About 20-25% too big for a standard K40 Laser. Main part is 380x240mm. Might be to down size it a bit though.
This is awesome! I agree on the possibility of downsizing it a bit. My sister works in surgery at one of the major hospitals around here, I’ll try to source some material and cut one as large as possible on my machine. I can currently cut about 9"x12", but angled strategically I could cut this shape larger than that.
She can give it a test in real world circumstances and see if it’s feasible to produce a large run of these!
So, I got a 48"x96" of .020 PETG from my supplier this morning, it was about $25. I was able to dice it into 8"x12" pieces, it yielded 48 of them.
I resized the file to the max it would fit while leaving me a little room for error. It was a good bit smaller than the original but I thought I’d give it a shot.
I actually got the settings pretty close the first time, it was tedious to separate but workable for a test. My sister tried it on and was impressed, but thought it could use more coverage around the sides. I did some magic in Inkscape and came up with a design that, while shorter that the original, actually had more coverage on either side!
I was also able to arrange the forehead straps to maximize the material usage and meanwhile got the settings dialed in to near perfect.
I was unable to locate any rubber bands so I improvised with some of my wife’s hair ties. It’s a little tight on top and a little loose on bottom, but with the correct size bands I believe it’ll be perfect!
My sister is going to present it to the powers that be at the hospital tomorrow and see what they think. If they like it, I can knock these out in bulk for less than $0.60 each! Also, my brother-in-law is a firefighter, and they’re taking extra precautions on calls these days, so they be of use to them as well.
I’ll report back when I hear something.
Excellent! Thanks for reporting back
Any news on whether the hospital is interested? (And what kind of suppliers have 4’x8’ PETG sheets on hand?)
For anyone just tuning in, shields like this are necessary for surgical masks to be considered sufficiently protective, is what I understand.
Another design going around, to print and add transparency sheets. Three designs, including US letter transparencies with holes aligned to use with a normal three-hole punch so you can make them without a laser cutter.
It looks like the US is not running out of transparency sheets; I see them available in large quantities from many sources.
The frames use about 15g of plastic each. I’m doing my first prints in PLA+ because it’s a bit more flexible than undoped PLA. I’ve made 14 of them so far and given some of them to friends.
These are cough/sneeze/talk-spit shields, not masks. They are primarily part of the “my mask protects you, your mask protects me” discipline as far as I’m concerned. They aren’t certified anything, and the transparency film I have isn’t optically great like PETG would be. But for grocery shopping under lockdown, I’m happy to have them.
But they print easily and quickly, and it’s a good design.
Good evening everyone!
My sister showed the mask I made to the materials guy (as she called him) on her unit and he has taken it to his boss. I haven’t heard back yet, but I’ve also made a couple of the updated shields from the original link above.
Just last night I was watching a YouTube video about the 3D printed frames with the projector sheets and was very interested. Now I need to convince my wife we need a 3D printer!
My local supplier is Piedmont Plastics here in Greensboro, but apparently they’ve got branches across the country. When I called the other morning they had about 75 sheets of the .5mm (.020) PETG on hand as well as a few other thicknesses.
Hopefully I’ll hear something this week from the hospital, but there are TONS of makers pitching in to help, so even if mine aren’t needed it’s good to know that the people in the community are willing to get involved.
If there are people local to you able to print the frames (“TONS of makers pitching in”), you could make PETG shields that fit those frames. If you cut it into 8.5x11 sheets, you could more quickly laser out the holes than a three-hole punch could, especially for thick plastic like that. My punch sometimes jams slightly even with transparency film; I’m sure it would not like cutting that 0.5" PETG.
PETG would provide better optical clarity for those frames, and it would make more efficient use of the PETG because all of it would directly be used for shields, and not require any rubber bands or elastic.
My experience so far is that I haven’t managed to shake this shield off my head, and it’s comfortable to wear.
We’re getting mixed messages in the triangle about whether the hospitals could consider anything like this at this time. It would be awesome if they don’t end up needing them, but it seems more likely that they will.
I saw @Ariel_Yahni_UniKpty post a video today on CNCing a frame from 3mm polycarbonate that could be laser cut as well.
Cnc and laser files here on openbuilds
It’s based on this 3D print.
Page also has instructions for hole punching the plastic which seems to be transparency sheets for the shield.
Of course the polycarbonate is probably going to be more expensive than 3D printing.
If laser cutting it, looks like I could nest them and get 2 in a piece 214 x 209mm (includes 1.5mm margins).
Quick look on Amazon shows I can get a 1/8x24x48 piece of polycarbonate for about $37. In a 24x48 piece I could get 20 headbands at the current size.
If you shave off about a bit of the design from front to back you could probably get another 6 (assuming you can cut down the sheet with minimum loss of material, like scoring and snapping).
Of course with a bed bigger than a K40 you could probably do a better nesting scheme to get a better packing efficiency.
Polycarbonate does not cut well on lasers, how are people using it?
That’s roughly how I nest them to print two at once, though I leave a little more space between them because I’m not wasting air.
Each of them uses about 15g of plastic. Even at $25/kg (I’m using PLA+/PLAPro which is I think glycol-modified) that’s 4 cents of plastic. I could save 1¢ each by using cheap normal PLA… So it’s an order of magnitude cheaper to print than to cut from polycarbonate, as well as far less wasteful. The sides do need to bend substantially so I wouldn’t use acrylic, either. They say that you can use cheap printers to print them, and recommend large nozzles (0.8mm) which would be faster; I printed with 0.4mm nozzle already on my printer.
The transparencies are the more expensive part. I’ve been three-hole-punching mine (that’s the same design I linked to above). Inexpensive transparency sheets were $13/100 so 13¢; boxes of 10 usually seem to cost around $10 so $1 each.
Oh, good to know. Never tired it before.
Yeah, polycarbonate is bad, it burns and melts with a brown edge and toxic smoke. Acrylic is good, especially if you use cast acrylic.
Ooooh, ooooh, it’s almost as if we just had a new topic posted with relevant information!
Material Class Engrave Cut Cautions Why/Notes > Polycarbonate (Lexan) P ~ ~ Poor results Melts and discolors, not clean
Looks like BPA is the primary toxic byproduct, unless the particular sample has been doped for fire resistance? @Nedman can you update the table with possible toxicity issues?
The 3dverkstan / faceshield.nu masks are set up for A4 or US Letter.
One of the better transparencies for face shields is this:
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.
These transparencies are not as good as the PETG sheets that @ProfessorE found.
I found it interesting that when I wore this face shield grocery shopping on Monday morning, I got some surprised looks; today, I got comments like “I like that!” so maybe public sentiment is starting to shift toward masking.
I have learned that the Fellowes and similar clear binding covers are made of clear PVC and are therefore unsuitable for laser cutting. (But they punch nicely with a three-hole punch.)
If you want to laser-cut them, here are some PET covers. They might even be clearer than the PVC covers I’ve been using.