Pipe, Tube and Conduit
Searching for pipe/tube/conduit can
be frustrating and confusing. You may not know the right language and the sales
person may not know what he has or what it is called. Here are some definitions.
The terms should be tailored to the person that you are talking to. A hardware
store clerk will not know as much as a industrial pipe and tube salesperson.
When your request is passed to a production person, then to the supplier it
can get garbled in transmission. Talk to the supplier yourself if possible.
Water Pipe- Galvanized steel with threaded ends max. 21'. Sold according to
it's INSIDE DIAMETER (ID). Many people don't understand diameter, but only read
what's printed on the rack or the pipe itself. For example, 1-1/4' pipe has
an OD (OUTSIDE DIAMETER) OF 1-5/8" and 1-1/2" pipe has a OD of 1-7/8". 1-1/2"
pipe is often mistaken for 2" "pipe". Tube goes by OD.
Galvanized water pipe is available in most places except in the tropics. It's
heavy, but will do if it is all that's available. On flat surfaces is makes
good dolly track with or without ties. To join two lengths you need to cut the
threads off and file the ridges flat. A pipe cutter will cut it square, but
will leave a ridge that you can file off with a flat file. Cutting it square
with a hacksaw is difficult. It can be screwed to ties with effort. Water pipe
can be used for rigging with Speed Rail (c). If you are asked what schedule
you want say "schedule 40". Don't confuse people if they don't ask.
Gas Pipe- Steel usually rough and tar coated, cheaper, but usually too rough
E.M.T., Electrical Conduit (Thin Wall) is available except in the tropics. Cheap,
galvanized, 10' lengths and sold by inside diameter. (A bit larger). 1" E.M.T.
has an O.D. of 1.160". E.M.T. is very useful. It telescopes inside each progressive
size. It can be bent smoothly with an E.M.T. bender. 1/2" and 3/4" is good for
rigging and 1-1/4" and 1-1/2" is good for short dolly track. Take your track
couplers and a rat-tail file to notch the ends. Ties will attach easily with
metal screws. E.M.T. doesn't fit any Speed Rail (c) fittings.
Aluminum Electrical Conduit is OK for one time rigging, but is soft, comes with
threaded ends and is only 10' long.
Rigid Steel Electrical Conduit is thinner than water pipe, cheaper, but comes
in 10' lengths. It has threads and is the same size as water pipe and Speed
PVC Plastic Pipe / PVC Electrical Conduit is good for curved track screwed to
a wood floor or plywood. Lay it flat on flat surfaces with no ties. 1" and larger
are OK. Make sure your dolly truck wheels clear the floor. Smaller sizes are
very available. Larger sizes can be found at irrigation suppliers. You can make
couplers out of dowel and layers of tape.
Tube is an exact language. Tube is always referred to by OUTSIDE DIAMETER (OD)
and WALL THICKNESS. ie 2" by .065" has a diameter of 2" (plus or minus .002")
The ID will be 2" minus two times the wall thickness or 1.870" Most camera cars
uses 2" tube and have their own special fittings.
For aluminum dolly track you must find an industrial pipe and tube supplier.
They will know all about pipe and tube. Their catalogs will help you understand
pipe and tube. Your price will reflect the amount you buy. Get together with
other potential users for a better price. It is wise to anodize your pipe to
prevent oxidation and hair loss from aluminum poisoning through your hands.
File the sharp edges off a little to prevent injury, but not enough to cause
a bump at joints.
Some types of anodizing will damage Speed Rail© fittings.
For Dexter dolly track, I suggest 1-1/2", 6061-T6, Schedule 40 aluminum pipe.
6061 is a weldable alloy and T-6 means it is hard. Do not buy 6063 T-3 hand
railing pipe. Pipe comes in various schedules: 5, 10, 20, 40, 80 and 160. Schedule
40 is the most common and cheapest.
Fence Post-comes in pipe sizes, is lighter, cheaper, but weaker. Don't fly people
or equipment with it. There are a few fence fittings that are useful, but much
weaker than Speed Rail©.
© Copyright 1999-2004 Ron Dexter. All Rights Reserved.