Kee klamps, and limitations

[mikienorth]

Hello.

I have been asked to come up with a design for a neat camera/followspot platform solution, as cheap as possible. My first idea of decking and legs has been suggested as maybe too high in price, and another idea of building it entirley out of scaffolding bits will be ugly, even if covered.

 

So, I thought of using Kee clamp fixings to build the platform with entirely. Neat, not too expensive, and a really good finish.

 

Can you support a platform on kee clamp joints? They do a stair attachment part, so I almost assume so, but need opinions, mostly based on fact.

 

Weblinks will help.

 

I've been googling for an hour already....

 

Ta

[Peter Tovey]

Simple answer - yes. As with most platforms, the issue is more with stability of the whole structure than any worries about loading on the kee clamp joints. I've certainly seen and constructed many custom bits of deck from a ply top on 4"x2" frame, supported on scaff legs (suitable braced) with kee clamp stair tread couplers bolted through the frame.

 

The couplers are immensley strong in slip when torqued up correctly (39Nm for size 8 clamps on standard 48.3mm OD steel scaff tube to BS 5973). They'll take up to 9kN in slip with a safety factor of 2:1, which is very nearly 1 tonne. And also very nearly as strong as a standard right angle clamp, which when done up correctly has a maximum SWL of 9.4kN for slip along a tube. Don't try torquing up kee clamps onto alloy tube, as it will just deform the tube and you won't get the same strength.

 

It's worth googling under pipe clamp and tube clamp, as many people manufacture and sell them under that name. Kee Klamp is a trade name. But their website does seem to have by far the best info and range of fittings - see http://www.keeklamp.co.uk/Catalog.aspx for the range and plenty of info. http://www.doughty-engineering.co.uk/shop/13/ is also worth a look.

 

Pete

[mikienorth]

So, using things like the cross joiners to insert a platform level isn't dangerous as such?

In the information on one suppliers page, it says not to be used for scaffolding, but on the kee website it shows play structures built out of them.

 

I could effectivley replace all my 90degree scaff joiners with kee fittings of various flavours, and then worry about cross bracing some other way afterwards?

 

Is this right, or, even though it has been done, is it dangerous, or mildly worrying?

 

I'm considering putting a super trouper and a truck driver on these platforms, so they have to be pretty solid, supporting about a tonne would be a fair guess....

[johnhuson]

I'm considering putting a super trouper and a truck driver on these platforms, so they have to be pretty solid, supporting about a tonne would be a fair guess....

 

Wow, how big are your truck drivers! FYI weight of a Super Trouper II with fixture, stand, ballast is about 140Kg.

[Seano]

FYI weight of a Super Trouper II with fixture, stand, ballast is about 140Kg.

 

The same weight as some of the more portly truck drivers then.

 

It seems bizarre to me that you (the OP) can afford a Super Trouper and a truck driver, but not a couple of sheets of Steeldeck. (Or, better, Litedeck) The amount of extra work involved in assembling a bits&bobs scaff platform may turn out not to be trivial. (Financially perhaps, as well as arse-discomfort-ly.)

 

If you're looking at scaff options, it might also be a good idea to look at 'system' scaff, ie: Kwikform, Lahyer or Cuplok. Again neater than tube & clip, but also probably quicker and simpler to erect than Kee Klamp.

[mikienorth]

It's not to tour, it's to stay in a venue, and we are looking at ideas, that, apparently decking is too expensive for. That was my first plan, seriously, why go down any other route if Decking will do it?

 

If people can satisfy me that Kee style solutions are OK to build platforms out of, then the scaff idea, which is cheapest, just got a whole lot neater. Image is everything you see.

 

A Kee system could have sections that stay made (Front, Back, Middle(Where extra legs are)) and a few extra poles to connect it together.

 

We are looking for an 8'x6' area for one spot + operator (truck driver)

 

I had this idea of using Kee because it looks better than scaff bits, and just wondered if it was safe to use as a platform method.

 

Is it?

Would you?

 

I want to but can't find the definitive Yay or Nay on the web....

 

If we go this way I'll get piccies of it for you too...

[Piers Shepperd]

Hi there,

 

I had this idea of using Kee because it looks better than scaff bits, and just wondered if it was safe to use as a platform method.

 

Hard to comment without seeing the finished design. You have described a product but hard for me to say that your use of the product will be safe.

 

Is it?

See above.

 

Would you?

No I wouldn't. Kee Clamp fittings IMHO should be used for handrails, ballustrade, etc etc. I would not use it as the basis for a structural deck.

Its use for playground structures is interesting, but look at the Kee Clamp website, and I don't see any structural platforms supported solely by Kee Clamp fittings.

 

I want to but can't find the definitive Yay or Nay on the web....

You may want to find it on the web, but the fact that you can't find anything definitive should tell you something.

 

I have used many conventional scaffold based systems to make followspot decks etc, but they are always erected by qualified companies, but ultimately I would recommend using one of the many existing stage deck products already suggested (kwikform, layher, steeldeck etc etc) all of which can be easily verified as being suitable to do exactly what you want.

 

You have seen an easy, cheap, and neat solution (by browsing the web), but this doesn't automatically make it a well engineered and ultimately safe solution.

 

note;

People talk about weight to get an order of magnitude for a project - which has happened in this thread - this is good. Remember that the weight of your Super Trouper gets resolved down to four small feet, and these impose a relatively high point load. For this reason alone I would not use Kee Klamp fittings.

You need to ensure that the ply is adequately supported - Steel Deck (only as an example) has very stiff ladder style truss spaced at 600mm centers which is flush to the underside of the ply. I would recommend laying another sheet of 19mm ply on top to ensure that the high point loads from the stand do not cause the ply to deflect (causing the stand to wobble).

 

I think if you went the route of Kee Klamps (which I'm clearly not recommending) you would need to spend alot of time trying to get all of the clamps / tubes / etc etc to be connected in a way which allows the Ply deck to be supported adequately, and ensure the spot didn't wobble.

 

Cheers,

 

Piers

[Peter Tovey]

Remember that the weight of your Super Trouper gets resolved down to four small feet, and these impose a relatively high point load. For this reason alone I would not use Kee Klamp fittings.

 

Agree with much of what you say, but certainly not all. This above is completely irrelevant to the germane issue of whether or not the kee clamps are suitable. Yes, the feet impose high point loads. On the platform. Hence as you say the platform much be suitably constructed. But the clamps attaching the patform to the scaffold substructure, and the clamps within the substructure, see no difference in loading. The platform (assuming rigid, and if it isn't then there's a bigger problem) will present the same loads to the stucture beneath regardless of whether it's loaded with a perfect 2D UDL or a single point load. Of course, different loading conditions mean that one leg may take more load than others (your spot op is standing near one corner), so design for each leg to take worst case scenario load with appropriate safety margin.

 

I think if you went the route of Kee Klamps (which I'm clearly not recommending) you would need to spend alot of time trying to get all of the clamps / tubes / etc etc to be connected in a way which allows the Ply deck to be supported adequately, and ensure the spot didn't wobble.

 

Yes, you would, and yes, it takes longer than with other systems - you need to have the correct selection of clamps, and you need to to cut all your tube to quite tight tolerances to fit. Which is why it's usually only worthwhile for something which must look good and is going to be around a while. Pretty much as the OP describes then...

 

It is worth bearing in mind as Seano points out that the clamps are not cheap - think £5 to £10 apiece for most of the more common designs. So the cost could well end up being comparable if not more to standard decking solutions. Especially once you factor in construction time. But I'd still argue that in the right circumstances (eg custom shaped deck) and given careful design then using kee clamps as structural parts of a platform is perfectly feasible and sensible. It's something I've done and I've overseen others doing on my stage multiple times.

 

Don't use the clamps anywhere they could conceivably be hit while in use, eg by another scaff pipe. Biggest downside is that they're brittle. And if you're not happy designing a safe structure, then don't. Or find someone who is competant to. The concept is possible - as ever the devil is in the detail.

 

PCT (MEng)

[mikienorth]

Thanks Piers.

 

Thanks Peter.

 

just the sort of answers I needed, spot on.

[Ike]

Biggest downside is that they're brittle.

As well as protecting them from direct damage this also means you need to think more carefully about the forces involved than if you were dealing with standard 'tube and clip' stuff. While the slip forces are impressive there are many situations involving excessive torque which would result in a bent bit of tube with a standard double coupler but could concievebly end up with a kee klamp failing catastopicaly. It's probably not however something that can't be overcome with a bit of extra bracing and protecting the legs from overenthusiastic humpers, flightcases etc.

[Piers Shepperd]

Hi there Peter,

 

completely irrelevant to the germane issue of whether or not the kee clamps are suitable

Agreed - but it might be germane to someone who was trying to build a follow spot platform as a general note.

 

I agree that it is possible to build a structurally safe structure solely using Kee Klamps - I however wouldn't.

 

1) The manufacturer clearly states that

Fittings must not be used in Scaffolding

- I think this statement is made because cast iron fittings are brittle?

 

2) In a seperate web page about camera platforms, see this comment about Kee Klamps

Camera Platforms - Don't use Kee Klamps

 

I think this thread gives some very good overall points and agree with you that the

devil is in the detail

 

Cheers,

 

Piers

[Malcolm Gordon]

I think this statement is made because cast iron fittings are brittle?

It might be if they were grey cast iron. However, the manufacturer states that the fittings are made from EN1562 - malleable cast iron and EN1563 - Spheroidal Graphite (SG) cast iron, both extremely tough and behaving more like steel. Malleable and SG irons are also more expensive then grey CI, hence the cost. I haven't managed to break one yet.

 

Key Klamps state that, in the case of most couplings, structures should be considered as pin-jointed, so that cross-bracing in all planes needs to be considered. Calculation of the brace lengths needs a sound grasp of trigonometry. It is worth pointing out that, apart from some more recently introduced "open" couplings, all the couplings needed on a tube have to be slipped on before construction commences and extras cannot be added between couplings afterwards. Experience building onstage structures which have had to be partially dismantled is a salutary reminder.

 

The load capacity of 900kg per grubscrew has already been mentioned. If more is needed, a coupling with two grubscrews can be selected or couplings doubled up. This is for "correctly tightened" grubscrews; tighter does not equal better. Using an over-long Allen key or ratchet wrench it is possible to distort the coupling and/or crack the grubscrew, which is then extremely difficult to remove.

 

Finally, Kee Klamps do provide a design guide for pallet racking, which can involve greater loads than the OP is considering.

[Seano]

I would recommend laying another sheet of 19mm ply on top to ensure that the high point loads from the stand do not cause the ply to deflect (causing the stand to wobble).

 

As mentioned already, not strictly relevant to the kee klamp discussion - but this is serious overkill imo. The feet on a Super Trouper aren't that small, if the spot op sits on a chair (and is the size of the average truck driver) that's probably a more concentrated point load than at the feet of the spot stand.

 

Sean

x

[musht]

Certainly a lot to think about involving kee klamp style structures, much appreciated.

 

For visualising kee klamp structures this might be handy:

 

http://www.simplifiedbuilding.com/sketchup.php

[patrick_keys]

Kee Klamp is certainly strong enough for what you want - we've used it for platforms (albeit of a small height) without any issues. I've even seen it used for tiered seating before, but that's another story.

 

They do have a number of design brochures that discuss maximum loads and torque necessary to tighten the hex grub screws to achieve the rated figures. They're very friendly to talk to (0118 931 1022) - they used to have a design department which might be able to advise further.