I am going to build a cradle for my step daughter. Here is the one she picked out.





My question is how to size the rockers so that they go the width of the cradle instead of the length???

Post deleted by Ernie

To me the best place to learn is NOT a class some where, Not by watching it on TV, NOT by buying a book, but from people. Like everyone that post here. Who better to learn from than those who have gone before us. You get experience and wisdom. The most important thing is that everyone is here and helps because of the love of woodworking, not because they want to make a buck with a class. Thanks to each and every one of you

Take some plywood and cut test rockers. You could clamp them on. Start with less curvature and you can recut if it isn't enough. Once you have the radius, you can rescale the design elements to suit your eye.

You can see the gentle curve of the plans, and that will determine the degree and rate of rocking. I doubt that you would want to change that. Also note the knobs on the ends to act as stoppers.

Realize that the cradle will be less stable with the rockers going the other direction, so be cautious about shortening them.

The rocking characteristics will definately change. It will take a few trials with some test pieces to get the right radius and length.

Magoo, that is a beautiful cradle and what a wonderful gift!
Now, I don't know an answer for you, but I keep looking at that grid diagram. That seems to be the key to shortening the rockers. If someone could figure out the ratio between the cradle length and rockers (on the diagram) and figure that ratio to the width and rockers,it seems like the key...I'm lousy at math but there are clever enough folks here!

Liz

MD magoo could downscale the design simply by reducing the grid square sizes and drawing in the design as close as he can to how it appears in the original scale.
But he can't just do that. Bob F is right that shorter rockers could cause a problem, although it would be more of an issue in a schoolyard where the kids drive the playground stuff to the limit. This is for a young baby and Mum or Dad will be rocking it, not the baby. If the original design offers gentle motion (which fact we don't know)then magoo wants to find a new rocker that will do the same. The best way is trial and error, not too scientific but it works. To my eye the curve in the original is a bit quick and an easier curve would give the passenger a more comforting ride to sleep.

The curve on the cradle rockers is an ellipse as you probably know. Here is a link that describes the string method to freshen your memory.

I would think if you shorten the length of the ellipse you may want to shorten the rise of it as well. Be warned that shortening the rise will affect the ellipse's ability to return the cradle to center somewhat.

Wouldheart's advice about trial and error is the best method to find a good medium area on this one.

I like Wouldhearts suggestion of trying it with plywood.

I am interested to see how it will work. Seems it will be tricky to make it rock and not roll with the smaller radius.

Keep us posted!

Shauna