Designspark Mechanical tips

 

Resizing Solids

Creating a new solid is quick and easy using the Sketch and Pull tools. Once a shape has been created, it can be resized with reference to the original dimension. In Figure 1, when some simple cylinder shapes were originally created, the right-hand cylinder was 25mm tall. This can be reduced to 20mm by clicking on the Pull tool and dragging down the top surface; the tool indicates how much the surface has moved. At any time during this action, the keyboard can be used to provide the precise dimension required. The Pull tool can also be used to resize with reference to the overall height. Selecting the top surface, a small menu appears (see Figure 2). Selecting the Ruler tool allows the pull action to be performed, but with reference to any chosen point.

Figure 1: Reducing the height of a cylinder

 

  

 

Figure 2: Pull tool menu

 

For example, if the ruler is anchored to the bottom surface it will show the overall height of the cylinder

– 25mm (Figure 3); the required height of 20mm (Figure

4) can also be entered to complete the action.

 

 

Hollow Bodies

There are a couple of ways to create hollow bodies, but the simplest method is to turn a solid into a hollow body by selecting the Shell button (Figure 5), and then choosing a surface for removal. The default wall thickness is 1mm, but this can be changed following surface selection. The Complete button (Figure 6) can then be used or another tool selected to finalise the changes. The Shell button will also work on more complex shapes, such as that shown in Figure 7.


 

Figure 6: Complete button

Figure 7: Using Shell for complex shapes

 

Hollow solids can also be created without removing a surface. Following creation of a solid, the component can be selected in the Structure Tree (Figure 8), rather than clicking on the object. The Shell button can be selected to change the wall thickness, as before. The only difference is that once the operation has been completed, the changes will not be shown on the screen. The solid is now hollow, but all surfaces are intact. Selecting Section Mode on the toolbar (Figure 9) provides a view of the design in cross-section. The orientation of the section plane can be selected by clicking on one of the surfaces of the object, followed by use of the Move Grid button. The Move tool can then be used to move the section plane to show the internal structure of the design, as in Figure 10.

Figure 8: Component

Structure Tree

Figure 9: Section Mode

 

 

 

Figure 10: Move tool

 

Move – up to

The Move - up to tool is very useful in placing one part or feature accurately against another surface. A typical example could be populating devices on a DIN rail at the back of an enclosure. Trying to place the part in the conventional way by dragging into position with the Move anchor is difficult because the sides of the enclosure will obscure the view of the parts, even if the design view is revolved. To use Move – up to, the Move anchor is placed so its hub is located on the intended mating face of the object to be moved, as in Figure 11. This can be achieved either by selecting and dragging the hub of the Move anchor, or using the Anchor placement tool, which is in the design frame to the left hand side while the Move function is selected, Figure 12.

 

The axial arrow should be selected in the direction the object is to be moved (although sometimes the arrow will be pointing in the opposite direction, it will still work as long as the correct axis is selected). A command menu will appear following selection of the anchor arrow, as in Figure 13. Selecting the up to icon and then selecting the target surface enables the components to be mated, as in Figure 14.

 

Figure 13: Mating components using anchor arrow command menu

 

Figure 14: Components mated using Move – up to

 

Moving dynamically within a plane

The Alt key can be used to move an object dynamically within a plane. When in Move mode, and the Move anchor is visible, the Alt key can be pressed and held to generate ‘webs’ between the axial arrows of the anchor(Figure 15). By selecting and dragging on a web, the object can be moved freely in two axes but will be restrained to move within the plane as indicated by the web.

 

Figure 15: Moving dynamically within a plane

 

Zoom - extents

This is a very useful tool that is accessible from the Zoom drop down menu on the Ribbon bar and from the Zoom select menu at the bottom right of the design frame (the shortcut is key z). It is especially helpful when working on small details within a larger model as it will zoom in and centre on the selected portion of the model (if nothing is selected it will centre on the whole model). It is doubly useful because it zooms without changing the orientation of the model, whereas using the Home tool to centre the model will return it to its original orientation when it was opened.

 

Tumbling Models

Tumbling the model (or multiple selected models) can be difficult, especially when trying to reset the view in an orderly fashion, for example with axes aligned with the design frame. Attempting to manoeuvre the model in all three dimensions at once is very tricky and confusing. A useful technique is to revolve the model in only one axis at a time until step-by-step the model moves to its desired orientation.

 

Duplicating Devices

Duplicating the devices within an assembly is achieved using Ctrl Move Drag. Moving along the axis of the DIN rail in an enclosure will mean the new devices will only need to be positioned for a suitable clearance from the next device. The way the device is selected prior to moving is crucial. To copy the device details in the Move operation, the selection must be done either by selecting the device in the structure tree (Figure 16) or by using the Select Component tool (Figure 17) from the top left of the design screen. Triple clicking a device will select and copy it as a solid, but will not copy across the device details required for Bill of Materials lists for example.

 

Figure 16: Duplicating devices using the structure tree

 

Deleting Components

 Deleting components should be done wherever possible by editing the structure tree, as this will be reflected in the model and in the Bill of Materials. If components are deleted by triple clicking, an ‘empty component’ will be left in the structure tree and will still appear in the BOM. To ensure this does not happen, it is best to right click on the file name at the top of the structure tree and select Delete empty components (Figure 18). Empty components will show no additional content when the + sign is clicked on in the structure tree.

 Figure 18: Deleting empty components

 

 


 

 

 

Adding components for BOM listing

If components do not need to appear in the model but are needed for the Bill of Materials listing, they can be added by right clicking on the file name at the top of the structure tree and clicking New Component. An appropriate name and other details can also be allocated.

 

 

Shelled Solids

These can be confusing to work with especially when attempting to ‘pull’ a sketch through the shell to create an opening in the surface. The Maintain offsets option is selected as default and will help to maintain the coherence of the shelled structure as the model is modified and developed. In doing so, Maintain offsets will prevent the Pull tool from cutting an opening in the shell. To override this restriction either deselect the Maintain offsets option in the menu to the left of the screen or Ctrl Select the edges of the shape to be cut out before Pulling to create the opening.

 

And finally…

A few general tips that could help further in projects:

•     Before starting a project, mock up the idea in a simple material such as cardboard. This will create more awareness of the physical requirements and should shorten design time and also help to make a better design.

 

•     Print out a scale drawing of the design to get a better visualisation of its proportions and print as many iterations as feasible during the design.

 

•     Avoid ‘CAD eye’ – there is a temptation to

think something is plausible and adequate because it appears so on screen. Importing a reference part will allow checking whether walls are thick enough or buttons can be pressed and will provide reassurance that the design will work.