Maarten
Posts: 8
Joined: Wed May 28, 2014 6:19 am

raft separation/ model adhesion

Wed Jun 04, 2014 9:42 am

Hi folks,
I am getting used now to S3d, but here is something I am still fighting with:
If I don't use a raft, the print (abs) detaches from the heatbed halfway the print, and then gets pulled around by the printhead. So I use a raft. But I cannot separate the raft from the print. It is not difficult to separate, it is just impossible. What am I doing wrong?
thanks, Maarten Visser

tri-lite
Posts: 68
Joined: Tue Dec 10, 2013 7:08 am

Re: raft separation/ model adhesion

Wed Jun 04, 2014 10:45 am

This suggestion about a "brim" may or may not help you. I use it more with PLA, but as you'll find on this forum, most S3D users never use rafts.

S3D has a setting to create a "brim". A brim is like a skirt, but the brim is a flat extension that is actually attached to your part (zero offset). Find the setting in the Layer tab. Enter 1 layer, zero offset, and maybe 15-20 outlines. This flat extension helps hold down a part rather than use a raft, which takes more time, filament and removal.

Even if you don't use a brim on your ABS prints, it's a great technique to hold down delicate PLA parts rather than using a raft.
Attachments
Screen Shot 2014-06-04 at 10.37.09 AM.png

Maarten
Posts: 8
Joined: Wed May 28, 2014 6:19 am

Re: raft separation/ model adhesion

Wed Jun 04, 2014 1:39 pm

I did that and it worked. Thanks a lot. Also, much less costly on filament than printing a raft.
best regards, Maarten

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jimc
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Location: mullica, nj
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Re: raft separation/ model adhesion

Wed Jun 04, 2014 5:20 pm

the brim works well many time but many times it does not. in s3d it doesnt always follow layer 1 all the way around. the brim is made in the shape of the model from the top view so if you have anything sticking out of your model then the brim wont be attached. here is a pic of what i am talking about.
Screen Shot 2014-05-27 at 11.57.26 PM.png
i really wish s3d would fix that so the brim would follow layer 1. in any case another option i use occasionally is i will model discs in different diameters that are 3 - 4 layers thick. i will save them as an stl and keep them in a folder. i can drop a few onto the build platform and drag them around and usually place them on the corners of my model where lifting would be prone.

Garyhlucas
Posts: 25
Joined: Sun Mar 09, 2014 12:13 pm
Location: Hightstown, NJ

Re: raft separation/ model adhesion

Wed Jun 04, 2014 6:21 pm

Jim,
Does your post mean that STL models that intersect will get printed as if it were a single part? If so I could see that as a very useful.
Gary H. Lucas

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jimc
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Location: mullica, nj
Contact: Website

Re: raft separation/ model adhesion

Wed Jun 04, 2014 7:47 pm

yes gary they do. it didnt used to do that but was corrected in the most recent update.

tmoore
Posts: 14
Joined: Tue Feb 18, 2014 9:27 pm

Re: raft separation/ model adhesion

Fri Jun 06, 2014 1:07 am

I'm seeing that if you set brim to the parameters listed above and then turn on support the brim will not print adjacent to the model. What i would like to see is the ability to set a negative offset that would push the brim right up to the part edge where the part contacts the glass.

Maarten
Posts: 8
Joined: Wed May 28, 2014 6:19 am

Re: raft separation/ model adhesion

Fri Jun 06, 2014 5:30 am

That's all very nice, but I still have problems simply printing a Yoda head. Under the protruding chin no brim is printed and that is exactly where the model starts to wobble during printing. What really works in stabilising the model is a raft- but I cannot separate the raft from the object. Someone has tips in doing that? I already lowered the abs printing temperature to 180C.
regards, Maarten

dennisjm
Posts: 342
Joined: Wed May 07, 2014 9:51 pm

Re: raft separation/ model adhesion

Fri Jun 06, 2014 9:54 am

Sounds to me like you need to stop worrying about brims and rafts and address your sticking problem instead.

Here are a couple things I've learned as I began printing:
- level bed at the right height from the nozzle so plastic is pushed correctly on to the bed (too high and it won't stick)
- right temperature (hotter sticks better)
- print 1st layer slower can help too.
- I'm printing on Kapton tape w/ ABS. Most of the time it works well but I've tried adding some "abs juice" on occasion if a print seems hard to get to stick

I watch the first layer pretty closely and I can tell right away if I'm going to have sticking issues or not. If so it's usually the bed leveling or first layer speed to high.

Maarten
Posts: 8
Joined: Wed May 28, 2014 6:19 am

Re: raft separation/ model adhesion

Fri Jun 06, 2014 10:19 am

Thanks. This helps. So far:
- level bed at the right height from the nozzle so plastic is pushed correctly on to the bed (too high and it won't stick) OK, did that.
- right temperature (hotter sticks better)
I print the first layer at 210C, then gradually cooler till I print most of the model at 1805C. If I print hotter the supports are impossible to remove

- print 1st layer slower can help too. Will try that.
- I'm printing on Kapton tape w/ ABS. Most of the time it works well but I've tried adding some "abs juice" on occasion if a print seems hard to get to stick
Yes, I use kapton. What is abs juice? aceton? single malt whisky?

I watch the first layer pretty closely and I can tell right away if I'm going to have sticking issues or not. If so it's usually the bed leveling or first layer speed to high. /quote

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