Thread: All in one workbench / dust separator / dust collector

If you are using this bench outside I would just buy a big pedestal fan and run that when you are using it. It will be reasonably effective and save you a lot of money and headaches.

Very tempted to go that way... but I would like to collect the dust if possible simply to save the large amount of time I spend sweeping up after every time I use the power tools.

Until early next year I am in a rented split house, so I need to consider my immediate neighbour for mess and noise. There is concrete everywhere, so I cant even hide the mess in the grass.

So for the time being collection is a better option, even if it doesn't offer the greatest dust protection.

Putting the filter aspect aside for a moment, what do you think of the idea of making the work bench into an all in one?

Originally Posted by HeadScratcher

Very tempted to go that way... but I would like to collect the dust if possible simply to save the large amount of time I spend sweeping up after every time I use the power tools.

Until early next year I am in a rented split house, so I need to consider my immediate neighbour for mess and noise. There is concrete everywhere, so I cant even hide the mess in the grass.

Fair enough.

[quote]So for the time being collection is a better option, even if it doesn't offer the greatest dust protection.[QUOTE]
If you just want to collect sawdust then a cheap vacuum cleaner (VC) or DC is all you will need, the invisible stuff goes straight through these but being outside it would represent a reduced risk and being invisible the neighbours won't see it. I would punt for a cheap DC over a cheap VC. The DC might not pickup quite so much of the chips from a power tool compared to a cheap VC but the DC can be used later inside a shed and easily vented outside the shed. A VC cannot effectively vent a shed.

Putting the filter aspect aside for a moment, what do you think of the idea of making the work bench into an all in one?

I would find it too restrictive. For me benches are for safe storage of valuable or dangerous stuff but of course your rationale may differ.

A few things to bear in mind
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Small cyclones and trashcan separators rob more sucking power from a DC than small bag type filters.

A small std 30 micron clean bag uses 2.5" pressure whereas small cyclones require 4.5" of pressure.

When the small bag gets dirty then the pressure required can increases to more than that required for a small cyclone.

Small cyclones will filter to better than 30 microns but if you are venting outside (depending on how close your neighbours are) it doesn't really matter.

Small are useful for people who do not want to clean bags.

Larger well designed cyclones require about the same pressure as std bags but of course filter correspondingly much better than bags.

Ok lets give the idea a bit of proportion... This is what the individual items look like by themselves. Now remembering that I can get the work bench in the garage and little else.

The DC in the picture does down to 5 micron so that should be a reasonable level of filtering. Carba-Tec® 2hp Economy Extractor : CARBA-TEC

Moves 1200 CFM of air, has 2HP, and weighs 47 Kgs (need to move this in and out of shed every time)

In that case I would forget the cyclone, leave the DC as is and get a outdoor gas heater cover or double mattress plastic bag so you can cover and leave the DC in one piece and outside.

BTW when connected to a real system that DC will not move 1200 cfm even with 6" ducting

Here's a rough idea of what it might look like as an integrated unit. I have used the same images as in the first post, but rearranged then to show that nothing would have to be drastically reduced, just remade.

The intake would be roughly 1-2 feet long from the hole in the table to the cyclone and could be as big as would practically fit (possibly even bigger than 6"), and the DC pump would sit at the wheel end of the workbench, so there would be a lot of mechanical advantage when lifted via the handles.

Because the cyclone would extract the bulk of the sawdust a smaller collection bucket could be used and the filter would stay clean longer, mean less cost and a longer period where it filtered better...

When finished the filter could be put on top of the table and wheeled inside.

Could also line the cabinet with some acoustic dampening material to keep the noise down and keep the neighbours happy.

If you are outside and determined to use the cyclone you won't need a filter.

If you plan on using the filter then I don't see why you need to use the cyclone. OK it will keep the filter clean for longer but at the cost of reducing the DCs maximum sucking power. The under bench design also seriously aerodynamically compromises the DC flow because the connecting ducting bends will be too tight. Ducting radii of curvature of the bends should be a large as possible, at least 2.5 x the diam of the pipe i.e. for 150 mm pipe it should be 375 mm.

What's wrong with leaving the DC outside? You can chain it to a big block of concrete if you are worried about it being nicked.

I am also trying to plan for down the track as well, so while I am currently outside that hopefully won’t always be the way.
But down the track there is a good chance that the filter section will reside outside of the shed, preferably not the motor and pump which will be more susceptible moisture damage even if covered up.
A two second redesign and I believe I could do away with any need for either top entry and exit points, allowing better use of the height.
This is a basic concept that might be used. It would still use the basic principles on the Thien design but both entry and exit would be via the side.

Originally Posted by HeadScratcher

. . . But down the track there is a good chance that the filter section will reside outside of the shed, preferably not the motor and pump which will be more susceptible moisture damage even if covered up.[/FONT]

I wouldn't be concerned about external location, I've had DC's outside for 5 years without any problems. Ask Sydney members if they have had any probs.

A two second redesign and I believe I could do away with any need for either top entry and exit points, allowing better use of the height.

Those 3 tight 90º flex bends are going to soak up a lot of unnecessary pressure.
With externally located DC's, all that is needed is an an unrestricted straight run to the DC as possible and avoid flex wherever possible.

Redid the table closer to scale... After a bit more designing I can do the outlet with only one 90 degree bend and with shorter pipework (less than a meter) to the DC, which should keep the negative pressure / flow higher in the cyclone. Only problem at the moment is working out a way to empty the tray below.

Originally Posted by HeadScratcher

Redid the table closer to scale... After a bit more designing I can do the outlet with only one 90 degree bend and with shorter pipework (less than a meter) to the DC, which should keep the negative pressure / flow higher in the cyclone. Only problem at the moment is working out a way to empty the tray below.

This design wont work, dirt will build up around the outlet pipe in the upper section and flow into the fan unit. There is no need for the baffle if you are making a cyclone. Colin Thein designed the baffle for commercial chip separators, their design caused the dirt to be sucked into the vacuum when they were about quarter full.

The fan unit doesn't have to be vertical, it can be mounted directly above the cyclone removing any bends in the airflow. The inlet to the cyclone is positioned to cause the airflow in the cyclone to be in the same direction as the fan rotation.

The design isn't complete as it is missing the hat that would go on top (think hat on chimney) should stop any direct dirt entering. The more I look at it the more I am thinking that the fan shouldn't be in the work bench either. Quickly losing the appeal of an integrated solution leaning back towards separate components. But that is the point of the thread just to kick the idea around.

Originally Posted by HeadScratcher

Quickly losing the appeal of an integrated solution leaning back towards separate components. But that is the point of the thread just to kick the idea around.

Leave work bench as is, maybe provide downdraft function - ie slots in work top with collector hood underneath. Create separate module that has DC and DS that can connect to WB.

Originally Posted by HeadScratcher

. . . The more I look at it the more I am thinking that the fan shouldn't be in the work bench either. Quickly losing the appeal of an integrated solution leaning back towards separate components. But that is the point of the thread just to kick the idea around.

Threads are good for that but also nice to see you are prepared to change your mind.