Tuesday, February 05, 2008

Making Dolly Track

I found this article online from Ron Dexter at http://rondexter.com/. In it, he describes making dolly track in the 60's. The article goes on at the website to give instructions on how to build your own, but it's a little dry reading even for this site. The whole aricle can be found at the site as well as a LOT of other stuff.

Making Dolly Track.

In the 60's I built my first portable dollies using ball bearings at 90 degrees on pipe track. For sound I tried wheels flat on the top of pipe and idler wheels to keep the dolly on the track. I didn't come up with the skateboard wheel idea for sound. I think Pat O Mara Jr. might have. It has become a standard.
I like track wider than 2 foot Elemack track in the field and on dirt. It's more stable, easier to level and can be made in longer lengths that reduce the number of joints.When we were making and selling track we used mahogany for ties not considering that we were cutting down rain forest trees to get it. Mahogany is an ideal wood as it is light, doesn't warp and low grade varieties were cheap. Seasoned Douglas Fir will work fairly well. It would be nice to find a substitute for mahogany or any of the threatened woods.We and others track builders tried metal ties, but they don't work as well in the dirt and with wedges. (See Nesting Apple Boxes) Sections of pipe or tube and even PVC pipe will work without ties on flat surfaces, but don't try them on dirt or uneven surfaces. It is very difficult to level the track.
When laying track it does not have to be perfectly level side to side, but should be laid out in so it lies in a plane. On a slope one side can be a couple inches lower. One person can "eye ball" it into a plane from one corner as others wedge it up to level or in a plane. Use wedges or boxes under each tie and not a plank under many ties to raise one side. You want separate support under the end of each tie. If you are working with a crew that is used to leveling track with a level, don't fight them with your own different method. It will take longer.
Shingles work well on stage for smaller adjustments. Place wedges or shingles under the ties to avoid stepping on them.
Circular Track
Tom Ramsey, the key grip ,got me going on circular track. We ended up with radii from 4 feet to 60 feet. The longer radii are hard to set up with long lenses. They need a very solid base and to be perfectly level. Joining large radius track for long lenses is also tricky. Small bumps show up more on long lenses. I stepped my radii out so that each outside track was the same radius as the next inner track. So except for the outside two tracks, two pipes were bent to the same radius. In a fixed set up the middle tracks could be eliminated and the outside of one #1 track could work with the inside track of #3 Etc. Label each track and make a diagram of radii and dimensions. It will help in planning what track will fit in a location.The beauty of circular track is a subject in the middle of the radii stays in frame and in focus making it much easier for the operator. Moving super close ups are possible.To go from curve to straight the dolly trucks have to turn and change gauge (track width) easily.For one-time situations on a flat floor that you can screw into or where you can put a floor down that you can screw into, consider 1" PVC screwed on radii drawn from a center point. You can't do this on the dirt or uneven surfaces.You can also curve PVC pipe with a rope and get approximate circular sections. Try this before committing its possibility to the director. 1" PVC works.Making aluminum track.Get together with others who want track to pool resources and skills. Cut notches in 2" x 4" x 36" wood ties. Cut them accurately on a large table saw or radial arm saw. Make them all identical. Bill Bennett says the Hollywood gauge is 31-3/4 inches. I started at 32". Round the edges, drill two holes 5/16" center of where the pipe goes and countersink the holes on the bottom side. Paint the ties with a good exterior paint, varnish or sealer.


Michael Taylor said...

D --
I used to work with Ron in the early days of my NABET juicing career, out of that crazy, crowded junk-yard of a stage he had down on Sunset (I think it was Sunset -- it's been a long time).

There wasn't much Ron could't do, though, and he always seemed happiest when building some device to get a particularly difficult shot. He was (and probably still is) a very creative and capable guy, but like many such dynamic individuals, wasn't always realistic in the demands he made of the crew. He never could understand why we wanted ten whole hours of turnaround between 18 hour work days. He was happy enough to get by on four hours of sleep, so what was our problem?

The only thing that saved us were those NABET union rules.

onno said...

wow, it sounds like "those were the days" to me... When I manufacture circular tracks I have a tolerance of 1/10 millimeter = 0,0001 meter!! for each joint

D said...

Yeah I love those old guys. They are definitely a tougher breed and a lot of the things we use are a result of their ingenuity. Glad you liked the article.