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3.
Directional changes should be kept to a mini-
mum. The more directional change fittings
you use directly increases the overall resis-
tance to airflow.
4.
Gradual directional changes are more effi-
cient than sudden directional changes (i.e.
use the largest corner radius possible when
changing hose or pipe direction).
5.
Each individual branch line should have a
blast gate immediately after the branch to
control suction from one machine to another.
6.
The simpler the system, the more efficient
and less costly it will be.
Step 4. Determine Required CFMs
Since each machine produces a different amount
of sawdust, the requirements for the minimum
amount of CFM to move that sawdust is unique
to the machine (for example, a planer produces
more sawdust than a table saw). Knowing this
required CFM is important to gauging which size
of duct to use.
Refer to the Figure below for a close estimation of
the airflow each machine requires. Keep in mind
that machines that generate the most sawdust
should be placed closest to the dust collector.
If the machine has multiple dust ports, the total
CFM required is the sum of all ports.
Machine
Dust Port Size
2"
2.5"
3"
4"
5"
6"
7"
8"
9"
10"
Figure 40. Approximate required airflow for
machines, based on dust port size.
Model G0440/G0441 (Mfg. Since 03/12)
Approximate
Required CFM
98
150
220
395
614
884
1203
1570
1990
2456
If the machine does not have a built-in dust port,
use the following table to determine which size of
dust port to install.
Machine
Table Saw ...................................................... 4"
Miter/Radial-Arm Saw ....................................2"
Jointer (6" and smaller) ................................. 4"
Jointer (8"-12") ............................................... 5"
Thickness Planer (13" and smaller) ............... 4"
Thickness Planer (14"-20") ............................6"
Shaper ........................................................... 4"
Router (mounted to table) ..............................2"
Bandsaw ........................................................ 4"
Lathe .............................................................. 4"
Disc Sander (12" and smaller) .......................2"
Disc Sander (13-18") ...................................... 4"
Belt Sander (6" and smaller) .........................2"
Belt Sander (7"-9") ........................................3"
Edge Sander (6" x 80" and smaller) .............. 4"
Edge Sander (6" x 80" and larger) ................ 5"
Drum Sander (24" and smaller) ............... 2 x 4"
Drum Sander (24" and larger) ................. 4 x 4"
Widebelt Sander (18" and smaller) ................ 5"
Widebelt Sander (24"-37" single head) ...2 x 6"
Widebelt Sander (24"-51" double head) .. 5 x 4"
Figure 41. Dust port size and quantity per
average machine.
Write the required CFM for each machine on your
sketch, as shown in the figure below.
Jointer Sander
Planer/
Moulder
395
Miter
Saw
98
220
Shaper
Table Saw
Figure 42. CFM requirements labeled for each
machine.
Average Dust Port Size
395
790
Dust
Collector
395
614
Planer
-29-
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