Kevin's Fixed Height Tripod Project

Page last updated: 2001 September 12

Fixed Height Tripod

Start of the Project: 2003 March 21

Intro

Every year I and many other Astro-Dudes partake of the Star Party known as StarFest, held at Mount Forest Ontario. And every year we come back full of ideas and energy to do something about them. This fixed height tripod came from the design of Les Dempsey of the Belleville Astronomy Club, which he brought to Starfest 2001 and also to the 1st annual Fall'N'Stars 2000.

Benefits

to replace a rickety old variable height tripod that was a pain to move around and was always pinching fingers off!

to use as a mount for the Voyager telescope, where standard camera tripods were often too small and unstable.

Building an add on wedge to mount a barndoor tracker, which also suffers from too small camera tripods

Design

The design is not changed from Les's basic design (195kb adobe acrobat file). Three legs which are friction fitted to the top table surface and three smaller arms that limit the leg spread, with a tray sitting on top.

Parts List

x4 1"x2"x8' pine (legs and tray arms) $3.50
x1 12"x16"x1/2" plywood (can use 3/4" as well) (table top and tray base)
x1 12"x12"x1/4" plywood (tray)
x1 2"x2"x12" pine (leg mounts)
x3 2" hinges $3
  and x7 #4x1/2" wood screws (tray base to hinge)
  and x6 #4x3/4" wood screws (tray arms to hinge)
x3 1/4-20 carriage bolts 3.5" long (leg mounts) $1
x3 1/4-20 carriage bolts 2.5" long (tray arm mounts) $1
x6 1/4" washers
x6 1/4-20 lock nuts $1
x6 1 3/4" (if using 1/2" plywood)
   or 2" wood screws  (if using 3/4" plywood) (table top to table mounts)
x6 1 1/4" wood screws (legs)
x1 24" of 1/2" quarter round molding $2
carpenters glue

Supplies needed:
tape measure, tsquare, drill, jigsaw, palm sanders
#80, #240 sandpaper, clamp, counter sink drill bit, 1/4" drill bit, small 1/16"
drill bit

The Assembly

1. Table Top Mark the centre of an 11x11 square and drill a 1/4" hole. Cut an 11" circle from the 1/2" or 3/4" plywood. We used a large dinner plate to trace the circle then a jigsaw to cut it out and then #80 sandpaper on the palm sander to smooth it out, followed by #240 sandpaper.
2. Legs Cut two 48" long legs from the 1"x2" pine. Clamp the two together and pilot drill holes at 4" and 8" from one end. Glue from the bottom to the 8" mark or a little further, put back together and install two screws, 1 1/4". The free ends should be able to spread apart 2" without a problem. Mark out a drill hole 3/4" from the open end of the legs and drill a 1/4" hole through both pieces of wood. Using a jigsaw or saw round off the open end to allow the legs to move without running into the bottom of the table top.
   Repeat for the other two legs. Sand down the legs
3. Leg Mounts Cut a 4" long piece from the 2"x2". Drill a 1/4" hole 3/4" from one end and offset more towards the bottom of the block rather than centered, say 3/4" from the bottom. You can taper them (which we did for the first prototype but not the second) as well Repeat for the other two mounts. Sand down the mounts
4. Tray Arm From the leftover 1"x2" cut out a 9" piece. Drill a 1/4" hole in one end 3/4" from the end and centered. Taper the other end by slicing off a piece approximately 1" from the top. Repeat for the other two arms. Sand down the arms.
5. Table Top Draw 3 lines on the bottom (to align the mounts) and top (to align the screws) of the table top 120 degrees apart. Glue a mount and align in so the outside edge just comes up to the outside of the table top. Clamp and turn over. Drill pilots holes 1" and 3" from the outside edge, drill counter sinks and then install two 1 3/4" screws. Drill them down past the surface of the table top. Repeat for the other two mounts. Sand down the table top.
6. Leg assembly Line up a leg with the leg mount and insert a 3.5" carriage bolt. It should go all of the way through with a little force. secure with a washer and a lock nut. Tighten all of the way for now.. then loosen off the lock nut a little later to test the leg swing. The carriage bolt head bites into the wood and prevents the bolt from turning. Repeat for the other two legs.
7. Tray Mark the center of a 12"x12" piece of the 1/4" plywood and drill a small pilot hole. Next mark out and cut an equilateral triangle (inside angles 120 degrees), 12 inches a side. Then mark out 2 inches from each point, draw a line across and cut them off. You should be left with an 8" a side equilateral triangle. We cut off the ends as they stick out quite a lot when the legs are stowed. You are now going to cut out an equilateral triangle tray base from the leftover 1/2" or 3/"4 plywood. This should be a triangle with 6" sides. Attached the hinges to each point with the hinge itself inside the wood so the tray does not overextend when deployed. Drill pilot holes and use two small #4 or #6 1/2" screws in each hinge.
   Attaching the tray arms is next. With the tray base upside down, fold the hinge up, place the tray arm with the pointy end onto the inside of the hinge, align and drill a pilot hole in the farthest hole from the hinge then put in a #4x3/4" screw. Drill a pilot hole in the next hinge hole (it might have 3) and put in a #4 x1/2" screw. Repeat for the other two arms. Now attach the tray to the tray base by gluing and using a single #4x1/2" screw in the centre from the top
8. Tray walls Optionally you can cut up three 8" sections of 1/2" quarter round molding and glue it onto the tray, leaving three "openings". This is to help items stop rolling off the sides.
9. Mounting the Tray Set up the tripod with the legs apart. Insert the tray from the top and bring the tray down with the arms entended until the tray is level and the arms are level. Pull out the legs until the arms no longer jut out from the legs. Mark a leg for a 1/4" hole and measure it (it should be approx 18" +-). Mark the other two legs. Remove the tray and drill a 1/4" hole in each leg (through both pieces of wood). Put the tray back in and connect each arm to each leg using a 2.5" carriage bolt and secure it with a washer and a lock nut until the carriage bolt is firmly in the wood, then loosen off a bit. The tripod should now be able to close by putting your hand under the tray base and pushing upwards and open by pushing down on the tray and pulling out one of the legs.

   Lastly, open the tripod to it's fullest extend. Draw a parallel line to the floor on the feet so that when you cut that bottom bit of leg off, the entire foot will rest on the ground, and not just the tip of the foot. Repeat for all three legs.

After the Fact

Total Cost: under $20
It helps to have scrap wood hanging around (1/4", 1/2" or 3/4" plywood). I happened to have 1/4" and 3/4" plywood leftover from another project and used it.
You can shorten the legs by up to 3 inches or so (up to the first screw) if you are a vertically-challenged person.