creating 3d printed face-shields quickly
Over the last few weeks I’ve given away more than 3000 face shields to hospitals, nursing homes, home-care companies, vets, and even a few fast-food companies.
In order to ramp up production, I’ve had to figure out ways of producing more shields, with less effort, while keeping a good standard of production.
The tricks here will help you speed up. The results will not be perfect, but they will be fast and scalable. This article assumes you are already producing face shields and juts want some ideas to speed up. I’m not going to walk through the basics.
The visor is the simplest piece to produce. Take an A4 clear PVC binder cover, cut an inch off the side, round the edges on that side, and punch holes in the other side in precise places based on what frame you are producing.
Speedup level 1
To cut many sheets to size at the same time, take a prepared visor sheet and place it on the near right corner of a work surface you don’t mind cutting into (if you’re left-handed, reverse these directions).
mark a line along the top edge of the visor in heavy marker. stretch the line out a few inches to the left, and all the way to the right edge of the table.
take a pile of maybe 20 sheets and square them to the table corner. place a metal ruler on top so it is in line with the marked line on the table. clamp the ruler down (you can get reasonable clamps for about €3 in any discount store).
you can now run a craft knife along the ruler edge to cut a few sheets at once. Angle the blade gently in towards the ruler, or the cut may veer away.
To quickly and accurately punch up to 3 sheets at a time: Buy two punches that are the same make and model. get a small wooden plank. screw one of the punches to the plank. carefully place the second punch on the plank so that if you put a sheet in them both and press down on both, you get the correct holes. Screw that punch down as well. Now you don’t need to measure. just push the sheet in, punch punch done.
to cut the curves, just use a scissors right after doing the punching.
Speedup level 2
Here’s where I am at the moment.
Buy a pillar drill and a band saw. They’re about €149 each in Lidl. Well worth it if you’re at the stage where you’re producing so many shields that visor cutting is eating up hours of the day.
Create two “templates” by getting two plywood or MDF sheets and drawing a prepared visor onto them, then very carefully drill 5mm holes into the correct place through both the sheets. Get this right. Then you can cut out the rest of the shape of the visors. This part is not important to get right.
Take a full block of sheets (including its wrapper) and place between the templates, then clamp this in place.
Put the 5mm drill bit in the pillar drill. With the drill off, carefully pull down the drill until it is in place in the template and touching the visor. This is to make sure you’re aligned. Lift up again and tun on the drill. Push the drill bit down through the vinyl in a few passes, each pass going a little further. This gives the drill time to evacuate the plastic from the previous pass before going further.
Then just repeat for the other holes.
Next, on the bandsaw, prepare the “fence” so it is 1 inch from the blade.
You can take the block of sheets from the template now. keeping the wrapper on the sheets means they’re all still held together so you should now be able to push the block through the bandsaw to cut an inch off. To do this, use the pushstick thing to push the block in. Don’t press the block in with your hands as you may influence the blade to veer off. Or you may slip and have to go to hospital, which is not a good idea right now.
Once that’s done, you can round the edges easily using the bandsaw.
Easy! I took my time with this earlier and was able to prepare 100 visors in only 3 minutes 40 seconds.
This one is tricky. We’re all using different frame types, so use whatever instructions make sense to you. I’m not going to walk through everything button by button (that’s why god invented search engines) but will explain the steps in general.
I’m using the “Europe” version of the Verkstan model, as that’s what I started with, and my “clients” are happy with them.
There are two versions of each Verkstan model – a “solid front” and the original “plate” version. We’re going to use the plate version.
Using the solid front makes sense if you’re using a dual-extruder, but most people are not.
First, create a “cookie cutter” outline of the frame. To do this, I open the STL in FreeCad and export as PDF. This creates a top-down image of the frame. I then open that in Gimp, delete the background and the grayed-out “plate” part of the front so I’m left with the frame outline.
Select the outline and “shrink” the outline by 1px and save that.
Now load that outline in Inkscape and convert it to an SVG.
Then convert the SVG into an STL using this tool. I think the size I used was about 180mm, and 0.6mm height (twice the height of your nozzle’s line-height). tick “reverse winding-order”, untick “base plate”, and then re-render before downloading the STL.
That STL has a lot of nodes in it, so I then use Meshlab to reduce it in size. I think I reduced mine down to about 2000 nodes from …who knows.
Next, open FreeCad and import the Verkstan model.
I turn the model over so the plate is at the top and there is a space under it. This way the printed plate will always have a nice finish on the “bottom”, and there won’t be a problem of the second frame in a stack’s plate drooping down and sticking to the first frame.
now import the cookie cutter outline and manouvre it into place on top of the frame. It will actually be better (for reasons you’ll find out) to just manouver the frame into place under the outline.
In my case, this just involves moving 60mm in Y.
Using the Parts menu, convert both STLs to solid. you can then delete the imported STLs.
Now go into the Draft menu, and create separate matrices from the frame and the outline (so you have 2 matrices).
Change X and Y multiple to 1 in both. Change Z multiples to 5. If you want, you can use a Spreadsheet object to make this dynamic. The Z distance should be 5.6mm (5mm for the height of the frame, 0.6mm for the height of the outline)
Okay – select both the frame and outline matrices, and export as STL. You can now print that.
After your first print you’ll notice some really bad “stringing” issues. I don’t have any left so can’t photograph them, but they look a little like this:
The reason this happens is that when the printer is laying down lines for the outer wall of the second frame, it’s pretty much drawing on empty space. So the line pulls away from the print and follows the path of the nozzle until the nozzle touches against the frame enough for the printed line to stick.
So now we get to the fine-tuning.
Print out a stack of 2 frames. Take note of where the stringing takes place.
Create a new FreeCad file and import the cookie cutter outline. Convert that to solid.
Now, wherever you noticed stringing take place, put a little line right across the outline from the inside to the outside, using a cube block that’s 0.6mm high, whatever length is required, and 0.2mm in width. I use 0.2mm because it’s a little less than half the width of my nozzle. we want this to be an easy-to-remove line, so don’t make it heavy.
Now you can save that all as an STL and import into the main model and repeat the creation of the Outline matrix (delete the old one).
Load up in Cura or whatever. If you look at the print path at those new lines, you’ll see that the printer skips from inner to outer, etc, which forces the line to reconnect with the main model, making it stronger.
The next print of the 2-stack should be better than the first.
Repeat until happy.
Then create a 20-stack and print.
Oh – almost forgot. There’s an art to separating the stack as well. Place the stack down on a cutting surface on its side so there are 20 end hooks touching the surface. Press a blade (I use a butchers knife) down between each end hook one at a time. Turn the stack over so the other 20 end hooks are touching the surface. Repeat. Now place the stack on its “back”, hooks in the air. You should be able to place the blade between the end hooks of two frames at a time, and just push down to separate them.
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