I spent some time over the summer playing with rhino but I’m still stuck with some basics problems. I’m trying to design a sled/ toboggan to make for my nephew this Christmas. I want to send this file and have it cut on a cnc. Now, all my work in the past has been more organic in style, and don’t mind errors generally but this time I’m really trying to learn how to properly design an object in Rhino. I am following and old woodworking design for dimensions. I simply want to redesign it in rhino.
My problem starts at the runners of the sled. I want to make the entire thickness to be an 1 inch deep. I’m not sure what I am doing wrong but my planar line doesn’t make a solid. I know I could loft or pipe a line but my goal is to put in proper dimensions. I can make a box or a circle with no problems but I can’t seem to make a line with an arc into a closed solid.
Can someone suggest something. I tired making the design in the ‘top’ view but the it’s more free-form at the arc point and not exactly 1 inch all the way around. I’ve also tired this by extruding the curve but it only works in one direction.
Could any one suggest some tutorials for product design. I can’t afford to really mess this up and would like to learn the right way. I’ve played around with organic free-flowing but I really want to design something with proper dimensions
the runners of your sled must be bent, not CNC-milled, so all you have is straight/linear pieces of wood. You can make the entire thing with a circular saw and router. You can also make the runners by laminating thin strips of wood bent into a jig.
For the runners, I would start in the side view rather than a plan view. Trace over the outline then extrude taht shape to the proper thickness. You can the add the bends and twists to the extrusion from the top and end (right) views. Check out some tutorials on how to set up top, front, left and right views using the picture frame option in the create surface menu. That should help you a lot.
i have to underline what Lagom said, its important that you dont cut this with a cnc. there may be some who really produce it that way but since this is a sports device and a lot of pressure will act onto the structure i would seriously recommend to use a bending technique. if you interrupt the flow of the fibers through just milling the wood out you will loose all the strengt it could provide. the wood would just fold together at any serious impact.
one method is using hot steam till the lignin gets soft, while the wood is carefully bent and locked till its cooled and dried or hot flamed and bent at the same time there may be some more techniques but i am not a specialist. wooden freeform furniture is also being produced like that if you are interested, for example Charles Eames was a pioneer in that field.
generally if you really must have it thinner in front i suggest to wait till you are around the bow till the vertical tangent. definitely dont make it thinner midway and get thicker again.
you can use Offset with one curve it will have the same distance which would be natural for the wood. or for the tapered version you can use Sweep1 with 3 profile curves and extrude the outcome or Pipe with 3 diameters at those indicated points and extract the isocurves from both surfaces and delete the pipe again then close the 2 curves and extrude the outcomes.
If you CNC the runners from solid piece of wood, the front curved shape is milled across the grain. This way, the part becomes very weak when forces are acting upon it. This is why with sleds, the runners are bent or laminated from straight pieces.
CNC milling across the grain also makes it very difficult to obtain a smooth finish and waterproof those areas as the end-grain becomes a nice capillary sponge.
