Astro_Al Posted November 4, 2008 Share Posted November 4, 2008 Howdo folks. I thought I'd ask here as you guys often point out something silly I have missed! I need a large flat-surfaced steel worktable. I'm thinking between 2mx3m and 2.5m x 3.5m, so pretty big. I need it to be reliably flat (though not necessarily 'ground-flat' accurate). Plus I want to be able to clamp things anywhere on the table, not just near the edges. Talking with a blacksmith friend, he suggested I line up a whole lot of I-beams (on top of a sub-frame) with a gap in-between the beams just large enough to take a T-slot clamp foot (as per milling machine bed, for example). I could then use any of the off-the-shelf machine tool clamping tools available. Sounds like a good idea to me. Thinking around that idea, I thought why not have a lower frame of I-beams, with strips of steel 'flat' across (say, 1/2" thick by about 15cm wide). That'd cut down on the number of I-beams needed. I would weld in a small spacer to lift the 'flats' above the I-beams so that the clamp-feet could slide past. So, advantages / disadvantages of either? Flatness differences? (I think some I beams are flat, and some are 'crowned / domed' on the upper surface???) Anyone know where I can get a lot of the necessary materials, still clean, cheap? (Had to ask). Any other ideas? I need to sort this pretty quick. Let me pre-empt some irrelevancies and save us all the time: 1. Yes, it needs to be that big. 2. Yes, it has a lot of steel in and is therefore going to cost a fair chunk of cash. 3. Yes, the features of heavy-weight, flat-surface and clamp-able-anywhere are required and non-negotiable. Cheers for any thoughts. Al. Quote Link to comment Share on other sites More sharing options...
FridgeFreezer Posted November 4, 2008 Share Posted November 4, 2008 If you're talking 1/2" thick it'll be fairly flat of its own accord, why not just drill a series of holes in a bit of plate and stand it on some legs? If it's too weak for what you're doing (building a supertanker perhaps) you could always put some strengthening ribs or beams underneath. Most I-beams I've seen are not "square" I shaped, rather the edges taper out slightly so that could cause problems Quote Link to comment Share on other sites More sharing options...
zim Posted November 4, 2008 Share Posted November 4, 2008 If you're talking 1/2" thick it'll be fairly flat of its own accord, why not just drill a series of holes in a bit of plate and stand it on some legs? If it's too weak for what you're doing (building a supertanker perhaps) you could always put some strengthening ribs or beams underneath.Most I-beams I've seen are not "square" I shaped, rather the edges taper out slightly so that could cause problems our welder has a 3m x 3m bench, made from 1 1/2" steel plate it's a dream to work on, because nothing moves and you can weld big stuff to it, to keep it flat whilst welding sadly i cannot afford to do the same in my workshop G Quote Link to comment Share on other sites More sharing options...
Les Henson Posted November 4, 2008 Share Posted November 4, 2008 How securely do you need to clamp anything to it? If you want an unbroken flat steel surface, then electro-magnetic clamps would be ideal. Steel erectors use such things (110v though), and they are very powerful - I hung on one once and it didn't budge. Les. Quote Link to comment Share on other sites More sharing options...
dollythelw Posted November 4, 2008 Share Posted November 4, 2008 have a look at goindustry Al and look for a bench - going to be cheaper I would have thought Quote Link to comment Share on other sites More sharing options...
steve_d Posted November 4, 2008 Share Posted November 4, 2008 If you're talking 1/2" thick it'll be fairly flat of its own accord, why not just drill a series of holes in a bit of plate and stand it on some legs? If you tapped the holes then a selection of stud lengths would deal with a variety of workpiece heights as well as not having to crawl underneath to insert bolts. Steve Quote Link to comment Share on other sites More sharing options...
steve b Posted November 4, 2008 Share Posted November 4, 2008 Hi Al, One of the places I contract weld at has a large -4m x 1.25m cast iron machine table c/w tee slots and machined cast iron flatness , not sure what it was part of originally maybe a large shaper?....it's super heavy though cheapest and easiest would be a bit of 20mm plate and then make clamping to suit the work on blocks/heavy box which can be welded to the plate and ground off when finished. cheers Steveb Quote Link to comment Share on other sites More sharing options...
bishbosh Posted November 4, 2008 Share Posted November 4, 2008 Most I-beams I've seen are not "square" I shaped, rather the edges taper out slightly so that could cause problems These are joists Fridge and usually have a 5 degree taper to the flanges. If you want parallel flanges you want universal beams (UB), columns (UC) or channels (PFC) Quote Link to comment Share on other sites More sharing options...
roguevogue Posted November 4, 2008 Share Posted November 4, 2008 These are joists Fridge and usually have a 5 degree taper to the flanges.If you want parallel flanges you want universal beams (UB), columns (UC) or channels (PFC) Thank god Charles, I was starting to think I would have to explain. Quote Link to comment Share on other sites More sharing options...
Astro_Al Posted November 4, 2008 Author Share Posted November 4, 2008 Ta for the thoughts. John - I'm not sure you can rely on plate being flat. Also I don't fancy drilling all those holes! Thanks for all the reports of the fantastic welding tables out there. They sound great... I was trying to avoid welding / grinding off fixtures if possible. Steved - no crawling necessary, just screw a threaded rod into a foot, and slide in the side of the slot, holding the bar from above the table. Thanks Bish, I was actually looking at universal beams / columns - they have a more suitable aspect ratio than I-beams. Cheers, Al. Quote Link to comment Share on other sites More sharing options...
simonr Posted November 5, 2008 Share Posted November 5, 2008 If you buy plate from a laser cutter - it tends both to be good quality steel and unusually flat. It has to be to cut it as the distance from the cutting head to the material needs to stay pretty constant. You could also get them to cut a selection of slots in useful places at the same time. To level, what about drilling & tapping holes along the length of each I beam and use bolts & lock nuts as screw jacks? Quote Link to comment Share on other sites More sharing options...
FridgeFreezer Posted November 5, 2008 Share Posted November 5, 2008 John - I'm not sure you can rely on plate being flat. Also I don't fancy drilling all those holes! Two questions: - Are you after / do you really need an "engineeringly flat" table, or just a normally flat one? - Is a thick steel plate going to be any less accurate than a load of beams? Quote Link to comment Share on other sites More sharing options...
Milemarker Type S Posted November 5, 2008 Share Posted November 5, 2008 Would you not be better to have a look around for one being disposed of from an engineering works? It would save an awful lot of building effort. There must be an autioneers or similar that specialises in disposal of such equipment? Quote Link to comment Share on other sites More sharing options...
Astro_Al Posted November 5, 2008 Author Share Posted November 5, 2008 Thanks again all. I have had my eye open for a few months on surface tables etc. I don't mind putting some effort into building this thing - the chief challenge being dealing with the weight when it is near completion. The problems with the surface tables I have seen is that the dimensions are usually not what I need and they don't provide quick and easy clamping anywhere except at the edges. John - I need it to be reliably flat, so that things made on it will be known to sit correctly on a flat surface, but as said above, an 'engineering flat' table (like a ground/machined surface plate) is overkill. However, a top sheet with a gentle curve in would not be good enough. Simon - I was thinking of using scaffolding screw jacks, or maybe acro-props for the legs to give some levelling (unless someone wants to come up with a self-levelling hydro solution?). I figured if the steel stock used to build it was known to be flat, then the structure / surface itself should come out pretty consistent. The beauty of the universal beam or sliced-up-plate method is that the slots are provided automatically. Anyone know the flattest 'type' of steel stock? Hot rolled plate? Cheers, Al. Quote Link to comment Share on other sites More sharing options...
dollythelw Posted November 5, 2008 Share Posted November 5, 2008 There must be an autioneers or similar that specialises in disposal of such equipment? yep - as posted earlier, GoIndustry, all sorts of toys - sort of fab ebay if you want some plate sourced and cut to shape Al let me know - as long as its 150mm thick or less Quote Link to comment Share on other sites More sharing options...
Superpants Posted November 5, 2008 Share Posted November 5, 2008 I've seen a fab table in the US that had a grid of square holes about 25mm square on a grid of about 100mm in a plate about 40mm thick. There were then clamps that sat into the holes and locked in (something like carver clamps). I'll have to have a dig and see if I can find out who made it (was a commercial bit of kit). Quote Link to comment Share on other sites More sharing options...
Astro_Al Posted November 5, 2008 Author Share Posted November 5, 2008 Yeah, they are called 'Acorn' tables or something like that. Nice... Cheers Jez. I'd forgotten about that site. I may well be in touch about having a plate lasered... If I go 6" thick, this thing is going to sink through the concrete floor! Al Quote Link to comment Share on other sites More sharing options...
Superpants Posted November 5, 2008 Share Posted November 5, 2008 Acorn is what I was thinking of- Nice bits of kit, but they are definately pricy! Quote Link to comment Share on other sites More sharing options...
secondjeremy Posted November 5, 2008 Share Posted November 5, 2008 Large scrapyard at Northam Southampton (Princes Street) used to keep things like beams etc with a view to re-sale. I don't know if they still do it - I think its now called EMR (European Metal Recovery, used to be Cohen then Speppard as in Fat Freddy, former chairman of Newcastle) - tel 023 80336288. Quote Link to comment Share on other sites More sharing options...
bishbosh Posted December 2, 2008 Share Posted December 2, 2008 In anticipation of the arrival of my new fabrication table I am looking into ways of clamping things to it away from the edge. I have several welding magnets but want something that will really hold something firm. Is this kind if thing any good? Is 60kg enough? The cost of the 100kg one seems disproportionate? I don't mind drilling a couple of holes at strategic spots so I am also trying to find the vice grips that have a leg that goes through the table if you know what I mean? Any other ideas? Quote Link to comment Share on other sites More sharing options...
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