Thread: tricky dust extractor upgrade

No. For now i've just requested the 150mm clearvue blast gates so at the very least i can replace the cruddy black plastic ones I have now that leak like a sieve.

Might be worth calling Felder and see what the wait time on their units may be or if they have any in stock. SCM seem to make very similar spec'd units, too and i've recently had a good customer service experience with both SCM and Felder when trying to find a new Combo thicknesser/Jointer.

Would their smaller unit be big enough for you? The RL 125

Sorry I didn't explain it properly but the brand new price is definitely out of my budget. I'm stretching it already with what I'm looking at. Haha.

I have some nice homemade blast gates that I hope aren't leaking everywhere. I will look into getting the particle Meter and check for leaks in my current system and make changes as necessary.

I still haven't been able to get ahold of Clearvue. Hopefully they are ok

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Originally Posted by Storm2point0

Sorry I didn't explain it properly but the brand new price is definitely out of my budget. I'm stretching it already with what I'm looking at. Haha.
I have some nice homemade blast gates that I hope aren't leaking everywhere. I will look into getting the particle Meter and check for leaks in my current system and make changes as necessary.

I makes no sense to check blast gate leakage using a particle meter as they leak inwards, which is a good thing. With my DC outside I don't tend to worry about them too much because these sort of leaks act like general shed dust scavengers.

Checking for blast gate leakage is tricky. Even using a flow meter (which is in itself a whole can of worms - see DRAFT: FAQ - Dust Extraction (Practical Aspects)) is hard work

Measuring air flow at the impeller with all the blast gates closed will generate an over estimate of the gate leakage as the entire vacuum pressure of the impeller will be directed at the leaks. The correct way to do it is to block all of the gates (not close them but hard block them) except one gate that open and connected to a machine and measure the flow rate at the impeller. Then one at at time unblock the gates but leave them closed and measure the flow but this is a lot of work.

A simpler way is (provided you have the DC outside) is to just listen for any whistling at any open or closed gate and then do things to the gate to reduce or eliminate the whistle. A couple of quick grip clamps the force the BG body closer together may be instructive.

I have a question for Bobl. I have attached the rough layout for my piping and was wondering if the felder RL160 would be a good option or would I be looking to go with a cv1800 or cv max. If I use the CV I will have to mount it on a 45 degree angle to fit my space. I know there are other bagged options, but I also know if it's not easy I won't maintain it. So I am looking at a higher end solution. That is easy to maintain.

Thanks.

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Here is the attachment. And HBS is a horizontal belt sander. And Ds is a small drum sander.

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What BobL alerted me to and what I confirmed during the installation of my dust extraction system is that Amp draw, static pressure and other performance measures are rough guides only. What we are interested in is the actual airflow and this varies from shop to shop because the installations are different, as are mods made to machines and hoods.

For instance, the CV1800 does not look so flash when static pressures generated are compared with other systems, but open a blast gate and measure the actual air flow and the reason why CV's are so popular becomes obvious very quickly. From what I can gather the impeller design/efficiency for the CV is superior to most, and that seems to help a lot.

Here are the 2012 static pressure readings for my CV1800. A foot of water is OK, but nothing to get excited about.

Manometer Readings.jpg

Then Ron Boulton visited my shed ... bless him ... he brought his instruments to measure air velocity in my ductwork.


Measurements were taken just before the air enters the cyclone. Interestingly, the velocity readings were the same from about 12 - 15 mm in from the wall to the centre of the duct. The outer 12 - 15 mm averages a velocity 30% lower than the centre of duct readings. The velocities and volumes given below have been integrated to allow for the losses close to the duct wall, so I am confident they are pretty good data. Bill Pentz's site says we need 800 CFM to meet OHS standards and 1,000 CFM to meet medical standards. My data are:


Drop Saw ........4,850 FPM and 906 CFM
Drill Press ....... 5,200 FPM and 971 CFM
Drum Sander ... 4,550 FPM and 850 CFM
Band Saw ....... 4,300 FPM and 803 CFM
Table Saw ...... 5,100 FPM and 952 CFM
Linisher .......... 4,650 FPM and 868 CFM


No big surprises. The inlet for the drum sander is a bit close to the drum, and this restricts air a bit, but it is still pretty good. The bandsaw has three 90 mm lines and a bunch of bends/flexy, so whilst the CFM is only 803, the blade and dust speed is slow, resulting in great dust capture. The hood on the linisher has been moved by 30 mm to open up the throat of the hood, but these figures indicate what was suspected, that it need to be opened a little more, so this will happen ... one day ... maybe.


For those of you considering installing/upgrading a dust collection system, these figures clearly demonstrate that it is not the length of straight duct that causes most of the losses. It is the fittings, the hoods and the machines. The linisher, table saw and drill press have the longest runs of duct.


Another thing I was alerted to during my design period was to ensure the exhaust tube was bigger than the inlet tube. If the exhaust tube restricts air, it can choke airflow into the machine. I solved this problem by using 8 inch insulated HVAC vent (covered by 12 inch insulated HVAC vent) for the exhaust.

I'm going to be really helpful by saying it doesn't matter which you get as either would do the job for your machines

The limitations to air flow are are the machine ports and provided these are attended to both will deliver the same airflow through the proposed.
Both have 3P motor so could utilise a VFD - not sure if the Felder's motor will run on 240V 3Phase.

Re Your drawing.
Just a heads up that it's not possible to penetrate in one place and turn ducting hard up against a wall that has just been penetrated.
You could do this by either penetrating the wall in two places or move the run up to the jointer further inside the shed.
Ducting.jpg

Thank you John and Bob for the replies. I know there will be a fair amount of work involved getting the piping and machinery to a sufficient level to actually allow the dusty to do its job. Dust extraction is definitely a journey.

As for my layout of the pipes, the reason I have it like that is because I run the pipes on the floor because my workshop only has 2100mm clearance. I am a tall guy and would definitely hit my head on it. I am currently using a 45 degree wye through the brickwork and then a 45 degree joiner to bring it parallel to the wall. It sticks out around 300-400mm off the wall but it's close. Is that ok or will that restrict airflow?

Thank you

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I know it will restrict airflow but as for wether it's alot or a little.

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I guess if you have no option but to run it on the floor then there's not much you can do about it.

Originally Posted by Storm2point0

Thank you John and Bob for the replies. I know there will be a fair amount of work involved getting the piping and machinery to a sufficient level to actually allow the dusty to do its job. Dust extraction is definitely a journey.

As for my layout of the pipes, the reason I have it like that is because I run the pipes on the floor because my workshop only has 2100mm clearance. I am a tall guy and would definitely hit my head on it. I am currently using a 45 degree wye through the brickwork and then a 45 degree joiner to bring it parallel to the wall. It sticks out around 300-400mm off the wall but it's close. Is that ok or will that restrict airflow?

Thank you

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Originally Posted by Storm2point0

Dust extraction is definitely a journey.

It sticks out around 300-400mm off the wall but it's close. Is that ok or will that restrict airflow?

It is indeed a journey. Several times when I thought I had things figured out I'd learn something new that changed my decisions. Nonetheless, it is a journey with a great ending.

There is no right or wrong with ductwork layout. I looked at each "run" and tried to minimise the number of fittings. I got lucky. There is one major line and one branch line in my setup. I got kinky with the main line, which only had one 90 degree bend so I made it with six 15 degree fittings, because space etc was not an issue.

If you must make compromises, which is likely, do so deliberately, being aware of the ups and downs of each decision. For instance sometimes it is helpful to move machines around a bit to optimise the solution. You will know which machines you use the most, and which are the dirtiest. Try to give these machines as few fittings as possible between the machine and the cyclone. As BobL keeps reminding us, fittings, along with machine hoods and the machines themselves, are much more important than length of straight pipe in terms of airflow loss. I was worried about my table saw. It ended up with one wye into the main line and the six 15 degree fittings between it and the cyclone. The dust collection on my table saw has been beaut ever since. On the other hand, there are several more fittings between the drum sander and the cyclone. However, dust collection there was not bad with the old 1 HP machine and a 4 inch port. These fittings reduce air flow to the drum sander and band saws, but the loss here is less critical than is the loss at a table saw or a linisher.

I am not suggesting you design your entire workshop around the dust collection system. It must still make sense as a workshop, and suit your needs. If you think about this and try to minimise the number of fittings between the important machines and the cyclone, you'll likely be fine.