Ducting source?

[ondablade]

Back again guys. I'm laying out the ductwork for the dust system in my shop, and am struggling a bit to get good cost and dimensional information on standard galvanised steel bits. Mostly 6 inch, or better still 160mm.

Flexible vacuum hose with a smooth bore is also needed, but it's quite tough to separate out what's suitable, and what's not. The flexy concertina stuff is not really the plan due to very high flow resistance. I'm wondering if it's worth chasing up some industrial suppliers rather than what's labelled for 'woodworking'.

Felder do list a very similar system in the shop on their site, but i don't know if it's reasonably priced or not. They are charging £14.69/1.5m for straight, £22.54 for a 90 deg bend (which is a bit tighter than is ideal), £19.19 for a 45 deg bend, £54.10 (ow!) for a 45 deg 'Y', and £24.15/m for their better quality PU vacuum hose - all 160mm and excluding VAT.

Anybody know of some good UK sources, ideally for ex-stock 'system' stuff like these examples and priced on the web? These guys in Taunton http://www.swtestingltd.co.uk/qfducting.html (SW Testing Services Ltd selling Nordfab Quick Fit clamp together ducting) look promising, there's a .pdf catalogue with drawings but no prices on the web page. The manufacturer is in the US: http://www.nordfab.com/..

ian

PS just found Nordfab have a web shop with pricing. http://www.nordfabducting.co.uk/product ... amily_id=1 Seems on a first look that they are a bit more expensive than Felder on some stuff, a bit less on other...

 

[yetloh]

I think the answer to your question is "yes". I have just taken delivery (but not yet installed) an Oneida cyclone system.

From them 1.5m of 150mm spiral galvanised duct is £4.60. This has a spiral ridge on the outside but is pretty nearly smooth on the inside with just a very small spiral indentation on the inside. A 90 deg elbow is £10.88 and a 45 deg is £7.86. A 100mm blastgate is £12.57. The most expensive item is a floor sweep at £37.30; this is achute placed at floor level into which you just sweep the rubbish on the floor and is a brilliant device. All these prices are ex VAT. Oneida buy it in so are clearly adding their own margin although they no doubt get a good price because of the quantities they will be buying. I feel sure it must be worth shopping around.

Jim

 

[ondablade]

Thank you very much for that Jim, it looks significantly cheaper and it's still stuff sold for woodworking applications - i gather some of the lighter HVAC stuff is not ideal as it's thin and dings too easily.

I didn't realise Oneida had a UK operation http://www.oneida-air.co.uk/, so i've made contact with them and asked for information.

Their US website lists ducting parts and prices anyway, so i can get designing now.

ian

 

[Paulgy80]

Any of you guys thought of the Camvac range? made in the UK and quite competative?? Oneida is a nice demo but nowhere near as effective on fine dust ??

Paul

 

[dickm]

Not much help to anyone in this thread so far, but I'm wondering what is the best thing to do with some spiral galvanised ducting that is sitting in our loft, left over from the forced ventilation/heat recovery system. I'd been eyeing it up thinking to make a permanently fitted extraction system, but the bulk of the ducting (4 x 3m lengths) is 6" diameter, which I guess may cause problems if connected to the 4" outlets on my machines and (mobile) extractor. The options seem to be:-
Try it out and see what happnens
Advertise it in ScotAds and see what I can get for it, then buy 4".
See if anyone wants to swap the 6" and 5" stuff (and various fittings) for a couple of lengths of 4".

Any suggestions?

 

[ondablade]

I don't know anything about Camvac Paul, as i've just bought a Bosch GAS vacuum to use with power tools.

From what i'm picking up as i've read lately (i'm just planning my system) it's pretty clear that vacuums don't shift enough air volume to be much use on full size machines like table saws, planers, spindles and so on.

On the other hand the sort of high volume dust system that works on these is not a great lot of use if hooked up via the small diameter hoses used by most power tools - you need the extra 'suck' of the vacuum there.

On your galvanised ducting ****. Six inch is actually about the right size for decent extraction at most machines if you are ducting a small garage type shop, but it takes more than the typical 1hp dust collector (more like 3hp + depending on the detail design of the system) to deliver the required 800+ cfm at 4 - 4,500 fpm air speed in it to stop dust and chips dropping out and causing blockages.

Other factors are thickness (some metal HVAC ducting is apparently very thin at about 30G and may collapse under suction, and ding if wood block are sucked back), and it needs to have a smooth bore and to not be convoluted or it restricts flow a lot. End fittings vary too - some is push together, and some (e.g. Nordfab) uses very nifty quick action ring clips but is more expensive..

ian

 

[yetloh]

I have the small Camvac and it is hopeless when hooked up to my planer thicknesser; inlet clogs, a pain to empty as the chips clog up on the cross bar of the cage then descend like an avalanche into the open bag sending a cloud of dust into the workshop. If the cloth filter bag really is more effective than the Oneida's large corrugated paper cartridge (which I seriously doubt) the emptying palaver must negate this advantage several times over.

Jim

 

[Modernist]

I visited the Camvac stand at Harrogate recently and was seriously unimpressed with their kit. What is the point of collecting all that dust if you have to pour it out of the bin afterwards. They said the system will not work with bags in the bin, unlike my normal two bag machine. It may be OK for a small home workshop not is not up to full size machines or anything other than very small chip/dust volumes IMHO.

 

[Vinny]

I have a twin motor camvac hooked up to TS. SCMS and RT with Wickes rain water pipe (63mm ish)and fittings coupled to camvac blast gates, Really can't fault it. OK you have to empty the bin into a dustbin but its not exactly a chore. I'll get another camvac with 100mm fittings for my planned P/T and bandsaw.

Vinny

 

[dickm]

On your galvanised ducting ****. Six inch is actually about the right size for decent extraction at most machines if you are ducting a small garage type shop, but it takes more than the typical 1hp dust collector (more like 3hp + depending on the detail design of the system) to deliver the required 800+ cfm at 4 - 4,500 fpm air speed in it to stop dust and chips dropping out and causing blockages.

Other factors are thickness (some metal HVAC ducting is apparently very thin at about 30G and may collapse under suction, and ding if wood block are sucked back), and it needs to have a smooth bore and to not be convoluted or it restricts flow a lot. End fittings vary too - some is push together, and some (e.g. Nordfab) uses very nifty quick action ring clips but is more expensive..

Thanks for that, Ian. Exactly what I needed to know. The ducting is smooth bore and pretty tough (about 18g at a guess and you can stand on it) but I've only got 1hp for the extractor. Also the fittings push in, so there are ridges at each join. It'll have to go in ScotAds

 

[ondablade]

Just in case of misleading you ****, plus it's an excuse to get the message out again: I was drawing on the data published by Bill Pentz in what i said. I'm relying on it too in planning my own system. http://www.billpentz.com

Judging by positive feedback all over the place it seems to stand up 100%. The site is quite spread out, and takes some reading to get to the bottom of, but the data is there.

The reason there's so much disparity in the airflow numbers quoted as being required for chip and dust collection by differing sources is that differing standards are applied.

As he makes clear it depends a lot on what you mean by 'effective' chip and dust collection.

As most of us using basic floor units know you you can collect coarse chips from a saw at 350 cfm/4000fpm using a 4 in duct and 1 hp fan (which smaller duct gives roughly the above provided the duct run is short) and so stay tidy. You won't however be drawing in air fast enough from the volume of space around the blade to pull in the fine sub micron dust it flings about that poses the big health risks.

This situation is made worse by the fact that the bag filters fitted to most 1hp floor units are too coarse to trap fine dust either - much of what you do catch gets spewed back into the shop, especially when the bag is fresh. Plus HP/cfm are a bit marginal even at that so even the coarse chip collection goes south pretty quickly as the filter starts to blind up.

These units typically claim much greater cfm rates, but fairly demonstrably don't deliver what they claim in real operating conditions. (the above has been my own experience with a floor mounted mobile 1hp unit)

When you up the game to saying that 'effective' means satisfying the US OSHA or ACGIH or better still Euro health and safety at work standards it seems it gets a lot tougher - you need around 900 - 1000 cfm at your saw/machine depending on exactly what it is.

You basically need 6 in ducting to deliver this efficiently in a smallish shop with fixed ducting.

It's worth noting that while the US standards were determined by negotiation/trade off with a hostile industry that didn't want the cost, the Euro standards are based on medical data.

Where this really hits home is when the issue of filtration is added - with a pretty inefficient (open weave - not much use for very fine sub micron dust) bag filter (or exhausting outdoors if the weather is warm) you can probably move this much air with 3hp provided your ducts are fairly short (small garage sized system), and the layout is such that restrictions are minimal.

Up the game to something that's medically correct using something like Donaldson's 262-5001 or 262-5002 UltraWeb 2 Filter Cartridge that's ASHRAE MERV 15 99.99% efficient at 0.3 micron (this is equivalent to the EU standard - sources previously discussed in another thread) and a larger garage sized duct system with one machine connected at a time and you need more like a steady 4hp to achieve this - and will draw more HP if additional ducts are left open. (Bill's blower design uses a 5hp 3,450rpm motor to leave sufficient reserve for this sort of intermittent higher loading)

Fit these finer filters and it becomes highly desirable to install an efficient cyclone that separates the dust and chips before they get as far as blinding or damaging these filters which run about £150 a set. Which is why Bill is into cyclone design as well.

Bill's table in section 1 (c) here sets out the hard test based numbers: http://www.billpentz.com/woodworking/cy ... Basics.cfm

Pardon the length, but maybe it will help somebody. I've seen several uncles/father of friends that worked in the saw/grain milling businesses go down with emphysema in later life, and i've had lots of sinus trouble too - the risk is real.

ian

PS Pentz cyclone made by Clear Vue in action: http://www.youtube.com/watch?v=TJ_I8Sx8T38