Intro: EZ Style Stair Step
Welcome to the instructable on how to build an EZ-Step style stair step.
I built this one for a client of the Tetra Society of North America. Check them out for some neat project ideas.
The client requested the following specifications for the finished product that necessitated a different design from what is commercially available.
Those specifications were:
1.It was to be used in home and pool - requiring it to be corrosion proof, non-buoyant, and grippable in water
2.It was to be moved around by a removable adjustable cane
3. It was to be lightweight enough to be carried comfortably
Step 1: Design
For basic dimensions and specifications, I first met with the client to discuss the project she had requested. Once there I took measurments in her house of her stair heights in her pool and her interior staircase. We then discussed various existing commercial solutions (EZ-Step, Pilot Step) and why they would not work for her and what she wanted for the end product. The dimensions in the end came out to be 9"wide by 12"long by 6" tall.
After the meeting, I drew up a 3D-model in Sketchup (attached) that gave me a fairly solid idea of how to proceed with the build process. I thought about what I would have to buy to make this a reality. I also was able to use materials from my local Hackerspace to build parts of it.
Next I emailed the client an invoice (also attached) for the materials and a picture of the product design before I proceeded to make it.
The materials that were free were from the hackerspace, I charged for the rest of the materials, and donated the hours used to build it, the consultation time and the milage on my vehicle.
Step 2: Materials and Tools
The materials changed a little from the invoice but in the end they were largely the same, and the extras came from the hackerspace so I did not charge for any price overruns.
The final list of materials is as follows:
-Two pieces of HDPE plastic for the top and bottom (I used cheap plastic cutting boards)
- a rubberized grip material (I used cheap silicone baking trays)
-Nuts (I used 3/8" because I had lots of 3/8" threaded rod around; also you want non-nylon lock nuts for reasons that will become apparent later
-3/8" threaded rod (4 feet or more in case you cut incorrectly)
-2" washers and lock washers
- white spray paint
-adjustable single point cane
- 1" pipe flange (pvc is preferable but the local canadian tire only had metal in stock so I used that0
-pipe nipple (1" reducing down to 3/4")
-3/4" pipe cap
-pin with chain
-small diameter bolts and or long rivets for affixing the silicone rubber to the HDPE plastic and the pipe flange to the plastic
-Galvanized wire for cross bracing
-small lengths of lumber for spacers during assembly
The tools from the hackspace that were used in the making of this item are as follows:
-Drill press (this is really a must) with these tools:
-3/8 - 16UNC Tap
- C-clamps and small vise
-3/4 drill (I used a forstner bit because that is what I had)
-1/2" drill bit
-scribe, punch and rule for layout
-sketchup to read the file with the dimensions
Step 3: Layout
The first real build step is layout. Take the dimensions from the sketchup file for the top and bottom of the piece. I first did the layout on a piece of paper just so I knew where everything was before I started making indelible marks on the workpiece. Next I laid out the holes on the workpiece by measuring their center points from the edges. You want to lay out the holes for the threaded rod supports (7 of those in both sides if you have a handle like my finished piece, 8 if you do not like the original sketchup model), for the 3/4" hole (1 of those in one side) and for the 1/8" holes for the securing rivets and/or small bolts (I used 8 in each side but you can use more or less depending on preference; also these holes are not in the sketchup model they were added in later around the edge between the 5/16" hole and the edge of the workpiece). Sketchup is the key here all the dimensions you need are in the file from the previous step.
Step 4: Cutting Stock to Size
Cut the top and bottom pieces of plastic with a table saw. Don't make my mistake seen here - use a riving knife and anti-kickback pawls for this cut - HDPE plastic will grab that blade and will kick back. Not that it happened to me, but it just about almost happened and I had to turn off the table saw mid cut. Use the bandsaw to cut the corners and a sander (if you have one) to make them smooth to the touch. The horizontal band saw was used to cut the threaded rod at 5 7/8" as follows:
-take the threaded rod and two 3/8" nuts
-double nut and tighten the rod to prevent slipping at the 5 7/8" measurement
- place the whole thing in the saw and cut down the side of the nut face (the nuts keep your measurement accurate as well as preventing the saw from following a thread or grabbing at one and shifting the piece [highly unlikely])
-clean up the burs in the thread with a 3 square file or knife file (ideally a thread file but not everyone has those)
After cutting the rods you will want to paint them to prevent rust in the pool environment. Another item to cut at the end of the process is the silicone rubber, cut it to the shape of the top and bottom pieces.
Step 5: Drill Press Time!
You are going to love your friend the drill press by the end of this! I drilled each plastic piece individually because I couldn't find the clamp that day to clamp the two pieces together while still allowing me to drill holes at the edges. This was a mistake, not only do you get poorer alignment of your holes but it also takes twice as long. A small part of you also dies of boredom.
To maintain alignment I cycled through all the cutting processes without removing clamps (I know I'm insane - this results in changing tools 28 times). Doing that is really not necessary because HDPE is a soft plastic with lots of forgiveness for misaligned taps. HDPE by the way is a self-tapping plastic so this seems even more crazy, however there is method to my madness. First of all I am a machinist and I wanted to do things properly even if this was plastic. Second of all these holes really did need to be tapped in this scenario because in assembly I would not be able to thread threaded rod into the holes freehand without a driveable surface. In addition, the assembly in general was pretty janky and I didn't want to have to worry about things falling apart or misaligning while trying to use a double nut to drive a rod through the assembly with a drill and nut driver. Regardless HDPE taps quite nicely with no issues in terms of ripping and tearing, producing an accurate thread with nice surface finish.
In the second to last image you can see me stacking the different layers to align for drilling the 1/8" holes around the edges. This ensured alignment as well. Also if you are going to go with small bolts for securing the rubber to the plastic, you may want to consider the extra step of drilling a counterbore with an endmill if you have one - this allows the bolt head (if using pan head) to be sunk below the step's surface, preventing it from rubbing on your feet or scratching the floor below.
Step 6: Securing the Cane
The cane is attached via the pvc pipe affixed to the bottom of the top plastic board. The pipe itself is screwed into the flange which is attached via small bolts through the plastic board. To make the cane removable a 1/2" hole was drilled through the cane and the pvc nipple. The pin fits in the hole. In the end I did not use a pipe cap (from the invoice and the sketchup file) at the end of the nipple as it was not necessary.
Step 7: Assembly!
Assembly! My favorite part. The time in which you see if you did everything correctly and your idea made sense. Thanks to good design, my assembly went without a hitch. Sorry for the self promotion but I am 12 hours in at this time.
First I attached the rubber to the plastic with bolts, I only affixed the bottom piece and part of the top, however it is best to leave it off until the boards are together so that the rubber is out of the way
Next I clamped the two boards together at final height by cutting some wood spacers between the boards and clamping on the whole stack. Then I threaded the rod through the top of the piece, stopping half way to thread on the nuts and washers in the right order to secure the rod in place latter. Finally I threaded all the pieces together and snugged up the nuts on the rod. Don't overtighten the nuts as they will likely pull the plastic threads out of the boards and all your hard work will go down the drain.
The step is ridiculously strong in vertical loading, however side loading was something I became worried about. Not only was there not a very good bearing surface in the event of a side load but all side loads would stretch the plastic threads, causing looseness and slop in the holes. This slop would then feed back into the performance of the step, causing more non-axial loading on the threaded rod pieces- resulting in side loading- and so on. Therefore as an additional last step I tied some cross bracing guidewires from each corner to the other.
Step 8: Product Testing
The client was very happy with the product. She has used it in the pool and says that other residents in her seniors condo association want steps of their own too! Looks like I have my work cut out for me. In total the project took about two 8 hour days to make from start to finish, although I could probably build one much faster the second time around!