NIH-recommended Face Shields (3DVerkstan)

Now NIH-approved:

https://3dprint.nih.gov/discover/3dpx-013306

Lots of discussion about printing these frames at Laser Cut Medical Face Shield starting from the idea of laser-cutting transparencies, since they can also be laser cut.

The 3dverkstan / faceshield.nu masks are set up for A4 or US Letter.

These take about 15g of plastic to print and print quickly, and they are what I’m using as a face shield. Much less plastic than the Prusa version. Cheaper and faster to print. Easy to don and doff.

One of the better transparencies for face shields is this:

https://www.staples.com/Fellowes-Crystals-Binding-Presentation-Covers-Oversize-Clear-100-Pack-52311/product_719620

https://www.officedepot.com/a/products/118001/Fellowes-Clear-Presentation-Binding-Covers-8/

But that’s not the 8.5x11" size that the punch guide was designed for, it’s the 1/4" oversized covers 8.75x11.25". It has two rounded corners on each sheet, perfect for the side that is near you neck, and it’s clearer than typical transparencies.

The spacer block that is provided with the 3dverstan files is 1/2" wide, which when used with a 3-hole punch set up to put standard US letter paper in and punched twice puts the holes an inch apart to fit the mounting lugs on a frame exactly. However, it’s not the right size of the oversized transparencies. For that, shrink the part to 75% in the 1/2" dimension (Y as it comes in the STL) which will make it 3/8" wide instead of 1/2". Then punch the transparencies using the smaller block.

I printed a 1/2" spacer for normal transparencies in one color, and a 3/8" spacer for the oversized transparencies in another, to make it easy to use the right one for the job and not waste transparency sheets.

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Now that I’ve built a real printer, I’m actually able to use the ABS I bought a few years ago. I’m successfully printing the 3DVerkstan frames from ABS now, as well as the PLA+ I’ve been using.

I’m trying to conserve PLA+ because my replacement order is currently scheduled to arrive around the end of the month. But ABS sure does smell!

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I just sent a batch of face shields to a local nursing home by their request. Someone from my church made the connection, and he picked them up while practicing careful social distancing.

I’ve had a few contributions of transparencies. One neighborhood family used to home school and had leftovers from that project, and provided the transparencies for me to match to frames I print and give to essential workers.

I’ve learned that GizmoDorks low-odor ABS might be lower odor than normal ABS, but not that much. My family are putting up with the smell only as a gift to the community. I need to work something out to deal with this. :thinking:

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Add an extraction unit to it after enclosing the printer?

I don’t want to exhaust the hot air when I enclose it; that would defeat the point. So my first thought is whether it would be possible to have a recirculating filter inside the (future) enclosure. That leads me to a question whether crushed pure hardwood charcoal (not self-igniting briquets) would be a long-term cheaper source of odor absorption. I could make up packets, and then when the printer starts to smell, swap in the next fresh packet.

I have a dehumidifier in the next room that runs a lot. I could put a layer of carbon filter in it or in front of it and it might capture more of the odor that escapes. Belt and suspenders.

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I have a new recommendation for transparencies for the 3dVerkstan frames:

Oddly not available on 975supply’s web site, but they came more quickly than originally projected ordered through Amazon. They shipped from GA, which was convenient for getting to NC quickly.

They are optically clear and punched easily.

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And the mandatory hint: do not use PVC for Laser cutting, the fumes are toxic!

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Yes.

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I’d love your info on this: how are you getting good prints with PETG at high speed? What PETG are you using? What speeds precisely? What nozzle size? My family just rebelled at me printing the frames in ABS until I get some filtration set up, so I ordered 4kg of PETG, and I’d love to know what you are doing to print these fast.

I have only .4mm nozzles, but I could drill one out to 1/32" — that’s very close to 0.8mm if that’s an important point. I’m using a 24V 50W heater so heat shouldn’t be the problem for me.

I am doing all mine on 0.4mm nozzles. 85mm/s, 0.26 layer height, 0.56 extrusion width, 3 perimeters, 270C hotend, 70C bed, 4 bottom layers, 4 top layers, 0% infill. Retraction is really machine dependant, but I run high acceleration in firmware on the extruder, and 65mm/s retraction speed. 0% cooling.

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Thanks! I think it’s the 270⁰C that’s the difference for me; my PETG temperature has been 240⁰C. I’ll try cranking the heat up and see whether that makes a difference for me. (I’ve also had to learn that PETG prints at slower speeds than PLA or ABS; I never had to learn that on my old slow gantry printer, but on my new corexy I had an opportunity to learn!)

I think I’ll also try drilling out the nozzle, because that should also make it substantially faster. I suppose I should try one thing at a time though! :slight_smile:

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Yeah temp increase can make PETG less stringy which is not usually the case for other filaments. Getting the viscosity just right for clean retraction is key. I recommend making a test print with three cylinders spaced apart in a triangle two close, one further away. Then adjust print temp as you go up the cylinders and find the location where retraction gets the most crisp. For PETG I run a tiny bit of “coast to end” in the slicer. Maybe even a slight negative “extra restart distance” if your slicer supports it. Also z-hop can be your enemy on PETG as it tends to pull a string as it lifts.

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I broke my #60 (~1mm) drill bit trying to drill out a larger nozzle. Printing with .6mm extrusion width with a .4mm nozzle right now. I didn’t run a retract test at this point, as long as I can print workable visors prioritizing that, and test looks good so far. I laid out three on the bed.

Did you use the same extrusion width for first layer and subsequent layers? I’m wondering whether extra extrusion width on the first layer is a workaround for unflat beds. It looks weird with PETG and I’m wondering if I should get rid of that just like I got rid of the extra thickness in the first layer when I switched to an actually flat bed.

I just use the extra extrusion with to put out more plastic and make them a little bit stiffer in PETG. I run a 0.3 mm layer height on the first layer and then 0.26 on all the rest of the layers. I found over the years that running a 0.3 mm first layer makes up for most bed inconsistencies within reason. Although honestly since I’ve gone to BL touches my first layer is always perfect so I don’t probably need to do that anymore but it just helps with that adhesion for some of the trickier materials.

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Starting from your suggestions (with slight modifications) definitely helped! I used 270⁰C, no Z lift, 2mm minimum travel after retraction, -0.5mm extra length on restart, and 85mm/s for all my speeds other than small movement and 50mm/s first layer. It worked much better. I can tweak from here, but it produced usable frames. One of the nice things about a 330mm square bed is that I can fit three frames on at a time!

I wasn’t clear about one question: I already quit using the slic3r/prusa-slicer default 0.35mm first layer extrusion thickness with the default 0.3 first layer thickness. But in using 0.56mm extrusion width, do you also use 0.56 extrusion width for the first layer, or do you use a wider extrusion width for the first layer.

I’m using prusa-slicer right now. No coast at end at this point. I could fire up cura again; I used it first and only have a vague memory that some limitation annoyed me at the time, no reason not to try it again. It looks like Cura has experimental support for volumetric coasting. I can start by trying its default 0.064mm³ which is about .5mm length of 0.4mm nozzle width. It’s about time for me to try another slicer again! Worth a shot!

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If I use prusa slicer I’ll use a slightly thinner extrusion just for the outside perimeter which can help make it a little prettier 0.5. But I actually sliced mine in simplified 3D because at least on my long Bowden I seem to get cleaner prints with less manual cleanup. And simplify 3D doesn’t have extrusion width modifiers by feature.

I don’t use a thicker extrusion width for the first layer. I agree a wide first layer can make for an ugly elephant foot bottom. You can turn on elephant foot compensation to try and alleviate that in prusa slicer, But I haven’t really seen a huge benefit in extra extrusion width on the first layer.

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Ah, I have basically direct drive, just a 2" tube between the extruder and the hot end.

Cura had a few nice features but it’s blobbing more than prusa-slicer on the same model with as close as I can come to the same parameters, so I think back to prusa-slicer to generate gcode for the next print. But when I have more time to experiment I’d like to try it again.

I don’t know whether 270⁰C overcooked my filament or I had some slight underextrusion, but a bunch of the frames I printed delaminated in vertical cross section. They seemed brittle for PETG which is why I wondered if they are overcooked. My trash can is now holding a lot of dead frames. I think I need to slow down to speed up. :frowning:

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Are you doing active cooling? I am running cooling at zero %fan, layer bonding is crazy. But yes start slower and cooler, then start working your way up. Faster until under extrusion, then hotter until flow seems correct, then try faster again… Tick tock your way up until you are no longer happy with the results.

I’m using zero fan. It’s possible that I was seeing underextrusion, or that I was using too high a width for my particular nozzle due to a finer point on the tip, so that the layers weren’t reaching each other. The filament bonded great to the filament under it (Z); it was the filament next to it (X, Y) that didn’t bond well. So on reflection, I was probably pushing extrusion width too far for my nozzle…

I got a batch of various nozzle sizes yesterday, so I just installed a 0.8mm nozzle, which 3DVerkstan recommends anyway. First time trying it. I’ll try default extrusion width, except not using extra first layer extrusion width (by default, prusa-slicer makes the extrusion width twice as wide on the first layer), and slow down a bit.

Go slow to go fast, I know… :slight_smile:

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