there are also shops like Graingers.com, which may be local to you and, if they don’t have it in stock, can usually get orders in stock within a day or two for you to pick up.
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What I did was peel off the masking on both sides, save one of the sheets of masking and use it to line the crumb tray, and placed the sheet on the bed. That seemed to do a pretty good job of protecting the underside, and no weeding at all.
I clean them in a Simple Green bath, rinse and dry, and they look pretty good.
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Cutting the center out increases flexibility but does it create any concerns about durability - I love the idea but dont want to risk one snapping during the day while someone is using it. Any thoughts?
1/8" Acrylic will measure about 0.118". The manufactures actually make the material in metric thicknesses. 3mm (0.118") is marketed as 1/8" in the US.
Generally, all plastics are done this way.
I’m going to be a bit general to provide basic guidance. An in depth answer is much more complicated than it seems and gets into material science.
Acrylic is a crystalline material and is inherently stiff and brittle as a result. Any geometry you add (to this design) to make it flexible will lower the strength because you are introducing high load points. As those points see tension and compression loads they stress the material which compounds over use. To reduce the stress you want to avoid sharp corners, use generous radii, and leave a decent amount of material. The thicker the material the closer to a square cross section you can have. You can look at the load physics of theoretical beams to go deeper on the subject.
The load point stresses are especially true with cut Acrylic because you’re breaking the molecular bonds to provide the shape, which weakens the material. Molded acrylic will be stronger because the molecular structure is formed and set during the molding process in a way that conforms to the final geometry. Molded will be much stronger than cut every time.
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What are your thoughts on annealing after cutting?
Although I agree with your point that adding geometry to make the design flexible will increase stress concentration points, I suggest one correction. Acrylic, or poly(methyl methacrylate), is not crystalline, but is instead an amorphous thermoplastic. It’s stiff and brittle at room temperature (where it behaves like a glass) because the temperature at which it softens (the glass transition temperature) is much higher than room temperature, typically 185 to 330 degrees F depending on what copolymers are added to the different commercial formulations.
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Correct.
I’m used to describing the difference between PC and Acrylic to people. In which we describe Acrylic to be more crystalline in property in the way that it acts and breaks at room temperature. Which is more like shattered glass than the permanent stretch/deformation/ or tear of other plastics.
I just donated 5 to a local worker and she said one of them snapped immediately 
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We’ve made and donated 2090 as of a few moments ago. Menards acrylic works fine. I’ve had no requests through glowforge so my wife just reached out and the avalanche started.
Disheartening to see that some are selling these on ETSY vs donating… 
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My understanding is that these are for surgical earloop masks.
N95s have straps that wrap around the head and are designed to be fitted without any clips needed.
Here’s a pic of the two masks. (the teal one is an N95 - model 1860) All N95’s have the around the neck/around the head strap.
Just curious. Could you ask her what snapped? What type of mask she was using? This would help with improvements.
This is not correct. Most of the N95 masks I have seen have earloops, but N95 refers to the filtration, not the mask style or how it secures to the head, so there can be N95 masks both with and without earloops.
The blue mask in your picture may rate as N95 by the effectiveness of its filter but it would not protect very well against an airborne virus such as Covid-19. I hope, for their sake, that healthcare workers have better masks. In addition to having earloops, the N95 masks I have seen are significantly larger.
All of the mask clips, including my next-generation designs and GF’s design, are intended for any masks with earloops, which would include most (but not all) surgical masks and many (perhaps most) N95 masks, and an unknown quantity of homemade masks.
No offense Roy,
Ear loop masks, no matter the material they are made of, cannot be true N95’s. They may market them that way, but they’re not rated n95 for medical use.
Medical professionals cannot use ear loop masks if they need a rated mask.
Being a paramedic, I find your statement regarding my 1860 N95 a bit odd. It’s a fit tested mask. Annual testing ensures we wear the right masks.
It’s 95% effective at 1 micron and gets better as the particles grow larger.
Where do you get your info?
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Understood. Although acrylic will creep when it’s loaded - it just takes a really long time to observe it, unless you have very sensitive instruments.
https://www.cdc.gov/niosh/npptl/usernotices/counterfeitResp.html
Please pass this information on as ANY N95 with earloops is considered to be a counterfeit by the CDC. N95 is a rating that can only be attained through proper fit. Ear loops cannot do this.
These clips are helping surgical masks feel and fit a bit better and I am helping produce as many as I can.
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https://www.cdc.gov/niosh/npptl/usernotices/counterfeitResp.html
All ear loop “n95’s” are counterfeit.
https://www.cdc.gov/niosh/npptl/topics/respirators/disp_part/respsource3healthcare.html
From the FDA: “The ‘N95’ designation means that when subjected to careful testing, the respirator blocks at least 95 percent of very small (0.3 micron) test particles.” — again, N95 refers to the filtration, not the style. It’s 95% of 0.3 micron particles, not 1 micron particles, but Covid-19 is approximately 0.125 microns, so even an N95 mask is not perfect protection.
Your 1860 is a fitted mask; it didn’t look like one when I looked at the photo (it looks almost like the crappy painter’s masks I have). It’s also disposable, not cleanable, so that is a downside to masks like that and one reason for the shortage. I hope it fits well without gaps. Your work as a paramedic is appreciated — always has been, even if people don’t say it all the time — we all want you to be as safe as possible!
I have not found confirmation of your statement that no ear loop mask can be an N95 mask. You might be right, but neither the FDA or CDC web sites confirm. If it has to do with fit and tightness, perhaps an ear loop mask with a mask clip would meet the standard?
Aside from this, the goal of all mask clips that I’m aware of is to relieve ear pressure caused by earloop masks, whatever the type, and also to help get a tighter fit. Whether they are N95 masks or not, there are millions of them in use every day in hospitals and other healthcare facilities. (note I did correct my previous comment)
It’s completely material dependent in this case. On acrylic it could cause issues. I’ve been using more flexible material (PETG .020”)
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