Thread: Downdraft Sanding Station

What kind of dust collectors/vacuums are you using?

Originally Posted by Arfur

Any one have any suggestions about their effectiveness?
Our Mens Shed is about to undertake the annual total clean and in spite of having all the major equipment including fixed sanders connected to dust collectors there is still lots of dust. There are also suspended air filters which are catching plenty of air born dust.
Something to help at the source when using ROS or hand sanding might be worth a try and put a vacuum cleaner to additional use.
Thanks
Arfur

First get a serious assessment of your present dust extraction installation, pictures and what type of extractor would help.

As EJ and CP say we need to know what type of extraction/ventilation you are already using

Also, are your DCs inside your shed? If so, no amount of dust collection will help while they are inside.

Down draft tables can be very effective but require very high volumes of air flow.
The efficiency of teh table can be greatly improved by reducing the initial scatter of fine dust by use of a large cabinet or curtains around part or all of the table.

At our mens shed we have a very large capacity Evap AC unit.
The quickest way to vent fine dust from sanding is to run this (just the fan) and it clears the shed of dust in a couple of minutes and will easily keep up with a couple of power tools generating dust. I realize this method won't suit all setups especially in very cold weather.

I have the Delta down draft sanding station. When I use it, a 1½ HP dust collector is connected to the 4 inch port. The ROS has a ShopVac connected to the machine. The shop is a double car garage with the door open.

As for effectiveness, the garage door is always open. In all honesty I really don't notice any improvement over just the ShopVac connected to the sander. If asked would I purchase the down draft station again, the answer is no. The down draft station was reduced 50% and I had a coupon for 30% off. The effective price was about 25% of the original price.

For the money I could have made one with about 4x the surface area from a bit of plywood and peg board. If you can leave the dust collector running and connected while members are in the shed, I would encourage you to do so. If the application is for a single man shed I can only say that connecting / disconnecting the dust collector is a pain in the patotie.

In my shop and if I had to do it again, I would have made the table saw out feed table as the down draft sanding station. That way the sanding station would always be connected to the dust collector.

I have not made or used a downdraft table for woodwork but I have made and used a number of downdraft tables for use with acids and other chemicals in laboratories. Usually these are incorporated into fume hood cabinets but I have made several for open bench top operation. There is no mucking about with these tables - they have to work or everything in the lab corrodes including the insides of lab workers noses and lungs.

My experience is that an open top 600 x 600 mm down draft table requires very high air flows ( for WW that will be at least a 3HP DC with 150 mm ducting connection all the way through the DC) otherwise there simply won't be enough air flow into the table.

The holes should be of variable sizes with hole size and spacing depending on the inverse distance from the dust collection port. Some WW tables I have have seen have uniform hole size and spacing while others have the larger holes just in the middle (which are often covered up by the workpiece) and and only small holes at the edges. Neither of these are very efficient. Instead of holes long slots along the edges and a few smaller holes in the middle should be more efficient. But you need lots of air flow ie 1200 CFM.

One issue often ignored is that the sanding action and sander itself generates heated air and this will quickly carry the finest dust upwards and away from the reach of the air flow around the table. That is why a 4 sided fume hood style enclosure over the table is required to constrain and capture the finest dust. Given that he finest dust will stay in suspension for hours and early spread all over your shed, an additional extraction point above the table may be more effective - this will require even more air flow.

Originally Posted by Arfur

Any one have any suggestions about their effectiveness?
Our Mens Shed is about to undertake the annual total clean and in spite of having all the major equipment including fixed sanders connected to dust collectors there is still lots of dust. There are also suspended air filters which are catching plenty of air born dust.
Something to help at the source when using ROS or hand sanding might be worth a try and put a vacuum cleaner to additional use.
Thanks
Arfur

I have never seen a DD table that works outside of a full on commercial unit. Place something flat on it and the flow is reduced by the amount of holes covered. If you have the room and can dedicate a good high flowing dust extractor or large exhaust fan to the job I would build a sanding room to isolate all sanding activity, it wouldn't take long and wouldn't cost much. Build a frame then line it on the internal side with 3mm MDF, leave the MDF clear of the floor by about 10mm all round and have a bench inside with an overhead hood that has multiple outlets to a big extractor or exhaust fan and exhausts outside the building. The room does not have to be large and one wall might be two french style doors to allow for getting bigger stuff in. Then shoot anyone who sands outside. The reason I would line it only on the inside is to prevent any dust not captured from building up on the frame. It could have an external wall to cover the frame but if money is a concern then that can be ignored.

Metal working places often have dedicated a grinding/linishing/polishing rooms.

At the local vets hospital that was being decommissioned they had a workshop dedicate to making prosthetics. Our mens shed got access to take what we wanted from the hospital including this workshop.

As well as offices and what looked like a drawing room, a stock room, there were work specific rooms the biggest one about 8 x 4m dedicated to cutting, eg bandsaws, shears, benches etc. A second smaller room for welding. Then there were 3 smaller rooms (~2 x 2m) for grinding, sanding and polishing. In these rooms there were full faced pressurised air masks hooked up on wall pegs connected to a large external air compressor, and posters stating masks MUST be worn in this room.

The used a lot of SS strap so they were probably concerned about chromium dusts. The facility was exhausted by a 7.5HP DC. The metal dust trap was a rectangular bin about 1.2 x 1.2 x 600 mm high on cast iron castors and it contained ~ 300mm of metal dust. Two of could just move it.

Most of the welding/cutting/grinding gear was gone, there was one variable speed, 3 wheeled BS but it was too big to get through the door.
We scored a beaut welding bench with a 12mm steel thick top from the welding room, a bunch of stock and a heap of buffing and polishing wheels and sibs and bobs.

Thanks everyone, I think you have answered my question.

The shed has 3 large exterior dust collectors with self cleaning filters. They are permanently piped to saws, a lathe and an assortment of disk and belt sanders.
There are three suspended filters, two about beer barrel size and a larger rectangular unit.

Most of the ROS are fitted with filters.

I didn't appreciate how much air volume would be necessary to make a sanding station effective, thanks for the advice.

Regards

Arfur

Originally Posted by Arfur

Most of the ROS are fitted with filters.

As in those little bags that hang off the back? Or an actual vacuum?

Originally Posted by Arfur

Thanks everyone, I think you have answered my question.

The shed has 3 large exterior dust collectors with self cleaning filters. They are permanently piped to saws, a lathe and an assortment of disk and belt sanders.
There are three suspended filters, two about beer barrel size and a larger rectangular unit.

It sounds like you have a number of problems not necessarily related to the use of ROS
How big is the shed?
What size ducting is used - especially to the machines
Some photos of the piping , machines and Dust collectors might help to identify the probs.
Do the users remember to ensure teh dust collectors are turned on and have the right gates (valves) open?