Rafts

I'm trying to get ABS to print properly on my robo. Seems like every time I have it figured out, the extruder moves the parts on the platen, so I have to start over again. No matter had often I clean the blue tape surface to be sure the ABS sticks well, it seams that some areas of the platen stick better than others. (I think the platen may not have a truly level surface)
Specifically, I'm trying to print an eight legged spider like thing- 8x6 in tall. I decided a raft might be the best way to create a stable base, but when I add that to my slicr spec, there is no raft under the entire model. It just seems to be under the parts that touch the platen. Is there a way to create a raft in my design program that will break away like the support material does? I'm using the Repetier-host software. I cannot find a raft selection option in the Robo software -mattercontrol program
-mark

 

You could design your own raft, yes. Make a flattened box, with the height equal to 1 or 2 layer heights, and the width/length similar to your model, or at least covering its "footprint." Add some additional boxes directly under your spider's feet, equal to 1 or 2 layer heights, and a width of about 0.4mm (one wall thickness with the stock nozzle). Space these at least 0.4mm away from each other so they don't stick together, and can be removed cleanly. Can space them further, of course. Raise your spider up so its feet are on top of the little boxes. Make sure to combine everything tidily and probably run it through Netfabb just to be sure.

I also like to run a really thick brim (about 10 lines, 5mm width-ish) and if I start to notice a corner peeling up, um, I just tape it back down as the print's going. Using a thin spatula helps to get the tape in there even when the bed's moving, without burning yourself on the hot end (of course, watch the motion, do it when it's doing a big fill that you can predict where it's going to be). I'm mostly doing PLA so it's not as much an issue unless I do something that covers most of the print bed but... well, tape helps, as silly as it is.

 

Thanks for responding- I never tried a brim - I used it on a small part today, and I can see its benefits.

I'll try this on my spider part.

Thanks, mark

 

My recommendation is if you have smaller parts being suspended by rafts and support material you move to a honeycomb method. As the default one tends to shift right-to-left too much.

 

Thanks I just tried the honeycomb on a different project I was having issues with and that worked great.
Now I'll try it on my spider
-mark

 

I have discovered something I'd like to share.
In an effort to keep the models affixed to the build plate when printing with ABS, I have been using a thin 2 sided sheet tape on the blue tape. When printing with a brim, my models have adhered quite nicely. They remove easily when the build plate is still warm.

I can reuse the sheet tape several times. To remove I just remove the blue tape. I don't even change the extruder height.

-mark

 

ABS slurry has been working incredibly well for me. Though it's a bitch to remove.

 

Im having same problems with my prints not sticking im using blue painters tape is there any other tricks then the ones posted above? What are you using for temps with ABS. I have extru at 220 and bed at 85.I did read some other forum some people are using tape and sparying on some hair spray its a thought i guess....

 

http://forums.robo3dprinter.com/index.php?threads/vinyl-decal-on-printbed-awesome.1596/

it's not tested on abs yet, but maybe...

 

I did use tape and a little hair spray and the print stuck so good had a hell of a time getting my print off. Its was my first print. I had the printer for 3 month collecting dust so thought i better take it out and try it out...

 

I was messing with RAFT the entire ABS roll.
What i learned is:
Raft=filament waste.

You should use american CREW hail gel on your glass bed.
To prevent warping of ABS, set bed to 110 or above. 150 max

To prevent your model being a mess all together, switch to CURA. Print times are half the Repetier and it gets your prints done the way you tell it to.

 

When my print is too stuck, I remove the glass from the bed and put the whole thing in the freezer for a few minutes. Print falls right off

 

To me its a problem. I dont want to remove my bed (mirror on top) to remove the model, i would just wait till it drops down to 40 and then move it with the top of my finger.

I dont normaly wait on small prints, but large prints i leave to print when i leave home, so when i come back they are already done and cooled

 

For all of you that use a spray adhesive, or hair spray to help hold models to build plate -I assume you cover the extruder and other moving parts to protect them from the spray?
-mark

 

Just use hair gel. Why mess with spray.

 

Vinyl is the end all. It may stick too well if anything...but its gunna stick and not lift.

 

Interesting.
This may be cheap alternative to kapton tape.
All those tape is making me sick. Even if vinyl works, it would still need to be removed sometimes.
There has to be a permanent solution:

 

With PLA I could probably do 100+ prints on the same sheet. The ABS bites so hard that you sometimes damage it prying it off, but with the right tool I am sure it wouldn't be a problem to use for a long time. My part had a big base so it was hard to get started to pop loose. I bet using a can of air upside down would get it cold fast enough to pop right off. I wouldn't try that with a hot bed though, may break glass.

And I don't mind removing it anyway, its dirt cheap and its easy to remove. ABS on vinyl is like gorilla taping the part down. It makes it easier than PLA. The first real attempt at ABS and I did a part that I have never got to work with PLA.

 

So ABS sticks to vinyl without any ABS juice ?
Do u have to heat the bed or it sicks fine room temperature for ABS ?

 

No juice...just vinyl. Heated bed to 90/85...i think it needs the heat to get a good print...cant say i tried without though. I know even when bed fully cooled it was still stuck very well.