Introduction: Medical Face Shield
With the global pandemic of Covid19 virus, supplies of personal protective equipment (PPE) for medical/care staff are running very low or are non-existent in certain locations.
This Instructable shows a way to very simply manufacture a shield to help protect the front of your face from someone coughing or sneezing towards you when caring for them.
(Please note: It does not currently have any 'approvals' from regulatory bodies, so it should be considered a basic resource that is for use only when approved supplies are unavailable; i.e. it is certainly better than nothing.)
The method of manufacture is very simple, with strips of plastic in varying widths/lengths, effectively just riveted together.
The materials are all readily available, and often found already stocked in school/college/university workshops.
The only significant workshop equipment is:
- a bandsaw to speed up cutting and (or a Laser Cutter - please see Updated Design step)
- a strip heater to fold over both ends of the main headband strip.
There are simpler workarounds to both of these; craft knife/steel rule for cutting plastic and the edge of a household iron for bending/folding might work ok.
These are the materials that we have used:
- Visor: ‘Food Grade’ Clear PVC 0.5mm
- Headband: High Impact Polystyrene (HIPS) - strips cut from a 1mm thick, 457mm x 254mm regular sheet (sold to fit a school vacuum former)
Note: Polypropylene is also suitable and more durable - please see Updated Design step.
- Forehead Cushion Strip: Plastazote (soft foam) & 20-25mm Double-Sided Tape
- Tensioner: Regular Rubber Band, approx. 80mm unstretched
- Fasteners: Brass Plated (Steel) Textile Hole Reinforcers/”Rivets”
- Headband - Polypropylene 0.8mm Sheet 1100mm x 650mm
- Fasteners - Presco Swatch Fasteners 0-3mm
Our main supplier (UK based) of most materials for this product is:
Tilgear Limited: - https://www.tilgear.info/index.php?route=informat...
Presco - email@example.com
Seawhite of Brighton - firstname.lastname@example.org
Step 1: Updated Design Points...
During the four weeks (so far) of mass-manufacturing these face shields, we have learnt from our own mistakes and from user feedback, that certain aspects of the design needed some improvements:
- the line bend in the HIPS could be weak and break if it wasn't quite hot enough when shaped.
- the HIPS could also fracture (very occasionally) where the rivet/eyelet goes through.
- some of the rivets/eyelets occasionally pulled through the plastic layers and thus the components came apart.
- the supply of metal eyelets became problematic (in the current situation).
So we decided to:
- switch from HIPS to Polypropylene for the headband. Polypropylene is very much more durable and also just as comfortable against the forehead. This enables us to use our laser cutter. We can get 44 headbands out of a 1100mm x 650mm sheet of polypropylene; DXF file attached.
- opt for a non-bent end design with instead a set of graded attachment slots for the rubber band to attach to.
- remove the extra small front section of headband and just attach the clear visor directly to the headband, still with the 'push out' to leave room for users' nose and glasses/face mask etc.
- change to using plastic two part fasteners (instead of metal rivets/eyelets) which grip really strongly; we have not yet managed to get one set apart! A simple wooden jig enables the fasteners to be assembled without bruising your thumbs.
The rest of the instructions below are the original ones and are still fine to follow, just factoring in the points above as/if you see fit. Good luck and please keep us updated with your feedback and suggestions. Thanks.
Step 2: Cutting the Clear PVC for the Visor
The trimmer works well for cutting the clear PVC. A craft knife and safety rule also works fine.
(Trimmer might need sharpening sooner rather than later after this though!)
Cut it off at 240mm in width. As it comes on the roll, this is the direction of the natural built-in curvature; handy!
We had already cut our roll in half on the bandsaw (for existing vacuum forming projects) so it was approx. 270mm which seems fine. This will be the depth of the visor from forehead to chin.
We suggest you round off the two corners that will be at the bottom of the Visor, as they will otherwise be very sharp.
Step 3: Cutting the HIPS for the Headband
The HIPS headband strip is cut at approx. 35mm width, down the long side of a regular sheet . We buy it this size to exactly fit our school vacuum former; CR Clarke machine. In the UK, Tilgear Ltd supply this size in school packs.
Sand off the ‘swarf’ from the cut edges with some fine abrasive paper.
Step 4: Bending Over the Ends
Place the headband on the strip heater with about 20mm (min) over the element. Heat steadily on both sides until flexible enough to fold over.
If you don't have access to a strip heater, the edge of a regular domestic clothes iron also works. Place a piece of oven proof silicon/baking paper between the iron and the plastic to avoid it melting onto the iron. Something heatproof underneath as well. In the picture we have used a plumber's soldering heat mat.
Please Note: we found this to be trickiest task of the whole process; getting the temperature just right, so it bends neatly and retains strength/spring.
An alternative fixing for the rubber band is to only fold over one end on the strip heater and in the other punch a hole instead. The rubber band can then be looped through itself and will be less likely to fall off and get lost when the shield is not actually in use.
Step 5: Assembling the Main Components
Textile ‘rivets’ (also called 'eyelets') work well for fixing the visor to the headband. If you don’t have any/enough of these then small cable ties will probably work fine; however you won't be able to lift the visor up at all.
The holes in the main headband strip of HIPS need to be punched at 185mm apart (hole centre to hole centre), equally distanced from the centre of the strip.
The three sets of punched holes in the shorter HIPS strip need to be made: central and then approx 10-15mm in from both edges.
STEP 1 - The Clear PVC visor is attached to the short strip of HIPS with just the central rivet first. Do not put all three in at this stage (yes, we have done it and had to pull them out again with pliers!)
STEP 2 - The Visor is then aligned with the main Headband, one end-hole to another and the rivet goes through all three layers (2 HIPS and 1 PVC). Ensure your rivets are long enough. This is where the use of small cable ties either instead or for additional security could be helpful.
Please note: the way the end-bends on the headband face; upwards. (Yes, we got it wrong more than once!)
STEP 3 - Now the Visor needs to be 'flexed' so that the other end sets of holes can be aligned and the rivet punched through all three layers again. This is a bit tricky and sometimes feels like you need a third hand. You could clamp it while you assemble the rivet and get the rivet punch in place.
Step 6: Adding the Foam Headband Cushion
The strip of foam can be as short as 150mm, or longer.
Apply the double-sided tape onto one side. We suggest leaving approx. 10mm gap at each end. This will help users to get hold of the foam and pull it off for replacement in due course.
Stick it centrally onto the inner headband strip of HIPS.
Please Note: We decided to supply the masks without pre-fixing the foam. We reckoned that the medical staff will need to give the whole product a thorough clean upon receipt from a non-hygienic workshop environment. So they can easily apply the foam strips themselves once cleaned and dried.
We also supplied the rubber bands separately, for later self-assembly.
Step 7: Bulk Production Timescales & Feedback
In terms of timescale, it took 4 of us about 8 hours to make 120. (only 48 of them in the picture).
If you develop some really efficient manufacturing and/or assembly methods we would love to hear about them please.
Initial feedback from local Primary Care staff has been very positive, but there are undoubtedly points that could be improved, based on a longer period of usage.
Good luck with your own manufacturing and any improvements you come up with. Our email addresses are just below and we would love to hear from you and receive any pictures of your products and your making processes please.
Stay Safe! (and you'll be helping others too as well)