Introduction: Kneeguards

While Feline was diagnosed at the young age of 17 with MS (Multiple sclerose) she never gave up the fight against it. Her passion is helping others, so we were lucky to be able to help her.

because of the problems and limitations linked to a wheelchair, she likes to move around the house on her knees, while this grants her a lot of independence and freedom, it also causes painful knees.

she used big kneeguards for construction workers, and smaller ones for volleyball players, but they weren't fit for her needs. the kneeguards for construction workers are way to bulky and the strap breaks within a few weeks. the ones for volleyball players just don't help enough to bother to wear them.

with this in mind we set out to make a custom kneeguard for Feline, that suits her needs. We made a kneeguard that uses a custom silicone filling and a easy to make, replaceable, washable cover for it.

we use wider straps that don't slide into the kneepocket, Bra closures for a low profile closure.

The result is a smaller, slimmer kneeguard that is comfortable to wear and won't break in the next few days.

the video is in Dutch, but our blog is (mostly) in English, if you want more details about the development go to:

http://knielap2014.blogspot.be/

this project is a part of

http://designforeveryone.howest.be/

This instructable is just one way to make this, we used low tech techniques, but you can use several other techniques like CNC milling, lasercutting,...

you will need some templates for the construction of the mould and the fabric pieces. you can choose between a lasercutter file and a printing file ( the printing file shows more information where to stitch while the lasercutter file can be used to cut the pieces).

Step 1: Make a Positive Mold of the Knees

The knee guards are made to fit the knee of the client exactly, this means we need an exact copy of the knee. This can be done in several different ways, you can use a 3D scanner and CNC mill, or 3D printer. We chose for a more low-tech approach, we wanted a technique that everybody can use.

We made imprints from the knees in plasticine, and used these imprints to create moulds to cast a hard copy of the knees, we used Polyester resin to do this (because the fast curing Polyurethane was sold out) but you can use almost anything that allows you to copy the shape and hardens.

Once you poured the resin, you need to let it cure for a while, this depends on which material you used to cast the part. (Axson F15 PU cures in about 10-15 minutes while the polyester resin needed about 45minutes.)

once the resin has cured enough, you can remove the plasticine and clean the part with a paper towel and some water.

Step 2: Make the Moulds

the next step is building the container to pour the silicone into, we used another low tech technique. We could have lasercut this, but this is cheaper and the mould doesn't need to be pretty. the tools used in this step are: a jigsaw, a large size drill bit ( we used a 32 mm drill), a drill and a hammer (or a pneumatic nailgun).

first you will need the template from the File, print it out and use it to draw the contours of the hole.

then simply drill a hole in the shape so you can cut the hole with the jigsaw. If your planks aren't thick enough for the cast of the knee (the mould should be the hight of the positive casting + at least 5mm) then you can stack several plates so you get a mould that is high enough for the silicone.

don't worry if the mould isn't completely smooth on the inside, the silicone won't be visible in the finished product.

once you have the mould completed, you need to glue in the positive casting from the last step. this will create a cavity for the silicone that perfectly fits the knee.

finish of the mould by filling the gap between the wood and the casting with plasticine to create a open end for the leg.

Step 3: Casting the Silicone

in this step the silicone fillings will be made, to do this you need a few things:

a release agent,the silicone itself,a few mixing cups and a few sticks and some latex gloves.

First you need to make sure your silicone will come out of the mould when it's dry, we use a release agent for this, this can be a wax or a spray can. you just need to cover all the surfaces with it, the wood is the most important, because if you used MDF or something like that, the silicone may seep into the material, allowing the silicone to bond to the wood.

the silicone we use, requires a 50/50 ratio of component A and B, this can differ from silicone to silicone so consult the box.use 2 cups to weigh the right amount of each component and then mix them very good with a flat stick (flat sticks mix better then round ones) one filling needs about 200grams of silicone.

when pouring it is very important to minimize the amount of air that is caught in the silicone, you can do this by pouring very slow and from higher.

once the silicone is cured, you can remove it from the mould.

Step 4: Cut Out the Fabric

using the templates from the intro you need to cut your fabric pieces, this can be done with a lasercutter or manually.

numbers 1 and 2 need to be cut out of a stretching fabric, while the rest can be cut from a breathing fabric.

the straps are made from bands you buy at your local fabric shop.

you need al the parts from the templates to create a single kneeguard, so if you want a pair make sure to do it twice.

Step 5: Sew the Parts

now that we have all the patches of fabric, we can start the sewing. first connect both sides of the cover with pins (see the photos). Then use a zigzag stitch to follow the curves and connect all 3 of the pieces. Then lay both patches with the inside outwards and connect them using pins, where the template says a band or Bra Closures comes, you need to place the bands and closures (keep in mind the cover is inside out, so the straps should point inwards) and then follow the contours with a straight stitch. leave a hole for the filling. the hole should be located between the 2 straps. attach velcro on the borders of the hole, and turn the whole cover inside out.

Step 6: Assemble the Kneeguard

now that you finished the cover and the silicone, you can simply put the silicone inside the cover and press the velcro closed. Once this is done, just test fit the guard and position the silicone correctly. If everything fits and it sits great, then you are done. you now have a fully custom kneeguard.

Step 7: (optional) Anti Slip Dots

if you plan on using the kneeguards on slippery surfaces like wood or smooth tiles, then it may be interesting to add some anti slip dots. We did this using a latex mixture you can buy at your local hobbyshop.

you can even add some different shapes if you use a rules with the shapes cut out as a guide.

Comments

author
Lorddrake made it! (author)2014-06-06

Fantastic work.

What material did you use for the parts of the kneepad that come in contact with the ground?

author
timothy demaegdt made it! (author)timothy demaegdt2014-06-07

we used a synthetic cotton , but you can use anything you want. We also added rubber anti slip dots, to improve the grip on stairs and other slippery surfaces (i'll add another step about this)

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Bio: student industrial engineer, industrial design at Howest industrial design centre in kortrijk Belgium please look at my portfolio @ http://www.timothydemaegdt.portfoliobox.me/
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