Fill when printing

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Fill when printing

Postby bot719 » Tue Feb 17, 2015 4:54 pm

Should parts be printed as solid or can they be done with a % fill? If not solid what % have people used?

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Re: Fill when printing

Postby laird » Tue Feb 17, 2015 5:03 pm

I've been using 2-3 shells (outer layer) and 25-50% infill, depending on the part. Fingers and palm don't need much infill, since the parts designs are strong shapes, while the gauntlet need more because the large arch isn't as strong a shape. IMO, of course.
- Laird Popkin

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Re: Fill when printing

Postby skjain2 » Tue Feb 17, 2015 5:06 pm

Agree with Laird. I take the extra step to print the fingers in 200 micron and the gauntlet in 300 micron, as I've observed thicker layers tend to be stronger and delaminate less.

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Re: Fill when printing

Postby LydiaOST » Tue Feb 17, 2015 5:40 pm

Hi Bot,
I cross-posted your question in the G+ Community: ... rsCHWwtGT8
eNABLE'S Organizational Support Team founder, Team Facilitation Team member, eNABLE Help Desk member, Google Plus teacher, and Junior Forum Admin.

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Re: Fill when printing

Postby AdamArabian » Tue Feb 17, 2015 5:44 pm

It depends significantly on how well your printer is printing, but in general the number of outer shells is much more important than the infill percentage. I've seen good prints anywhere from 25% infill up to 100% and just based on the engineering stresses it won't make much difference - your big payoff is on shell thickness - this is how many solid layers you have on the outside. What we are trying to do is make these very strong in bending and your maximum stress (material damage) occurs on the outer surfaces in bending.

So if you want a quick best guess, go with about 40% infill and at least 2 outer shells.

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Re: Fill when printing

Postby hertfordkc » Tue Feb 17, 2015 6:20 pm

I generally print with 3 shells and 40%. The gauntlet deserves a bit more infill.
With some slicers (maybe all), you may create voids when the number of shells approaches the width of the object. This can be rectified by changing the number of shells and increasing the infill. I ran into this in the fingers of my first print, a 100% Cyborg Beast. I've seen it a few more times while experimenting with whippletrees.

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Re: Fill when printing

Postby bot719 » Tue Feb 17, 2015 6:52 pm

Thank you all for the quick replies. I have downloaded the files for the Raptor and Beast. I suspect I will try the Raptor as a first test since I can easily purchase the kit of parts.

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Re: Fill when printing

Postby droomurray » Tue Feb 17, 2015 7:53 pm

I tend to print at 35% infill, 2 shells, 3 top and bottom layers and .2 layer height.
I found that not all plastic is the same, some stuff seems allot stronger than other stuff.


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Re: Fill when printing

Postby PeterBinkley » Tue Feb 17, 2015 8:19 pm

For small prints, like 100%, I go with 2 or 3 shells, and for larger prints, up to 5 shells. I make infill dense too, except in the fingers, which I usually print with 20% infill. Lightweight fingers respond better to extension, be it elastic or mechanical.

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Re: Fill when printing

Postby jameshs » Wed Feb 18, 2015 2:43 pm

for strength I go for 4 shells and 25% infill

So there seems to be quite a bit of variation - and therefore margins of error.

If we wanted to optomise then I guess we would need to develop an objective test and test some things to destruction - taking into account variations in print quality and part location etc.

We could pare this down and really save some time printing (worldwide) if the guidance was to print it strong enough - but I would rather spend more time and avoid breakages.

do we have any breakage reports?


James Holmes-Siedle

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Re: Fill when printing

Postby droomurray » Fri Feb 20, 2015 1:09 am

Devising some standard tests could work well as the variation is more than just outlines, shells, layer height but also varies by machine and plastic quality / type.

Thing is we need to devise tests that can be measured and the measurement equipment to support the tests needs to ideally be cheap, easy to perform and easy to source.


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Re: Fill when printing

Postby aaverill » Fri Feb 20, 2015 2:38 am

What would be the type of measurements that would be gathered?
Each type of test would require a different process, so to gather tensile strength we would need to use one type of machine, to determine compression we would need to have another one, and yet another test for impact.

Some measurement Ideas:
Tensile strength

Jason M Bryant
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Re: Fill when printing

Postby Jason M Bryant » Fri Feb 20, 2015 8:50 am

I'm planning on doing some tests on shells vs infill. I've already developed a rig and I ran the tests on PLA that was dipped in boiling water. I posted those results on the google groups page.

I'll try to get started on the new tests soon.

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