Thread: Airtight joint?

Can you physically move the DE outside when you are working? Just a thought.

I use clear packing tape for both the lower bag and pipes.

The lower bag is held in place with a few rare earth magnets, made tight, except for one fold to remove the slack, then the tape is carefully applied in 30cm strips around the top with a half overlap. The magnets are removed as I go. The metal strap is then put on to add some reinforcement.

The pipes are the same. The clear packing tape tapers nicely to fit into the groove and when wound carefully over the grey pipe and onto the metal forms a perfect seal. You can see this for after a bit of use the ultra fine dust builds up on the inside of the tape

Where did you get the 1 micron PF?

Cava,
I do use it outside but dust can drift back in depending on weather. Just seemed a waste having a nice filter and having dust from other parts.

woodPixel,
I am liking the bungee cord for the bag looks to do the trick.
Was sort of looking for something other than tape as I have it taped for now. Perhaps I'll look for some smooth walled pipe or something.
Filter came from Hare and Forbes BTW. Its a carbatec machine but I find H&F better to deal with. Just check the diameter of the drum before ordering. Got 10 plastic bags with the deal also.
Regards
John

Your example highlights the problem for all DCs and VCs.
Unless a particle counter is available AND used on a regular basis only visible dust can be monitored, and remember it's the dust you cannot see that is the problem.

When you say your DC is used outside, if the major opening for air to enter the shed is on the side of the shed opposite where the DC is located the amount of dust that come back into the shed should be very small. Dust and air that goes through a DC is warmer than ambient air and should rise away from a shed. If dust is drifting back into the shed then your opening to the shed is too close to the DC.

I see a lot of effort going into filter and collection bag seals but I also see a lot of leaky plastic collection bags being reused, whereas they should be re-placed.
If you can vent or locate a DC outside, complete sealing of a DC is not necessary and neither are high efficiency filters.

The manufacturers efficiency ratings of DC filters seems to be as variable as the claimed flow rates.
A figure like a 5 micron or 1 micron filter is meaningless unless accompanied by an efficiency rating.
I have only tested on H&F filter and it was 70% efficient at 1 micron.
It took many hours of condition to get it t o clog up a bit to reach about 90% efficiency.
This is good and not so good - good showing they don't clog as quickly as bags but bad if you use it inside a shed.
All new filters look good for a while but lets see what happens in 12 months time.

Originally Posted by BobL

Your example highlights the problem for all DCs and VCs.
Unless a particle counter is available AND used on a regular basis only visible dust can be monitored, and remember it's the dust you cannot see that is the problem.

At $2000 to $3000 I don't think the average hobbyist woodworker would have one handy and I would be reasonably confident in saying that a high percentage of Men's Sheds and even professionals would be in the same boat.

I tape all my joints and keep the extractor outside.

I must admit that I have been giving dust collection a lot of thought lately, and have come to the realisation that I may have gotten it wrong.

My latest thoughts are to have a sawdust/chip collector before the motor, to collect visible detritus and the motor venting invisible dust outside the shed without additional filters/bags etc into ambient air.

A crude example could be a 44 gallon drum setup as a cyclone/thien coupled with an impeller motor venting through a wall on the opposite side of the shed to door/window openings.

The downside is potential noise considerations for neighbours in suburbia - fortunately I am on acreage, however noise can travel further in some situations.

Orraloon, not wrong about Carbatec being hard to deal with. Every enquiry is a trauma. They seem systematically incapable of answering a straight forward question. H&F and incredible... Not only is the query instantly answered, but they ask for the order and ship it immediately.

With the filter, is it the ones on their website? I've been thinking about a 1200mm tall one as part of my upgrade.

Lappa you can get a partical counter that will give you an idea of what is going on in the shop and it's only about a tenth of what the certified ones cost.

Air Quality Monitor $199

Pete

Well getting the impression most of you use tape on the positive pressure pipe joints so until I can find something better tape it is.
I realize there is never going to be zero dust escape from the thing on this level of investment but wanting to make it as good as it can be. Have the next door house very close to my drive where the dusty sits when used. Dont want to be pumping too much at them if I can help it.
BobL,
Are you saying that I should let the filter clog up a bit and it will filter better? If so I'll go easy on the flapper handle. Feel another learning curve coming on.
Regards
John

Originally Posted by orraloon

BobL,
Are you saying that I should let the filter clog up a bit and it will filter better? If so I'll go easy on the flapper handle. Feel another learning curve coming on.
Regards
John

Correct.
The bit below only applies if you are using the DC inside a shed

The filters are actually designed to work correctly at filtering fine when they are slightly clogged. This is called filter conditioning.
Before they are conditioned the filers will let a surprising amount of one dust through the filter
On a thick needle felt bag it takes about 20 minutes to condition while on on a thin needle felt bag and pleated filter it can take a couple of hours.

The quickest and safest way to do this is to
- put the DC outside
- tip or suck up a bucket of sawdust into the DC
- let the DC run for the times listed above.

This embeds very fine dust into the filter itself and helps the filter to filter more dust.

With a pleated filter, once conditioned, moderate use of the flapper handle won't remove the conditioning dust. However, if you do it too vigorously the conditioning dust will start ro be removed.
With a felt or cloth filter moderate flapping of the filters should be OK but vigorous flapping or washing the filters will remove the conditioning dust.

If the DC is used OUTside the shed Vigorous flapping on a regular basis will sustain increased air flow for longer.

Thanks Pete.
the only Dylos unit I could find in OZ was from ClearVue AU and it was the Pro version at close on $400. Unfortunately the monies are allocated to my shed sub board which should have gone in this week but was put off due to the rain, then more rain, then more rain etc. etc.
Also, in my mind, it would be better spent on other more useful woodworking machinery.

A few folks have asked me about the dylos unit and I tell them to save their money. I equate them somewhat to exercise bikes - fun for a few weeks but unless used on a long term regular basis of little benefit.

As well as having limited sensitivity and restricted particle size range, like all particle counters they don't just measure wood dust - they measure a restricted size range of ALL dust particles.
This means the wood dust component has to be untangled from each measurement but of course they don't tell you how to do this because its much trickier than it first appears and if they told you that you would need to use a stats package or a spreadsheet most people would not buy them.
They do provide some useful information in the hands of someone that knows what they are doing and has a feel for the overall dust problem, but most novices use them incorrectly.
For example, local changes in the weather, traffic and industrial activities can dramatically change results.
There are a lot of people buying them in the US for use inside houses and they end up making very expensive decisions about this and that with no proper reasons.

There better and more forgiving units out there for novices to use with more definitive results but unfortunately they are in the thousands of $ price range.

The main reason for not getting a particle counter is that to really benefit from these devices one has to collect a lot of data, over and over and over again in a systematic fashion. WAY MORE DATA is needed than most wood workers have the stomach and patience for, especially when they would rather be doing woodwork. This is best left to nutters like me who were expensively trained with your taxes in these measurement methods , who have the necessary working background/experience, and who don't mind doing the measurements.

Originally Posted by BobL
Your example highlights the problem for all DCs and VCs.
Unless a particle counter is available AND used on a regular basis only visible dust can be monitored, and remember it's the dust you cannot see that is the problem.

Originally Posted by woodPixel

Orraloon, not wrong about Carbatec being hard to deal with. Every enquiry is a trauma. They seem systematically incapable of answering a straight forward question. H&F and incredible... Not only is the query instantly answered, but they ask for the order and ship it immediately.

With the filter, is it the ones on their website? I've been thinking about a 1200mm tall one as part of my upgrade.

Sorry I must have skimmed by your question
Yes from the website. I figured as the carbatec and H&F machines look to be about the same it would work fine. Important that the diameter mesurement is the same as your drum.
Getting more airflow now than with the cloth bag. Can see the dust swirl faster in the lower bag.
Regards
John