Hi there,

Not a very much used part of the message board it seems here, but seems most appropriate for my question...

I finally have a great space to use as my own stop motion workshop/studio, hooray!
I have done some ball and socket armature making while I was at University and had access over a metal workshop with brazing and welding equipment and all that. I want to set up my new space so I can do silver soldering, perhaps even a little brazing sometimes...

My workshop will be in an attic. There is a window I can open, there are also two holes in a wall where simple vents are fitted now. I will be insulating this wall as it is just a bare brick wall but am thinking to use the holes and build some sort of extraction for fumes of silver soldering, and possibly also a little spraybooth... I've been looking online what diy methods people use for extraction systems and found al sorts of different solutions, some using bathroom fans, computer fans, those big fans you use to cool a room, etc... just not sure what will be the best to use.

Can anyone help me with this? I am looking probably at two extraction set ups, one for silver soldering, and one built in into a spraybooth... Wondering what are affordable options.

Or do you all have small torches and the fumes aren't much of a problem? I used to work with big oxy-acetylene torches, which were used for brazing as well and definitely needed extraction. I've also done a bit of silver soldering just with a fire brick on a pile of boxes inside a studio with not much ventilation... worked out ok but probably not good idea for long term use.

Would appreciate any thoughts, thanks!


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Litres per minute, perhaps?!

Complicateder and complicateder.. 

Roos I reckon you need something with more power than the little soldering fans. Something like this:


It is rated at 1200 cubic metres/hour, which is 20 CM/minute. Compare this to the first one in your list at 1 CM/min.

or this, which is even more powerful at 4200 CM/hour:


Avoid the 110V models on eBay!

I would attach ducting to the back and then fix that to the wall/holey bricks. The article about adapting a tabletop extractor used styrofoam to fill in around the ducting. Might not be such a good choice for hot fumes! Aluminium sheet or plywood would be much better.

I reckon a single extractor like this should be fine for spray painting and soldering. It is not as if you are doing massive quantities of spraying. And you could build a temporary surround from cardboard and polythene if needed.


You mentioned a window you can open. I wonder if you could build a small platform that hooks onto the window, with a fan off to one side blowing on a lower setting  toward it.

If you could get the platform to be hanging outside, like a window sill bird feeder, that would be ideal. (Pretend the chain is not attached to the glass in this illustration and the window is open).
That way, any fumes would already be outside and if they wanted to come in, the fan would prevent that from happening. Not sure how big of a platform you would need, but if the window wasn't too small this could work. To keep the platform from accidentally being burned, you can cover it in aluminum foil. You might even be able to hang the platform from inside the window, if the fumes weren't too bad.  That's one idea.

Another idea would be to place your work desk under the window with a box fan at the back of it, blowing out.

The fumes would be sucked out of the room as soon as they were created, and you would have no further problems.

Best of luck!

Thanks a lot for all the thoughts. I tried looking for the CFM or any equivalent for the small fans, I found something on an American website, can't find it now but it was something like 38cfm or so, Right, yeah indeed, you mention it already, those fans go up to 4200cfm, that's a huge difference. So would I need that much air sucking power? If I'm only soldering small steel balls on small rods I suppose it will be a bit overkill. But I do want to build more armatures from scratch. There will be some bigger parts. Although I don't have a massive torch at the moment either. But will have to try out what I need. It'd be a good for all sorts of fumes probably, from spraymount to mixing and casting resins if I'd get to doing stuff like that... And spraypainting indeed.. the only thing I read often in tutorials where people build their own spraybooths is that they use certain filters and stuff to avoid the paint getting into the ventilator and messing things up...

Strider, there is a window, but as it's in an attic it is on the diagonal ceiling/wall. I have to stand on a chair to open it. It would be easier then to just do the work outside in the garden/yard. But I've tried silver soldering once outside and it was a nightmare. You can't see the flame of the torch properly in the direct sunlight and the wind causes all sorts of problems.

Anyway, there are holes in the brick wall in the attic with little vents in front of it at the moment. So that's perfect to lead ducting from an extractor to I imagine.

Right, so the bigger extractors are obviously a lot more expensive, but there seem to be some listings on Ebay at least under a hundred pounds. As we're talking about reducing health risks perhaps not something to go too cheap on. If I get my set up ready I'd hope to be making a lot of armatures eventually... :) 

Below in the picture where you see the workbench I built, you can two little white vents, that's where the holes are.
Also been preparing a basic animation stage and unit on wheels for the laptop screen while animating. Yay! starts looking like a workshop/studio. :)

Oh yeah, that's looking like a great workshop space now!! Nice sturdy tables. I especially like the design of the animation table, where the only supports are at the corners - leaves room for more tie-down holes! 

I like Simon's idea of just getting one powerful extractor fan and using it for a spraybooth and for brazing, but I would keep this in mind - I've seen a lot of complaints from people about having to work on things inside a booth where it's hard to get good lighting and you have limited arm movement etc. I personally haven't used a booth so have no experience with that but I can imagine it can be frustrating. One thing I really like about the Xytronic is that it's small and portable - when I'm ready to braze I just pull it up close enough to catch the fumes. The only problem I've had is that once I wasn't paying enough attention and started to melt the front of it by aiming the torch directly at it - oops!!! But if I were going to use the same motor for a spraybooth and for brazing I'd try to work out a design where there's a hose you can place close to your work area so you don't need to use the torch inside the booth. And probably some kind of metal housing at the end of the hose (so you can't melt it!) Or maybe the booth itself could be removed when you don't need it. But I'd want the mobility to  place the extractor unit where you're comfortable working, rather than having to stretch out and work where it is. 

Personally since I don't do much brazing I'm happy with the extractor, but if I were planning to do a lot then I'd want to look into it further. But I do recommend, whatever solution you opt for, do the candle test so you'll know exactly how close you need to be to your extraction unit while working. Once you've seen how powerfully it sucks the fumes out it gives you a sense of satisfaction and security. I don't imagine that using a pinpoint flame to braze small armature pieces together makes much more fumes than blowing out a candle does. Though it sounds like you might be planning to do some larger scale brazing as well. If that's the case then you're outside the range of what I know about. 

Another thought - if you do plan to go for a more powerful unit check on the oven rangetop blowers and clothes dryer fans to see what kind of CMH they pull - they might be as powerful as the specialty units and probably less expensive. 

Thanks! All mostly made out of scrap wood. It's not very visible on these images but I used a perforated metal sheet as the top, so I can experiment with both magnets and tiedowns. And already have a lot of holes, so when I make a ground surface I'll try to keep it flat and thin so I can still poke through to get to the holes, or use magnets...

Yeah I reckon I wouldn't build a booth permanently around it, but maybe have some box I can attach when I do want to. Otherwise spraying is easier to do outside than silver soldering! Those more powerful extractors still look reasonably small and portable...Maybe I could mount it above the work area. Ideally still so that it's easy to move around. I remember the extraction in the metal centre at university had the hose made so that you could position it closer and further away from above if that makes sense. But that was a nice and expensive system of course. ;)

I reckon your extractor is fine for doing little bits indeed. Are you mostly brazing the steel balls onto rods? I think a lot of what I will be doing will be small scale. but a bit bigger then only steel balls onto rods (well, and maybe sometimes a big steel ball onto a big rod :P). Hmm... I want to get something that will do the job properly but it would be silly to overkill. I've done it at both extremes: an oxy-acytylene set up with big torches and big extraction systems on steel work surfaces in a metal workshop and a tiny torch you'd use as a kitchen torch, on a fire brick on top of a few plastic boxes in a not particularly well ventilated studio with no extraction. :P Not sure what's the best middle way. ;)

Yeah, the real question is - how much ventilation is required? That's the part I really don't know, and if I were planning to do a lot of brazing like you are, unless I could find out for sure, then I'd want to err on the side of too much rather than too little. 

You mentioned the ventilation units at school hanging above the worktable - one thing I thought about was just buying a complete rangetop fan setup with hood, and you could attach some sheet aluminum to the sides of it to make it into a booth. I thought maybe you could just stick your head in under the hood while brazing (without the booth sides in place, they could go on with duct tape or something) - but then I realized your head being inside there pretty much negates the benefits of having ventilation at all. And that's the beauty of the small extractor units - you get them in close enough so they suck up the fumes before they can get to you, right next to where you're working. Like those vacuum hose attachments on the sides of some table saws or belt sanders. What might be ideal (or overkill) would be a rangetop hood above your table and a small portable extractor as well. 

But I think you already understand all this - I think I'm overtalking it.  

Oh, to answer your question - I've done more than just brazing balls onto rods - I've also made pieces very much like the one you're working on in one of those pics, with the square tubing and the thumb nuts brazed on for making aerial braces, as well as brazing pieces of steel plate together and short rods onto plate to make chest and pelvis pieces. But I use a propane torch and then got myself a small Mapp gas torch which looks the same - a handheld canister that the torch head screws onto, so I'm working with flames not much bigger than a candle flame. But I've only done it occasionally, not often at all.

Actually, I still don't really understand the difference between silver soldering and brazing, but if brazing is done using big oxy acetaline torches and rod rather than wire, then I guess what I've done is technically silver soldering. Just to correct my last post.  

Right, found this video, should explain the difference between silver soldering and brazing.


Basically I thought Silver soldering is always brazing, but apparently you can also do it at a lower temperature. Soldering is at a lower temperature. But silver brazing is often called silver soldering which makes it more confusing. I'm pretty sure I've been silver 'brazing' then as I remember it had to be around 600C* http://www.lucasmilhaupt.com/en-US/brazingfundamentals/properbrazin...

But as far as I remember what I used was called 'silver SOLDER' with easy flo silver SOLDER flux. :S and that worked, different than this guy in the video explains. I'm confused as well now.

No you don't need the big oxy acytylene torches, but that was what was available at the metal centre I had access over at the time I made Moonbird's armature. They were for brazing and a lot of people would braze bigger stuff. They also had heavy duty welding equipment and stuff. They had a few small dremel torches which I tried to use as well, but for some bigger parts, maybe just because I was setting it up the wrong way and a lot of heat was absorbed rather than bounced back, I couldn't get what I was brazing heated up enough.

So yeah, I'm actually not sure now what will be needed. Maybe I should actually have a go once trying to silver solder/braze something with the window open and see how much smoke and fumes it causes... I bought a torch quite a while back which I haven't actually had a chance to use yet, and for some reason I can't get it to work... grr! :( I can't even remember if I did get it to work when I bought it. I was going to try using it outside in the garden then, but I had to move house again before I had properly set up anything.. It is the Rothenberger with multigas 300...
It's supposed to get hot enough at least for silver brazing, the flame would be a bit bigger then a candle flame, but not as big as the oxy acytylene torch.

I don't really know either how much ventilation is required. Maybe time to find some brazing experts to talk to...

Ah ok, I know what you're talking about with the high and low temp silver soldering - and the low temp isn't strong enough for armature work. I also know that at hardware stores that carry equipment for this, the low temp silver solder stuff is in the soldering section, and the high temp stuff is with the welding supplies. So I guess that is what's considered brazing. Maybe you had the wrong flux before? Or maybe some fluxes can be used for both? 


How could I forget - I have The Complete Metalsmith sitting right next to me on my bookshelf??! It says in Brazing "the parts being joined are heated to near their melting point and a non-ferrous metal like brass or silver alloy is introduced and drawn into the joint by capillary action. The dividing line between soldering and brazing is 800 degrees f (430 celsius)". It also says "what jewelers call silver soldering is properly called silver brazing"

So blame the confusion on those jewelers!! 

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