Cor
Posts: 24
Joined: Tue Jun 26, 2018 4:50 pm

Ball form comes loose from bed

Greetings,

I am printing a wheelpant with ABS , finally I am getting somewhere , but still some issues , I hopeone some can give me some pointers.

Printing this:
2018-07-04 09_31_05-$.jpg
After about 15-20-ish Layers , these 2 parts come loose. (ussing support 40%, support base layers 0 , dense support 0)
2018-07-04 09_35_17-$.jpg
Last night I played araound with the support settings , made infill percentage 50% and dense support layers 1. Although I got a useable print the support is very thick , and way too much.
I think the problem is , since it is a pointy/ ball form , and almost does not touch the bed, after building on it , it becomes unstable after several layers and than just brakes off.
I use ABS -juice and everything sticks good on the bed, so I don't think that is the problem , the bed is also heated ( 100 degrees) and in an enclosure

Anyone has an idea how I can solve this?

Also the bottom part is very rough:
20180704_092223 (Medium).jpg
Maybe due to the support? any solutions for this , although this is not the most important , I can sand it. But it would be nice if the bottom part of the model comes out a bit better.

Biggest issue is the 2 parts which touches the heatbed and comes loose , that is realy a pain .

Many thanks,
Cor
blackbird2016
Posts: 134
Joined: Wed Aug 02, 2017 1:24 am

Re: Ball form comes loose from bed

Although basically it is not entierly impossible to print this part given the right settings
I would say, that this design is not really suitable for 3D-printing.

If it was my design, I would divide the shell in two parts (vertical) and either use a push-in or screw connection
to put them together.
Benefit would be that the supports then would be neccessary only for the inside of the shells (if that model is hollow at all)
and hence perfect outside walls without supports....
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dkightley
Posts: 2405
Joined: Tue Mar 10, 2015 4:09 pm

Re: Ball form comes loose from bed

This is where dense support comes into its own.....

Set the following:

* Support Infill %age of say 20%,

* Extra Inflation Distance of say 4mm

* Support Base layers of say 2

* Dense Support Layers of say 2 or 3

* Dense Infill %age of 100%

* Horizontal Offset of say 0.1mm

* Upper vertical Separation of 1 laye


Try printing the model agaim. You may want to have two profiles...one for the lower half and one for the upper half so you can have different properties for the upper and lower halves.
Doug Kightley
Volunteer at the National Tramway Museum http://www.tramway.co.uk
Railway modeller and webmaster at http://www.talkingtgauge.net
Cor
Posts: 24
Joined: Tue Jun 26, 2018 4:50 pm

Re: Ball form comes loose from bed

pfff , frustrating.


@blackbird 2016: thanks . I will do that later , first I want to know the limits what is possible with my prusa i3mk3 , so I know in the future what to expect.

@dkightley: I just tried with the settings above and I had to stop after a couple of layers. The beginning looked good, a nice white surface., but then after about 10-15 layers , suddenly the layers didn't look right anymore:
20180704_184138 (Medium).jpg
20180704_184118 (Medium).jpg
What am I doing wrong?

-I3mk3 prusa
-White ABS ( from prusa)
-100 degrees heated bed , 255 hot end.
2018-07-04 20_25_20-$.jpg

Thanks,
Cor
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dkightley
Posts: 2405
Joined: Tue Mar 10, 2015 4:09 pm

Re: Ball form comes loose from bed

Input is needed from someone used to printing in ABS...….I'm a PLAer and don't suffer from print adhesion issue like this!
Doug Kightley
Volunteer at the National Tramway Museum http://www.tramway.co.uk
Railway modeller and webmaster at http://www.talkingtgauge.net
greybeard
Posts: 178
Joined: Mon Mar 02, 2015 1:23 pm

Re: Ball form comes loose from bed

I’ll just post what I would do, along with Example of the setting/File for my two Prussa's (both are I3 MK3, built from kits).

1) See if the file works for you but add the supports as you think are best. Note: I seldom need supports but, when I use them, I set them with parameters that (hopefully) show up in the attached file.
The file is for PLA but is good for ABS just set the Temps as you need (I use higher temps).

2) Consider splitting your part lengthwise and printing with the cut (flat) surface on the bed so that no curved surfaces are considered (by software) as overhangs. Thus, you won’t need supports. Then, glue the two halves together.

3) For adhesion to the bed, I use only Glue Stick (noting that I put picture-frame glass on both my beds). Between the glass and the glue-stick, I have zero problems. Note: not all glue-sticks are equal. I prefer AVERY Permanent Glue-Stic.
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Cor
Posts: 24
Joined: Tue Jun 26, 2018 4:50 pm

Re: Ball form comes loose from bed

@ greybeard: Thanks , I will try that tomorrow.

From the pictures in my previous post, the first layers were just fine.
Can anyone tell me what does it mean when after the 15th layer or so , the material does not seem to bond correctly anymore?

Thanks,
Cor
greybeard
Posts: 178
Joined: Mon Mar 02, 2015 1:23 pm

Re: Ball form comes loose from bed

Regarding ‘..after the ~15th layer…’ Things to consider:

• The material being laid down within those layers is warm from the heated bed and extrusion but, then it cools. At the 15th layer, the Fan further cools the material perhaps too quickly - causing shrinking away from the layers it was extruded on top of before is adheres.

You can reduce the Fan to 40% speed and position so it's not blowing directly on the new extrusion.

It looks like something happens at the layers where it goes bad:

Are your Temp settings changing at that layer?

Print speed too fast and/or changing?

Can you successfully print other items beyond 10 to 15 layers?

Perhaps aside from this issue; I suggest setting your Acceleration Jerk to a low value of around 2 to 4. (Some Prusa machines have the default at 20. That will shake the machine apart and cause print problems).

Might be worth posting screenshots of print settings…
3D Print Parts
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airscapes
Posts: 403
Joined: Tue Mar 06, 2018 10:35 am
Location: Philadelphia PA Area

Re: Ball form comes loose from bed

ABS should have no fan, and your printer should be in an enclosure if it is not.
If you go to file > save factory file as and then post that factory file we can all see your settings and even print the model if we like.
I am currently printing a Jig for an E-nable Phoenix hand on natural ABS and this model has lots of support. I have set it up as Doug suggested, and will let you know the out come. I have attached ached my factory file if you want to look at it. Not saying mine is correct but I hope so!
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dkightley
Posts: 2405
Joined: Tue Mar 10, 2015 4:09 pm

Re: Ball form comes loose from bed

And to make the support a little more rigid, try setting the Support infill angles to 45, 45, 45, 45,45,45,-45

The support will look like this....
Capture.JPG

This technique works well on tall thin supports....gives it a lot of strength.
Doug Kightley
Volunteer at the National Tramway Museum http://www.tramway.co.uk
Railway modeller and webmaster at http://www.talkingtgauge.net

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