New workshop time (nearly there...)

Sporky

Slight change in plan - the Alfa doesn't have an invertible motor so there'd be a huge S-loop of duct to get to the top of the cyclone, which means excessive losses. There's a Record Power/Startrite that looks promising:

http://www.recordpower.co.uk/assets/products/product_images/prod_000379_asset_0_1336648504.jpg

And plenty of 205-litre steel drums on eBay that'll make decent drop-boxes for the cyclone, for about £35-40.

I did some ducting design today, and found some ultra-low-loss flexible duct too which'll help with corners. Still looking at £760 of duct and adaptors and splitters and so on. Ouchies.

Sporky

And today I paid the second installment on the building itself.

That's the most money I've ever spent on something that isn't a car or a house.

Groundswork chap is starting next week, then the concrete pile foundations go in week of the 21st and the building from the 28th.

Sporky

Is anyone interested in the ducting design?

WezV

Sporky said:

Is anyone interested in the ducting design?

yes, i need to re-do mine at some point

Sporky

Okey coke then. Also this reminds me I need to photograph the old extractor, chop saw and pillar drill and put them up for sale...

So. Ducting. Three main aims:

1) Stop machines from clogging - particularly the planer/thicknesser, because any chips left in the machine get embedded into the wood leaving little dents.
2) Keep the workshop clean without lots of sweeping and vacuuming.
3) Keep the air clean.

To do (1) you need lots and lots of air moving very quickly, which is about the extractor and the ducting design. To do (2) you need efficient collection at the tools themselves. To do (3) you need (1) and (2) and good filters. Most extractors let anyhting under 3u through - the most damaging stuff is 1u-3u, so the extractor will be fitted with a HEPA mesh/paper filter and the felt bag filter will be chucked. The other way to improve filtering is to have a cyclonic separator (Dyson got his vacuum cleaner idea from these) that means no chips and very little dust even makes it to the extractor.

The workshop will also have an air cleaner, but this is for between sessions. Ideally it won't be doing a lot of work.

Sporky

On the ducting itself there are a whole load of resources on the inferweb and a very good book from Fine Woodworking.

There are three important factors:

1) Extraction capacity in m3/h - cubic metres per hour (or cubic feet per minute if you're American) - how much air the extractor can move.
2) Air flow speed in m/s - how fast the air is moving - derived from (1) and the duct cross sectional area, in metres per second
3) Static pressure in Pascals (or millimetres of water) - how hard the extractor can suck - this varies with how fast the air is moving.

So (1) is down to the extractor. (2) is down to the extractor and ducting, and is fairly easy to get right. (3) is down to the extractor and the ducting, and is harder to get right because most extractor manufacturers quote capacity at zero pressure and pressure at zero airflow, neither of which is terribly useful. The really good stuff has a graph like this:

http://www.leader-group.eu/upload/medias/graph_amca_240_500x300.jpg

Basic rules of thumb:

1) The duct should get bigger as it gets closer to the extractor
2) Vertical duct needs the air to move at at least 20m/s so that chips are carried with it and don't settle
3) Horizontal duct needs the air to move at at least 15m/s for the same reason
4) Bends should be as gradual as possible so as not to reduce static pressure
5) Ducting should be rigid as much as possible so as not to reduce static pressure (no flexible hose in corners)
6) Where the duct splits it should do so at an angle, not at a T-junction
7) When the duct splits it should be smaller on the side away from the extractor to maintain air speed
8) Any inlet not in use should be shut with a blast gate or similar.

Sporky

Generally accepted practice is that the last vertical run to the extractor or cyclone must be at least 6" (150mm) to keep static pressure loss low. Combine that with the need for 20m/s air speed and various online calculators will be happy to tell you that you need about 1300m3/h from your extractor.

GIven that the extraction capacity will drop as the static pressure increases (because there will have to be bends and branches and suchlike) I've gone for an extractor that'll do three times that. Factor of safety, right? Right.

This is a branch-on-reducer - the inlet is smaller than the outlet, and the branch to the machine is at 45 degrees to keep air flow high:

http://www.ducting-online.co.uk/Files/104457/Img/14/CTV45-100on.jpg

Keeping things simple the main duct will be 150mm. The extractor will go in the front corner of the workshop furthest from the door. Along the front wall will be the pillar drill, bandsaw, and a connection point for the tablesaw and thickness planer to use. Heading towards the back wall will be the wood CNC machine, then the bench which'll have a port for sanders and a router table, then the lathe, then finally on the left wall a port for the chopsaw.

So the 150mm main duct gets split into two 150mm runs - these will all be short enough that I don't need to reduce the diameter here. A branch-on-reducer will provide a 100mm port to the pillar drill (for a hood-type collector or some semi-rigid hose), continuing as 125mm to the next branch-on reducer that has a 100mm port for the tablesaw and planer/thicknesser. Final 100mm run goes to the bandsaw which has two 100mm ports - the last bit from the wall to those ports will be semi-rigid duct rather than trying to fit rigid which would have tighter bends.

The second run is 150mm to the CNC machine, then branch-on-reducer for a 100mm port and a 125mm run onwards, 'round the corner to the lathe which'll have a hood on a stand on 100mm flexible hose as it'll need to move around for different jobs. Finally that last 100mm run goes around the corner  to the chopsaw, which has something ridiculous like a 37mm port; I'll probably use the lathe hood as well.

I've drawn all of this up in CAD so I can measure runs, so the next stage is to calculate the static pressure loss and make sure it's not ridiculous. The extractor should be so massively overspecced that it doesn't matter. If there's one thing better than engineering it's over-engineering.

Roland

Sporky said:

I've drawn all of this up in CAD so I can measure runs, so the next stage is to calculate the static pressure loss and make sure it's not ridiculous. 

Surely the next stage is to post a picture for us to make inane comments about?

Sporky

Roland said:

Surely the next stage is to post a picture for us to make inane comments about?

It would be churlish to disagree.

The ducting is in various shades of pink. As you can no doubt see.

http://monkeyfx.co.uk/pictures/new_workshop/ducting.PNG

Roland

That's a lot easier to understand. A picture tells a thousand stories etc.

Is there no extraction for the table saw in the middle of the room?

Sporky

The tablesaw and the planer/thicknesser (which I might call the PT in future to save typing) will have an outlet between the bandsaw and pillar drill - where it goes from mid to dark pink. They'll both be used in the middle of the workshop so will be on a run of semi-rigid hose and a bit of flexible hose at the end.

A lot of the theory stuff is more important in large installations where you have multiple machines running at the same time, but given the time and effort that'll be involved I thought it was worth getting right. The current workshop runs 50mm throughout with just a chip extractor - it's good for everything except the PT. There's a lot of flexible hose in it though, and all the joints are Ts rather than angled so it's not awfully efficient. Still much better than nothing of course.

Sporky

I got a tax refund this year, so I'm considering one of these for the CNC machine, which is a serious mess-maker...

https://www.kentcnc.net/nc/content/images/thumbs/0000260_standard-split-shoe_450.jpeg

Sporky

Also I just saved about £260 on the machinery movers by phoning and asking nicely and being flexible on dates. Coolio.

Sporky

My word there's a lot of crap in that shed.

I have hired a skip. It's like being a grown-up!

Sporky

And four hours after the skip was delivered, the skip is full, the shed is empty and I got rid of a load of other crap too. Having a skip is awesome.

I'd post a picture but my web hosting is a bit borked.

Sporky

http://www.monkeyfx.co.uk/pictures/new_workshop/skip.jpg

BigMonka

I still can't believe that no one took you up on having that blue cab (2x12?) - I saw you offer it in a few threads and if I'd been closer then I would have definitely had it :-(

Sporky

I hereby give permission for anyone who wants it to remove it from the skip. Same goes for all the other crap in there - two mowers, a strimmer, a barbecue, patio furniture set...

TTony

Sporky said:

I hereby give permission for anyone who wants it to remove it from the skip. Same goes for all the other crap in there - two mowers, a strimmer, a barbecue, patio furniture set...

no cuddly toy?

Sporky

TTony said:

Sporky said:

I hereby give permission for anyone who wants it to remove it from the skip. Same goes for all the other crap in there - two mowers, a strimmer, a barbecue, patio furniture set...

no cuddly toy?

Frankly there could be a lady and a tiger in there for all I know.