Who are we to believe?

[Anonymous]

I have sorta compromised on this dust extraction business, partly because of restricted space, secondly the cost and thirdly because of the apparent conflicting advice.

An article by Andy King suggests that using the Axminster 63mm dek kit

"I have installed a small system in my home workshop using the Axminster 63mm dust extraction kit and the Axminster WV100 drum extractor. Although the bore size is smaller, it works fine for me,...."

does the trick.

However, according to the link provided by 'Scrit' to a site authored by Bill Pentz, piping less than 150mm or 6inches just won't cut the mustard as far as dust extraction is concerned.

Now call me old fashioned but there is a whole world of difference between 63mm and 150mm, some might say 87mm, so who do you believe???

If 63mm is adequate, why in Gods name do we need 150mm and if 150mm is the minimum how is 63mm even gonna get close.

Perhaps Andy King would like to comment, both on his own ideas and those of an apparently acknowledged expert Bill Pentz.

I tell you, life ain't easy if you wanna join a couple of pieces of wood :?

 

[Noel]

Bill,

I personally look at the situation in rather simple terms: plan your system to suit the characteristics of the extractor. Big 2 or 3 hp extractors need and will cope with 5 or 6 inch ducting. Lessor powered (and subsequent lesser static pressure) will happily perform with 4 inch ducting. Bear in mind that most of the US sites cover systems that use a proper cyclone extractor that need up to 6 inch ducting to take full advantage of the vast amount of air that a cyclone can move.
With regard to the Ax system that Andy K has used it certainly works. I would have suspected that the 63 mm ducting would have been a handicap but I suppose that with the smaller (2.25 inch) port on the extractor 4 inch ducting would not have worked. If the extractor had a 4 inch port a short run of 4 inch ducting may be suitable. But than again I may be talking nonsense. Suggest you have a look at books on the subject by Rick Peters and Sandor Nagyszalanczy, both available from
www.amazon.co.uk
or check the US site for more extensive reviews on these and other books
www.amazon.com

Rgds

Noel

 

[Scrit]

Noel, to shift wood waste you normally want high volume, rather than high vacuum unless you have a very big vacuum cleaner on short runs. I've had a couple of the Record RDX units and they left me singularly unimpressed when compared to even low-cost chip extractors - they simply couldn't shift enough air to exhaust even smallish machines (like a small linisher I have) and also suffered badly from clogging when exhausting certain machines, most notably the planer/thicknesser.

From what I have learned about it over the years the smaller the pipe the less the distance you can suck. The technical term is "static pressure loss" - in layman's terms increased air resistance inside the pipe. The smaller the diameter of pipe the greater the internal surface area of the pipe relative to its volume (cross-sectional area). In other words if you use sub-4in pipes with a chip extractor don't expect your extractor to suck too far and round loads of corners - it simply can't overcome the resistance in the pipe. That's not saying it won't extract - it just hasn't got the power to suck down long lengths of pipe or through loads of corrugated tubing (and remember every bend adds the equivalent of 6 to 10ft of straight tube SP loss) Whilst the smallest chip extractors do come with 4in pipes, many of the next-size up units are equipped with 5in or even 6in pipes, so I'm not advocating cyclones, just improved design with reasonable pipe diameters.

Before I bit the bullet and went full-time I used to have a system plumbed-in through 4in galv. steel ductwork into a 1-1/2HP (1-bag) chip collector. It worked alright, but enlarging the "main-line" of the system to 6in and increasing the opening for the impeller to 6in from 4in improved the performance about 100% (I also replaced the filter sock with a 2-micron job).

Scrit

 

[Anonymous]

Bill,

I'll be perfectly honest, the physics involved in working out airflow rates and CFM values on extractors is a nightmare/minefield or both!
Manufacturers will tend to quote a favourable figure to enhance it rather than give a uniform CFM or cubic metre airflow as a benchmark standard, and getting the information from them is even more difficult! (This goes for power tool specs as well!)
Back when I first started at GW, it was left to me to try and chase up such figures for a group test and it was impossible.
If I remember correctly we actually resorted to hooking each machine up to the same diameter and length of hose and timed it to see how quickly it would empty a bin full af woodshavings and dust. Not overly scientific i'll grant you, but it gave an insight as to efficiency using the same parameters for each one.
As to hose diameters etc. My own workshop is not used on an industrial scale and I always only have one machine running at any one time, so the extractor is only pulling from one blastgate.
My biggest concern in a small shop is dust so as long as it can deal with dust from the tablesaw, router station, bandsaw and general bench stuff, I am happy.
The planer is a little different. Despite the ability to plane 10x6 stock I tend to use it for smaller stuff. I have the DW733S which while a good planer, its dust port isn't the best, but it does pull a fair bit away. As planers tend to generate more shavings than dust, I can live with this, but if I was regularly working wide stock where the amount of shavings increase dramatically, then the smaller diameter pipe would probably be overwhelmed and block so I would need to upgrade the pipe diameter and extractor to cope.
I've been monitoring my own set up since I installed it and it works very well, the bin extender collecting the shavings and the extractor getting the fine dust. The only blockage I have had is when I thought i'd hoover the floor to pick up general woodworking debris and a few chunks of timber went flying around the pipes and got stuck on a bend.
Not long after I finished my apprenticeship when I was working in a small commercial joiners shop our own Health and Safety guys insisted that an extraction system had to be installed. It soon became apparent however that with three or four machines running at any one time the 100mm bore ducting was not efficient enough, and this was upgraded to 150mm on the main runs, branching to 100mm wherever necessary, and as close to the machines as posible to maintain maximum airflow.
If you are working with this type of operation in mind then you need maximum bore diameter and an extractor with a big airflow to cope with it.
Mine is fine for what it is designed for, a small hobby woodworker set up who wants a clean environment to work in at a reasonable cost. Stick bigger machinery in place or use more than one at a time and an upgrade is going to become a necessity. All the pipe runs on my system are 63mm, with reducing expanding collars for specific machines where required. The run is about 30feet maximum with two bends and five blastgate positions.
I hope this sort of clarifies some of my reasoning for my choice and why I am happy with it!

Andy

 

[Noel]

Scrit,

I did say I may be talking nonsense.....
Granted, SP and SP Loss are more specific than the general term Vacuum.
I was only using the term to describe air movement.
Ref your point about enlarging an extractor port from 4 to 6 inches - other than a warranty issue I realise this would be of benefit. I have only about 12 to 14 feet of 4 inch run (+ flexi hose) on a DX 5000. Would it be wise to enlarge the port considering this model is not of the squirrel type of motor / impellor? I will moving the unit at a later date which will need further ducting.
Andy , I believe you mentioned you have a DX5000 in the GWW shop. Comments welcome.

Rgds

Noel[/b]

 

[Anonymous]

Noel,

We do indeed have the DX5000 in the workshop. This runs in a similar vein to my own Axminster one at home, running one blastgate at a time. It's linked to the extractor with a 100mm soilpipe system with a run of about 20-25 feet, two bends 4 blastgates. There are two vertical lifts of about 4ft and a horizontal run of about 16feet along the ceiling.
Although not the ideal position, the planer is the furthest machine used in the run so the heavy shavings have further to travel, but the system deals with it very well, I certainly have no complaints about its performance.
This last port in the system is also used for machines on test as it has a flexible hose attached so it can be linked up to each one as needed.
With twin motors and triple filtration it is ideal for our workshop, but again, in a workshop running more than one machine at a time it may struggle to supply the suction.
Andy

 

[Anonymous]

Hi

Thanks for the replies and thanks for the clarification Andy.

It would seem then its 'Horses for Courses'.

Depending on what you want to achieve and its consequent loading on the dust extraction system regulates the size of piping, length of run, and the source power of extraction needed.

Actually then andy, according to your results I should be quite able to run a piping system of 63mm around my shop,( no bigger than you have at home) connected up to my dx4000 and achieve very acceptable results.

At the moment I have arranged my shop so that five of my machines can be connected to the one extended flexible pipe ( supplied with the dx4000) and although it is a bit of a pain moving it from one machine to another the extraction performance is very good.

Considering my machines including hand held range from 2x 100mm ports, 1x 68mm, 2x63mm, 1x38mm 4x32mm, the thought of trying to pipe round with 110mm soil pipe with all the ensuing bends and reducers and blastgates apart from being a nigh impossibility seems more of a nuisance and a nightmare than its worth.

The 63mm system however is more realistic.

Maybe! :wink:

 

[Anonymous]

Yep, in theory it should be OK! (Don't quote me on that!! )
Just bear in mind as I said that hogging great lumps of wood off with a planer will probably result in the pipe not being able to cope with the volume. Mines fine with the dusty stuff though and the wife is a dab hand with the sweeping brush i bought her for her birthday! :shock:
Andy