Thread: Theory V Practicality

It may not be practical now but I would get the family storage off the ground so the floor space it occupies can be used as part of the working area.

fat chance when its a whole bloody household of furniture. mind you a match would be a useful idea but then Id have to live with the nuclear aftermouth.

Yes the Timbecon one is definitely better for dust extraction.

Stiff versus flexible has pros and cons.
- Flexible means you can make it turn tight corners easier than the stiff type.
- Flexible may mean it's softer so more likely to tear
BUT
In term of air flow stiffer has lover resistance to flow.

The galvanised Y connector shown above are really made for slow speed air AC ducting and will struggle in DC operations. It has a Y angle arm/flow separation of 120º which means the flows each have to diverge by 60º to make it into the main flow. This is not that different to a T junction which diverts by 90º and has the worst of all junction flow characteristics (well there are far worst ones but that is a topic of itself).

What happens is the two incoming flows end up bashing almost head on generating severe turbulence which severely restricts flow

None of the engineering books I have even mention a 60º divergence but to give you an idea of how restrictive a 60º junction is, for converging flow and assuming 50% of the air goes through each arm.
The only ones listed are the 7.5º, 15 and 22.5º divergences and these are such that a 7.5º divergence has ~1/3 the resistance of a 15º divergence and 1/6 the resistance of a 22.5º divergence

Now extrapolating and reverting to the other way.
Roughly speaking (once again compared to the 7.5º divergence) a 30º divergence has 9 times more resistance, a 45º divergence has 12 times more resistance, and a 60 has 16 times more resistance = than a 7.5– divergence

When a conventional stormwater or DWV 45º Y junction is used, although the flow is not even, it can be approximated by a 22.5º divergence so a conventional "Y" will be 2.7 x less resistance that the 60º divergence galvanised junction described above.

Clear as mud eh - well you better like it because it took me a long time to condense this out of the engineering book.

Y connector.... fair comment. I thought of using where 2 mainlines join, go through the wall to dusty outside, but I do have a few dwv ones ...

Originally Posted by Tonto

Y connector.... fair comment. I thought of using where 2 mainlines join, go through the wall to dusty outside, but I do have a few dwv ones ...

Yes that's a RPITA (Right PITA) situation. If you want to branch 90º right or left (OR at any angle) as soon as you come in thru a wall, it is difficult to make that branch lay up against a wall. You have to suspend it from a ceiling about 500mm away from the wall.
OR
Make the connection outside and start the bend outside the wall and make the hole sort of oval shaped so the 90º arrives flush with the wall - awkward but doable.

I had the same problem on one of my DC SYSTEM arms and even employed two 15º bends to bend the ducting back so it came up flush against the wall - not the best but it solved my problem. I had a small advantage in that the area of wall over which this happened was an odd shape.

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your the man, where is all your artwork/drawings done. i know my limits

Originally Posted by Tonto

your the man, where is all your artwork/drawings done. i know my limits

Mostly it's done in Powerpoint. Not because I think it's a particularly fancy app, I actually think it's pretty clunky. It's just that I got quite quick with it when I was lecturing at uni.

BobL, where is the thread of your making bell mouths on your lathe please, I have an idea but need to look at it first.

also someone when modding their dusty turned it sideways so the motor was under, they also had details on what sizes of metal they used...could I be pointed in that direction. Now that Iam allowed the dusty outside thick MDF as a stand wont do.

Originally Posted by Tonto

BobL, where is the thread of your making bell mouths on your lathe please, I have an idea but need to look at it first.

Yeah that is squirrelled away in the "improving-machine-cabinet-dust-ports" thread
Improving machine cabinet dust ports

. . .also someone when modding their dusty turned it sideways so the motor was under, they also had details on what sizes of metal they used...could I be pointed in that direction. Now that Iam allowed the dusty outside thick MDF as a stand wont do.

If you look on the side of the upright it will tell you what it is.
The steel plate used as the base and for the motor to bolt onto was 6mm thick but I reckon you could get away with 4mm

looking again at bell housing...disregard ideas...wont work again we bow to your wisdom and knowledge. dont get big headed about it though..

Shed sort out is well under way, stuff & machines been locked away in container for many years coming to see daylight

This old Ryobi thicknesser had new blades just before in went into hibernation, but looking at it with its little 50mm mouth/throat suggestions on how/if I could enlarge it, improve its cleanliness.

If it was me I would remake the whole hood from scratch with a 4" port - that way you retain the old one so if you stuff up the new one you still have the old one to fall back on

An alternative is this - buy a 90º sort radius bend and cut it to suit the shape as shown and glue it in place. Add half a floor drain flange and tek screws for a bit of extra strength or the vibe will crack the glue.

ND it does not have to be super air tight.

Old hood on left, adapted hood shown in middle and right
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me...love gambling on life. Think adding the radius bend and plate will be up my capabilities. thanks again.

from basic to own version custom mod.

Had to do it this way as...IF I wanted to put a BIG piece through the elbow would allow the full height, But hopefully this will work