Machine Shop Tips
Rubber, such as wheels can be machined if frozen in a cooler with dry ice. The
rubber can thaw while machining and may need to be refrozen to finish.
Delrin, nylon and many plastics are easy to machine, look good and are durable.
Nylon is cheaper than Delrin, comes black, but is not quite as strong.
Many shaped can be made by epoxying parts together. Roughen and clean parts
well before gluing. Epoxies set faster when warm.
Consider aluminum castings. They are cheap and the molds easy to make if no
cores are needed. Castings are not as strong as forgings, extruded shapes and
hot formed shapes. Get to know your alloys for strength, welding and bending
You can burn cutting tools in any material if the feed is too fast or the chip
clearance restricted. Use cutting solutions and slower speeds.
When band sawing or hack sawing, select a blade that has at least 2 teeth in
contact with metal all the time. Too many teeth will restrict chips clearance
and slow down cutting. Take full medium speed strokes. Short fast strokes will
burn the blade. I stroke per second is OK. Keep the frame tight.
Be very careful with thin metal. Cutting tools can break through and grab the
piece. Clamp down anything you can to prevent it spinning when the cutter or
drill breaks through.
Drill and tap camera mounting holes straight. Gear head and many other tie down
bolt head bolts have no play and will not enter a crooked hole.
Use a drill press, tapping table or block of metal with straight holes for working
in the field.
Drilled and taped holes are faster to assemble than putting nuts on the back
Don't tap or drill through metal at an angle on the bottom side of a piece.
It can break the tool. Start a drill or tap on a flat surface.
You can't match the threads in a hole by taping from both sides.
Use a few standardized sizes of bolts. I like #6-32, #10-32, #1/4-20, #3/8-16
and #1/2-13 best. I prefer cap screws (bolts) to hex head screws. A bolt is
a screw with a nut.
A collection of studs and stud couplers helps fill out a variety of bolt lengths.
Welding is a learned skill. Send out questionable welds until you learn to make
safe welds. Brazing thin steel can be easier than welding. Consider epoxy, rivets,
bolts, and angles for corners.
Many extruded shapes can be the start of a rig. Look at the remnant departments
of your metal suppliers. Keep on the lookout for 5" x 7" x 3/4" angle. It's
great for camera rigging.
Look into methods of aligning blind holes.
To make variable friction surfaces, pull the center of disk of flexible plastic
like nylon in a lathe toward its center and turn it flat. When it relaxes you
have a slight cone. Different tension will increase or decrease the amount of
surface and friction. Dampening fluid will give a fluid feel. Bearings are needed
to keep it aligned and support weight if supporting much weight.
Having a selection of shapes, tubes and plate will always be handy when building
something. Don't throw away any usable scraps. Boxing or racking stock will
help keep visible what you already have.
Watch for telescoping sizes of tube. Speed Rail is often the easiest way to
make things, but not always easy to interface to the rest of the world.
2" OD x 1/8" wall tube can be turned down to fit 1-1/2" IPS pipefittings and
1-1/4" IPS pipe will fit inside the 2" tube. Some scaffold fittings will take
both 1-1/2" IPS pipe and 2" OD tube, some even 1-1/4" IPS pipe. (See Pipe,
Tube and Conduit)
A few milling machine operations on small parts can be done on a lathe or drill
press with an X-Y milling head.
A 6-jaw lathe chuck is a very useful tool for lens mounts and thin parts.
Hole saws clog as soon as the teeth reach the hole depth. Constant cleaning
and lubrication help and drilling through from the backside is helpful. Tilting
the piece a few degrees can help chip clearance. Clamp your work.
Fly cutters are dangerous and the work should be well clamped down. Use a hole
saw if you can.
Weird shaped holes can be made with many small drill holes and a file. Hand
and power nibblers work with thin metal. Power nibbler chips are sharp and steel
ones can be picked up with a magnet covered with a cloth or plastic. Pull the
magnet away from the chips to drop them.
For one of a kind rigs, surplus parts are often cheaper and will work OK. For
commercial rigs you need a supply of parts for the future and commercial sources
should be used. The Thomas Catalog is a place to start looking for anything
mechanical. Mc Masters-Carr is a good source of parts and mechanisms. You have
to be a company to get their catalog.
There are car parts that can be of use. Wheel bearings make turntables. Rear
drive axles can make crane post bearings. Sharpened and trimmed rear axles make
large stakes. Window motors and mechanisms can work rigs. The lights are 12
volts. Torque tubes are very light and have fittings on ends. Disk breaks can
be modified for crane brakes. Mag. wheels can make simple "Dutch" round-e-round
heads with 4 or 6 bearings. Cut the center out and roll the wheel on fixed ball
bearings or skate wheels. Counter gas springs can give a straight line "fluid"
effect. VW steering shocks will reduce shimmy in wheeled rigs.
© Copyright 1999-2004 Ron Dexter. All Rights Reserved.