Click to read more about Part 2 of this wheelchair platform build! In part 1 we got the platform and ramps built, Now it is time to build the adjustable and fold-able legs.
MEASURING for the legs
The first part of building the adjustable legs was to look at the height specs then make sure I built the legs to meet them.
I took the height of the necessary pieces and added them together then subtracted them from the minimum height to see how long the larger tube of the legs needed to be.
Expanded steel ~1/2″ + angle iron 1/8″ + hinge thickness ~1/4″ + crutch foot 2 1/4″ = 3 1/8″ of necessary height (I’m going to round this to 3 for simplicity though)
Min height 12″ – Necessary parts height 3″ = Outer tube length for the legs 9″
The inner 3/4″ piece of tubing will never be fully inserted into the 1″ outer tube because the crutch foot extends up ~1 1/2″ over the smaller tubing, I could also make them 9″.
So I went ahead and cut both the 1″ and 3/4″ square tubing to 4 pieces of each size all 9″ long.
Leg tubing cut to 9″ long. Also pictured are the hinges I was planning on using (but did not use the hinges in the final design).
I also put on one of the crutch tips so I could confirm the total length.
DRILLING FOR ADJUSTABLE HEIGHT
Next step was to mark, center punch, and drill holes in the larger 1″ tubing for the retainer pins. I used a 1″ wide ruler that happened to have a hole in the right spot to mark them with a sharpie.
After center punching I drilled the four 1″ tubes all the way through with a small pilot drill bit then again with the bigger final bit.
Next I needed to mark the 3/4″ tubing for the adjustable holes. First step was to take my sliding combination square and mark along the middle of each tube.
Sliding squares are CHEAP and can be used for A LOT of different measurements. I probably use it for purposes other than it was made for most of the time, but it works good for me!
Then I made 5 marks for the adjustable holes by adjusting the combination square in 1″ increments.
I had to make sure to leave ~2″ of tubing blank at the bottom because the crutch foot comes up the tube 1 1/2″ and the pin hole on the outer 1″ tube is 1/2″ in from the end. (marked with a line and an X in the picture)
Center punch each of the five holes on the 4 tubes then drill them out with a smaller pilot bit.
Close up of the adjustable holes (I didn’t get a pic of them drilled with the larger final holes)
Hinge design #1
I then welded the outer tube onto the hinge and the hinge onto the platform frame.
All 4 legs welded on with some extra support crossmembers just laying there to make sure it would all work together.
In my design I made sure the legs could be folded in even at full height without hitting each other.
I got excited and wanted to test the platform out so I went ahead and flipped it over onto the legs for the first time.
Platform on the legs for the first time!
Unfortunately I very quickly realized that the hinges were a COMPLETE FAILURE and were way to small for the weight this platform needed to handle.
Back to the drawing board, I had 3 options:
- Go buy some bigger hinges (but it was Sunday so I was stuck with only hardware store home quality hinges)
- Do a bunch of bracing to reinforce the hinges I welded on (but I still didn’t trust them)
- Build hinges from scratch
Because I ran into nap time again, I had to find something quiet to do for ~2 hours so I went ahead and painted what I could on the platform.
Then when Sam woke up I cut the failed hinges off (I also left an unpainted spot in the middle for the future crossmember).
Hinge design #2
So I ended up choosing to build second set of hinges from scratch because I was out of options. I had on a whim bought 4 predrilled 4 hole plates ~3″x3″ when I bought materials ‘just in case’. Turns out that they came in handy.
I am a pretty smart guy but unfortunately am NOT all that good at math or geometry so this took A LOT of brain power, some cardboard cutouts, and time for me to figure out, but now that it is made it is actually really simple.
I needed the legs to have a rake outward for extra stability, so after some measuring I tacked one of the outer tubes onto the prefab square plate with 4 holes.
These hinges actually attach to the side railing of the platform, they will have one bolt then the other two holes will be used to pin (lock) the legs in the down or folded position. The leg itself covers one of the holes.
I marked for the holes using a Transfer Punch.
TIP: What is a transfer punch? A transfer punch is similar to a center punch but they come with different size outside diameter so you can put the transfer punch in the hole and always mark the exact center (instead of marking with a sharpie or normal center punch and hoping that you got it in the middle)
This is my Transfer Punch set.
Here is a close up of a transfer punch in the hole so you can see how it works.
In this pic you can see a normal center punch in the background that doesn’t work very accurately for establishing the center of an existing hole.
You DON’T need to spend lots of money on a transfer punch set, just find a simple set on Amazon and order them. I only use them a couple of times a year, but when I do they are really handy and help speed up the project (and reduce errors).
Once I determined that my idea was going to work, I went ahead and final welded the legs to the 4 hole plates.
I then notched each end of the tubular crossmember so it would sit all the way against the expanded steel and be easy to weld on.
Legs bolted on, getting ready to weld in the three crossmembers. The angle iron between the legs really stiffens them up considerably.
All crossmembers welded in and legs folded out.
I then whipped out my transfer punches once again to mark and drill a hole to hold the legs in the stowed position.
Legs fully assembled at tallest height using pins with round wire retainers and crutch tip feet (the crutch tip feet are round and my tube is square so I had to spray some WD40 in there as lube to get the feet on, also the only feet I could find were white so I decided to spray paint them black, I touched them up later).
You will have to stay tuned for Part 3, the final product after painting and in use!!