Question for PL Riggers...

[dsli_jon]

Hey Kats -

..And now for something completely-different...

Backstory: Have a new show-project, for a long-time Client, that has significantly changed their venue-layout - Going from the 'classic arena' layout - where the stage / show-action was located at the one-end of the arena, and we had, for 6-years running, shot a customized graphics-based show, from an area behind the stage, thru a large scrim, filling the arena, thereby soliciting wild cheers and applause... and no, it wasn't 'audience-scanned', etc...

..Last year, this changed to, a 'Center-arena stage', with a large box-truss lighting / FP video 'cube', build 'around' the scoreboard, overhead... Which, in of itself, is no real 'worry' - already have an 'inner-core ring-scrim' design, all worked out - to be flown in / out, via 6-motors / top-pipe, etc - all worked-out, nice and buttoned-up..

...But the Client is objecting to our initial-proposal that the 4-banger Full Color 'Projector-cluster', center-mounted (from below the scoreboard..) simply *stay* 'dropped' in-position, during the 'sessions', and we only fly in/out the scrim-rig, for just the laser-shows - which are only ~4-5 min, at the beginning of each daily session... (..ya know, typical 'rah-rah' opener...) Even-though the 4-RGBs 'cluster' will be relatively small, especially compared to the 'cube' overhead, the Client still wants it 'raised' / out of the way, visually, after each show... (at least up to the trim-line of the moving-heads / etc, around the base of the truss-cube..)

..Now, I've come up with this bit of a 'solution'...



..Question is: What sort of DMX-controlled 'winches' or motors, can anyone suggest, that can 'pull-up' - at about a 45˚ or-so - on a well-designed, low-friction pivot-joint, as-shown - about 150-180 lbs? I am 'estimating', since the 'mount', shown here, is still 'concept-stage', so, don't know the total weight.. The 4x RGBs are seen in the 'comp', each are about 30 lbs... there will also be a 'signal / power snake' running down / zip-tied to the drop-post, so, adding a tiny bit of weight...

I've found these: http://www.wahlberg.dk/Products/Moti...%2cProductName - which look very-nice / well-designed, and certainly have the 'fine-control' we'll need, here (at least on the top-stop point...) - but, they state: 'only up to ~110#'...and... they're a pretty-penny! I mean, if we end-up using this, as we are proposing, for another 6-yrs.. then, no-worries on 'ROI', but, I guess what I am looking for is if any you Rig-Pros, here, can suggest something else, and/or any 'known' solutions / products...

I suppose another approach is to 'solid-works-model' the mount, and better-estimate the final weight, and then have someone build-something.. but with the 16-bit DMX-control and all machining / couplers / cable / other materials, etc - Wahlberg's unit is prolly a pretty-good price, in the end.. ..but, it seems like this will be too-much weight for that unit, even at a 45˚...

Would also be open to other 'completely different' suggestions, too.. Plenty of better brains than mine, here in PL...
Oh, and uh, Yes - Client has already considered / shot-down the idea of simply raising / lowering the *scoreboard*.. too slow, too noisy, too costly (xtra-labor from the house...) etc, etc - not an 'option', thanks anyway...

So, let the darts fly...

cheers..
J

[buffo]

Hey Jon;

I'm not a professional rigger, but I've done more than my share of rigging here at the plant nonetheless. I can offer two suggestions:

1) if you are 100% sold on the idea of purchasing a commercial winch that already has DMX capability built-in, and you are only concerned with the weight limit, then just use multiple pulleys to increase the mechanical advantage of your winch. IE: if your rig weighs in at 180 pounds, but the winch only lifts 100 pounds, then mount a movable pulley on the rig and anchor the bitter end of the cable to the winch support structure. The winch can now lift twice the weight, but at half the speed. You can continue to add movable pulleys to increase the advantage even more if you need to.

2) if you don't mind a little do-it-yourself assembly, then simply purchase a standard commercial winch that already has the proper weight rating for your rig, and then add a DMX controller to it. This will involve replacing the "up" and "down" switches on the winch with relays that can be triggered by the output of a DMX receiver board, but I'm sure you can handle the wiring yourself.

Finally, a cautionary reminder: Based on the geometry of your diagram, the winch will be pulling at a 45 degree angle at the start. That means that when the rig is in the fully-raised position, the cable will be nearly horizontal. This is not an ideal solution, since as the cable angle decreases towards zero (horizontal) the tension on the cable will increase dramatically. This effectively reduces the lifting capacity of the winch. It would be better to position the winch such that when the rig is in the fully horizontal position (that is, stowed), the winch is directly above the connection point on the rig so the lifting cable is nearly vertical.

Adam

[dsli_jon]

Hey Adam -

It would be better...the winch is directly above the connection point on the rig so the lifting cable is nearly vertical.

Thanks, all good-points... I had-thought about the 'DIY' solution, but, finding a commercial-winch that is not 'overkill' is also a factor, here - need the thing to have bear-like power, but gazelle-like control, as-to post-shutoff 'travel' - can't have either too-much 'drift' nor a 'jarring' stop - most commercial winches could 'care-less' about finesse.. So, yes, I'll keep 'digging', but also looking for possible PL 'field-experience'...

Also, a challenge is there's not much 'meat' (..nor loads of 'wherever-I-want to put-something' vertical-space, above the center-point...) on the scoreboard base -



...so, therein lies the challenge for 'pullyed / outrigger' designs, ya know? But, thanks for the 'food for thought'... I'll give it another bake, later-on...

Thx again...
j

[Jem]

Hi Jon

What about something like this...

http://www.alibaba.com/product-gs/49...ing_mount.html

Looks like this one will only handle 40kg, but i'm sure i've seen similar ones with much better load capacity.

Have a scroll down the screen to see better pictures

[ShortyInCanada]

Not that I have any experience but I'm thinking that you might be overlooking a simple method.
Instead of mounting all the projectors to a single mount I was thinking that you mount each to it's own upside down "L" shaped mount with a pivot point in the bend of the "L".
Try drawing an upside down right angle or "L". Put your projector at the bottom, mark the angle point as your pivot, and think about applying force to the end of the top leg of the angle to swing the bottom up. Change the distance out from the pivot to change the speed at which the motion happens. It requires more force the closer to the pivot point you get while moving faster. Farther away required less force and makes for a slower and more controlled movement.
This would allow for multiple smaller lifting devices. If using a single winch, you could tie the cables from each together and with simple pulleys mount the winch just about anywhere to do the pulling.
Or you could put smaller winch units in and lift each individually. Or in pairs.
There would also be the ability to make the legs holding the projectors as long as you want or even adjustable for other applications. (Maybe another event you can "lift" your units up from the floor behind an obstacle to make projections then slip it back down out of sight when other lights are on.)
With the weight of only one projector on each the assemblies could be fairly lightweight too.
I could see this sort of assembly being used in many types of applications.
Then again, you could also use threaded rod and simple motor assemblies to make movements too. Much slower but very good for fine control of the movements and ending positions.

Maybe this can help you or even get you thinking about other methods you hadn't considered.
Just my thoughts.
Now I think I should get back to work...

[dsli_jon]

Hey Gents -

Great thoughts, but again - look at my 'playing field' a bit closer...



..this has got to be a clean, neat, 100% no-fail *proven* solution - simple, on-off, done... if the thing glitches, and does not fold-up or somehow get's stuck? - we've just ground to a halt, a live convention with over 6k people attending / paying attention... and there ain't no 'cutting to a commercial'... that silence / subsequent 'booing' would be the most awful torture one could endure, never-mind the destroyed show-contract / relationship, etc.. So, Thankums, sincerely, but... this needs suggestions bourne of *experience*...

@ Jem - 'Like the 'scissor-lifts' - if they are not boku-bux, I suppose we could 'gang' 4 of em, and wire from the same buss... Hmm... worth a think, anyway... Thanks...

j

[GT500]

Hi Jon,

This is the type of thing you need

http://www.desisti.it/download/Data%...TA%20SHEET.pdf

Could be a $$$ investment though as rigging is not cheap or i could lend you a couple of chain winches we used to haul this lot up last night... only joking cables will be the only option for a smooth lift of your prized RGB's...

[Doc]

Hey Jon;

I'm not a professional rigger, but I've done more than my share of rigging here at the plant nonetheless. I can offer two suggestions:

1) if you are 100% sold on the idea of purchasing a commercial winch that already has DMX capability built-in, and you are only concerned with the weight limit, then just use multiple pulleys to increase the mechanical advantage of your winch. IE: if your rig weighs in at 180 pounds, but the winch only lifts 100 pounds, then mount a movable pulley on the rig and anchor the bitter end of the cable to the winch support structure. The winch can now lift twice the weight, but at half the speed. You can continue to add movable pulleys to increase the advantage even more if you need to.

This was the first thing to pop into my head, it's exactly what you do when speccing a crane lift: more pulley reeves = more line pull; loop the cable through a single pulley at the load end and you have double the pull.

I would also add gusset plates to the radial arms.

[loopee]

Hey Jon

Looking at that photo of the “Playing field” you seem to have a convenient slot to have the projector fold up neatly into (as long as it’s big enough of cause) but you’d need to change your design to something similar to this



As for raising and lowering it, why don't you get a high quality geared motor and used a Variable Speed Drive (VSD) and use DMX to control the VSD, this way you can utilise the soft start (or ramp up/down) feature and use limit switches to stop it

Cheers
Troy

[WookieBoy]

Hi Jon.

Do the projectors absolutely have to be in a 'cluster'? If not, why not build a second smaller box of astrolite or thomas 12" truss on 4 motors around the scoreboard and hang a projector on each side of the box firing across to your scrims? That way you can fly it completely out to the roof when it's not being used and it might also be useful for lighting or pyro or whatever to hang extra stuff on if things change in the furture... four high speed pro-star or liftket 1/4 tonne motors would do the job really well and move the trusses pretty rapidly up and down. (it's what I used to do for the cage on WWE shows when they came over here.)
If I remember rightly, the liftkets are even available with a slow start/stop mode on the fast ones to keep everything smooth and not give the bounce you get on cheaper 'pro' event hoists. This won't be a cheap option, but it would be a 'proper' option and would keep the very strict HSE happy over here.

In my experience, DMX controlled motors of any sort aren't reliable at all. Even Bandit Lites' Motor-Data system, which has it's own computer control that you program and trigger from DMX, doesn't always hit it's mark. The only system that seems to work 'most of the time' is Kinesys and that'll cost you a fortune! Unfortunately, the most reliable and cost effective method of flying stuff in and out is still the go/stop button and the mark-1 eyeball...

Also remember that if you have something like your drawing made. you should always have a secondary means of securing the load after the joint, whether it's a wire or whatever, so it doesn't drop out the sky if the hinge joint breaks for whatever reason.

On a final note, I'd just like to point out that although they might look tempting from a budget point of view, I'd be VERY wary of any rigging or lifting gear sourced from China that you're not totally happy to inspect and certify yourself. You mentioned that reliability was a must have and in my experience, a lot of Chinese gear has quite low quality control. This isn't always a problem if you know how to take it apart and put it back together again properly, but if a lift fails 'catastrophically' all your expensive gear (plus a large lump of steel) could come crashing to the deck...
I only mention this because a friend of mine bought a batch of Chinese rigging shackles because they were under half the price of the locally produced ones. He wasn't worried about the quality too much because he said "How wrong can they get casting a lump of steel?" Turns out the answer was VERY. In the end the whole batch was scrapped and he had to buy the local more expensive ones anyway...

Food for thought maybe?

If you want some professional rigging advice, I'd recommend you call Atlanta Rigging and ask to speak to Scotty... There's not much he doesn't know about rigging from what I hear and arena temporary and permanent rigging was his speciality when I saw him last (which was a few years ago to be sure)

Anyway,

Hope that's helpful and not too much doom and gloom!