Panel versus Mold Construction for Longer Camera Crane Arm
Panel versus Mold Construction for Longer Camera Crane Arm
(OP)
I am looking at replacing an existing aluminium camera crane arm (see photo) with carbon fibre box sections. Creating and using molds seems expensive and hard to get the high tolerances required. Cutting panels and edge bonding them and glueing/riveting to aluminium end pieces that would allow them to be connected to the crane end to end and would be significantly cheaper. Can I get similiar gain in stiffness and weight reduction using this method? Is there a study or any information about these opposing constuction methods. Beauty is not the major concern: cost effective lightness and stiffness is.
Thanks,
Simon
Short arm cranes shown at www.cameracontrol.com
Thanks,
Simon
Short arm cranes shown at www.cameracontrol.com





RE: Panel versus Mold Construction for Longer Camera Crane Arm
Conjecturally, the simplest, cheapest (but not cheap) thing you could do now to save weight is vacuum- chuck the panels you've got and pocket mill them to thin the 'webs'.... assuming they're currently overdesigned and primitive, which is not apparent from the photos.
You need to hire an aerospace structures engineer to answer your questions, or to help you rephrase them in a way that makes it possible to answer them with some precision.
Mike Halloran
Pembroke Pines, FL, USA
RE: Panel versus Mold Construction for Longer Camera Crane Arm
I'd probably go for flat carbon panels, bolted and bonded to extruded aluminum end pieces.
Flat panels are relatively easy to manufacture even with the highest modulus fibers.
RE: Panel versus Mold Construction for Longer Camera Crane Arm
Rob Stupplebeen
RE: Panel versus Mold Construction for Longer Camera Crane Arm
In this way you don't need curved mold, as in a conical geometry, and it will be easy to layup sandwich panels that will be later jointed by adhesive or bolt.
For stiff and cheap solution try glass fiber for outer and inner skins of panels, and unidirectional carbon as reinforcement if the loads applied give excessive displacement. If displacemnt is not high, maybe only glass could work,
For extremely stiff structure you can use only carbon in fabric and unidirectional tape (solution more expensive) but be aware of contacts with any part of aluminium ( fittings, plates...)to prevent galvanic currents and corrosion
2) You can create two open C sections and join them frontally to form a rectangular close section ( as F1 monocoques or airplane fusolages)
3)For core of panel use pvc or in alternative honeycomb if you want to keep the weight as low as possible
bye
Cpinz
RE: Panel versus Mold Construction for Longer Camera Crane Arm
But, if it's not satisfactory, that could possible come from localized deflection where the loads are applied, or from odd distortion of the tube involving wrinkling of the walls and shear of mechanical joints.
[ It's not clear from the photos: Does the big tubing separate or collapse for shipment? How are the sections held together? I can conjecture ways to separate and telescope the structure for shipment, such that it would require far fewer than 15 big crates. I assume there's some reason why that wasn't done already, or was done and then un-done. ]
I.e., exactly what problem are you trying to fix?
Mike Halloran
Pembroke Pines, FL, USA
RE: Panel versus Mold Construction for Longer Camera Crane Arm
He is a composite guy and did some funky stuff. I am guessing you are not;) His boom was used in a shot on the Wedding Crashers where you start with the birdseye wedding view and come down and travel down across the lawn into the tent etc...seamless and beautiful.
cpinz has got the simplest concept of the equations. Determine a Carbon plate that has the properties of the aluminum and go from there. I recommend using a composite or aluminum extrusion to bond (rivet minimally) the panels on the corners. If done right, with no rivets, you could probably go to the inside edge and use it as a bearing rail.
There are a ton of options for adhesives, call your local guy that you trust and he can hook you up. Also whoever you buy the panels from should be savvy enough to work you through alot of this.
Let me know if you need help, sounds fun.
RE: Panel versus Mold Construction for Longer Camera Crane Arm
Thanks to everyone who posted a response - it's a great help as I have 0 experience in this field. (I will attempt to answer some of the questions that people have posed)
The arm that is shown in the picture is a single welded fabrication from 5mm ali sheet. I am looking cut the nose off and insert 1-3 5' box sections between the arm on the base and the nose section (which may have to be re-fabricated in composite to reduce weight) This way I can have a 8' arm or a 13' arm or a 18' arm or a 23' arm. Telescoping is a later possibility, but beyond my current engineering plans.
The arm needs to be light and stiff so that it is easy to transport and the camera does not shake (much) when the arm decelerates and I do not need huge counter weights which then require more power etc to accelerate along the track. The larger rig on my website is 1600 lbs so it is lighter than many would think.
So - My current plan would be to cut out 4 panels with a 45 degree bevel and corner bond the panels into a box section and maybe overlay some carbon on the inside and outside seams for extra strength/beauty. Once this is done, I could bond some ali sections onto the open ends to allow me to bolt the box sections together. I would use pre cured honeycomb panels of appropriate strength.
There seems to be some back and forth about the galvanic action of aluminium as well as the differences in thermal expansion. I could limit the thermal expansion effect by using several smaller sections rather than an entire square frame on the ends, but if I use the right epoxy and the rig does not live outside (though it does on occasion get wet) I should not run into trouble with corrosion?
Is there a book/manual on doing this or is this forum the best source of info in this area?
Of course for accuracy I would have to fabricate an entire jig to get the aluminium inserts to all line up, but I could not see a way to make this whole thing and THEN bag and bake it so precured panels seems the best.
Photo is of the existing design with all ali construction (I have a single piece protype of this arm)
Thanks,
Simon
PS PanelGuy I saw that shot and thought it was a steadicam operator on an Akela crane? Not so? Simon at my website
RE: Panel versus Mold Construction for Longer Camera Crane Arm
For other polymer or composite material suggestion you may also want to take a look at:
h
Their experts give advice on material selection and service/shelf life of polymer and composite materials (their global/baseline assessments are for free)
Cheers,
RE: Panel versus Mold Construction for Longer Camera Crane Arm
RE: Panel versus Mold Construction for Longer Camera Crane Arm
Mike Halloran
Pembroke Pines, FL, USA