Current Build
I always have at least one project currently going through the design and build phase. Check out my progress and ideas along the way of my current build.
Current Build Update – Santa Sleigh Project – December 1, 2021
This project began as a Christmas present for my wife. My original plan was to design/build her a 1/4 scale antique looking Santa sleigh. My wife’s sister found out and the plans changed from one sleigh to two, and both ladies insisted it be bigger to support grandchildren for photos. I increased the challenge by adding the design condition that it be a parent drawn sleigh, actually useable on snow and ice.
The Current Build in my shop is a ½ scale Santa Sleigh capable of carrying a child rider pulled over ice and snow. It will have some interesting challenges including steam bending oak for the rails, sheet metal rolling for the fairing, and laminating bendable plywood to get the classic curves of an antique sleigh cab.
This is an example of an antique horse drawn sleigh studied as a go-by for this project. My goal is to design, build and produce plans for a sleigh with similar cab, fairing and rails.
This is the 3D model of my Santa sleigh today. It is ½ scale with overall dimensions about 2ft wide x 3ft high x 4ft long.
A couple new tools were added to my shop for this project, namely a steam generator for bending oak and a slip roll for bending steel parts on the sleigh. I’ve done some oak bending for boats, snow shoes and the like and it always impresses me how it can be formed without breaking if steamed sufficiently and stressed correctly. Steaming properly requires a box
allowing steam to surround and saturate the wood at 212 deg F. Stressing properly requires a setup to ensure that all parts of the oak stick remain entirely in compression during bending. Using a bearing block and flexible strap to react tension, fibers on the stick outside surface are prevented from seeing any tensile bending stress, a requirement for wood to crack.
The setup essentially crushes the wood fibers on the inside surface of the bend from compressive stress, effectively shortening its length, while the outside surface sees no stress and no change in length.
I paid $70 for this steam generator from Amazon for bending oak. It works as advertised providing 2 hours of steam from about 1 gallon of water. Manual says 1hr/1in of wood thickness.
This slip roller will be used for forming thin metal up to 18 gauge. Its width capacity is 12in which will impact the design width of the sleigh fairing. I paid $120 for the roller from Amazon.
The setup for steam bending oak requires the use of a bar and bearing block securely attached to a flexible strap. The stick and strap are clamped against the form and then bent around the form. Forces between the anchor block and strap can be very high, so use a strong strap and several screws
securing strap to bar and form.
I did some testing to see how well the white oak sticks would bend before breaking. In this test I was able to bend a 1in thick stick around a 9in radius form. It took a good bit of force to bring it around after an hour of steaming. Bending thinner strips and glue laminating back to design thickness will be easier and faster.
There are two set of sticks needing bending on the rails. One set is the forward part of the ski that joins and supports the front of the sleigh fairing. Based on geometry of the 3D model, this form has a 10in radius with a bend angle of 135 degrees.
The other bent oak required for the rails is used to join the forward part of the step to the fairing. This form has a 3 1/2in radius with a bend angle of 135 degrees.
Similarly, I needed to play with the new plate roller to determine its ability to roll an “S” shape and set the bend radius to finalize design of the sleigh front fairing. With some wide spaced blocking up of the roller, I was just able to form the 4 1/2in radius “S” shape from a 24in long steel sheet.
Where shapes don’t allow for a proper setup with a tension member strap, I will thin the sticks before bending and glue laminate back to the thickness needed. These “S” shaped bends are needed for the support straps down the front of the sleigh fairing.
My research on antique sleighs soon concluded that the cab sides and back require curves not possible using ordinary plywood. Fortunately, after finding and testing some Radius™ bending plywood from Home Depot, I’ve confirmed that two thin sheets can be easily bent and glue laminated into shapes seen on classic horse drawn (and reindeer drawn) sleighs.
The cab on this antique horse drawn sleigh includes the classic curved sides and back.
The challenge was to find a way to construct the cab sides and back with these classic curves.
The solution is to glue laminate two sheets of bendable plywood into the shape required.
There is still much design work left on the rails. Wooden joint details need developing and some creative diagonal stiffening and strengthening is required. This is not a sled capable of withstanding impact loads during downhill sledding, but rails will support the cab and rider being pulled over the snow and ice. Kids, parents and grandparents will love it!
