OpenLock 2.0 Spiral Stair Infinite Tread

thingiverse

A curved stair tread, 30deg/8.4mm tall and 38.1R (3in dia/1.75R), was used to create a spiral stair that could hold figures. The idea was to use as many treads as needed to get as high as required. Kudos to Printablescenery for providing the necessary resources, including Rampage, OpenLock 4.0, and DevonJones designs from Thingiverse. Using the Devon Jones Curved wall "cut_stone.wall.TA.1.5rx0.5.curved.openlock" design, a wall was created that fit within the H floor tile (a 2" inside radius) and had a 2" outside radius. The stair was designed to fit within this open 3in diameter (1.5 in radius). To finish an 8"dia tower floor or 9"dia with walls, OL2 HE was used. Here is the design process: Starting with a 38.1 dia tread and peg made to fit the "hole", the initial set of treads were printed upside down without supports. After printing, it was realized that filament could be used as the peg through the treads. Individual treads would spin around and had to be glued together to make the picture. The 2nd Gen tread had a pattern and was still printed upside down, but used a 3.3 hole. It was tight for a 3mm filament as it expanded when a heat gun was used with the filament in the "V" of a metal shelving unit leg. A change was made to the tread to have a "key" to set the 60 degree tread to have a 30 degree overlap, and the attachment to the round middle support was set to the outside dia for greater strength. This prevented breaking on the bed at that point. The 3rd Gen tread had pattern and supports to allow printing right side up. It still used a 3.3 dia hole as the dia is a snug fit for the filament. If using 1.75dia filament, you can print with it or use painters tape on the outside edge to keep the treads together. The bases were updated on 01/23/17 to correct clip size and added BASE FROUND and DOWN FROUND which is a 3" halfround married to 4" halfround (2xF Tiles). On 01/25/17, the "math" was corrected and notes clarified. On 01/27/17, the treads were corrected to match original design size with new supports to print right side up. On 02/2/17, a re-thought occurred on why have supports/tabs etc. Why print upside down? Now treads print right side up. Only issue...need to have a different top tread, and a spacer at the bottom. Spacer, 10 cobble treads, 3 tops + plain/top set (for both plain printing or to add your own pattern) and the same plain/top set with a tab with the correct spacing for 30deg treads as shown in the picture. The typical wall height is 50.8 and you will need spacer first, then 4 treads + 1 top tread to utilize. Tread heights are 8.4. If using floor supports, add an additional tread in the 180deg stair by cutting off the tabs and rotate counter clockwise equally to add in the extra tread. On 02/16/17, a photo example was added from Nigel Brown's Flickr page (https://www.flickr.com/photos/nigel_brown/9708771924) similar to the memory that was lingering in my head on the spiral stair design.