The happy coincidence of a family gathering means I am thinking of going to the London MEE at the Alexandra Palace this year. I went to Sandown park the other week and noticed that someone was selling very cheap sealed lead-acid batteries. I rather stupidly didn't buy one and wondered if anyone here happened to notice the name of the vendor and/or have any ideqa whether they are attending the Exhibition at the end of this week ?
Also thinking of buiying some kind of propane torch for general model-engineering use (heat treatment, brazing etc and probably eventually including boilermaking) and wondered if anyone here had any advice on what to look for ? I have seen references to Sievert gear being of good quality and wondered what the chances are of picking some up cheaply at the same place ? Any tips as to useful stalls to visit for this ? Also what is the best torch to buy for general Model Engineering purposes (I know it's something of an open question but just need general advice on what to look for) ?
There aren't many choices when it comes to propane gas burners, and I think you're more likely to find Sievert than you are any other brand
- so it's just as well that it's top-notch kit. Other brands are Bullfinch ( thought not seen any of their kit around for a while ) and Rothenberg ( or Rothenburg, Rotherberger...) - who used to make some very posh kit indeed. The 'Cyclone' guns are particularly useful for pipework.
Only experience will suggest which setup best suits your needs - but your basic kit should consist of a gun, a pressure reducing/safety valve ( shuts off the gas in the event of a hose breach...very important bit of kit, this ) and a few nozzles....plus a bottle of propane. If you're feeling flush get a dual output valve, which allows for a second tool to be connected. It's only a few quid more than the single variant, and having the option of two guns is always useful.
It's the nozzles where there's the most choice - but unless you're going to be doing very fine soft solder work I'd recommend you start with a medium one ( mine's about 15mm. dia across the top ). For brazing etc. you'll need a substantially larger nozzle ( 25mm dia upwards ). If you're buying used kit, budget for new hoses.
If you can find a choice of guns, go for one with a heavy handle - I find these balance in the hand much better than light ones.
Bullfinch is available from adams gas (.co.uk) I think they do Sievert as well. I bought a Bullfinch handle and a couple of nozzles which Adam's delivered in double quick time from internet order (they also do "quick connects" making it easy to change devices on the regulator). I can't help thinking though, where all the money is when you lay it out on the bench!
I can relate to that! Tell you what though...if you ever experience a hose burst you'll thank your lucky stars you forked out.
My first one was in a basement workshop one Sunday in Winter. I had the calor gas fire on, and was busy working away at my bench, when there was an enormous bang! My colleague's gas torch hose had burst, and with no safety valve on the bottle there was gas blasting out of the hose....some 10 feet or so from the gas fire. I leapt over to the hose and wrapped my hand round the breach, whilst desperately trying to both turn off of the fire and blow the thing out at the same time.
By the time I extinguished the gas fire and turned the torch bottle off I had a very nasty freeze burn on my hand.
I *made* him buy a safety valve.
I like the sound of those quick connects....I'll have a mosey at the site, thanks for the tipoff.
Although nowhere near the quality of the Sievert kit I've got a couple of gas torches that I bought from machine mart. For under £25 you get a regulator, hose, torch and three different sized nozzles. It depends how much you'll use it, but for my occasional use it works OK, and was definately value for money. Go for the larger sizes (15, 40,
50mm nozzles), I started with the smaller one and it was too small for silver soldering anything but the smallest jobs -so I bought the large ones as well.
How much of an issue it is very much depends on the circumstances when/if the hose fails. If it bursts on a Saturday morning while you're sitting there wondering whether to tidy up the workshop or just move things around a bit, it'll probably just make you jump. By the time you've sussed out what's happened the breach will have pumped out a fair quantity of propane into your workshop...but provided you turn the bottle off pretty smartish and ventilate the place there won't be too much harm done.
If it bursts on a Saturday afternoon while you're halfway through a brazing job, it'll make you jump. The burner flame will probably go out ( no gas ), but the job will be red hot and sparking...and there'll be lots of propane flying around. Two things will immediately spring to mind - one is that you're standing next to a busted hose that's spewing out propane. The other is that you're standing next to a piece of red hot metal. Life typically becomes quite frantic at this point.
If it bursts around Saturday tea-time, when you've nipped indoors for a cuppa and a sticky bun, the propane will leak out of the breach and, as the gas is heavier than air, sink to floor level. Neat propane gas is pretty dangerous stuff...highly flammable...but a mix of propane and air in certain proportions is a very much more dangerous affair. On your return to the workshop you might be lucky enough to hear any remaining gas hissing out of the hose...in which case all you'd need to be able to do is recognise what the sound meant and take the appropriate action. If you're not so lucky you might enter the workshop and cause, by some means...perhaps turning a light on or off, a spark. Life typically becomes a bit brief at this point.
So...in the first instance you might get away with slightly soiled underwear ( it really makes a hell of a bang when the hose bursts ). In the second instance you'll still have the soiled undies, and third degree burns too. In the third instance you'll also have soiled undies...but it will be a few days before anyone finds them some 30 or so yards away from the wreckage of the workshop.
Honestly..for the sake of what they cost, and what they do, don't take the risk. I was lucky with my first hose breach, and simply inconvenienced with my second. That £25 outfit might be OK...as long as the regulator contains a shut-off valve...in which case, it's a bargain.
Just a point, but instance one shouldn't really happen because if you aren't using a gas torch it should be turned off -at the bottle. I know I'm in the habbit of always doing that, perhaps because I use cheap gas torches without auto cut-offs -but I thought it was just good practice. I think I got into the habit from my father always insisting on turning the gas off at the bottle on the camping stove when we were on holiday when I was a kid.
I'm curious though, why would a hose burst? Surely if you are using the correct regulator with a correctly rated hose the only reason for failure would be using a damaged hose (or an old, perished hose). Perhaps anyone who has experienced, first hand, a burst hose could share the exact circumstances and cause with us -I'm always keen to hear about safety issues and, more importantly, know how to avoid them!
Just to add a bit of context to this debate, the Sievert hose failure regulator currently costs £24.60, but the Sievert demonstrator at the Ally Pally didn't have any with him at the show. The Sievert starter kit currently costs about £109 , consisting of, I think, a handle and neck, a hose, a simple regulator and nozzles in three different sizes.
How much do you value your safety? --
Chris Edwards (in deepest Dorset) ..."There must be an easier way...!"
I agree that turning the gas off at the bottle when not actually using the torch is a sensible move - but more often than not 'using' ends up as being defined as the time you start thinking about doing a torch job, to the time you finish putting the final touches to it. I use various gas tools throughout the day, so the bottle goes on first thing and gets turned off last thing. As pointed out in another post in this thread, the Sievert safety valve is about £25 - and given that you'll one need buy it the once it just seems like a good way to protect yourself when you're actually using the torch...or when you've plain forgotten to turn the bottle off as per Sod's Law.
The most common cause for hose bursts is the age of the hose. By their very nature the hoses are flexible, and where there's flexibility there's stress and strain. Ideally the hose should be replaced every so often ( though I guess this depends on usage patterns ).
Another common cause is damage to the hose. This typically comes through the hose being trampled underfoot, and from spillage of hot materials from the job in hand. In the former case it's obviously impossible to see any damage. You might tread on a hose a hundred times and not have a problem, or you might step on it just the once...
The least common cause is just plain failure - but in these cases you're often given some warning by the formation of a visible bulge in the hose. This happens when the interior lining fails ( there are usually three layers to a hose; the inner, a woven reinforcing layer and the exterior ).
In both the failures that happened to me, the hoses blew at a point roughly halfway along their length.
As it happens...I was just making a brew and I remembered that I kept the last hose that blew ( gawd knows why! ). Here's an interesting thing... there's a 3/4 inch split in the hose outer sheath about midway along the hose. At one end of the hose ( hard to tell whether it was the bottle or the torch end ) there's a split in the inner core. Blowing down this end whilst blocking up the other end shows no leaks at all. What it looks like to me is that the inner core has failed at one end of the hose and allowed gas to flow down the hose through the woven reinforcing - thus blowing open the exterior lining. Presumably the reason I can't detect a leak through blowing is that I can't generate sufficient pressure to force air along the reinforcing layer. I can't see any particular damage to the exterior at the point of the breach ( there are other points on the exterior that have very visible nicks and scratches ).
Well, thanks all for the answers. I found the battery supplier at Ally Pally (WCN Supplies). Picked up a 40Ah sealed LA battery for the miserly sum of £16, paid for the entrance fee anyway :-) I didn't see any specially good prices for torches though so I may try eBay of the homeworkshop.org.uk site.
I thought the show was pretty good btw, and certainly a lot better supported than Sandown Park a few weeks ago. It's still nothing like the glory days of the eighties though when there were model planes and cars in abundance as well as the other stuff. Anyone else remember watching the electric round-the-pole at Ally Pally in around '82 or '83 ?
Actually not a patch on Rex Hays' diesel-powered slot racers on a huge track at the Horticultural Halls around 1952! Never heard of an electric aeroplane in those days.
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