts down that bottom layer.

There's lots of ways to do glue. For PLA on glass my favorite by far is PVA wood glue. I use "Elmer's wood glue" and mix it with mostly water (90% water, 10% wood glue). Mix it in a glass jar with a lid. Shake it well. Then use a paint brush and paint it on the glass. Heat the glass to at least 50C and wait for it to dry until invisible. This works very well.

And use Brim! At least 6 passes. 12 passes of brim if the part is very large (> 150mm across).

The temperature is not important for the glass - there is a sudden transition around 40C so I recommend 50C to be well above the transition. Below the transition the part won't stick well. Above the transition it sticks very very well. 70C is too hot as you get some caving-in near the bottom of the part but it's not too serious. So 60C is good, 50C is good.

Next you will be asking how the heck to get the parts off the glass! Use a very sharp putty knife.

 

[pm_dude 27]

And wait for the glass to get back around room temp. If you didnt use glue the part will detach really easily from the glass when below 40C

[ultiarjan 1,223]

For pla yes. Around 40c. For colorfabb xt it can be more like waiting to go down to 20celsius.

[thomas-roager 0]

Thank you for your inputs, i just what daid said. i lowered the temp from 220 to 210 and now it works wonder with 0,33 in airgap.

The part is easy to detach from the raft and only a little miscolor from the raft.

About the brim feature.. i like that its making it but what i dont like is the little edge on the printed object and i dont like that.

i will consider the wood glue thing, it sounds like a great solution. Right now im just adding a layer of glue from a glue stick. it works but seems like its just adding more and more and i have to re adjust the bed each time i add a layer.

 

[pm_dude 27]

Apply glue stick in thin layer. Wash it away after the print with some warm water if you need to reapply another layer for a different print.

You should not really need to change bed leveling so often unless there is a firmware bug with z consistency like there was in firmware version before the summer of the UM2.

 

[thomas-roager 0]

Its not that often more like when the bed gets too much glue and the layers are kind of warping inside the perimeters at first layer.

But i just found out i was using a wrong layer height, so after a few layers, there would be a negative effect on the prints. Im still wondering why but thats for another thread

[pm_dude 27]

Mind sharing a few pictures of the problem?

 

[thomas-roager 0]

Mind sharing a few pictures of the problem?

Sure !

Well the problem is when i choose 0,15mm layer height in cura i get this wierd layers like theres some kind of wobble.

But when im using KISSlicer with the same, then there's nothing on the print. could i be setting up Cura wrong ?

But thats nothing about the raft settings

 

[pm_dude 27]

Interesting.

Did you configure both with the same speed and temp?

Whats it infill on both? I know there is an issue in Cura with 0% infill and it caused something similar.

 

[thomas-roager 0]

20% infill, and yes same settings and same speed. i think i experimented on the cura part with the temp but didnt make a difference :/