Dust extraction systems.

[TRITON]

As we all know, its made up from lengths of tubing. But does it have to be round ?.

What I mean is these lengths are , imho, overpriced. So is there anything stopping me/us from making square ducts using something like 12mm mdf. Easy enough to cut in a hole and fit a plastic insert for take off to specific machines/etc

 

[Doug B]

The very old workshop I first worked in had ducting made from timber & ply, I don’t remember it being supper efficient but then I am going back 40 years, I guess one of the main draw backs would be keeping the inside surfaces perfectly smooth so as to avoid blockages, but as long as it’s sealed well it should work.

 

[Inspector]

It is occasionally done. I'm likely going to go that route myself as big ducting is expensive here too.

Dust Extraction Don't use the pair of hoses from the DC to the duct. More flow from a single large.

http://www.lorencook.com/PDFs/Catalogs/Cookbook_Catalog.pdf At page 53 you get the information on fitting drag in the form of strait duct equivalence. Add up every fitting and length of duct and it tells you how much drag the system has. Flex hose has three times the drag of smooth duct so if you use some triple the total length for each piece.

Duct Friction Loss This one is in imperial measurements and calculates losses in inches of water. You'll have to convert the inputs and result to metric if you prefer that format. Use half the airflow claim of your DC in order to get realistic results. The calculation will have to be done for each type of duct and added to get the results if you are changing duct sizes and using hose for sections of any length. The loss results of a set of calculations can't get close or exceed the static pressure your DC can produce or it won't work properly. A useful way of playing with different sizes and shapes of ductwork. You can also do the same with the equivalent round dust to understand how much difference the losses of the two types have.

The Generic 2HP DC A link to an Aussie forum that has the best dust collection information and this is how a 2 hp DC like yours can be modified to get the most performance.

ESD Floor Finish - 1 Gallon Bottle S-22449 - Uline A product like this will dissipate static electricity in your system better than running wires over, under, around and through the ducting.You'll want a finish anyway. It is used in computer rooms and benches to prevent zapping delicate electronics. You should have equivalent products in your country.

Tempered hardboard (masonite) has a smoother surface and 1/8" can be bent into the radii needed and either laminated to make thicker or used to line the MDF.

Pete

 

[Jameshow]

Would it make sense to increase the size of the tube to 150mm sq thus increasing volume and reducing losses.

 

[Inspector]

With an increase in volume you have a decrease in velocity which may lead to the dust dropping out of the airstream if the system is marginal. The first link in my reply (post 3) has a link to a chart of round to rectangular equivalents. Best to go that route rather than guesstimating.

Pete