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Stage Jacks

Discussion in 'Scenery, Props, and Rigging' started by OldGrover, Nov 12, 2004.

  1. OldGrover

    OldGrover Member

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    The is similar to my platform question over in Carpentry - basically, I'm going to describe how I did something and invite comments and criticism. What I did WORKED, but I wasn't able to find a really good description of stage jacks on the internet... and my books are on order :) (*grumbles* Local bookstores useless)

    Anyways, these were a combination of a request from the TD and my own thought pattern. Tools were a brad nailer firing 1 5/8ths inch 18 ga brads and glue, plus a miter saw, with the joints expected to be primarily held by the glue once it dries.

    For a previous play, I built 4' stage jacks for the 8' flats (so, up to the toggle, though most of our flats are doublesided with 1/4th plywood, except the one I just built, which was done very much like ship's /long/ description in this forum, but faced with 1/4th luan mahogany instead of fabric). For this one, I was asked to build full 8' high jacks, so they could be screwed to the panels at top, toggle and bottom. Fair enough. Also, I was asked to make sure they would not flex vertically and the TD suggested the mechanism I ended up using.

    So, to start, took 2 8' 1x4s, built an L out of them, with glue and brads. I cut the L at both ends to make the total slightly shy of 8' and to ensure a flush fit on the top and bottom (don't want the jack peeking over the flat if the guy who built the flat made it a little low). For the bottom piece, I cut a 1 x 4 to length (I did about 4 1/2 feet) and glued and stapled to the bottom of the vertical piece, flat to the floor. The side of the L obviously gave me more stapling and gluing room. Carpenter's square made sure it was level and a piece of plywood (was actually half inch, because that's what I had) in a triangle made it stay that way, glued and bradded. A small triangle on the other side added strength. That gave the bottom and the vertical, but I needed the diagonal to give it strength. I attached a 45 degree triangle (again half inch ply) on the horizontal, measured from there to where it intersected the vertical. Cut a piece of 1 x 4 to size, attached it to the triangle. With nailgun and level in hand, plumbed again the vertical and attached the diagonal to the brace. Another triangle braced that joint and yet another did the other side at the horizontal joint. Adding a probably extraneous brace from the diagonal down to the horizontal completed the job.

    Picture :

    [​IMG]

    I'm sure there were better ways to do this, but any comments on flaws in this mechanism? Every joint is glued and bradded (though as I say, the brads don't add /strength/, they just hold the joint flush until the glue dries.

    (edited to fix the picture)

    -OG
     
    rgwhite and (deleted member) like this.
  2. avkid

    avkid Not a New User Fight Leukemia

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    there are many kinds of glue available, some stonger than others so stronger joints may have been possible, but overall it looks like a solid plan!
     
  3. OldGrover

    OldGrover Member

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    This was just carpenter's glue. In general, especially with, say, pine 1 x 4's, the wood will break before the glue joint, provided it is properly made. The key is the glue must be a thin layer and that the wood /must/ not have gaps - carpenter's glue does not bridge them. The wood MUST be in contact with each other. If you need to bridge gaps, you need something other then carpenter's glue, like epoxy. That's what the brads do in this system, just hold the wood together until the glue dries. Scews work just as well (and are extra strength, though I wouldn't think I'd need it here) and I'd imagine you could just clamp it, too, though that'd be a pain in the rear and make making this thing take /forever/ :)

    -OG
     
  4. jwl868

    jwl868 Active Member

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    I had a similar problem - I couldn't find any good examples in any books either. We had built a few 8' stage flats and we needed to stand them, But this was only for 1 show. And one rehearsal (but that's a detail, though maybe an important one.) Anyway, we built an "L" from 2x4 with an 8' vertical, and a 4' horizontal, and then used a 6' diagonal brace. The "L" right angle joint was made with two corner blocks, lke yours, but we used drywall screws. We cheated on the diagonal brace by attaching it face to face with the L with drywall screws (rather than cutting an angle joint and using corner blocks.) The 2x4 contruction was selected for weight in the back - I had concerns about the flats tipping forward.

    We also happened to have alot of 2x4s left over that had been used to hold up two massive (to us) 10' x 4' flats that had been constructed out of 2x4s in the first place (live and learn).

    Joe
     
  5. OldGrover

    OldGrover Member

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    We sit sandbags or fly weights on the long end of the jack. It means they are portable when we want them to be and light otherwise.

    And, yeah, the diagonal is on the flat - I didn't cut it, though I could have, just glued and bradded as is, with most of the contact area coming from the L or the triangles.

    -OG
     
  6. ship

    ship Senior Team Emeritus Premium Member

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    Thinking that 2/3 up on a stage brace or stage jack and I think 1/3 tp 1/4 out though I would have to check the last is the norm, in any case, you are text book correct in thinking that the finish nails just hold the corner blocks in place up until the time that the glue holds the diagonal or cross grained 1/4" blocks (Not Luan) in place oficially. A finish nailer at 1.5/8" is a wee bit long for a 1/4 stage jack L-Stiff based operation but what ever works. What in reality also works is using M-Gun 7/16" staples for a minimum of support or drywall screws to supplement the glue joints for strength. (Clout nails being a lost art.)

    So it was “a hard flat on the flat” as normally described when hard flat but with it’s framing members flat to the surface instead of perpendicular to it. Nothing wrong with this method.

    In flex, learn the engineering of the “L-Stiff” construction or two 1x4 pieces formed into a L or T shape for strength when glued and stapled. As strong and more so than a 2x4 given the L-stiff has it’s strength both horizontally and by means of construction also vertically over even that of a 2x4 un-supported.

    Not sure about your 45 degree angles given a height longer than the width, but you have the idea. Normally stage braces will be a “L-Stiff” type construction as you mention but they no matter the thickness of plywood corner block will be using a double corner block on all seams due to the stresses involved. Such blocks especially on the outward side of the brace will be spaced to later fit and properly support a stage weight. Your corner block than is not just a question of thickness, but it’s length will correspond to that of you stage weights in stacking them on both the back and towards the flat bottom edges. Double plywood corner blocks also help support such stage weights. Sand bags can also be used but the double corner block is still also useful in counter acting the ripping apart of the seem from the “live loading” due to the adding of the weight onto it. The bottom of the L-Stiff is also frequently lined with rubber or vinyl matting in preventing it from slipping once the weight is applied to it. No matter how well glued, in later years, this glue in having various moisture differences opposed to shrinkage of the lumber, opposing loadings on the lumber and in general stress against the blocking in forcing the glue to come loose, the staples/brads/screws will still play a factor in keeping the thing together at least one more show, beyond their advantages of keeping it together in general in adding holding power to the seam. Proper glue is necessary, but once you add some oil based fog say to the problem, that glue wears away fast it’s holding power. An alternative to this is in screwing the stage jack directly to the deck. This as opposed to the “tip jack” type of similar support. Just wait until you get your book. What did you buy anyway? "Stock Scenery Construction" I hear is good in addition to "Scenery for the Theater" in it being a Bible, but there are lots of other boods including "Stagecraft Handbook" that are of note on the subject.

    On glue, yes carpenters glue in bonding to the wood is often stronger, but it’s also given proper coverage and thickness. A 1/4" bead of glue ain’t what Norm would do. When possible watch him for ideas as he is still the god of all carpenters. In your reply, you already know this - kudos.

    You and your TD have quite the future together in recommending and doing good and better work as opposed to hack - this is how we do it and it has always worked in the past.

    You buy the Senco brand trigger - not slam fire, Medium Crown "M-Gun" 7/16" staple gun. Have the theater buy you some 7/8", 1.1/4" and 2" staples for it if not some 1/2" staples if you can find them, it's going to be well worth the effort. Also buy a valve assembly for it so you can adjust to line air pressure - it ain't going to work the same as the finish nailer and you no doubt will need either more volume in at least air hose size in the case of hang fires or less volume in regulating it downward in the case of multiple fires. Once you have such a gun you won't turn back from it in any construction. The brad nailer is useful but nowhere near the M-Gun for scenery. Later comes the narrow crown gun, but for now the M-Gun. Also given a lack of oiler in-line assembly, buy a canister of pneumatic tool oil and put two to three drips into the tool after each day of use to maintain any of your pneumatic tools.
     
  7. OldGrover

    OldGrover Member

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    Thanks for the comments, ship. I sort of eyeballed the height to width ratio, ignorance again, but felt that given the vertical board being stiffened (as an L) provided I supported at least half way up it'd be fine. I ended up going up about 4 1/2 feet, out about 4 1/2 feet (hence the 45) but may well use a steeper angle next time.

    I'll have to look at what weights we have and how I can support them - mostly it is sand, but I know we have some fly weights somewhere. Unfortunately, at no theatre that we have access to can we scew directly to the deck. How I wish I could scew to the deck. *snickers* In the current show (at the dollar store, as I mentioned) the deck is tile. Heh. While I've got all the tools for screwing through that, (ie, tile cutting bit, hammer drill, tapcons), I doubt the people donating the space would appreciate it.

    Yes, the flats are hard flats on the flat. We do those (rather then the 'hollywood' style) because we have very limited storage space (not currently having a theatre of our own). We can store three flat flats in the space of one hollywood, and that's significant to us.

    When you say double corner block, you mean one corner block on each side? That's what I did, though with the L-stiff construction (whee, I learned a word) the far side joint where the bottom meets the vertical, the second corner joint doesn't properly overlap, is merely glued flush and bradded through the corner of the angle. If the glue fails, those particular brads aren't going to hold, though unless oil or something degrades the glue, there's no reason it should fail.

    I used the 1 5/8ths (as long as my little combo narrow stapler/brad nailer shoots) because I'm shooting always into the thick edges of the 1 x 4s, never into the flat. Figured since I had the length, I might as well use it.

    I picked up the stage rigging handbook (or will when it gets here) and one other whose name escapes me at the moment. Heh. Something else about stages :)

    -OG
     
  8. ship

    ship Senior Team Emeritus Premium Member

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    Re-read because I edited it while you replied.

    Yep, the hard flat on the flat in needing less space to store, not to mention not as opposed to soft flat needing much corner blocking often is a advantage.

    In any case “L-Stiff” or “Wailer” are local terms but the two main terms for this type of construction. Ah’ corner meets overlap.... ??? Read the book, I’m sure we are on the same subject however. Having worked a few shows where the even wood glue could not hold up to a good Taste of Chicago type grease flying out of a grill, much less rain, I know wood glue is useful but at some point it’s still is all that is holding the seam together. Them little creeks in the brace as you move it about and hit a doorway with it or in someone leaning against the wall are tell tail of not just the lumber but the glue cracking loose from a seam. I stress on those creeks and other movements, much less the shrinking of the lumber in factors in why this thing even if glued won’t stay as such 5 or 10 years from now at best.

    Your brace also shows more width than necessary and less height than normal but what will no doubt work anyway given the hard flat and L-Stiff. The stage brace in your 90 degree angle corner seems to be screwed to the hard flat in overlap. This is a no-no in a stage brace as a individual component in that it won’t than support intermittent seams as a stock universal part.

    Still on vinyl tiles when you can’t screw to the deck (LOL), the vinyl or rubber cladding under the bottom of the jack is all that is needed once weighted. Also if I remember right you knock off a 45 degree from all outside corners and make the thing even if full length 1" shorter.

    No matter the case, what you are doing is safe, and what fun you seem to be having!
     

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