norty303 Posted August 12, 2007 Share Posted August 12, 2007 I'm wondering whether these are generally interchangeable in use? As far as I can see the scaff swivel couplers are not so easy to use on short jobs by virtue of them having nuts rather than wingnuts, and they're cast unlike the regular swivel couplers and most importantly about 1/8th of the price. So is there a catch or why shouldn't I buy scaff couplers? Link to comment Share on other sites More sharing options...
Modge Posted August 12, 2007 Share Posted August 12, 2007 Steel scaff couplers do ali truss no favours - they dig into it and dent it. Using couplers on steel is fine as far as I know but a waste of expensive couplers. Link to comment Share on other sites More sharing options...
indyld Posted August 13, 2007 Share Posted August 13, 2007 Steel scaff couplers do ali truss no favours - they dig into it and dent it. Using couplers on steel is fine as far as I know but a waste of expensive couplers. Expanding this point, the reason that pressed steel scaff couplers dig into truss is that steel pipe is 48mm whereas truss and ali pipe is usually 50mm. This is why Aliscaff and other couplers are recommended for the job. The pressed steel ones have a claw that digs into 50mm truss like teeth. Although you can now get 50mm pressed steel clamps, they still mark the pipe. Most lighting hire and rigging co's will hit the roof if you use 48m clamps on their (very expensive) truss systems. Aliscaff clamps actually ship with both wingnuts and regular ones, for the user to choose which to use. Which nut is better is a whole debate in itself. Best Wishes Link to comment Share on other sites More sharing options...
Dave Posted August 13, 2007 Share Posted August 13, 2007 Expanding this point, the reason that pressed steel scaff couplers dig into truss is that steel pipe is 48mm whereas truss and ali pipe is usually 50mm.Not quite, I'm afraid. I can categorically say that aluminium scaff tube is 48mm. To be precise, it's 1 29/32" x 7 gauge wall thickness (I've ordered enough of it from aluminium stockholders so I should know). I make the od as 48.41875mm, but for some reason it's normally given as 48.3mm - no idea why. However, just to confuse matters, Thomas Par bars are made from 50mm tube, but other IWBs normally use scaff and are 48mm. Truss is indeed made from 50mm/2" tube. Link to comment Share on other sites More sharing options...
PoppaDom Posted August 14, 2007 Share Posted August 14, 2007 Aliscaff clamps actually ship with both wingnuts and regular ones, for the user to choose which to use. Which nut is better is a whole debate in itself. Now I always thought the 2 nuts shipped like that to enable you to lock the primary nut off with the wingnut. Thats the way I have always used them and seen them used. Poppadom Link to comment Share on other sites More sharing options...
Jivemaster Posted August 14, 2007 Share Posted August 14, 2007 Pressed steel scaf clamps are very narrow where they actually grip the tube and if applied to the wrong size tube will crush the tube wall and ruin the section. - Expect a Loss or Damage claim from the hirer or a LOLER FAIL for a piece of your own truss. It is important to chosa the right size and spec clamp to maintain the rating and truss condition. Link to comment Share on other sites More sharing options...
ianl Posted August 14, 2007 Share Posted August 14, 2007 I can categorically say that aluminium scaff tube is 48mm. To be precise, it's 1 29/32" x 7 gauge wall thickness (I've ordered enough of it from aluminium stockholders so I should know). I make the od as 48.41875mm, but for some reason it's normally given as 48.3mm - no idea why. in an ideal world maybe, but my stock of "aliscaf" includes quite a lot of 50mm tube (purchased from a well known lighting company) as well as 48mm incidentally you can get converter clamps designed to attach 50mm aluminium scaf towers to 48mm steel scafold Link to comment Share on other sites More sharing options...
indyld Posted August 15, 2007 Share Posted August 15, 2007 Aliscaff clamps actually ship with both wingnuts and regular ones, for the user to choose which to use. Which nut is better is a whole debate in itself. Now I always thought the 2 nuts shipped like that to enable you to lock the primary nut off with the wingnut. Thats the way I have always used them and seen them used. Poppadom I believe that's what yer spanner's for. I have also seen them used like that but.... Link to comment Share on other sites More sharing options...
adamharman Posted August 27, 2007 Share Posted August 27, 2007 Not quite, I'm afraid. I can categorically say that aluminium scaff tube is 48mm. To be precise, it's 1 29/32" x 7 gauge wall thickness (I've ordered enough of it from aluminium stockholders so I should know). I make the od as 48.41875mm, but for some reason it's normally given as 48.3mm - no idea why. The original spec for steel scaffold tube was that for 1.5" nominal bore steel pressure pipe, which has an outside diameter of 1.9" (48.26mm), hence 48.3mm being stated as a standard size. I've seen both ali and steel tube in a variety of sizes from 47.6mm (1 7/8) up to 51mm (2"). They'll make it to whatever size somebody wants if they order enough of it. Your average scaffolder isn't qualified to calculate what the scaffold will take. They just know that BS1139 says that standard parts can be used up to certain maximum limits, so they all use standard size tube, etc and stay within those limits. Truss will have been designed by an angineer, who probably worked out that the extra 1.7mm diameter increased the cost by 5% and the strength by 10% (that's a guess, not a calculation!) so it was worth doing. I suspect that a lot of ali lighting bar is single tubes from the same suppliers as the truss...... Link to comment Share on other sites More sharing options...
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