Dust Collector Shavings Extractor

By Keith Jeeves
Sydney Woodturners Guild

A dust collector is essential in a woodturners workshop to keep fine sanding dust under some sort of control. The dust collector can also be used as a vacuum cleaner for removing shavings from the workshop. A simple cloth bag type is quite adequate for sanding but has problems when used as a shop vacuum cleaner.

The inlet to the dust collector is fitted with a guard to prevent large objects being drawn into the fan and causing damage but when sucking up shavings, the guard rapidly becomes blocked requiring frequent removal of the hose and clearing of the inlet duct. Wet shavings are much more prone to blocking the duct than dry shavings but both cause problems.

For a number of reasons, vacuum cleaning is preferable to brush cleaning for cleaning up the shop;

Chips tend to get amongst stored wood and equipment where a brush cannot easily reach
Tools and pieces of equipment get dropped in shavings and are sometimes difficult to spot when sweeping and they get thrown out. A vacuum cleaner will pick up the shavings and leave more solid objects behind where they can easily be recovered.

An industrial dust collector is often fitted with a cyclone which will separate the heavier particles from fine dust but is not a practical proposition for a home workshop. If a simple shavings extractor could be devised which prevented shavings from entering the dust collector inlet duct, the device would be much more useful. It would not matter if some dust remained with the shavings as long as the shavings were kept out of the dust collector inlet.

After a little experimenting, a very effective separator was built comprising a plastic garbage bin with 2 PVC plumbing type pipe flanges fitted into the lid. One flange was piped to the dust collector and the shop hose was fitted to the other. The dust collector draws a vacuum in the garbage bin which, in turn, draws air from the shop hose. Any heavy material entering the bin immediately drops to the bottom but fine dust remains airborne where is is drawn out by the dust collector pipe and ends up in the collection bag in the normal way. Almost no shavings are transferred from the shop hose to the dust collector hose unless the bin is allowed to fill towards the top. As a bonus, it is much easier and less messy to empty the garbage bin than the dust collector collection bag.

The general arrangement is as follows - the sketch should be self explanatory;

Points to be aware of when building the separator are

A garbage bin is not intended to be airtight so a foam rubber strip needs to be fitted between the bin and its lid to prevent entry of air. The seal does not have to be perfect but should be good. The lid clamps will tend to distort the lid when tightened down against the foam strip but can be bent to give less clamping pressure. By putting foam strip around the outside of the bin, between the side of the rim and the lid, a good push fit can be achieved which will not require use of the lid clamps at all.

The pipe flanges can be fixed with either silicon sealant or hot melt glue. Rough up the surface a bit before applying the adhesive.

The hoses will probably not be a good fit into plumbing type pipe flanges and purpose made flanges which will provide a snug fit are quite expensive. The fit can be improved by wrapping PVC insulating tape around the end of the hose or by permanently fixing the hose into the flange with sealant or hot melt glue.

The bin should not be allowed to become more than about three quarters full. If overfilled, the dust is held by the shavings and does not transfer to the dust collector hose and shavings will be picked up by the dust collector hose where they will find their way into the dust collector inlet.

Although some loss of air flow at the end of the shop hose occurs, the loss is surprisingly low. If it is important to have maximum available air flow at the sanding area, a separate length of hose connected directly to the dust collector can be used during sanding.

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Dust Collector Shavings Extractor

By Keith Jeeves Sydney Woodturners Guild

By Keith Jeeves
Sydney Woodturners Guild