THE MAIN BOOM
The entire boom can be pretty much built with items purchased from a typical hardware store like Lowes or Home Depot equivalents. Some clamps and pipes used in this article were on hand already, but substitutes can be easily found.
Some of you will stop reading at this point, loosing interest that its not durable or just flimsy. This thing is
solid, relatively easy to assemble and strong. There is nothing chintzy about it.
The main exterior body of this jib boom is made of 1 7/8" galvanized pipe intended to build chain link fences. It was purchased in pre-cut, pre-painted black, 7'6" lengths for about $15 each.
Below you see the jib with the section lengths marked for visual references.
To allow easy transport, the boom's interchangeable sections come lengths of 4', 6' and 7'6". Its been used to a reach from about 8' to 21' reach from the fulcrum point.
Each boom section uses a slightly narrower 1 5/8" pipe that are 4' long each and are inserted into the main boom to increase structure strength and used as "pins" to connected the various sections together.
The picture below is of a prototype pipe that was about 5' long (vs finished 4') hence the uneven length. The red line indicates the actual 4' length.
Bolts are used with washers located top and bottom. Washers reduce scratches that the bolts and nuts will do in the surface of the pipe.
The significance of the uniform method of measuring the holes at each end of the boom and pins means boom extensions can be assembled easily like building blocks. Each section will fit together with another without fussing around with it.
Here you see the sections being connected together. We've since reduced the bolt lengths
The main 7’6” boom section that attaches to the tripod has to bear a lot of weight. Taking that into account, another 7'6" of
1 5/8” pipe is inserted into it. This smaller diameter pipe is effectively sandwiched in to add structural support of the fulcrum boom without affecting the required additional counterweight at the back. Holes in it are drilled to align with the fulcrum and other bolts to go through it.
This smaller inserted pipe is not completely inserted. Approximately 18” of it is extended out the front. This acts as the first primary attachment point for the first section of boom being connected.
A fulcrum hole drilled at the 4' (measure from back of jib) point the boom, matching the size of the now removed dolly wheel axle point is used as the fulcrum point. The 3'6 in front of the fulcrum signifies the beginning of the actual boom.
In this picture the 3/4 bolt going through the main boom pipe, white plastic spacers are keeping everything centered.
The bolt used is not threaded for its entire length. The pipes fulcrum point is on the smooth section of the bolt to ensure smooth booming up and down of the jib without thread grooves affecting the motion.
The hole for the boom to mount to the pivot point (fulcrum) is critical to get drilled right. If not drilled perfectly horizontal, the entire jib would be off rotation and boom up/down at an angle that might be undesirable. A jig was used (pictured below) in conjunction with a drill press to ensure the holes were drilled completely "square". There is a picture of the jig towards the bottom of this post. It was about $15 and worth every single penny.
GUY WIRES
As the boom is extended out the weight of it will cause it to sag in an arch. This can cause significant unwanted movement and control problems. This is a safety concern of it collapsing. Its also very visually unsettling.
To counter act the pull of gravity on the boom, guy wires are utilized extending from a 2' vertical mast to various points on the boom front and back. Approximately 6" in front of the fulcrum a threaded 3/8" steel road is mounted through the boom pipe with a series of bolts to ensure its secure. In this jib, a black piece of pipe was used around the rod, in this construction it provided some more vertical stability, and a uniformed black look. The rod that goes through the main boom is held into place by both a clamp, some bolts, and the downwards force place on by the bolt and shackle at the top, and the eventual cable forces applied to it.
Guy wires are attached at each connection point of the boom through an eye bolt and back to the mast. The wires are 1/8 braided steel cable, carbines on one end to speed up connection and turnbuckles at the other end to adjust tension individually. An eye hook doubles as a bolt for each boom section at the 4” point, and the guy wire hooks onto it. The turnbuckle allows for tension adjustments of the boom to remove any sag or bounce.
These cables and turnbuckle adjustments can take some of the load from the main boom and keep it straight. An additional cable going from the mast in the opposite direction back to the main weight bar provided the counter pull action, the resulting in the mast remaining evenly at a 90 degree angle to the boom arm at all times with relatively equal pull in both directions being provided. Performance improvement of the crane with these cables is very noticeable. Locking clamps keep the loops in place.
When the boom is extended, especially 15' and longer, with proper adjustment of the tension on the guy lines, the boom is very very straight and very little up/down bounce (if any really).
COUNTER WEIGHTS
For counter weights at the operator end of the main boom, a 1/2" x 3' square box steel rod is used hold the weights at the very end of the jib arm. Although its sqaure, it would still fit through the hole of the weights. Its held in the boom using a 5/8 bolt and the rear guy wire eyebolt goes through it. The end of it has several additional holes to accommodate different combinations of weights and to hold them in place without slipping off.
Weights on the back of the boom will give a coarse adjustment of the counter balance, getting it pretty close to even balance, but in order to get the fine tuning of the weight distribution, a sliding weight makes this very easy. This boom achieves that with a separate 5lb weight on a clamp can be placed anywhere along the boom where required to accommodate the slight variation of weight front to back. Having this feature is very necessary allows very precise adjustment of the balance of the boom.
CAMERA MOUNT
A true PTZ unit wasn’t required at time of construction as the camera being used on it is already a all in one PTZ HD camera, only a stable constant horizontal platform for the camera is required.
The original plan for the camera mount arm was to bend a 2 1/2 foot section of 3/4" conduit pipe (used for fire alarm cables running through etc) and spray paint the entire length, including the hanger black.
This jib utilized a mount already on hand with the shape that was desired. This was a former CRT television stand that would go on the wall, so it is quite strong.
To attach the camera mount bar to the end of the boom and give it the horizontal movement needed, a 2x10 metal joist hanger was chosen to attach the fulcrum of the camera mount to. A 3' section of 1 5/8" pipe was cut to slide into the very end of the jib's outside 1 7/8 pipe. The 1 5/8" pipe extends about 8" out with a joist hanger riveted to it, the hanger itself extending out to give about 3" of clearance between the pipe and the end of the joist hanger. This is the point where the "L" shaped camera mount pipe comes through.
About midway in the 3" gap of the joist hanger a hole was drilled to allow a 1/4 high grade bolt to be connected through the joist hanger and the camera arm. This design allowed the camera bar to move up and down, unimpeded from ground level up to approximately 50 degrees of pitch of the boom upwards. I used a couple of washers to center the "L" pipe in the middle of the joist hanger. The 1/4 bolt used was about 3" long, so to keep it centered, a nut was used on either side of the joist hanger to keep it tight.
Horizontal Stability of Camera Platform
To control the horizontal level of the camera mount, a metal bar is attached at the booms fulcrum point in a manner that regardless of the booms up or down pitch, it always remained perfectly vertical in line with the tripod center mast.
This jib design uses gravity to naturally pull the camera arm down, so to counter act this force evenly as the boom is moved up and down, a cable is run from the top of the camera arm all the way down the jib to this vertical rod. As the camera is boomed up or down, the cable keeps a constant even pull on the camera mount causing it to stay in the same degree of horizontal plane.
With this cable attached to the vertical bar of the camera mount at the top, as you boom up or down, the camera platform always stays horizontal (or whatever angle you decide you need during setup) automatically. Essentially the cable allows the horizontal mount to counter act the boom's pitch, causing it to stay horizontal.
In this application the metal bar purchased was for scaffolding and upon visual inspection at purchase appeared that it would fit with some minor modifications.
The cable has a turnbuckle on it that can be adjusted to make the camera mount line up on the same horizontal plane as the jib.
Although this job doesn't utilize it, the arm could probably be modified to allow for manual movement of the cable, which would give easy tilt adjustment of the camera if desired.
JIB BOOM STAND TRIPOD
This will NOT work with a camera tripod stand. Don't even think about it. The center point weight and momentum is tremendous.
An all steel PA stand was utilized from a parts bin. What was used is discussed here, but you will need to do something that will handle the weight, momentum and movement of the boom. You need something that is up to the task.
The tripod used for this project was a heavy duty steel stand. Not aluminum, not white metal, nothing plastic.
Here's how the legs look spread out. A 12" piece of pipe is slid onto the stand from the bottom of the fulcrum to the top of the leg supports coming out of the center. This maintains the legs spread out, and the center pipe support are "all one", meaning the entire stand legs are "locked" to not move. You can pick up the light stand and the legs will maintain their stance pictured
BOOM UP/DOWN and PANNING (Fulcrum)
Now the boom needs to be mounted to a tripod in a way that would give reliable smooth panning and booming up and down motion.
What was decided on was a construction dolly wheel used on scaffolding. Designed to handle 750lbs+ of weight, a ball bearing rotation system that had a grease fitting and the supports for the axle for the wheel were ideal for handling the weight.
We removed the wheel and the 'brake' assembly. This left a great mount for the boom, and another connection point for the camera horizontal adjuster.
The mount for this dolly wheel is the same diameter of the center support bar on the tripod I'm using, so I need to ensure it stays upright. When its inserted, the base of the dolly wheel sits on the the center mast of the tripod, transferring the entire weight straight down.
A piece of 1 1/2" metal tube was fitted over the center mast of the tripod stand, extending up just enough to allow the fulcrum to be inserted and locked by a pin.
An additional pipe was slid over it again to double up the strength. you see the two pipes slide over each other with the holes lining up for the bolts.
This is the final assembly of the support system. The bolts are in place holding it together. The entire unit is "one". The bolts and pipe inserts keep it as one solid structure. I can pick it up from the dolly and the entire tripod lifts, but maintains its leg spread, since the extra pipes below hold the legs in their ideal length.
OPERATION
It worked. Exactly as hope, and better than anticipated!
Unfortunately at this point no production examples are available due to copyright, but here is a quick JIB video test done when it was first assembled.
JIB VIDEO
The jib really didn't take very long to make and wasn't complicated to manufacture. Everything was off the shelf with some items modified using basic hand-tools. There was no need for any custom fabrication using welding, CNC or 3D printing.
To ensure all holes were drilled precisely in the center from top to bottom, a drill press was used in conjunction with a "self centering" pipe jig. This is placed on the drill press base plate and secured in place with bolts to prevent it from moving. All pipes are laid in this jig and are center drilled every time.
When the balance is set on this jib, its amazing. The jib can be moved to almost any position and the operator can let go of it and it will stay there, not moving. You'll notice in the video, and this is the same with an actual camera on the end, it easily can be put into motion and let go, and it will continue in that motion autonomously.
The entire boom breaks down into some relatively easy to manage parts, albeit there are quite a few of them. A road case is used to contain all the necessary mounting hardware, as well as some basic had tools and spare bolts and washers that seem to get lost during every tear down.
NOTES ON CONSTRUCTION AND FUTURE CHANGES
1 5/8" pipe has a bit of a gap of 1 7/8" pipe when they are inserted together. Initially electrical tape was wound around the 1 5/8 pipe on either side of the mount holes to accommodate this gap. Building this up evenly allowed the 5/8 pipe to slide and it works really well. The pipe is evenly centered, and allows for uniform snugging of the bolts when its connected.
This will be upgraded to fiberglass.
No pan/tilt lock on the boom yet. Will work on something as this is kind of a work in progress and I'll update the progress.
Doesn't have real monitor mount for it yet. Possibly a self leveling monitor system that connects to the guy wire mast
Possible chop of boom to be 6' length (vs 7'6") to simplify transport.
Side guy wires are going to be installed. At 15' its ok, but as it gets longer, they would really help i'm sure. The plan is to use a 3' threaded road and use it at the fulcrum when required vs the 3/4 bolt going through it now.
Update of nut/bolt hardware to use darker material to make it as dark as possible. Also at time bolts were purchased longer than required due to time constraints obtaining slight shorter ones.
Pipe material $100. Bolts, turnbuckles and wire about $100. scaffolding wheel $50
Tripod $75 (had one already) and weights around $50(?) maybe?
The 1/2" steel square rod used for the weights will be replaced by (probably) full length barbell. Unclear yet as to the exact design, but focus is being spent on more flexible mounting system for weights than currently used.
I mapped 3 of the 4 controllers (max 3 supported in Jack Box game), each of the "buzz in buttons" to their corresponding buzz in key (Q, B and P) and then each of the color buttons 1-4 in descending.
