Tower crane prototype construction

So I because we here in Taranaki had a long weekend I spent today in the workshop building a prototype of tower crane made by a children’s toy company called Hape.

They make some cool, if expensive, kids toys but their Crane Lift toy was the one that was doing my head in. Unlike most toy cranes I’ve found on the internet this one has a single winding for the hook head. This means from one winder the head can be moved forward or back. The other toys required one wonder to move forwards and another to move backwards.

The construction of the 🏗 was relatively simple. It’s just plywood and a couple of dowels. The holes were pretty simple to line up and the runs were cutout using a scroll saw (by far and away my favourite saw).

But the winding was what was doing my head in. Basically it took me about 5 goes to work it out and numerous views of the video I took of the original crane working. It turns out the whole things rests on everything being in constant tension and enough windings to traverse the arms.

Now I’ve worked it out I can’t unsee it. 😁

I made a video of the Hape unit and my prototype effort. Mine’s not pretty but it never was meant to be it was just simply to work the whole thing out so I could make proper ones.

https://esteem.app/hive-100421/@woodenwookie/ehlcroee

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Comments

Jason

Congrats @woodenwookie. It looks fantastic.

Have you got some photos you could also share for those that can't access the video?

Jason

woodenwookie

So for a more static view of what I was trying to achieve here's a little run down.

Screen Shot 2020-03-10 at 14.14.37.png

So this is the Hape Crane Lift toy with the windings that was doing my head in. The key windings to look at are the lower ones. The upper ones are simply just for decoration. So what these windings do is allow the hook (front winder) to move forward and back. EVERY plan for tower cranes I've seen have two winders, one for moving the hook forward and one to move the hook back. This adds a level of complexity to the toy. Considering these toys are being aimed at children this seems silly. Hape achieved the same thing with a single winder and I wanted to replicate it.

The first issue is how to get this part to move. This part is key to everything. The shaft in the centre would be where the hook is wound up and down. In the Hape version it's the part at the front with the winder wheels. Because I was only making a prototype I didn't bother with the wheels.

The key to making this work is to tie off the front first. Next move the entire assembly as far back as it will go. Finding a way to lock this off at full retraction is important. I used a 102mm cutoff piece but you could use clamps if you can get them to fit. Given that I only used hot glue I decided not to risk it.

Next you need to throw the string over the tower. This provides the needed tension necessary for the return motion (moving the head forward).

This part was the trickiest part of the whole lot. At first I had it run through the back dowel but this wouldn't work. Instead it just needs to drop straight into the hole in the large dowel and then you need to manually wrap the string around the large dowel a few times.

Next you run the string over the rear dowel then under the whole assembly and thread through the back hole in the hook assembly, making sure to keep the tension the whole time (seriously not easy to do).

Tie it all off and then remove the piece of wood stopping everything from moving. It's actually easier than it sounds.

One of the hardest things was threading the string through the holes but I used a small amount of glue using an Ozito hot glue gun. Would have loved one of their battery operated glue guns but these don't seem to be available at Bunnings NZ which sucks.

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