Making Protective Face Shields with a K40 Laser Cutter - Part 1

This blog documents my efforts to make protective face masks using a low cost K40 laser cutter using Kitroniks visor design.

The A4 'acetate' sheets for the transparent shielding bit haven't arrived yet, so consider this post a Part 1 , dealing just with making the strap shown below. The clear visor part will come later.

Early indications: Yes, it's feasible - if you have a K40, give it a go.

K40

These laser cutters are very low cost, but only have a small bed (about 330x220mm useable).

Their bed is much too small to take the files that Kitronik designed for their cutters, but if you have a bigger laser cutter then don't mess around with A4 it will be much more efficient to go to the full-size design here.

Design Files

Download the design files for A4 from github here or direct zip download here. The original DXF file was created by Dave at Kitronik and kindly passed on to me by Loraine Underwood, a fellow K40 owner (hers is in bit ATM)

The file A4 face shield band.dxf is the original file from Dave. I use the open source K40 Whisperer to control my K40, and this expects files to be an SVG, with vector cut lines to be in red 0.1mm wide. So the file A4 face shield band k40 whisperer.svg is an SVG version of the original with the lines made suitable for K40 Whisperer. I have also spaced things out a bit, because the K40 can be a bit 'melty' and close together lines can cause problems.

If you make a version of this for the default and highly suspect original K40 software, then please let me know and I'll add it to the repository.

The really nice thing about this design is that it just uses two materials, 0.5mm Polypropylene for the strap material and standard clear A4 OHP acetates (used full size without the need to cut). Whats more everything just clips together, no need for glue or staples.

Material

I bought a few sheets of Polypropylene Plastic Sheets 0.5mm here. It seems to be quite widely available as A4 to try. I now need to wait for a load more. Kitronic also sell this material, but not as A4. However buying some big sheets and cutting them up may work out cheaper.

Eventually you will need the clear 'acetate' sheets to use as a visor - Kitronic recommend this. My sheets haven't arrived yet, they will be discussed in part 2 of this blog.

Cutting Parameters

Your parameters will vary so, please cut a small test piece before wasting material. This was what I found worked best for my K40. Speed for vector cut 15mm, power (set by the knob on the k40) about 50%. My beam seems to diverge at higher powers than that, but I probably don't have the focus right.

The material is quite light, and I have seen people use small magnets in this situation to keep the parts flat to the bed. I didn't use magnets and it worked ok for me. But if yours starts flapping about, you know what to do.

Assembly

Please note that what I am describing here is making the first visor so, I am paying no attention to cleanliness at all. When making these for real, I think it would be sensible to be gloved and masked.

It took me a while to figure out how the pieces fit together, so here's what I learned. I have put numbers on each piece to make it easier to reference the parts.

1. Here's the cut sheet.

There is a bit of singing and in places the plastic had stuck itself together again. But I found it separated from the sheet easily enough.

2. The Pieces Labelled

For your first make, I'd suggest marking each piece like this (a sharpie will do). Or you may just be a lot better at puzzles than me and consider all this unnecessary!

3. Join Pieces 1 and 2

Bend the tabs of piece 1 and push them through the horizontal slots in part 2.

4. Join Pieces 2 and 3

Piece 3 feeds through the two end vertical slots in piece 2 like a belt through a buckle.

5. Join Pieces 1 and 4
Piece 4 fits on to piece 1 in much the same way.

6. Outer Strap
You should now have a long strap.

7. Inner strap
The inner strap is required to keep the clear part away from the wearer's face. Piece 5 accomplishes this by making a bow in the main strap.

Start by joining piece 5 to piece 2 and then to piece 1 using the horizontal slots.

8. Final part
The basic shape is there now, so it just remains to attach the buckle that connects the two ends of the strap together.

Join 4 and 6 together first. These have two positions, presumably for big and small heads. Fine adjustment of size uses piece 3.

My Donation Plans

Making these on a K40 is slow and so I don't expect to be making more than a few hundred of these visors at most. So, personally, we will be donating these to care-workers and other people we know who are desperate for protective wear and not too worried about the quality on the basis that something is better than nothing. I think, I'll leave supplying to the NHS as something for the big players (with big laser cutters) to do. But that's just what I think.

I hope to post part 2 of this tomorrow, if the clear plastic arrives.

Good luck and let me know how it goes.

Laser Cutting at FabLab Manchester

Manchester FabLab allows anyone to go along and use their kit for free on Fridays and Saturdays on condition that we make public what we do. So I paid them a visit on Friday to cut myself a new enclosure for my Arduino Lilypad Binary Clock.

The clock is one of the projects from my book '30 Arduino Projects for the Evil Genius'. Its a binary clock with four red LEDs indicating the hour, six blue LEDs the minute and six green LEDs the second. They all fan out from the Arduino Lilypad. A reed switch is used to advance the clock by holding a magnet close to it.

Its a little difficult to photograph, so here it is again on a white background. I quite like the effect of the white background and may fit a backing to the acrylic.

The clock was formerly housed in a picture frame. Which looked okay, but I thought it should be possible to make something nicer:

The new enclosure does not really do much enclosing. Its just a sheet of 3mm clear acrylic, cut in the shape below. This allows the LEDs to sit in the channels and allows a space in the center for the Lilypad.

The PDF for the clock face is available on the book's website in the download section.

The laser cutter is a Epilog Mini 24 Laser Cutter and I wasn't really taxing it much to cut the acrylic.

As well as a laser cutter, Fab Lab has a 3D printer, a Desktop Milling machine, a Vinyl cutter, a large CNC Router, a vacuum former and well equipped electronic workstations.

This is all backed up with a knowledgeable and helpful set of staff as well as well as lots of people around happy to help out.


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