Step 1: Picking up where I left off...
Step 2: Other Changes
Step 3: Updated parts list and tools
In this version I did add a professional tripod head as well as a set of RC shock absorbers, which added ~$35.00 to the total.
QTY - Description
Hardware Store List
8 - Stanley Strap hinges (this brand has plastic bushing that keep the hinge from wobbling)
1 - PKG Clear Bumpers
1 - PVC "T" - 1-5/16" Inside Dia.
1 - PVC "reducer" fitting 1-5/16" to 1"
2 - 4" x 4" "L" angle bracket
1 - EXT Spring 1/4"
1 - EXT Spring 3/8"
1 - 1-1/2" Dia. Hose Clamps
1 - PKG(2) Rubber Washers
2 - PKG(10) 1/4"-20 nuts
1 - PKG(4) 1/4"-20 lock nuts
1 - PKG(20) 1/4" lock washers
1 - PKG(10) 1/4" brass flat washers
1 - PKG(4) 1/4" flat (fender) washer O.D. 1"
2 - PKG(4) 1/4" Bolts (1/4" - 20 x 1")
2 - PKG(4) 1/4" - 20 x 3/4" countersunk bolts
1 - PKG(4) 1/4" - 20 x 1-1/2" machine bolt with flat allen head
1 - PKG(5) 10 - 32 x 1/2" machine bolts and nuts
1 - PKG(10) #10 lock washers
1 - PKG(10) #10 x 1/2" wood screws
2 - 10-32 FN Allen head cap screws
2 - 6MM right angle grease zerks
2 - 6MM nuts
1 - PKG screen door (plastic parts)
Misc Pipe fittings to use as counter weight (may not be needed if spring tension is correct for the weight of the assembly and camera).
Hobby Shop List
1 - pkg of 2 Radio Controlled Car Shock Absorbers
(Any brand should do as long as they'll provide a way to easily attach to the hinges)
Camera Store List
1 - Basic tripod head - your preference here, should be light weight)
As for tools, you'll need;
3/8" Electric Drill
Drill bits - 3/8", 1/4", 5/32", and 3/32"
4" Bench Vise
Assorted wrenches, 3/8" socket set and ratchet or adjustable wrenches.
A small "bubble" type level
a ruler (I used a small metal rule)
Step 4: Getting Re-started
1) The stem mount; all the PVC parts, the 2" x 2" L-angle brkt, 1 - 1/4"-20 x 1-1/2" bolt, 2 - 1/4" x 1" fender washers, 1 - rubber washer, 2 - #10 x 1/2" wood screws, 1/4" lock washer, 1/4" nut and hose clamp.
2) The 2 spring arms; 8 - strap hinges, 6 - 1/4"-20 x 3/4" counter sunk bolts, 8 - 1/4"-20-1" bolts, 14 - 1/4" lock washers, 14 - 1/4" nuts, 4 - 1/4" brass flat washers, 2 - 10 x 32 bolts, locks washers, nuts, clear bumper and springs)
3) The tripod head mount; 2" x 2" L-angle bracket, 2 - 1/4"-20 nuts, 2 - 1/4"-20 lock nuts, and the tripod head.
4) RC Shock Absorbers, 2 - grease zerks, 2 - 10-32 Allen head cap screws, 2 - 6-32 screws and 2 plastic bushings from the screen door parts pkg.
Step 5: Stem mount
2) Place the PVC reducer fitting into the top of the T as tightly as you can.
3) Pre-drill two 3/32" holes through the T and adapter for the two screws and install the two screws.
4) Next place the 1/4" bolt through the L-angle bracket, rubber washer and through the neck of the T. This is to check the length of the bolt as it will need to be cut. See the notes in the diagram.
5) Once the bolt is cut to length, assemble the parts as follows (per the diagram).
6) First the bolt goes through the L-angle bracket, then the rubber washer and through the top of the PVC "T" and reducer.
7) Now from the bottom insert two (2) 1/4" x 1" fender washers against the lip of the reducer fitting and push the bolt through.
8) Now you can place the lock washer over the end of the bolt and start threading the 1/4" nut.
9) Tighten the nut and bolt until the bracket is snug against the PVC fitting.
10) Drill several small holes in the side of the upper section of the PVC just below the bottom of the 1/4" - 20 nut (see diagram).
11) Use a small file or hack saw blade to form a slot that will allow the hose clamp to pass through the PVC (just under the 1/4" nut).
12) Pass the hose clamp through the slots formed in the previous step and then set this part of the assembly aside until the final assembly.
Step 6: The iso-elastic arm
Red hinges 1 & 2 - this is the outside end; #1 attaches to the stem mounted angle bracket and #2 attaches to Green #1
Green hinges 1 & 2 - outside end; of which #1 attaches to Red #2 and Green #2 will attach to the tripod mounting bracket.
The Light blue 1 & 2 upper hinges and the Dark blue 1 & 2 lower hinges (inner hinges) attached to the outer ones, which complete the parallelogram.
1) Use a hacksaw to cut one end of four (two per set) of the hinges (inner ones) to ~1-1/8" in length.
2) Once that's complete the short ends will be connected to the two outer hinges with brass washers separating the hinge straps (see notes in the picture). I used the countersunk bolts for this step as it helped to self center the bolts and prevented bolt heads from colliding when the arm moves through it's entire range of motion. Once this is done you should have two sets of hinges joined; the light blue and green pair and the dark blue and red hinge pair.
3) Next align one set (either the upper or lower hinges) of the long hinge straps (inner and outer) and secure with the short 1/4" bolts and nuts.
4) Now if you fold the straps around to form the rectangle you will notice the holes don't line up, because it's offset in the wrong direction for these hinges. But there's plenty of room to drill the required 2 hole, just mark and drill them out with a 1/4" drill bit. Then fold them back around and secure them as you did with the other straps.
5) Use the 10 - 32 x 1/2" bolts as the retainers for the ends of the springs (see picture) one of the bolts is in the upper left corner (here I used the existing 1/4" hole in the hinge strap). The other one is in the lower right corner (for this one I drilled a 5/32" hole, close to the hinge joint, to get the necessary spring tension). For now, just use a temporary spring or you can skip that step for now, until you put it all together.
6) For an initial calibration/alignment check, measure the distance (on both sides) between the center of the hinge pivot points. The distance between light blue and green hinges should equal the distance between the red and blue hinges. Likewise the distance between light blue and red hinges should equal the distance between the dark blue and green hinges. To adjust these distances just loosen the appropriate bolts and move the hinges and re-tighten, till the distances are correct.
Step 7: Tripod head mount
1) Drill two 1/4" holes in one side of the angle bracket to match the ones in the hinge bracket.
2) Drill one 1/4" hole in the other side to match the one on the tripod head.
NOTE: I had to attached a counter-weight on the camera end of the mount (using a couple of pipe fitting parts (an end cap and a reducer), but this will depend on how closely you match the spring tension to offset the weight. To attach the counter weight I drilled a 1/4" hole in the end cap fitting and attached it with a slightly longer hinge bolt.
Step 8: Adding shock absorbers
1) I drilled two #36 holes, one in each of the two hinge arm sections (see pictures).
2) Next, tap the holes for a 6-32 thread
3) Use one of the 6-32 x 1/2" screws and one of the plastic (screen door bushings) to secure one end of the shock absorber (see drawing of the shock absorber assembly).
I used two right angle grease zerks too mount the other end of the shock.
1) Remove (unscrew) the part of the zerk that extended at the right angle from the two grease zerks.
2) Then drilled all the way through the head of the zerk ,where the right angle fitting was removed with a #21 drill bit.
3) Next tap the holes for the10-32 allen screws.
4) Then for each shock, pass the 10-32 Cap screw through the other end of the shock absorber and then then secure it into the threaded zerk.
5) The zerks can then be secures to the hinges through one of the spare holes in the hinges with the threaded base of the zerk and a #6MM nut.
Step 9: Putting it all together
You'll need to check two basic functions of the spring arms;
1) Keep the camera in a neutral (balanced) position.
2) Make sure that as the tripod head moves up and down, it keeps the the camera level.
Place your camera in the tripod head and secure it. Now you may need to try several different springs or combinations of springs, as I did, to "equalize" the weight. Ideally it will require the same "pressure applied" to move the camera up or down when it is in the middle of the range of motion. I secured the ends of the springs with some brass washers and the #10-32 nuts and bolts.
--Level checking procedure--
To check the "level" of the arm place the entire assembly in a vise or mount it on your bike. Then put the small "bubble" level in the tripod in place of the camera and move the arm to the extreme top position. Now check the position of the bubble. NOTE: you may want to tweak the position of the assembly in the vise or on the bike to center the bubble and then re-tighten the clamp or the vise. Now move the arm to the extreme bottom of the range of motion and compare the bubble position. If it's off by more than a small amount, then you'll want check the measurements of the parallelogram (hinge corners) and re-align if necessary (see step 6).
Once you're satisfied with both of these requirements, you're ready for a road test, place the camera (mine is a JVC Mini DV GR-D250) in the tripod. Place the PVC "T" halves around your stem and use the hose clamp to secure the assembly. One note here, you may have to remove a little bit of additional material on one of the two halves, in order for it to clamp tightly enough.