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Frame for backgrounds and diffusion

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Ralph Chaney
Frame for backgrounds and diffusion
on Dec 3, 2009 at 7:58:00 pm

I'd like to buy or make an adjustable frame to support backgrounds or diffusion material.

Goal: Light, rigid, cheap... yeah right, "you can have only two of these"

Ideally:
  • Light enough... rigid enough.
  • Collapsable, easy to set up and pack up.
  • Expand from 6x8 to 12x8 ... these sizes are not yet set
  • Inexpensive... cheap source, used, do-it-yourself.
  • *If it's really "the way to go" I'd pay the money.
..

PVC? I can easily see how to make it fill the bill, but can it be rigid enough? I could add a cross-brace.

Suggestions?

Thank you!



-> Ralph


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Todd Terry
Re: Frame for backgrounds and diffusion
on Dec 3, 2009 at 8:22:49 pm

Keep in mind that PVC is actually very flexible, might not be what you want.

Not quite that big, but we have made a number of frames (4x4 and 6x6) out of 1/2" metal electrical conduit and elbows. I suppose bigger ones could be made, but I rarely use butterflys or overheads that are bigger than 6x6.

They work like a charm.

For the 4x4s, on one of the sides we welded a standard 5/8" post, so they will fit in an ordinary grip head just like "store bought" Hollywood frames. For the 6x6s, we welded posts on two sides.

Two of the opposite sides have the 90° elbows permanently attached. Heavy duty elastic shock cord runs through the whole frame. The cord keeps it all tight, yet it easily pops apart to fold up. They will set up or collapse in about 2 seconds, with no tools or knobs or anything else. Easy and rigid.

With the 6x6 frame, each of the long pieces are also cut in half and joined by female-to-female connectors so the rig is much smaller collapsed.

Easy, dirt cheap, and works well. We used 1/2" conduit for the 4x4s and 6x6s, for bigger than that you might want 3/4" conduit, but it would be a fair bit heavier.



T2

__________________________________
Todd Terry
Creative Director
Fantastic Plastic Entertainment, Inc.
fantasticplastic.com






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Ralph Chaney
Re: Frame for backgrounds and diffusion
on Dec 3, 2009 at 8:53:17 pm

Todd,

Great... had overlooked that elect. conduit is pretty thin-walled and lighter than regular pipe. Makes me want to check our sources for aluminum tubing, round and square. Usually expensive I'll bet but perhaps a nicely timed buy from a supplier could happen via the Net.

-> Ralph


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Todd Terry
Re: Frame for backgrounds and diffusion
on Dec 3, 2009 at 9:37:07 pm

I've checked on that a bit before. I usually buy those kinds of do-it-yourself raw stock from Aircraft Spruce, they sell all kinds of stuff mostly for people building their own airplanes... lots of high quality metal stock but with unbelievably good prices.

I never found any aluminum stock that was any cheaper than just buying the "real" frames from Matthews or whomever. In fact, the store-bought frames were quite a bit less than the sum of the purchased aluminum parts. Maybe a extra-special good deal could be found.

Conduit is actually pretty darn rigid... we've never had one bit of trouble using it for frames. It's also literally only a couple of bucks for a 10-foot piece. The connectors are a few dollars each which can add up, but even then the whole thing is still pretty cheap.

When I decided I wanted the frames collapsible, I was surprised to find that the shock cord (bungee cord) that I wanted to use was pretty expensive in long lengths. But I found it from a wholeseller on eBay, 100' of quarter-inch cord for only a few bucks.


T2

__________________________________
Todd Terry
Creative Director
Fantastic Plastic Entertainment, Inc.
fantasticplastic.com






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Ralph Chaney
Re: Frame for backgrounds and diffusion
on Dec 3, 2009 at 11:32:42 pm

Thanks again, Todd. Yes, the assumption is that something so common as Home Depot conduit couldn't rise to our rarified uses.

This will mostly be used for green screen and other backdrops. I could design an 8x8 that will accept a 4x8 addition. At 12 feet there may be some sag... can just put a support under the midway vertical member at the 8ft. mark to re-gain teh 8x8 stiffness.

I'm leaning toward 8x8 and 8x12 as I've run into green screens becoming too small whenever I'm lucky enough to have a ton of Z axis separation.

Is there a typical set of sizes for green backdrops?



-> Ralph


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Dennis Size
Re: Frame for backgrounds and diffusion
on Dec 4, 2009 at 2:07:09 am

An 8'-0" x 8'-0" greenscreen should be fine for single person chromakey work, as long as you don't need a full body shot.
You can have the fabric made to any size you want -- with pipe pockets -- at ROSEBRAND in New York City.

DS



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Richard Herd
Re: Frame for backgrounds and diffusion
on Dec 4, 2009 at 5:38:47 pm

A picture is worth a 1,000 words...can you snap a photo--if you get a moment--and post, especially the shock cord part.



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Todd Terry
Re: Frame for backgrounds and diffusion
on Dec 4, 2009 at 6:42:10 pm

Sure... just snapped some pics outside the stage door on the loading dock because I was too lazy to set up lights. Hadn't been outside today... it's cold! Was quickly wishing I was back in the studio standing in front of an HMI.

This is one of the 4x4 frames I made. The 6x6s are made exactly the same except they have the usual two posts on opposite sides and additional cuts that allow the whole thing to be collapsed to about three feet. The first ones I made used some "real" posts that I had laying around. For these (and subsequent ones), I just used long 5/8" bolts and cut the threads off the ends... plus the bolt heads make them easy to weld on. Oh... btw... you can easily weld the actual conduit, but you cannot weld the connectors. I originally tried doing that on the permanently attached sides, but the cheap "pot metal" that the elbows are cast out of won't take a weld, it just burns. So the screws are used there for the permanent attachments.

Alternately, on a bigger one like a 6x6 or larger you could use the 90° conduit curves which are also available for the corners... but I just used the regular elbows because they have a screw off "wire pull through" panel on them which makes threading and tying off the shock cord easy.

Not pretty, but they work like a charm, and are dirt cheap to make. Plus, seems that most 4x4s you see are the flat rigid kind... and these collapse (or pop open) in two seconds.

Hope this helps.





T2

__________________________________
Todd Terry
Creative Director
Fantastic Plastic Entertainment, Inc.
fantasticplastic.com






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Richard Herd
Re: Frame for backgrounds and diffusion
on Dec 4, 2009 at 10:25:18 pm

[Todd Terry] "have a screw off "wire pull through" panel on them which makes threading and tying off the shock cord easy."

Thanks! That's the part I couldn't visualize. Now I need to learn how to tie a square knot!


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cowcowcowcowcow
Todd Terry
Re: Frame for backgrounds and diffusion
on Dec 4, 2009 at 10:36:13 pm

You don't have to!

You pull both ends through the "trap door" in one of the elbows, and just tie each end in a single knot (you don't have to tie them together). Stuff 'em back in the elbow and put the cover back on.

There's room inside the elbows for the knots, yet they are still big enough to keep the cord from zipping back down the tubes.

If I recall, I think I used about 10 feet (maybe a little more) for a 4x4 frame and about 15 feet or so for a 6x6. About two-thirds the total length of the pipe run. Stretch it through, tie it off, and let it pop back.

DO however watch for sharp edges on the cut conduit. You'll want to file them down a bit so they don't wear and fray the shock cord.


T2

__________________________________
Todd Terry
Creative Director
Fantastic Plastic Entertainment, Inc.
fantasticplastic.com






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