I busted up my ankle pretty bad playing hockey and am trying to adapt to my new reality. I hate depending on people to get my hot coffee or cold beer, so I devised a removable cup holder for my crutches. I designed it to be made from a single piece of sheet metal and a rivet, and I am very happy with the result.
This is not a new concept (google image turns up a bunch of examples) and in fact there is a great Instructable showing innovative stabilizing design by duncanbelew. My design has the advantage that it is easy to remove and it looks like it is built in. Check out the video.
Step 1: ITEMS
You will need the following items:
- One piece of sheet metal (40cm by 20cm); mine was 22 gauge cold rolled steel 10$ on Amazon
- One rivet
- A piece of card paper for the template
Tools you will need are the following:
- Face shield
- Safety glasses
- Work gloves
- Angle grinder with a Zip Cut blade
- A left and right handed snips
- Hand drill with bit the size of the rivet
- A single rivet and riveter
- Sheet metal brake or hand seamer
Step 2: Paper Template
Always start with a card paper template. This will make sure that your design is fit for purpose and help you avoid any missteps that will cost you material and time. This was my first prototype and it was pretty close, although I did simplify the back flap after trying it out with the sheet metal.
Step 3: Cut Out the Shape
SAFETY WARNING: Cutting and handling sheet metal is fraught with danger. Make sure you wear a face shield and gloves while cutting, and gloves at all times until you've taken all the burrs off the edges.
I can't claim to be an expert on this subject, so I prefer to differ to others. Please do your own research.
So I made the big cuts with a angle grinder with a zip-cut blade. Make sure that your sheet metal is secure before starting and face-shield and gloves are a must. Once you have general shape, it is much easier to use the snips. There are many tricks to use these properly: this is not the kind of tool that you can just wing it. Please watch some videos, this will make it a much faster and cleaner job.
Refer back to your paper template if you lose your marks.
Step 4: Clean Up the Edges
To make a cleaner and smoother edge I used a sheet metal brake to make a single hem. If you don't have a brake, you can either use a hand seamer or smooth the edge with a file.
Place the sheet metal in the brake with the desired hem position lined up with the crack. Place the metal bar and vice it into place. Slowly bring the hand brake up to the maximum position. Remove the bar and place it on the moving part of the brake and secure it. Place the "L" base a millimeter from the crack on the brake and secure it. Pull the lever up to fold the hem down flat. I used a vice to squash the hem closed.
I repeated this process for the base of the cup holder.
Step 5: Cup Shape
Again, I am not a skilled craftsman and I tried several methods to get the desired result. I was able to get half way there just with my bare hands. In the end, I resorted to using a can of beans, a vice and a hammer to get the cylindrical shape. I am certain there is are special tools or methods to do this, what can I say... it worked. Please comment below for improvements.
Step 6: Crutch Crotch Notch
I like my design because much of the weight is sitting safely on a piece of the crutch (the crotch). This eliminates any swinging, or fear that it will come unclipped. I didn't trust my paper template for the placement of this cut, so I folded it first and see where to cut the grooves for the "legs". Please see the photos. Once the notches are cut out, carefully fold the "back flap" up at a right angle.
I then sketched the excess material with a pencil and trimmed it with the snips.
Step 7: Single Rivet
I used a regular pair of pliers to bend the top of the flap so that it was parallel to the cup holder. I drilled a hole through the flap and the cup holder that fit the rivet: start smaller and work your way to the snug hole size. Place rivet and snap it all together.
Step 8: A Few More Pics
I had initially planned a more complex back flap, but it became apparent that a simple flap was really effective to keep the whole thing snugly in place and easy to remove. You can use pliers and snips to make any last adjustments.
Feel free to suggest improvements and I'll try to incorporate them.