I've finished the upper and lower levels decks and now I need to connect them. I decided to get creative and use a 1/4 turn spiral staircase to save space and because it will look cool.

This is a slightly greater challenge to design than the straight stringer steps I did. In this case especially so as I am not using a central column and so cannot work directly in polar coordinates easily.

I had to map out the locations of important parts in order to calculate the necessary dimensions. This was a bit more than my 3d visualization capability could handle. Converting polar to cartesian is best done on "paper", electronic or otherwise. The rest is all in my head, as usual.

The dimensions:

I have finished the main framework for the steps, jigged up in the shop. This wasn't easy to judge square and level by eye so I was forced to actually measure everything.

After tacking it all I took it out and trial fitted to the deck. Perfect! This will be an easy set of stairs as the wood steps will extend further than the frame by six inches giving an outer radius of six feet.

I have today welded the entire frame and now need to attach all the little brackets to allow the wood steps and outer siding to be installed. A neighbour gave me some excellent 2 x 10 x 8' fir planks that he has had aging for 18 years to use for the treads. Should work nicely.

This is a slightly greater challenge to design than the straight stringer steps I did. In this case especially so as I am not using a central column and so cannot work directly in polar coordinates easily.

I had to map out the locations of important parts in order to calculate the necessary dimensions. This was a bit more than my 3d visualization capability could handle. Converting polar to cartesian is best done on "paper", electronic or otherwise. The rest is all in my head, as usual.

The dimensions:

I have finished the main framework for the steps, jigged up in the shop. This wasn't easy to judge square and level by eye so I was forced to actually measure everything.

After tacking it all I took it out and trial fitted to the deck. Perfect! This will be an easy set of stairs as the wood steps will extend further than the frame by six inches giving an outer radius of six feet.

I have today welded the entire frame and now need to attach all the little brackets to allow the wood steps and outer siding to be installed. A neighbour gave me some excellent 2 x 10 x 8' fir planks that he has had aging for 18 years to use for the treads. Should work nicely.

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