Thread: Advice please

Even though your DC is rated for 3200 CFM it won't deliver anywhere near this as it will be limited by using the 150 mm duct.
The most you can get through a 150 mm duct with a DC is about 1250 cfm.

Target flow is ~1000 CFM - this is very important for lathes and bigger machines

The longer lengths of 150 mm will be fine, however using 100 mm flexy will KILL the flow to ~350 CFM which is well below the target.

Even using hard PVC will only get you to about 425CFM.

Hard 150 mm PVC ducting all the way to the machine with no or minimal use of 150 mm flex is the best chance you have to get near the target.

You will have to open up the ports on the machines to 150 mm to get near the flow.

On machines like BS you will need 3 x 100 mm ducts to get near the target flow.

Read though the dust forum to get more ideas,

If you can move the DC to the point I have suggested in the diagram it will make things much simpler as it will avoid the complex junctions of splitting the trunkline as it comes into the shed.

My design uses a single trunk line around the wall/ceiling of the shed and then straight secondary lines over to each machine.
Because you are using 150 mm ducting the the extra lengths won't impact the flow much.
Blue represent where the BG should go.

Use 150 mm Y connectors and then an extra 150 mm 45º to make a 90º junction.
Note I suggest adding a line to just above your bench.
Above the bench use a 150-100-50 mm reducer so you can hook power tools (like sanders) into the DC.
PetesDCsystem.jpg

I've also found that with sketches like this it also helps if you put a mark on each machine location to indicate where the dust ports are.

One question: do you have a preference to run the ducts along the wall, or do you have the clearance for overhead ducts? The only change I would make to BobL's layout is, instead of routing the main around the wall, angle a straight run from around the SCMS (or close to where you marked the DC) to about the middle of the TS/jointer/BS trio. This'd have the effect of minimising the horizontal lengths, which is always a good thing even if it's only a minor improvement.

Originally Posted by Skew ChiDAMN!!

The only change I would make to BobL's layout is, instead of routing the main around the wall, angle a straight run from around the SCMS (or close to where you marked the DC) to about the middle of the TS/jointer/BS trio. This'd have the effect of minimising the horizontal lengths, which is always a good thing even if it's only a minor improvement.

This is a good idea but less so due to length reduction and more because it removes the 90º bend in the corner in the pathway to the TS.

Using Bill Pentz "staticalc" shows that the difference is length looses ~<1% pressure whereas the 90º bend looses 3% pressure.
If it was 100mm ducting and or a 2HP machine then length it would be important. When connected to a big DC, 150 mm ducting is very forgiving in terms of length .

The difference between doing it at an angle and as shown below is <0.5% and it will be a bit tidier.

PetesDCsystem2.jpg

When connecting machines from a trunk line its best to use all 90º connections or all connections with the same angle others the duct may cross over each other and as well as more awkward to install it looks terrible. All angled ducting is also a bit trickier to install. The advantage is it removes a 45º bend from the ducting path. My testing shows a 45º x 150 mm bend loses about 1% of flow

I would still put in the 90º bend and run the ducting around that wall because you never know what you might end up using in that area of the shed.

It's always better to connect each machine direct to a trunk line than to piggyback onto the ducting from another machine as every time this is done this requires an extra gate to lock out the other machine.

The same applies to machines that require maximum suck on more than one port. Eg on a TS with a cabinet port and a OH guard port. Its slightly better to run two ducts from the trunk line to each port than to split on duct from the trunk line into two at the machine.

At the mens shed we use 6, 3.5m long 90º arms on one side of the trunk line and 6 1m long angled arms on the other (red lines)

Arms2.jpg

The losses due to bends and length of solid ducting in a 150 mm system are usually not that significant.
The significant issues are nearly always the air flows through machines which few wood workers spend enough time on.
This usually requires opening up the ports to accept the 150 mm ducting, incorporating bell mouth hoods into machine connections and ensuring there are enough vents and openings into a machine to scavenge the dust out.
Little air in means minimal dust out.

Thanks guys.
I like the last design. I know sorting out the dust ports is going to be the big challenge. I didn’t realise that I had that much flexibility if I used 150 mm pipe. Now to start the installation process. I’ll post some WIP photos once I get going.

Cheers,
Peter

Another tip, use DWV wide radius 90º bends and not the tight radius stormwater bends.
DSCF4555_200px.jpgDSCF4551_150px.jpg

Originally Posted by Peter57

Thanks guys.
I like the last design. I know sorting out the dust ports is going to be the big challenge. I didn’t realise that I had that much flexibility if I used 150 mm pipe. Now to start the installation process. I’ll post some WIP photos once I get going.

Cheers,
Peter

Looking forward to your progress photos Peter

Originally Posted by BobL

The losses due to bends and length of solid ducting in a 150 mm system are usually not that significant.
The significant issues are nearly always the air flows through machines which few wood workers spend enough time on.

I am sure this has been mentioned a few times in various threads here, but as someone who is thinking about, and beginning the "mind's eye" planning for a dust extraction system myself, these two lines are incredibly useful information - thank you Bob!

Originally Posted by BobL

This usually requires opening up the ports to accept the 150 mm ducting, incorporating bell mouth hoods into machine connections and ensuring there are enough vents and openings into a machine to scavenge the dust out.
Little air in means minimal dust out.

Very important information. The question Bob is how big should the vents/openings in the machines be? 2 x the ducting, or more?

Another thing, where can we get some 150 mm bell mouths on this side of the world?

Originally Posted by cava

Very important information. The question Bob is how big should the vents/openings in the machines be? 2 x the ducting, or more?

2x should be plenty but I realise that sometimes this is not possible so you take what you can get.

Just as important as area is placement. Where possible the inlet vents should be place opposite, or as close to opposite, the outlet ports.
There's a whole thread on this here Improving machine cabinet dust ports

Another thing, where can we get some 150 mm bell mouths on this side of the world?

If you have a wood lathe its a doddle to make your own bell mouths - see half way through the above link.
If not PM me about this.

Originally Posted by BobL

This is a good idea but less so due to length reduction and more because it removes the 90º bend in the corner in the pathway to the TS.

I wasn't thimking so much of length reduction improving airflow... more "where will the gates be and how'll they be used?"

Ideally, the gates would be near the junctions but who wants to reach that high every time they switch 'em in and out? Most people seem to put 'em near the machines, usually around the bottom of the dropper.

I've worked at joinery's where the odd operators would finish a job, immediately bang the gate closed and then walk straight to the next machine and bang open the gate there. This has the unfortunate side effect of allowing dust & shavings to settle in the bottom of the dropper on top of the gate that was just shut (and we know how gates just love that!) as well as settling along the bottom of the horizontals up to the nearest junction with airflow.

I don't know how many times I've had to climb a ladder and break down the horizontals to 'declog' the results of this. Not fun when talking industrial sized DCs & ducts.

I'd rather design it with short horizontals in the first place to minimise the effects of poor work practises. I'm not implying Peter will be guilty, but the future is not yet written and who knows who else may 'borrow' his shed?

Originally Posted by Skew ChiDAMN!!

I wasn't thimking so much of length reduction improving airflow... more "where will the gates be and how'll they be used?"
Ideally, the gates would be near the junctions but who wants to reach that high every time they switch 'em in and out? Most people seem to put 'em near the machines, usually around the bottom of the dropper.

This is less of an issue if rocker style gates are used since they can be operated via cords hanging from the gates.
Apart from this rocker style gate, the other 13 gates in my shed can all be reached from the floor.
RockePVCr.jpg

Most of the mens sheds I have consulted to have installed these gates and they are all working well as long as they remember to open and close the appropriate gates. That's why I installed the pressure sensors down stream from the gates. If there's no suck at the machine dust port the machine will not start. It drove the blokes at my men's shed nuts for a few weeks but now they are used to it and acknowledge that they really do work.

Originally Posted by BobL

This is a non-issue with rocker style gates which can be operated via cords hanging from the gates.
Apart from this rocker style gate, the other 13 gates in my shed can all be reached from the floor.
RockePVCr.jpg

All the mens sheds I have consulted to have installed these gates and they are all working well as long as they remember to open and close the appropriate gates. That's why I installed the pressure sensors down stream from the gates. If there's no suck at the machine dust port the machine will not start. It drove the blokes at my men's shed nuts for a few weeks but now they are used to it and acknowledge that they really do work.

I would love to make something similar that is motorized

Originally Posted by ericks2

I would love to make something similar that is motorized

It'd be a lot easier and more efficient to motorise one of these than the more traditional sliding gates.

If you built similar but with a little tab sticking out t'other side of the axle - a bit like the 'fishtail handle' on japanese paper fans - you could set upa microcontroller (Arduino?) with a motor-driven rack & pinion on the outside circumference and a single limit switch on the tab.

I may have to look into this myself for my new shed's DC.

(More likely I'll be overwhelmed with getting it set up and productive while maintaining throughput... and little things like this will be put on the backburner. Just the same as 'most every other shed I've set up. Oh well, we all have a bucket list. )