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Duct Guardian – Grille (plenum) Box fitting


When designing ventilation systems it must be remembered that since most of the ductwork is installed within ceiling spaces, it is a good idea to liaise closely with the Architect at the early stages of design so that space requirements are met.

Figure 1 below shows a typical balanced ventilation system layout. One method, which can be adopted, is to run main supply and return ductwork in the ceiling space above corridors and the branches into adjoining rooms.

Ceiling heights in corridors may be lowered to accommodate larger ductwork.

It is common practice to use flexible ductwork to grilles and diffusers. These have several advantages; sharp bends are eliminated, flexible ductwork has better sound adsorption qualities compared to sheet metal, it is easier to install especially in a congested area and it allows more freedom in positioning the grille or diffuser.

A grille (plenum) box can be used to connect the ductwork system to the grille or diffuser. This has a larger cross sectional area than the connecting duct and reduces the air velocity before it enters the diffuser thus giving better air distribution over total diffuser area. A less expensive method is to use diffusers with factory-fitted square or round necks, which can be fitted directly to the flexible duct connection.

Each grille or diffuser should have a damper to regulate flow of air. This damper can be an opposed blade type incorporated within the diffuser or a butterfly volume control damper (VCD) positioned in the branch duct. All dampers require access.



Duct Guardian – Radius Elbow +ruters (turning vanes)

Turning Vanes and Duct Elbows

Recently, someone asked me if it made sense to add turning vanes to a radiused elbow.  That’s one of those questions where there is no exactly a right answer that applies for every situation. The impact of the turning vanes has a lot to do with both the geometry of the fitting and the velocity of the air moving through it. To gain some insight into this, lets consider a 12” square elbow with a 12” centerline radius (i.e. the centerline radius is equal to the duct width) like the one pictured below.

See more ->














Duct Guardian – FREE ventilation fittings creator

“Duct Guardian” is a sheet metal program that calculates flat (unfolded) sheet development of ducts, rectangle to round transitions, cylinders, cones, pipe intersections, connections, bifurcations, elbows, etc. For HVAC, hoppers, cyclones, dust extraction, ducts, conveying systems, silos, piping, etc.

Steps of use:

First select the 3D surface you want to unfold.(You can select: either inside, outside, or mid cross sectional dimensions and / or height specifications; to draw or not the 3D surface, and the unfolded sheet as a mesh [to help you when bending the sheet] or as 2D contour [to ease cutting]; the precision of the calculation of the developments).Metric Units / Imperial units: the program automatically sets the units according to the units used in the current drawing session. After finishing the input of parameters, the program draws the 3D object and the respective development.

Some common fittings:  Square to round, Radius branch, Radius offset, Cylinder, Cone:





















– one piece seam calculation

– limited bend position markers

– database sample

– 14 free fittings



Some ‘Duct Guardian’/’DG Nest Pro’ fittings examples and layouts nesting:





Automatic Nesting and Automated Nesting — Smart Shoppers Know the Difference

Many people do not release the difference between Automatic and Automated nesting functionality.
Before we start with nesting software comparison you can read good article on this blog:

Full text: Automatic Nesting and Automated Nesting – Smart Shoppers Know the Difference

Whenever user have to manual manipulate with nested parts (after algorithm computation) to
optimize nesting layout to maximum, we can say that it is about Automated process of nesting.
Maybe someone think that he will do easy job of manual optimization after Automated nesting,
but it is not so simple as expect.
A lot of people do not understand why good algorithm consume more time when struggling
to save every inch of material. The time required for algorithm calculation to increase
usable area (decrease scrap) growing exponential for every inch.
When some nesting software do nesting operation and perform nesting layout in a few seconds, that
indicate that implemented nesting algorithm does not consider all possible parts placement


Take a look on some nesting software comparisons at the same sheet sizes and parts (you can download these software from many
‘software download’ sites and try by yourself). We named these software as ‘X’ software.

In this case of X1 software we can see that fast nesting in few seconds produce array of parts as result :

Unlike nesting from the first X1 software, DG Nest Pro produce true shape nesting (nesting time 18 seconds) and approx. 15% better result in saving material:



Good automatic nesting software produce usable empty space on the right side of the sheet which is not the case with first image. User expect that nesting alignment have to be on the left side of the sheet. Again parts are not coherent and there is a lot of nesting gaps. This example shows less efficient (automated) nesting produced by X1 software:

On the other side DG Nest Pro produce coherent nesting layout with approx. 25% better result:

 DG Nest Pro produce coherent nesting layout with minimal gaps. We try to nest more examples with X1 software, but it often breaks down. Software stability and price are also went in favor to DG Nest Pro.




Let’s see how works another nesting software named X2:

X2 software produce fast and solid nesting layout, but it does not produce strait nesting area margin – comparing with DG Nest Pro nesting layout. X2 software has a problem with reading non closed dxf part contours so few parts was not nested.



In this case DG Nest Pro nesting area width is 160 mm smaller than X2 software nesting area with few parts more than X2 software. Real true shape nesting software produce minimal scrap material and produce rectangular ‘waste’ sheet suitable for stock storage.



Many of X software shows excellent performance when work with part duplicates, they behaves as array/rectangular nesting software. The power of true shape automatic software can be felt only with many
different shaped parts without duplicates. When you test nesting software, test it with many different shaped parts (irregular polygons), but without duplicates, also do test with enough number of parts
to fill out full sheet area and half sheet area to test nesting area right margin.






‘DG Nest Pro’ – Scrap sheet multi nesting on 500 parts! Material usability are increased on incredible 95-98%

This is example of multi dimensional scrap sheets/multi nesting with 500 parts.
You can draw your own contours and move your scrap sheet over virtual table.
Drawn contours are saved in database and waiting for right moment for use.
Material usability are increased on incredible 95-98% !


Scrap Nesting Example

Multi dimensional sheets – automatic nesting (1000 parts at 12 different sized sheets)



Multi-sheet automatic nesting with multi-dimensional sheets!

DG Nest Pro allow automatic nesting one by one sheet or multi sheets
nesting (all parts and sheets at one task).
For multi dimensional sheets just chose ‘Multi nesting sheet dimensions’ in
Settings menu and fill the list of sheets.
This image show 400 loaded parts and 4 dimensional sheets with different quantity.

DG Nest Pro / SheetCAM collaboration



Cut simulation


‘DG Nest Pro’ SheetCAM module in cut simulation action:




“DG Nest Pro” SheetCAM module support aprox. 180 post processors (G-code dialects)!


-Plasma, laser, waterjet and oxy fuel cutting-

SheetCAM  module has many useful features for plasma, laser, waterjet and oxy-fuel cutting.

For machines that have full control over the Z axis you can program the pierce height and cut height directly. This is useful for machines running Mach3 for instance. SheetCAM module combined with Mach3 and a torch height controller from CandCNC for an unbeatable plasma cutting solution.

The tool definition allows you define all of the important parameters for cutting. You can define as many tools as you like for different materials etc.

Kerf width. Draw your part the size you want and let SheetCAM module work out where to run the torch.
Automatic cut ordering to ensure that inside contours are always cut before outside contours.
Oxy-fuel preheat time.
Pierce delay time.
Optional ramp piercing. Instead of plunging straight in, the cutter torch can ramp in, reducing the amount of material blown back into the torch. This increases consumable life and reduces faulty cuts due to blocked or obstructed nozzles

Once you have defined you tool you can set up the cut. SheetCAM module gives you many options to optimize cutting.

Here is an example part. SheetCAM module automatically works out the holes are inside so it reverses the cut direction for these features. The holes would also be cut first. As the small holes are too small to fit a full sized lead in and lead out, the leads are reduced in size to fit. To prevent corner rounding, the corners can be looped.



This is a full list of supported post processors:

AB tube cutter
Allen Bradley 8400
Amada laser
Amada laser2
ANCA laser
Biesse Rover XNC
Biesse Rover
Bosch CC100 router
Bosch CC100
Bridgeport 32dx
Bridgeport V2XT
Burny25 inc
Burny5 inc with plate marker
Camsoft plasma
Delta Tau waterjet
Denford PCNC
DeskCNC plasma
Dyna DM2100
Dyna DM2400
Dynapath conversational
Dynatorch no feed
Dynatorch router
EaziCNC plasma with THC
EaziCNC plasma
EMC -Laser post-plasma mod
EMC lathe
EMC plasma – laser
EMC plasma
Esab vision 1000
Esab vision 3pos
Esab vision 500
Esab vision
ESSI noarcs
Fagor 8025M MotionMaster Router
Fagor Router PAUL-FINAL-Z
Fagor Router
Farley Rapier
Flashcut plasma no Z
Flashcut plasma
Flow omax ord
Generic plasma with optional scriber
Gerber Sabre
HAAS TM-2P inc arcs
HAAS VF3 inc arcs
Heidenhain TNC150 conversational
Heidenhain TNC150
Heidenhain TNC530 conversational
HPGL no arcs
Hurco Ultimax
Hypertherm edge
Hypertherm Microedge
Isel RG5996
Kinetic Touchcut
Linde CM350
Mach tube cutter
Mach3 2 heads
Mach3 2D
Mach3 flame with THC – G31
Mach3 G42 experimental
Mach3 plasma no Z
Mach3 plasma pauses
Mach3 plasma Rutex
Mach3 plasma
Mach3 tangential 180
Mach3 tangential with 3 heads
Mach3 tangential
Mach3 THC with scriber
Mach3 XCZ
Mazak L32B
Minimum G-code abs arcs
Minimum G-code no arcs
Minimum G-code non-modal
Minimum G-code
Mitsubishi laser
NC studio
NUM laser
NUM laser3
NUM plasma
OSAI plasma
Picopath inc
Plasma THC300 – G31 – corner slowdown
Plasma THC300 – G31 – lift for delay
Plasma THC300 – G31
Plasma THC300 forceheight
Plasma THC300 start marker
Plasma THC300 with scriber
Plasma THC300
Plasma with plate marker
Prototrak Edge
Quickstep plasma v2
Quickstep plasma
Roland CAMM3
Sentrol2 Plasma
Shopbot plasma
Shopbot reversed Z
Siemens laser
SteelTailor inc arcs
TeknoThc 160V2
Thermwood 2 heads
Torchmate plasma THC
Torchmate plasma V2
Torchmate plasma
Tormach Inch RG-G
Trumpf L250
Trumpf TNG
TurboCNC non modal
TurboCNC V4 with G83
TurboCNC V4
WinCNC Plasma THC
WinCNC Plasma V3
Woodstep Ima
Xilog fixed exp
Zinser CNC920