Projects

Pikler Ladder

View model on Fusion360

Preamble

Pikler Ladders are expensive. Building one seemed like a good idea. There’s many different designs out there, but none that I was terribly thrilled with. So I designed my own. Then I roped my friend Charlie into helping me build one (spoiler alert: other friends wanted one too…so we made four).

Design requirements:

  1. Safe to use
  2. As low-cost as practical
  3. Easy to store when not in use
  4. Varied angles of use
  5. Easy to make

Version 1

The original concept was this folding design that had two climbing positions, but could also be folded up. I originally was going to use ¾” diameter dowels, but wood is a rather vexing material in terms of strength — it’s what called an anisotropic material which means that it has different material properties in different directions. This is in addition to the varied strength tree-to-tree. I wasn’t confident that ¾” diameter dowels would be sufficient (“safe to use” requirement) and so I upped it to 1″ during Version 3 of the design. However, this designed was ultimately scrapped because the board along the bottom side was unnecessarily, a bit unwieldy, and wouldn’t fulfill the “as low-cost as practical” requirement.

Version 2

This used a removable bar that could be moved up or down a rung to vary the angle. I think this is actually version 2.5, which introduced the “scalloped” edges on the one side to allow the ladder to fold together all the way.

This design was ultimately scrapped because using 1″ diameter dowels didn’t leave sufficient edge margin (“safe to use” requirement) without going to a 1″x6″ board (which would have increased the cost — “as low-cost as practical” requirement). I experimented with offsetting the rungs, but decided that would make it harder to manufacture (“easy to make” requirement). Also cutting all the “scallops” would have been time consuming (also “easy to make” requirement).

Version 3

This is the design we ended up making (see the build notes for deviations and such) and the one I made the drawings for that you can download. I originally discounted this option because there’s no good way to get a 10″x20″x¾” piece of wood without buying an unnecessarily large sheet (“as low-cost as practical” requirement), but by building several ladders at once it helped make this more cost effective. This design also uses 1″ dowels

Material List

This was designed such that you should be able to buy everything at your local major hardware store (and probably most local stores as well). Poplar is recommended as a good compromise of quality, strength, and cost.

This was not sponsored by Lowe’s, but I did end up buying everything from there because they had Poplar dowels and Home Depot did not.

Total Cost: ~$74 (+tax)

Hillman ¼” Wood Insert Lock Nut, Brass
Hillman ¼”-20 x 1½” Machine Screw
Power Pro #8 x 2½” Wood Screw

Build Notes

  • Charlie and I built a total of four of these at first go and it took roughly 15 hours over five (I think) build sessions. So factor in setup and tear-down time as well.
  • You probably don’t need to secure the rungs with screws (though you will still need them to secure the Plate to the the Long and Short Leg Assemblies). We ended up only using screws for the first of the four we built (the rest just used wood glue). If you decide to use screws, it might be a good idea to use a shorter length for those that don’t go through the Plates — it’s a bit harrowing making sure the screws are sufficiently aligned so they don’t split out the dowels.
  • With the cabinet screws we used you don’t have to drill a pilot-hold for the dowels.
  • We broke the sharp edges on the boards using 120 grit sandpaper.
  • We sanded the dowels with 220 grit sandpaper to help give a good finish for little hands.
  • We put a small chamfer on the dowels to help them seat properly during assembly.
  • We used an edge-glued spruce board for the Plate, in retrospect we should have used a plywood with a veneer.
  • The Plate Assembly is a somewhat complex design to manually make. Because I needed to make eight of them I did some math and made a jig of sorts. However I also designed a paper template1that you can just adhere to your plywood.
  • The Storage Position hole is waaaay to close to the edge and will blow out. I’ve left it in the design because I like the idea of being able to keep the bolt with the ladder when it’s folded. If you want to include it then do what I did premptively blow out the hole and sand it so it looks nice-ish — otherwise don’t drill it.
  • If you’re building lots of these, maybe call ahead to make sure they have enough dowels. I ended buying every single 1″x48″ dowel that Lowe’s had on the shelf.
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  1. a trick I learned from https://www.youtube.com/user/Matthiaswandel  

Progress Continues

I got an oscilloscope for my birthday and was able to get through a very important hurdle last week.

I spent the weekend laying out a new PCB, which should arrive in late next week.

Interestingly I’ve also ventured into gray market IC chips from China. We’ll see how this goes.

Don’t worry, it’s still not a bomb…despite all the wires.

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