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BobL
30th May 2012, 09:56 PM
I've posted some pics and WIP details of my welding bay fume hood over in my shed fitting thread. (http://www.woodworkforums.com/f245/bobls-shed-fit-134670/index19.html#post1497164)

Here Sneak peak picture preview
http://www.woodworkforums.com/attachments/f245/210318d1338381897-bobls-shed-fit-fumehood2.jpg

Dave J
30th May 2012, 11:34 PM
Nice unit Bob, will look forward to your updates.

Dave

Ueee
31st May 2012, 12:29 AM
Good one Bob:2tsup:
I just open the back door.......

BobL
31st May 2012, 07:51 AM
Good one Bob:2tsup:
I just open the back door.......

Living in an inner city neighbourhood on a small block I really have to watch the noise especially at night so I tend to do metal work with the doors and windows closed. Hopefully the fume hood with improve my standard end of the metal working day booger test. We have a fume hood in the welding bay at work at work and I have always been impressed how effective it is even when someone is welding in it all day. The one at work is much bigger ~2 x 2 m and the fans are even bigger but I will try with a bathroom fan extractor for a start and upgrade if needs be. More important as far as other machines are concerned are the sparks and grinding dust that seems to settle everywhere throughout the shed.

Stustoys
31st May 2012, 09:18 AM
Hi Bob,
Looking good so far. If you feel the fan isnt up to it(and I think it might struggle as it is now...... but you never know). Try fitting a sheet over the opening like this. You are then extracting the fumes that were going to escape the hood rather than trying to "empty" the hood completely. Hope that makes sense.

Stuart

BobL
31st May 2012, 09:52 AM
Hi Bob,
Looking good so far. If you feel the fan isnt up to it(and I think it might struggle as it is now...... but you never know). Try fitting a sheet over the opening like this. You are then extracting the fumes that were going to escape the hood rather than trying to "empty" the hood completely. Hope that makes sense.

Stuart

Thanks for the idea.

I just measured the flow rate of the bathroom extractor type fan and it only moves 120 cfm which is almost certainly not going to to be enough. I do have a 1/3rd HP squirrel cage fan which supposedly pulls 1000 cfm (unrestricted, which it effectively it is in this case) which should do the business. I now wish I had measured it first (DANG!) but as I have already made the plenum for the bathroom type fan I will try the bathroom type one first to see what it can do.

Dave J
31st May 2012, 12:23 PM
Hi Bob,
If it's any help we had a IXL tastic light fan combo in the bathroom years a go and after it gave up (around 10 years) we bought another brand which looked good but had nowhere near the exhaust fan movement, so you might find other fans work better.

A mate of mine made a spray booth at home and after looking around he bought some fans from the Hyro place. They had 2 sorts, one style was around 10 inch and real industrial looking and the other was around 12 inch which was a lot larger. The were priced some around $180 and $300, but he had had enough of buying replacement bathroom fans and they never worked great. With these ones in it cleared the over spray in no time and they where guaranteed for something like 5 years.

Dave

Ueee
31st May 2012, 12:26 PM
Hi Bob,
I was going to suggest you use a 12v car thermo fan wired with a pwm controller, but it sounds like you have it sorted. I have 2 10" thermo fans in the roof of my shed, running off 40w solar panels. They remove heaps of hot air in summer, as well as plot of the fumes. If I have a lot of grinding to do I do it in the daytime, I don't want to push my luck with the neighbours.

BobL
1st Jun 2012, 05:16 PM
I have just scored a great little fan that should do the job - it looks like it is a 1/6 HP squirrel cage fan with variable speed control. It's also a fair bit smaller than the 1/3 HP squirrel cage fan unit which is quite bulky

I found this little fan in the to-be-chucked out pile at work. It's been used in an acid purification lab so the fan cowling has some rust and corrosion on the electrical terminals but it Meggers fine and it runs nice and quietly. Should be just right for my purpose.

Graziano
1st Jun 2012, 06:05 PM
It looks very good, on a related note I found welding fumes and rosin flux vapours caused bad sinus headaches which I could relieve with one of those saline nasal sprays from the chemist. When it runs out you mix less than a level teaspoon of salt and a pinch of bicarbonate of soda in a glass of hot water to refill the squirter.

BobL
1st Jun 2012, 11:28 PM
I have just scored a great little fan that should do the job - it looks like it is a 1/6 HP squirrel cage fan with variable speed control. It's also a fair bit smaller than the 1/3 HP squirrel cage fan unit which is quite bulky

I found this little fan in the to-be-chucked out pile at work. It's been used in an acid purification lab so the fan cowling has some rust and corrosion on the electrical terminals but it Meggers fine and it runs nice and quietly. Should be just right for my purpose.

I opened up the fan this evening to see how far the corrosion has got into it. There's a fair bit of black sticky gunk inside it which has a faint acidic smell so I took it apart and washed it out. Theres a bit of surface rust and the galvanised finish is lightly corroded in places. Large Patches of the paint have come off easily which suggests it was painted (probably by someone at work) without using any etch primer.

Unfortunately the label has been painted over but there is enough German embossed into the motor to confirm it is made in Germany. I put an ammeter on it and it is drawing just under 1 A so that makes it ~230W. Air speed wise it's pulling about 600 cfm at high speed and 350 cfm at it's lowest speed and is fairly quiet even on the high speed, much quieter than my old 600 cfm DC. . Should be good enough for what I need it to do.

While it's apart I'll give it a prime and paint to slow down the corrosion. I spent the rest of the evening making a little stand for it to sit on in the fume hood.

Stustoys
2nd Jun 2012, 09:38 AM
Hi Bob,
One thing you might like to check is how hot the motor gets. As strange is it seems they can draw more current in "free air". As the airflow goes down so does the current. So if the fan is design to be part of a system it may have less restriction than it was designed for so run hotter. Yes I know is sounds crazy. Maybe someone else can explain the reason or correct me. I've even come across it on one of the fans I have here. I replaced the motor and left off a piece of sheetmetal that blanked off a couple of inches of the outlet and the motor got hot, replaced the piece and it ran nice and cool.

Stuart

BobL
2nd Jun 2012, 11:25 PM
Hi Bob,
One thing you might like to check is how hot the motor gets. As strange is it seems they can draw more current in "free air". As the airflow goes down so does the current. So if the fan is design to be part of a system it may have less restriction than it was designed for so run hotter. Yes I know is sounds crazy. Maybe someone else can explain the reason or correct me. I've even come across it on one of the fans I have here. I replaced the motor and left off a piece of sheetmetal that blanked off a couple of inches of the outlet and the motor got hot, replaced the piece and it ran nice and cool.

Stuart

Ah ha - that makes sense - the motor is definitely getting quite hot. It is designed to force air through a HEPA filter I will insert a damper and see what happens.

BTW I have done a bit more on the fume hood - if you are interested look here (http://www.woodworkforums.com/f245/bobls-shed-fit-134670/index20.html#post1499026).

BobL
3rd Jun 2012, 12:49 PM
Before inserting the damper I decide to see what happened when it was running at slower speeds. At minimum speed I cannot feel any heat, at about 50% it ran fine and got just a little warm. At full speed it got hot enough to trip out - I'm exploring the region between 50 and 100% to see what an absolute max is.

It looks like the max is 60%, I will now try a damper.

Dave J
3rd Jun 2012, 01:16 PM
Looking good Bob,
I remember 20 odd years ago having what I thought was the flu. I spoke to my grandfather who is a retired boiler maker ship builder and after telling what I had been doing before getting sick, he strait away said you have gal poisoning.:o
He said it was common to give flu like symptoms.

Dave

BobL
3rd Jun 2012, 03:08 PM
One fume I find even more choking than ZnO is burning dichromate paint. My guess is that is one of the Chromium oxides, probably the really nasty hexavalent form. The couple of times I have been hit by this it has fair taken my breath away!

BobL
3rd Jun 2012, 08:45 PM
I added a damper and the fan seems to not cut out when I have it about 25% closed even when running flat out. Down side is it's noisier. I'm now seeking a compromise between damper opening and fan speed.

I also added the first lot of bifold doors.
http://www.woodworkforums.com/attachment.php?attachmentid=210898&stc=1&d=1338723418
These doors cover most of the sides and will be used to reduce spatter and sparks from spraying all over the shed. Sheet metal skirts will be added to bring the doors down to bench top level.

The doors just hang on the hood and can be easily removed or folded back as follows.
http://www.woodworkforums.com/attachment.php?attachmentid=210897&stc=1&d=1338723418

Stustoys
3rd Jun 2012, 08:59 PM
Hi Bob,
Looking great....I really should biuld something like that myself..... but I cant imagine its going to happen anytime soon.

As for yor damper problem, if you add a flat sheet like the one in my earlier post with small gap on the back and sides, a larger gap at the front, that may kill two birds with one stone.(though a damper would be easier if the fan is moving enough air as it is.)

Stuart

Ueee
4th Jun 2012, 09:30 AM
Hi Bob,
I spent some time last night going through your shed thread. Looks great:2tsup: although it could still look a bit more "lived in"! I like the idea of putting the dust collector pipe through the floor, and the mesh rack behind the lathe is great. It is fantastic having a sink in the shed, you probably don't need it over there but the only thing i really need is hot water! When the water coming out of the tap is less than 10 deg it's not too pleasant.
Now go make some mess!

BobL
4th Jun 2012, 09:58 AM
Hi Bob,
I spent some time last night going through your shed thread. Looks great:2tsup: although it could still look a bit more "lived in"! I like the idea of putting the dust collector pipe through the floor, and the mesh rack behind the lathe is great. It is fantastic having a sink in the shed, you probably don't need it over there but the only thing i really need is hot water! When the water coming out of the tap is less than 10 deg it's not too pleasant.
Now go make some mess!

Cheers guys, yeah I am really enjoying fitting this shed out to have some of the things in it that I have always wanted. It would have been easier if the shed was about twice as big but then I would probably only go scrounge up more machinery to fill it up!

Regarding the lived in look, right now I have a more than full time day job so I don't get anywhere near the time in it that I would like to have. That will change in late next Feb when I will be taking a redundancy package from work and plan to have at least a year off before I take on anything new and even then it will only be on a part time basis. My main headache is not letting SWMBO todo list from getting too long. :roll eyes:

Hot water would have been nice but the water never gets too cold here in Perth. What I really would have liked it to get the gas down here for a small furnace. I might still look at doing this next time I (reluctantly) get a plumber in to do another job.

It may not seem like it but I still have a lot of fitting out to do. I need to sort out the lighting, make a new bench for my ww lathe, make another grinder stand for my multitool grinder and make some cupboards for hand tools. Then I need to modify the dust extractor system to fit the refurbished arrangements and about then I might stop and make a few things.

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