Thread: Dust Extractor Question?

Pen, I'll get the wife to take some pics tonite of my Gregory Machinery adapted single stage dusty. Aside from the filter, it has an internal spiral that directs most of the flow downward.

I've had some problems (not many) with it clogging up - mainly when cleaning the floor of shavings from the lathe. Thick shavings from pine etc clog the most, and you have to take the filter off. So I'd suggest that you leave plenty of room between the cone and the outside housing.

Jeff

Originally Posted by jefferson

Pen, I'll get the wife to take some pics tonite of my Gregory Machinery adapted single stage dusty. Aside from the filter, it has an internal spiral that directs most of the flow downward.

I've had some problems (not many) with it clogging up - mainly when cleaning the floor of shavings from the lathe. Thick shavings from pine etc clog the most, and you have to take the filter off. So I'd suggest that you leave plenty of room between the cone and the outside housing.

Jeff

Jeff,
I gather you modified the spiral/onion ring prior to installing the dome. Were you using a pleated filter before modification and if so, what are the differences that you notice with the dusty after installing the dome/witches hat?
Zelk

Thanks for the points made above re possible clogging.

I have the "dome hats" as supplied with the pfc's, but am very hesitant to us them as the space between the onion ring and the dome hat is very restricted.

I propose only to fit the the section as shown in the photos above. The question is do I also fit the inner cylindrical section? Without that section there is the risk that chips etc will just blow straight up into the pfc.

I have to make a second one, so rather than waste my time I thought I might get an educated view from forum members on their experiences.

PEN

Pen, here are the photos I promised sorry last night.

Note the dust!

Attachment 105744

Attachment 105745

Attachment 105746



All up to you mate.

Jeff

Thanks Jefferson.
I have made direct contact with Bill Pentz and he has referred me to this site:

http://www.cgallery.com/jpthien/cy.htm

I am seeking his ideas on the solution. Whatch his video on cleaning the floor!!!!!! Amazing!

Bill suggest I am going in the right direction but a baffle under the cylinder may be the trick.

Will let everyone know the outcome.
PEN

Well the modification is finally finished. It has taken so long I have nearly forgotten where it all started but it works and that was the main aim.

On buying the large pfc's the main goal for the modification was to restrict the amount of dust and waste that could go directly up into the pfc. I must admit I have experimented with a number of ideas and wish to thank all those fellow forum members that have contributed along the way.

I wanted to increase the cyclonic affect in the bottom plastic bag whilst also forcing all the waste into the bag.

I finally have adapted a plumbing product to produce the end result. Its called a Tornado Rainhead - http://www.tornadorainhead.com/
and is used in box gutters to dramatically increase the flow of water out of the box gutter and down the downpipe. Not cheap but a very good product.

In the demonstration setup Tornado had at Design Build in Sydney you could actually see the tornado type spiral at the centre of the waterflow and didn't it increase the water flow out of the box gutter. So if it works to increase water downflow in a pipe if inverted increase the air upflow upwards out of the bottom plastic bag of a dust extractor? The answer is YES!

A point to note with the setup is that area of the two outlets from the bottom bags up into the pfc's is slightly less than the area of the inlet pipe above the dust extractor fan. Due to that there is a slight initial build up of backpressure in in the bottom plastic bags. That slight build up of backpressure helps the creation of the cyclonic affect in the cone on start up and speeds up the exhaust of clean air up into the pfc. Thus the airflow inwards virtually equals the exhaust affect up into the pfc's. I tested the units before fitting the pfc's and the bottom plastic bags fill strongly and the airflow from both outlets is even and consistent.

So the original goal has been achieved. So now to the photos:

1 -Final manufactured units
2 - As above but showing the downdraft spiral
3 - As above
4 - Units set into the dust extractor rings
5 - As above
6 - A view from the underside of the dust extractor ring showing approx 100mm gap between the ring and the bottom side of the unit. A bit slack in that I didn't paint these.

Photos of the units in the development stage are in posts above by me.

The units are bolted to the rings using tags and the outer circumference of the units are siliconed to the dust extractor rings.

Again, thank you to all who contributed to the design with ideas and photos. Your help and discussion has been greatly appreciated and led to a successful oucome.


PEN

Interesting design PEN, so how well does it work?

Harry72,
Great so far. I am away for the next two weekends, but when back I will create some heavy chip and shaving flow using the thicknesser to really test it out.

I cut some chipboard waste when I fiished the installation and everthing was great. Before I started the saw I turned the dust extractor on and it sucked everything out of the line that hadn't been cleared out before. I have been using my 2HP single pfc/ single bag extractor on the saw whilst working on the modification. It is sure a step above the efficiency of that.

PEN

This is a very interesting thread to read, huge compliments to you all! It is just like the ongoing process of improvement and fine tuning of products as R&D departments undertake in machine factories. I once read James Dyson's book about his vac developments. This man has a good talent for marketing himself, but now and then he has some fresh ways of thinking.

His vac story starts of with a suspense story of him rummaging around on a junkyard at night to inspect the inner workings of a discarded timber shop cyclone. To his surprise it was simple and hollow, there was no intricate mechanism inside, obviously just centrifugal force and gravity were needed to separate chips from air. Dyson appreciated a cyclone's continuous non-clogging function and set out to build filterless home vacs with cyclones. Which was odd, since at same the time he did that, all around the world cyclones without exhaust filtering were starting to get banned from factory roofs because they blew too many fine dust particles into the air. All these industrial dry residu suction systems were moved into containments inside the factories, with cyclones for coarse separation plus extra stages for fine exhaust filtering. In the wood products industry, cloth bags are the most chosen solution. Pleated filter cartridges do a better (finer) job, but clog sooner and are far more difficult to clean. The sizes needed for 10-plus HP fans would be very big and expensive as well.

I inspected a Dyson vac on display in a store. Haha, there it was, the little filter, just before the vac motor's intake. So it wasn't filterless after all. And i also wondered; when these things are so brilliant, why don't cleaning contractors use them? You see conventional Numatic vacs with paper bags and cloth filters in school and hotels and shop floors and such, but never a single Dyson, let alone a fleet of them. So Dyson seemed to focus on the consumer part of the market and not on the pro's. Pro's on average are tougher to impress and to convince and the Dysons were definitely toy-like, with fancy "dazzle-designs" and kindergarten-colours. My sister is a design-type and fell for it and now owns one. Which i must admit is handy, since i could keep an eye on its track record of lasting performance; something you can't do on a shop display. As Dyson claimed, the small filter seldomly clogs and is washable. I checked it and he seems to be right.

When i looked at the whole machine, i got more respect for the Dyson-engineers. There are several stages of cyclones, one big one (collecting most of the dust) and systems of ever smaller one, responsible for finer filtering. When the air reaches the filter and the fan blades, there is hardly any fine dust left. And that, constructed in such a small package and at such high air velocities and vacuums (a multitude of that in a timber factory vac system), is no small achievement. It incorporates a lot of airflow knowledge and cleverly uses turbulence and air speed differences between changing orifice diameters. This achievement is somewhat similar to optimizing streamlined shapes in wind tunnels for F1 cars or impeller blade shapes or high speeds trains. The knowledge and experience that is exchanged between your posts, reminds very much of this. Brilliant stuff to read!

lots of success

gerhard

gerhard, interesting comments. Have you seen the Bill Pentz mini cyclone in action ( ClearVue) ? It seems that here in Australia we don't see many 'small' sized commercial cyclone /vacs as the ones that I priced where way expensive. But not so in the USA.

As posted earlier, I have been away for the last two weekends for work.

I did an exercise with the dust extraction setup last weekend just to test how well it actuall works. I used the dust collected in my workshop vaccum cleaner and a plastic bucket full of dust from my 2HP unit.

Pulled the sliding table on the saw back and slowly tipped two buckets of dust down th extraction shute under the blade.

As the dust reached the dust extractor you can see it spiral down in the botton plastic bag and settle on the bottom. As it is a twin bag setup there was an equal distribution in each lower bag.

Having done that and then let the dust settle, I rotated the pfc cleaning arms one full turn. I then unclipped one pfc and tipped it up to see what amount of dust was on the top of unit I had fitted to the dust extracton unit rings.

Very little indeed, not even enough to worry about using a small brush to sweep in the reverse direction up the spiral fitting and back down into the bottom plastic bag. I estimate that this will be a task that will need to be done say every 6 months now.

So I am happy with the outcome. It took a long time to complete because of other reasons, but all in all very satisfied with the outcome.

Thanks again to all those who assisted with photos and advice along the way.

Regards

PEN

Hi Gerhard

Very interesting story and analysis on dyson and cyclones.

If you read the consumer testing journals over a series of years, it seems that when they were introduced dyson had a significant efficiency advantage over the established vacuum manufacturers. Some have played "catch up" and now rank with dyson; others are still asleep.

Also interesting if you look at the office cleaning segment of the market. Thirty years ago it was dominated by large commercial stainless steel vacuum cleaners - frequently nilfisk brand. Now they have almost totally been displaced by small, light backback vacuums. As far as I can tell no one markets a backpack vacuum cleaner into the domestic market. That the professionals use backpacks for reasons of economy, speed, health and safety (especially minimising back injuries) seems to have bypassed the marketeers.

Cheers

Graeme