Frame

The shape you choose, will determine how your piece will look.
Square is good, circle too, but let your imagination roam. You will
only see an ordered mass of wire from a distance, and the marbles on the
lift. But the frame will stand out. Don't be too worried about it being
artistic. First make sure it will support what you have in mind.

The frame you make will depend on how you plan to build
your sculpture. A wall hanging sculpture will be different than a
sculpture that stands on a table or the floor.

The nice things about wall hanging art is that it is easily secured.
A couple of screws through the frame, and it is held tight up against
 the wall. This serves to hold it up, and it also holds everything firm -
which means no shaking around when the marbles are rolling on the
tracks. Which is most important when making a table or floor standing RBS.

The frame, unless used for mounting, should be seen as the rough
draft of the size, and will be where you connect all of your supporting
rods to hold everything up. For a table standing sculpture, think more 
about how you will be connecting the track to it, and how it looks. Since
it will not be carrying the weight of the entire piece like a wall mounted
unit, then it can be more artistic. The big challenge with a floor or table
sculpture is that it will sway back and forth due to the energy of the 
marbles as they roll through the corners. Don't forget to make the sculpture
solid before you begin to add track and elements, if you have to add
these things later, they will be harder to fit in.

Make your frame first, then add the lift, and then add track. I would
start from the top, and build down. This way you can start the ball at the
top and know how fast it will be going when you go to add your next section.

I cut the steel for this frame with a metal chop saw, then welded it together.
You could also use copper tubing, which is easy to cut, has fittings to make
several angles, and is easy to solder to. And when shiny, looks really good.

I always cut the frame ends at 45 degrees. This way the ends fit right together
and I do not have to cap the ends. Lay out the frame, and then measure to get it
as close to square as you can. Then only tack weld the outside corners. Recheck
to see if it is square, and make any adjustments needed. Then tack the inside
of the corners on the face. Recheck for square again. Once it is right then finish off
all of the seams, welding them in place. Recheck again, and if any adjustments are to
be made, they should be very small. Take your angle grinder and grind down the
welds smooth, use a wire brush to take away any black marks, and you're done.

The whole frame process can be slow, but if you take the time to make sure
everything is straight and square, you will not have to worry about it again during
the building process. 


 

For making a frame that uses a lot of the same angles, consider making this handy angle guide for making your weld right on the angle your looking for. I have a metal chop saw that does a good job of cutting, but is not the best for accuracy. I can get the angle right on, but that type of cutting blade can flex and your cut can be off anyway. I recently made 3 - 12 sided circles. (36 pieces) Two of them were 45" diameter and the other is 27" diameter.

To make my job easier I made up this angle guide that makes sure all of my welds will be the same. To make this guide I cut two pieces of square tubing at 15 degree each - to equal 30 - and welded them together. Then, checking the angle carefully, made sure it was exactly 30 degrees. Once it was at precisely 30 degrees, I welded on the wire across it's open mouth to be sure it could not move again.

Here's my angle ruler laid upon the guide.

Here are the pieces of the frame ready to be welded. They are the pieces of tubing on the inside. The large stainless block is used to keep the pieces of metal flat.

Here is the new piece after welding. To figure out how long to cut each section, first decide how big your circle will be. Then multiply it by pi (3.14). That will tell you how long it is around the outside of the circle, which is the circumference. Now divide the number of sides you have on your circle into the circumference, and that number is the rough length you will cut each piece. Keep in mind, your math will give you the diameter of your circle, point to point, not flat side to opposing flat side. I had 12 sides on my circles, so that meant I needed an angle at 30 degrees. This meant I needed to cut each end at 15 degrees so that the angle would add up to 30. Confusing? I though so too. I cut my first two pieces at 30 degree each. When I tried them together I was surprised to find it a 60 degree angle. I would have only had 6 sides on my circle with that angle. I'm glad I tried it out before I cut them all!

Here is the 45" ring just finished, two to go!
The angle guide is at the top for reference. I had the luxury of cutting the tubing with a mill. It's cuts are precise to the half thousandth, give or take a micron. It did help, but I found that it didn't matter greatly. What is most important is firmly clamping the tubing so that it cannot move at all while cooling. That's the advantage of using the angle guide, it was easy to clamp the pieces to it and keep them from moving.

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