I already wrote about ‘DG Nest Pro’ scrap nesting feature but these days a new SheetCAM project named
Scanything inspired me to add a new feature into ‘DG Nest Pro’ which is a variation on a theme.
The first idea how to increase material utilization it was to remember material edges and (inside holes)
after nesting/cutting, and save scrap geometry into database (also save the physical scrap material into
When fabricator has many small parts he can use this scrap sheet from the stockroom, put on table, open
virtual scrap sheet in ‘DG Nest Pro’ with the corresponding ID (from database) and do nesting on it.
It was a case where we know exactly what we currently cut, but what can we do when we have not saved
the geometry in ‘DG Nest Pro’?
There is two scenarios. The first one is case if we have saved dxf layout of some part somewhere in
computer, we can open that dxf file, save it as a scrap irregular sheet into database, open and nest
smaller parts over it, and that is a new feature in ‘DG Nest Pro’.
Unused irregular parts in stock can be used as irregular sheets, saved via corresponding dxf into
irregular sheets database, after saving dxf’s geometry we can open scrap sheets and do single or
The second scenario is more acceptable, fabricator can simple put part on cut table, do scan of part
contours via SheetCAM Scanything module, save as dxf file, open this dxf and save as irregular sheet
in ‘DG Nest Pro’.
Now the fabricator can easily nest on every possible irregular shape in stock:
VENTILATION SYSTEM LAYOUT
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.
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.
“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:
FREE VERSION LIMITATIONS:
– one piece seam calculation
– limited bend position markers
– database sample
– 14 free fittings
Some ‘Duct Guardian’/’DG Nest Pro’ fittings examples and layouts nesting:
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:
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% !