dust/chip extraction

[marcros]

I need to sort out some dust extraction for my planer (probably), thicknesser, and bandsaw in the near future. I appreciate that the first 2 produce chips, and the latter dust. All have 4" hoses. I have a lidl vac for power tools, but it only has smaller hose inlets.

What is the difference between the 2 main types that I see on ebay:

type 1 http://compare.ebay.co.uk/like/31051048 ... =64&ff19=0

type 2 is a shopvac type with a 4" hose http://www.ebay.co.uk/itm/SIP-01929-Wor ... 27d095622b

NB I have just picked these as typical- not specifically looking at either model.

I don't produce a huge quantity of chips at any given time- emptying it half way through a job wont be the end of the world. Ideally I would prefer that the extraction is not noiser than the machine that it is supporting. Can I usefully use either type for both dust and chips?

cheers
Mark

 

[Jelly]

This thread may be instructive: Clickity Click.

The basic gist is that fine dust is more effectively collected by a Low Volume High Pressure system, whereas chips and shavings are more easily collected by a High Volume Low Pressure system.

The bag type HVLP extractors fundamental limitation is that they will pass fine dust through the bags, making a tremendous mess in the process; hence why sanders in particular and other tools producing fine dust like cross-cut saws with fine cut blades benefit from the LVHP systems not unlike a normal vacuum cleaner.

 

[siggy_7]

The basic gist is that fine dust is more effectively collected by a Low Volume High Pressure system, whereas chips and shavings are more easily collected by a High Volume Low Pressure system.

The bag type HVLP extractors fundamental limitation is that they will pass fine dust through the bags, making a tremendous mess in the process; hence why sanders in particular and other tools producing fine dust like cross-cut saws with fine cut blades benefit from the LVHP systems not unlike a normal vacuum cleaner.

I'd agree with this general principle. The advantage of a LVHP system is that fine filtration doesn't cause a big drop in flow rate, because it can generate a high differential pressure across a fine filter cartridge. The disadvantage of these systems is that they max out at low flow rates, so systems that generate lots of chips or have big extraction hoods won't be well served (shrouds around thicknessers, table saws and band saws need a lot of airflow to move waste effectively because the flow areas are so large). They are great for power tools like routers though, where the extraction ports are small and the flow paths contorted.

LPHV systems by comparison excel on stationary machines with larger ports, but will be ineffective when used with power tools and collecting fine dust really needs an inertial separator such as a cyclone, which separates out waste from the airflow without a filter and hence avoids the big pressure drop you get across filters. Filter cartridges will rob you of the air flow rates that these extractors generate, and are generally still not as fine as the filters on HPLV systems.

The twin/triple motor HPLV systems offer a halfway house compromise, which have all the advantages of single motor HPLV extractors but with higher flow rates. You still won't get close to the flow rates of a decent LPHV system though. I have a twin motor Record which copes fine with a 10" planer/thicknesser; not all the chips are collected but it's probably as much to do with the extraction hood as it is the flow rates. It also performs acceptably on my table saw, although a substantial portion of dust isn't drawn into the shroud and instead comes up through the saw insert. I don't have a band saw but I imagine you would find similar issues there. HPLV systems are also very noisy because they all use brush motors and sound like big household vacuum cleaners (which they are). LPHV systems generally use induction motors and are quieter. Planers and thicknessers are loud tools anyway, but it will probably make a difference to you on the band saw.

Given that you have a smaller vacuum already for power tools, I would recommend you look at a 2hp LPHV type extractor and see how you get on with the fine dust which you can do something about later. I think the 1hp ones generally don't have enough flow for this type of system, despite their widespread availability.

 

[marcros]

cheers. i will look out for a 2hp lphv and look to put a cyclone on it. if that doesnt work, i could always swap the small vac for a larger version with 4" outlets.

If using it with a cyclone, do I need the whole extractor, with the 2 bags etc, or just the motor? i have seen some systems using an oil drum, and have read about blanking off the top bag in some cases.

 

[siggy_7]

The oil drum would be used as a drop box for the cyclone, which if the cyclone is any good should catch pretty much all the waste. You could probably run without the bags if you wanted to save the space, personally I'd leave them on.