Introduction: Earsaver @ Vinylcutter
In the course of the maker-against-corona campaigns, we tried some production methods for effective production. The two most well-known, which are also perfect for the now well-known faceshields are, of course, 3D printers and laser cutters. After some optimization steps, the more mass-production-compatible injection molding processes and punching could take over mass production.
Another method - which I thought for a long time that I don't need it, since most things can just as easily be done with the laser cutter - is the vinyl cutter. This machine can also be used to cut films containing PVC, for example, which are otherwise less good for the life of the machine (and also the user) when laser cutting.
Which was not a particularly big limitation for me, since I am not a big fan of PVC. It is great from a disinfectability point of view, but at some point the usual laser-cut materials became scarce - a disadvantage of too fast production processes.
One good reason to finally deal with the vinyl cutter. Here we use a relatively inexpensive Silhouette Cameo 4 - one with the standard auto drawer for thin foils and the Craftblade 2 for thicker materials: the faceshields generally assume a minimum foil thickness of 0.2 mm, which is already just slightly above what the auto drawer can do. Thicker is better - what the Kraftblade should be used for.
Step 1: Thin PVC, the Autoblade and Faceshields
The first thing we need is a design. For the Faceshield we tinker around with Inkscape, basically we only have rectangles with a few rounded edges and holes in it: once to tie a rubber cord at the end and to connect the actual visor with a few fabric rivets to the head strap. Since I was still working with 0.2mm PVC film, it was actually very easy: The PVC film (using a simple and cheap cover film) was glued to the carrier (a CUT-MAT-24 for A3 - A4 films was too short on the side), the design exported as dxf and loaded into Silhouette Studio (but will be similar for other machines and software).
We also have to select the correct cutting mat and media size in the page settings. When loading the dxf document (just dragging it in) we sometimes had problems with alignment and missing lines: rotations in Inkscape and converting objects to lines helped at some point. The last step here was the correct scaling, since the size was also not quite right. Fortunately, this can be done simply by using the scaling functions in the studio when you click on the object (just make sure that the aspect ratios are scaled evenly with the small lock symbol).
Afterwards you can continue sending to the machine. Here we use the autoblade (after switching on and connecting the cutter you will be informed directly about the knives used, etc.), which would be the first choice of the software. There is no PVC in the material, i.e. we go on something first - the set for photo cardboard sounds good. In the settings we change the depth from maximum (set the "rotary wheel" to 10), contact pressure rather high and speed rather low. Then you can cut several times in succession. Sounds good at first to get through the material, but we work with a slick material on a mat that doesn't adhere well ... sounds like it could slip when cutting, and since the cuts have to lie exactly on top of each other, we'd better not do that.
Then place the cutting mat with the stop in the machine, pull it in with one of the arrow key and start cutting.
The two parts only have to be detached from the cutting mat, and connected with 13mm Prym sew-on snap fasteners (the holes can be used to adjust the distance to the nose, not unimportant for spectacle wearers) and finally the rubber cord is knotted.
After that had worked quite well with 0.2mm foils, you can also go megalomaniac and use thicker bindings (0.3mm), for which there is finally the Kraftblade (in reality: this blade of course not for that use case, but that shouldn't stop us) .
Step 2: Thicker Materials, Craft Blade and Ear Relief
The first approach was simply to take the latter design for the 3D printer, make it a dxf (load the stl into Openscad, and then make a projection out of it). That would be great for the laser cutter (... especially if you have a big one). With the vinyl cutter there are still some challenges, which is why the design had to be run through Inkscape again and modified.
The first point was the hole in the middle - it looks nice, but there is a leftover piece of film that had to be detached individually from the carrier, and i am lazy. The other point concerned the properties of the Kraftblade, which we are coming to in short time. In any case, the next steps are the same as before, PVC film on a backing mat (but here it is better to use only A4 and the smaller, supplied mat, it just sticks better) and loading and scaling the design (and duplicating some objects here), and then on to the "Send" tab. The box we used previously has no Kraftblade settings, so we just choose a different material, acetone sheets sounded like a force. Then do not cut anything with tool 1 and select force cut with tool 2 (the craft blade).
Here the knife actually has to be turned manually to the highest thickness, and as it turned out it was better to work with very little pressure and speed so that nothing slipped and the mat survived (ok, the scond mat survived :). In the blue contour lines we can still see short cuts below the band which are somehow strange - unfortunately the autoblade traces the cut edge, which only works with certain radii. If these are too tight, the knife must first be turned in the right direction at another point. That happens in these additional cuts.
To reduce these additional cuts, we redisigned it a bit: bigger radii should help. Of course, it would be optimal if this was only necessary once for each band at the start, but compared to how it initially looked with the original band, this is already quite optimized.
Bby the way, also a point about the face shield design from above: the holes would be a nightmare with 0.3mm material - here we used punches instead: Learned something again, there are megalomaniac punches where you can set number and spacing of holes: https://www.thingiverse.com/thing:4202906 ...
But back to the topic, after teh optimization the vinyl cutter could start again. Conclusion: 0.3mm PVC is also possible ... however, the vinyl cutter then sounds as if it wants to be finally released from its suffering (but there are earmuffs for that) and we still have to push the pieces out with some force.
At the end, we produced some waste until it finally worked. But after all, daily yield is not bad - but for real mass production, laser cutters (as long as it is not PVC), punching or just injection molding again wins.