I wasn't sure where to put this.

I just want your opinions on what you think of this new suction hose with the plug it cable imbedded in it because I'm thinking of looking into it.

Has anyone got one, how have you found it, is it worth it?

Chris

There won't be too many comments about the hose here because it is not available in North America. I do have one however, and I love it for the great convenience. I don't see there being too much of a reduction in suction because the vac already has such a high static pressure to begin with. If you can buy them in your country, then by all means I would recommend it. Oh, strike that without one caveat. The benefit of this hose is most pronounced when you are also using the boom arm on the vac.

I doubt it will make much difference. But your statement here made me curious, so let's do the math.

We want to know the percentage with what the cord reduces the surface of a cross cut of the hose. The formula for calculating the surface of a circle is surface = Pi x radius x radius.

The radius of the hose is it's diameter divided by two, thus 27 mm/2 = 13.5 mm.
So it's surface = Pi x 13.5 x 13.5
 
The radius of a Festool cord is it's diameter (roughly 7mm) divided by two, thus 7 mm/2 = 3.5 mm.
So it's surface = Pi x 3.5 x 3.5

Now the percentage of surface area that the cord takes away from the hose = cord surface / hose surface x 100%

> (Pi x 3.5 x 3.5) / (Pi x 13.5 x 13.5) x 100%  
= (3.5 x 3.5) / (13.5 x 13.5) x 100%
= 12.25 / 182.25 x 100%
= 7%

7 percent is not really a factor to be concerned about I think.

And ......

The way fluid dynamics works doesn't necessarily mean you get less suction when the size of the hole is reduced. When the motor of the vac replaces the same amount of air per time unit, it only means that with a slightly smaller hose the air will move faster through the hose but it's still the same volume.

Another thing to consider is the internal shape of the hose. It is ribbed and these ribs introduce an amount of turbulence in the hose which in turn negatively affects the airflow. Introducing a long straight cord into that stream might actually reduce the turbulence inside the hose a bit and thus affect the airflow positively.

But I mostly think the amount of influence is too small to matter.

I do not own a boom and I don't think I will because for my workshop it is impractical. I wanted to get it because often when I am working in my workshop I do have to often switch tools and it turns out in the end that I take most of their cables out of their boxes so I don't have them getting in the way when I put it back. This sadly leaves a big mess and rapping the cord around the hose only works for so long before it starts slipping down. I know thats a little silly but it would be nice having all their cables in their respective boxes so when I do work away from the shop I don't have to worry about whether or not the tool I grab has a cable in it or not.

Thanks for all the replies.

Chris

Personally, I don't use one. Instead, I made my own with some braided sleeving and adhesive-lined heatshrink tubing. Cost a lot less...

Thanks for the photo Jonathan. You have a nice setup there. I would kill to have that kind of space :/ Is that a box mount you were making in that photo?

I agree with Alex. I really don't think suction would change and depending on how much it costs I think I'll go for it. Thanks for all your quick replies and comments.

Chris

Hi Chris,

No problem with the pic, I've uploaded some more of my new setup into my album in the gallery if you fancy a look. As for the frames they are just beech frames for a series of ebony veneered panels I've been working on for an exhibition.

I'm glad you are going to go for the hose, I don't think you will regret it. As for any weight issue perhaps you could add the wire hose holder attachment that lifts the hose up from the extractor. I'm not sure what the part number is but might be worth considering if the boom arm isn't an option.

Jonathan

I have no direct experience with this product and I don't own a Festool dust extractor.  But I do know a little bit about fluid dynamics, and I wouldn't be so quick to dismiss 7% reduction in diameter as negligible.

Consider a biplane.  Upper wing, lower wing, fuselage, tail, landing gear...and the network of reinforcing wires between the wing.  Those tee-niny little wires contribute almost half of the drag on the airframe.

Now, we're talking an enclosed duct, and it may well be that Festool has done the math and formed the wire to minimize its impact on the airflow, but simply putting a cylindrical wire down the length of a vacuum cable might create a non-trivial reduction in airflow.  I'd start my off-the-cuff estimate by calling the reduction in airflow proportional to the twicethe reduction in cross-sectional area.

Now I kinda want to go buy a vacuum and experiment with it...
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Frank-Jan, I measured a normal 27mm hose. I didn't realise the plug-it cord had a wider mid section. John (CO_JCD) to whom I reacted also didn't mention this. And the first person I reacted to, woodguy, talked about less suction because of a smaller diameter. The plug-it cord still has two ends of the regular size, 27mm and if woodguy's theory was correct, those two ends would still work as a bottleneck. But my calculation was only intended to demonstrate it doesn't matter much, and in the most severe case of a normal 27mm hose fitted with a cord would only lose 7% of it's diameter. And 7% is almost negligible.



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