Source of Metal 4" Ducting

[OLD]

Planer thicknessers produce lots of dust/chips give it a nice smooth ride to minimise blockages.The other machines do not give the system a lot of work so pipe work can be less well engineered but all must be air tight.
Most blockages are caused by not emptying the bag.

 

[Scrit]

The other machines do not give the system a lot of work so pipe work can be less well engineered but all must be air tight.

Sorry, but don't take-up panel fielding or rebating on any type of spindle moulder, nor machining tenons the same way (or better yet on a single-end tenoner) - they all generate copious quantities of shavings which can block smaller diameter pipes and/or badly designed systems (see Bill Pentz's site 8) for full details.... ). The principle of solid wood dust extraction is completely different to that employed in a vacuum cleaner - what you are trying to do is to move large volumes of light but fairly bulky materials using the high air flow at low pressure. I'm not saying that duct sealing isn't important (and that's what duct tape or Duck Tape is for, after all) it's just that the overall design of a system makes a huge impact on how well your DX works - much more than air leaks in the first instance - and if the extractor isn't "breathing" the dust, then you will be!

BTW the extraction requirements for MDF and chipboard are significantly different. That's a whole different ball game.

Scrit

 

[OLD]

Scrit
is of course correct but i was looking at your drawing in previous post ,its the high volume that causes the problems .

 

[AndyG]

Bill's site is indead a mine of information. Although there are enough worrying health issues mentioned there to almost put you off woodworking for life (but only almost).
The reason I've gone for a 4" system is that my dust collector has a 4" inlet. So I'm guessing that having a 6" main duct wouldn't be a great idea because of the downsizing at the end.
I'm still recovering from an employee of camvac (At the north of england woodworking show) trying to persuade me that a 2.5" system would be adequate for all my dust collecting needs. I seem to be having a run of (seemingly) bad advice from companies, but that's a different story!!

Scritt, thanks for the pointer to Adams Sheet Metal. I'll add that the the list of potential sources! However, at the moment CCL seem to be the way to go. Just wish they had a price list online...

 

[Barry Burgess]

The reason I've gone for a 4" system is that my dust collector has a 4" inlet. So I'm guessing that having a 6" main duct wouldn't be a great idea because of the downsizing at the end.[S/quote]

Most of the suppliers of the dust extraction systems limit the inlet to 4" so that the motor does not draw too many amps so that they have no problems with they guarantee. You can open up the outlet to at least 5" or 6" and the motor will not draw the maximum amps.
If you are using any of the high volume chip makers use 6" or more for your piping and also used blast gates and no T's and minimum Y's

 

[Scrit]

I'm still recovering from an employee of camvac (At the north of england woodworking show) trying to persuade me that a 2.5" system would be adequate for all my dust collecting needs...

And they manufacture DX systems??!! :shock: The small diameter high vacuum approach works well enough over short runs for fine dust like MDF or particle board but simply doesn't hack it for shavings, etc.

As to your sources, the clip duct systems go together quicker than crimped connections, but it will cost more. When buying any future extensions make sure that the stuff is compatible with what you've already got - 4in isn't always the same as 100mm

BTW If you need a source for good quality fine DX sacks (not the 30 micron horrors most chip catchers have), I can help.

Scrit

 

[AndyG]

Scritt, Thanks for the offer. That would be grand. In fact do you have any pearls of wisdom when it actually comes to attaching them to the collector's output? My collector's so new I've not had a real chance to have a good play yet, but my first attempt of attaching the bag left gaps which dust was escaping through. Perhaps I just need to be more thorough with my Jubilee clips...
Andy