Can support increase accuracy/definition of small features?

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cc19
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Can support increase accuracy/definition of small features?

Post by cc19 » Tue Nov 01, 2016 9:30 pm

I believe older Stratasys machines lay down support material outside of the outer outline of the model, almost like the model's outside perimeter is being "boxed in" before being laid down... so that when the model's outer perimeter is actually laid down, it butts up against the support, for additional precision.... so basically your entire model comes out encased in support.

Can anyone comment if our desktop printers can do the same?
I'm trying to print really small parts, with, for example, snap fit "arrow heads" that overlap edges only by about 1mm. The issue is that the arrow head's sides are coming out round instead of sharp.

If I can get better definition of small features, maybe i'll deal with the hassles of the second extruder/dissolvable support.
Thoughts?

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Jules
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Re: Can support increase accuracy/definition of small featur

Post by Jules » Tue Nov 01, 2016 10:07 pm

You can control how close or how far away the support extends in S3D. (Horizontal Offset from Part, Extra Inflation Distance, Upper and Lower Vertical Separation Distance). In addition, you can control how thick the support is, how far apart the bands are spaced, and you can manually place support exactly where you want it to be, or remove it if you don't need it in a certain place.

"Snap-fit" anything with plastic might be a little bit tough to pull off, just due to the nature of the medium, but the support for it shouldn't be a problem with a little experimentation.

If you are referring to using dissolving filaments as support - once you have the dual setup you can butt them right up against the print. But it will not create an "outline" if you use Support. It is going to follow the shape of the Support, at the density that you specify.

Of course if you really want to create only outlines to support it (and burn through some serious material)....you can just attach a 2 or 3 outline skirt that is as tall as the bumpout, with zero offset separation. You should be able to specify that the skirt be printed with only the support material.

So yes, it should theoretically be possible. (It would be easier to cut your arrowheads in half and glue them together so you can print them flat, but that might not be the look you're wanting.)

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insta
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Re: Can support increase accuracy/definition of small featur

Post by insta » Tue Nov 01, 2016 11:45 pm

Jules,

Somebody coming from a Stratasys background is skeptical of the cheap price of printed parts from an M2, even at 100% fill and 100% support.
Custom 3D printing for you or your business -- quote [at] pingring.org

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Jules
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Re: Can support increase accuracy/definition of small featur

Post by Jules » Wed Nov 02, 2016 12:52 am

insta wrote:Jules,

Somebody coming from a Stratasys background is skeptical of the cheap price of printed parts from an M2, even at 100% fill and 100% support.
oh, that wasn't a request for how to do it? (Never mind!) :)

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insta
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Re: Can support increase accuracy/definition of small featur

Post by insta » Mon Nov 07, 2016 4:01 pm

I was just commenting on the "burn through some serious material" line :)
Custom 3D printing for you or your business -- quote [at] pingring.org

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zemlin
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Re: Can support increase accuracy/definition of small featur

Post by zemlin » Mon Nov 07, 2016 5:02 pm

My wee-little brain isn't working out how features/support/material outside the arrowhead would improve definition of the corners. If you need sharper corners, try a smaller nozzle.

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willnewton
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Re: Can support increase accuracy/definition of small featur

Post by willnewton » Mon Nov 07, 2016 5:47 pm

zemlin wrote:My wee-little brain isn't working out how features/support/material outside the arrowhead would improve definition of the corners. If you need sharper corners, try a smaller nozzle.
This. and smaller layers heights and reduce your extrusion so you have less buildup in the corner and maybe put a micro radius on your CAD model's edges so the printer takes the corner better.

The better solution for this application would be to print with 4 or more perimeters at a slow speed and 4 arrowheads at a time. Once they are done, file the the edges with a fine file.

What the OP is looking to do can be done (encasing in support, preferably stuff you can dissolve), but it will not give you the improvement in edge quality you seek.

I file mating surfaces often for good edges on snap fits. It is important on snap-fits to balance the grabbing tension vs. the potential to snap off and break or take a permanent set during assembly and disassembly.
I'm finally back to where I started two days ago!

A thread with some stuff in it I update every once in a while. viewtopic.php?f=8&t=9
See some of my stuff http://www.thingiverse.com/willnewton/about

cc19
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Re: Can support increase accuracy/definition of small featur

Post by cc19 » Wed Nov 09, 2016 6:41 pm

Jules,
Thanks for the insight into the settings to produce the desired effects!
maybe it's time for dual extruder!

willnewton,
Thanks!
I will look into micro radius. I haven't heard about it, but will experiment. I'm assuming something about putting a micro radius on the corners will change the slicer's behavior to make it more 'sharp'.
I'll also try lowering layer height.
Filing afterwards is a nifty idea I'll save for next time, since there's literally no space in this case. I have 2 half-arrows printing with the slant edges parallel @ 0.2mm apart, pointed towards each other.
And thanks for thoughts regarding encasing in support! Let's see if I can't get this right without encasing in support then.

Phil
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Re: Can support increase accuracy/definition of small featur

Post by Phil » Tue Mar 14, 2017 5:34 pm

I have been trying this very thing for a while. I have some switch covers I need to replace, and I would like to get the lettering to be as precise as possible. I really thought printing the cover in white PLA with the lettering in black PLA might do the trick, but alas, it still leaves much to be desired. I used black nail polish to fill in the lettering the black filament missed on the right cover, so you can tell the second extrusion does not help as much as you might hope. (The nail polish also leaves residual in the crevices, leaving what looks like a film on the switch cover.)
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Jules
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Re: Can support increase accuracy/definition of small featur

Post by Jules » Tue Mar 14, 2017 7:07 pm

The shape of those makes it impossible to do what I would have suggested, which would be to pause the print and print the text raised on the design in a different color. If it were a horizontal top, you could maybe get away with it. But that canted angle makes it impossible.

That would be a tough one.

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