Ye Olde Forge

[Parm]

Just to chip in, clean rooms are very different, but biological safety rooms are always under negative pressure. For example with a biological safety room where they may for example might handle anthrax, its under negative pressure. If there is an escape the dangerous stuff stays in the room instead of being spread everywhere if it were under positive pressure

 

[Screwdriver]

Doh. Got my wires crossed. It's the suits of course which are positive pressure.

Sorry, too busy having a rant...

 

[gaz1]

Do you have any experience in room ventilation or are you just reiterating something Parm said? This lean-to shed is not hermetically sealed, I see no problem with having a fresh air inlet. I am not entirely sure "rooms are always negative pressure" is true either. You wouldn't want to do that in an aircraft for example, or a clean room, or a biological facility etc.

There are exactly as many holes as required thank you. Not too many. Too many for what anyway? "The others wont get air" suggests you havent read my post. Thats a simple vent, not a flue, not a chimney and they won't have a fan attached at this stage though I might fit eight fans one for each If plan A doesnt work.

yes i do ive worked with air ducts and heating ducts, ive also added secondary air to my rocket stove that also uses a venturi effect works rather well

A venturi would be uneccesarily noisy. I am planning for large volume low speed air flow, hence my constant reference to "wafting" air out of the space. My only slight concern is superhot fumes from the forge possibly containing combustion byproducts from contaminated metal. That should go straight up to the hood anyway, encouraged by having a fan blowing from the other end of the room and otherwise it goes out the double doors.

You keep going on about "side blowers" and "<my> problem is a side blow" but I have never even mentioned having one or planning on having one. I don't know where you get that from.

On the other hand it occurs to me that having an outlet vent at one end of a funnel (where all the heat is) and a cold air inlet at the other end is the ideal scenario for expelling heated noxious fumes. I might not even need a fan at all.

a side venturi would allow you to have the unit outside but the push of air down the tube would pull air from inside of the unit without the use of a chimney something you said you didnt want also to note theres no chance of the heat effecting the fan when the air is being blown down the tube to the opposite end and expelling down the tube at side of your shed

There are four square cut outs so that I can happily start burning off paint in the forge. They can easily be shut off with a simple flap or flaps, maybe a sliding gate if I feel like it. It might get soil pipe ducting because I happen to have a few lengths of soil pipe. If I had a ton of spiral wrap ventilation, I'd use that. The holes are positioned and spaced such that I can fit whatever type of outlet happens to be flavour of the month on a removable panel.

Anyhow, this is all supposed to be a bit of fun and (as I said above) an experiment. Part of the challenge is not merely making it work but making it from found materials, recycling scrap and learning how things work along the way.

all parts can be freely gotten and made up to fit what your after

as you can see with this video this is venturi with secondary air input

 

[mrsbruce]

You could always set up a smoke test, just to see whether it will work. I’m thinking of those smoke bomb test things that the chimney folk use.
Or just set fire to something, and fling some wet leaves on it.

 

[angellonewolf]

^^^^^ or let me come over and do some welding there's normally a fire or two involved in that

 

[Screwdriver]

^^^^^ or let me come over and do some welding there's normally a fire or two involved in that

This is actually a very pertinent comment. I recently have had a number of incidents in my main shed, stupidly firing up a stick welder among the disaster zone I laughingly refer to as a workshop. Luckily I only set fire to my leg and not the piles of dirty rags and bottles of fuel haphazardly scattered around the place.

This is a dedicated space I can deliberately try to keep fire resistant. As much as is possible for a wooden hut with a brick wall and a concrete bench at the hot end. I may even clad the walls with metal sheet. Don't know yet, I am as surprised as anyone as to what happens next. That's why I build stuff which keeps my options open. The vents in the hood can (and will) be reconfigured by simply fitting a panel over the current gaps with whatever solution I discover works best for me.

I am stuck in this rut so have "nothing" to do currently except potter about in the shed(s). You're welcome to come over and have a go at welding, forging or play wth the flypress. Anyone is. Just ask...

 

[angellonewolf]

I am stuck in this rut so have "nothing" to do currently except potter about in the shed(s). You're welcome to come over and have a go at welding, forging or play wth the flypress. Anyone is. Just ask...

would be great some time but your a way from me but if i get over that way and your free would be good

 

[Gritineye]

Interesting to watch your progress, especially at minimal cost..

As someone who has had a lot to do with inglenook fireplaces and hoods to prevent them filling the rooms with smoke, may I suggest that if you're hoping to 'waft' fumes out, and hoping they will stay inside the hood as it is now is rather ambitious.

I think it would need quite a draw to achieve that.

I would suggest making the hood project at least twice as far out from the wall than it is now and a couple of feet longer with ends that hang down a foot or so.

A simple baffle board spaced 4"off the outside of your vents might help prevent backdraughts.

 

[Screwdriver]

Interesting to watch your progress, especially at minimal cost..

As someone who has had a lot to do with inglenook fireplaces and hoods to prevent them filling the rooms with smoke, may I suggest that if you're hoping to 'waft' fumes out, and hoping they will stay inside the hood as it is now is rather ambitious.

I think it would need quite a draw to achieve that.

I would suggest making the hood project at least twice as far out from the wall than it is now and a couple of feet longer with ends that hang down a foot or so.

A simple baffle board spaced 4"off the outside of your vents might help prevent backdraughts.

Yes, unfortunately I think that's about right. But I can't extend the hood for the simple reason the ceiling height is too low and it's right next to a door. Where it is now is about as close to headbanging height as I can get. It can't project into the room any further either for the same reason.

The baffle board is an interesting concept and one which I may have inadvertently "designed" in already. I have installed a ground level six foot tall baffle board which the vent will be firing right into. I call it the baffle fence.

All the hood needs to do is to give superheated fumes from the forge somewhere to go without heading straight for the wooden ceiling. The forge itself is right underneath it so whatever vents I go for should allow some of the heat/fumes to escape. It is right next to a double door too so I am not too worried about filling the forge with fumes.

There shouldn't be any smoke at all so my ambition is to mimic say the ventilation you might need in your kitchen. The hood is not dissimilar to a regular kitchen extractor so as I said before, it might get one of those one day. In all honesty, if I had managed to find a kitchen extractor, I would probably have shoved one of those in there to try first.

I could fit a ducted fan into the hood but I don't want too much noise right next to where the cameras will be going. It will be bad enough with the forge. So I would have to mount the fan much further away and fit ducting. That's too much to take on currently as I have a fair few other things I really need to be getting on with. I thought it might be fun to have EIGHT of those little bathroom fans sucking air out from inside some short lengths of soil pipe. BU I need to try one or two first see how it goes.

That's what this is supposed to show:

The whole lot is mounted on a board which is retrofitted under the hood, complete with whatever fan or vent design seems to work. Meantime I might just chop a hole on the other side of the shed and blow air in. Now I appreciate there's a LOT more to industrial ventilation systems than meets the eye but I really just need to get something in there that allows me to fire up the forge without the risk of suffocation or breathing in toxic fumes. It won't be perfect but I suggest it is better than nothing.

 

[Gritineye]

Just an example of how tricky fume extraction can be.

Some time ago I made this 'extraction' system from old bathroom extractor parts, in line fan, for those rare times when I use cutting oil or fluid.

The idea was to catch fumes before they could fill the shed on there way out the fanlight, which they rarely did as it faces the prevailing wind. The ducting ends in another shed that in theory, due to the wind, should be a slightly lower pressure area.

The business end moves with the carriage, at first it was just the end of the flex pipe, this was spectacularly feeble in it's waftyness and was pretty well useless cos hot chips got thrown in and added melted plastic to the fumes!

I then stuck the down pipe reducer on the end, ever so slightly more efficient cos it could be closer to the work, but really not worth the bother, possibly due to the flex pipe convolutions.

A proper extractor fan would just suck all the heat out so ain't gonna happen...

 

[slim_boy_fat]

∆∆. I'm clearly not as careful as some (most?) folk, given that I have no extraction when I'm working other than welding, and that's because I have to do that outside

 

[Gritineye]

∆∆. I'm clearly not as careful as some (most?) folk, given that I have no extraction when I'm working other than welding, and that's because I have to do that outside

Years of that sort of abuse have left me with a very sensitive nose, throat and sinus problems, be aware!

 

[Screwdriver]

Just an example of how tricky fume extraction can be.

Some time ago I made this 'extraction' system from old bathroom extractor parts, in line fan, for those rare times when I use cutting oil or fluid.

The idea was to catch fumes before they could fill the shed on there way out the fanlight, which they rarely did as it faces the prevailing wind. The ducting ends in another shed that in theory, due to the wind, should be a slightly lower pressure area.

The business end moves with the carriage, at first it was just the end of the flex pipe, this was spectacularly feeble in it's waftyness and was pretty well useless cos hot chips got thrown in and added melted plastic to the fumes!

I then stuck the down pipe reducer on the end, ever so slightly more efficient cos it could be closer to the work, but really not worth the bother, possibly due to the flex pipe convolutions.

A proper extractor fan would just suck all the heat out so ain't gonna happen...

View attachment 150662 View attachment 150663

Yes that's why I am "aiming" at a high volume low speed "waft" rather than the high speed concentrated airflow you would need for dense smoke extraction. For the lathe I have found just sticking a Dyson vacuum next to the tool helps. The forge itself merely burns propane and the byproduct is relatively harmless. It's just water and carbon dioxide BUT as I said above I have been lazily burning off paint from an old truck spring and that will produce toxic fumes (I assume!).

Even then, so long as I am not standing right over the forge breathing in the superhot gasses, they will dilute in the atmosphere. I just need to make sure there's enough clean air coming in (open the doors) or have a vent on the other side of the room. Rather than just rely on convection to create a sufficient pull to expel any fumes, I am going to try blowing in some fresh air. I appreciate that sucking those fumes out efficiently (and quietly) would be a lot more tricky and require some careful thought before I splurge out any money on a solution.

The funnel shape for this space is in itself a very interesting situation. The funnel stem is at the cold end and all the heat at the mouth. The walls flare out and the roof rises appreciably. My seat of the pants assessment is that hot air is not going to easily find its way back down a narrowing funnel and may tend to persist at the wide end for a number of reasons. Soon find out and due the the excitement this simple addition to the forge has caused, I will make smoke in there and see where it goes. I'll even video it...

 

[Welderpaul]

Chaps - 2 pages of unnecessary comments removed.

Please can you keep your postings within the good spirit of the forum and avoid any more nastiness to your fellow metal botherers.

Thanks

 

[tom-madbiker]

Love it was thinking of a similar forge thing but I was going to use waste engine oil to fire it as I have lots stored for just such a eventuality heating metal with propane is too expensive for me

 

[vbottles]

In my previous shed I regularly ran a propane forge. The main issue when starting to use the forge was working out how much carbon monoxide it would produce depending on the burner set up. I bought a couple of CO detectors.
First one was a straight alarm that would go off at about 75ppm. I then used a detector that gave a read out as well as an alarm at around 300PPM from memory. Be very aware of head aches using a propane forge as these are signs of CO poisoning which can take days to reduce. So going outside for ten minutes for a smoke to feel better than going back in could be very unhealthy.
I tried different extractors to remove the heat and fumes. An old kitchen extractor worked ok as did a lab fume extractor. Both would cut out after a time due to heat cut off switches in the motors.
In the end I basically would open the garage doors and have a fan blowing at the end of the room, blowing out the door.
The forge I mainly used was air blown and used for making Damascus so did get quite hot.
Andrew

 

[Screwdriver]

Love it was thinking of a similar forge thing but I was going to use waste engine oil to fire it as I have lots stored for just such a eventuality heating metal with propane is too expensive for me

Yes I would like eventually to move to either coal or some cheaper fuel but without a chimney, I can't do that yet. I don't know how much gas I am using, I sincerely doubt I will get through a whole bottle in a year, depends how much work gets put through there.

At the moment I am dithering between building a tong/hammer rack or an anvil stand. I might go do this later.

The floor is a decent level surface but being pavers, I don't think a large flat bottomed stand is sensible. Bound to be something sticking up for the anvil to wobble on. I quite like the idea of an all steel tripod but since I am raising the anvil height to a generous 820-840mm, I would need too wide a base (for a tripod). Need to see if I have enough 4x4 fenceposts left (I built the forge out of them!) but I have got a few scraps of railway sleepers.

 

[Screwdriver]

In the end I basically would open the garage doors and have a fan blowing at the end of the room, blowing out the door.

OMG. Don't even suggest it! You'll have the internet police after you.

(That's what I am doing but for goodness sake don't tell anyone.)

 

[Rob85]

Glad the thread is reopened, I'm loving the build, the furthest I've got with anything like this is building a wee anvil to mess around with...small railroad anvil with a hardox plate on top, planning on welding in offcuts etc into the sides to build up mass under the middle and grinding to shape but for general playing around I think it will be more than enough for me.

 

[Screwdriver]

Glad the thread is reopened, I'm loving the build, the furthest I've got with anything like this is building a wee anvil to mess around with...small railroad anvil with a hardox plate on top, planning on welding in offcuts etc into the sides to build up mass under the middle and grinding to shape but for general playing around I think it will be more than enough for me.

Thanks. I would say mine was a medium size anvil at 77KLG (!) even so it is an amazingly handy thing to have around for any sort of metalwork. Better than banging on a bench anyway with more flat surface than any (sensible) bench vice. Even the post leg vice has proved its worth by being so heavy, you can virtually treat it like an anvil too.