Frequently Asked Questions - On Sheet Lightning
 

Why do I keep zooming on the view?
How do I snap to the grid?
Why don't I get intersections between objects?
How do I define links as bends, tees and junctions?
How do I change the shape and dimensions of an object in the 3D CAD environment?
How can I input values other than the selection appearing in the number menu?
Can I design in  inches or some other units than millimeters?
How do I quit the program?
Can I assemble designs together?
Why do objects move after a drag operation?
How do I transfer designs from the 3D CAD environment to the Parametric environment?
How do I query the dimensions and links to an object in the 3D CAD environment?
Why do I keep getting 'Error:6 Element Active' when I select a command?

Please Help Me?
 

Why do I keep zooming on the view?

The cursor has 2 modes. The arrow-cursor mode and the cross-cursor mode. If you hold the cursor over the 3D design area and use the right hand mouse button the curror will toggle between the modes. If you are trying to design something you must use the cross cursor in the design area. If have the arrow cursor over the design area and click the left hand mouse button this will be interpreted as a zoom on the selected point. To reset the view back to the default simply select the 'ZOOM' command in the design menu on the left. The view will return to the default zoom magnification. Now move back into the 3D design area and use the right hand mouse button to toggle to the cross cursor so that you can continue creating your design. Note that whenever the cursor is over the menu areas it will appear as an arrow even if you are in cross-cursor mode. The proof that you are still in cross-cursor mode is that when you move the arrow back over the 3D design area it automatically changes back to the cross cursor.
 

How do I snap to the grid?

The short answer is you don't! I assume by this you mean the grid that appears on the floor of the room in the 3D view and 2D plan view. In fact you are looking at a room with a tiled floor. The lines between tiles are not a grid in the sense that conventional CAD systems use a grid. The whole of the room is only shown to give a sense of perspective. It is not used in any way in the design process. If you are experienced with CAD you may find the 'room' distracting. If so you can turn it of using the toggles in the 'Room' menu leaving you with only a familiar 3D direction icon.

With regard to snapping it is important to understand that your position in the 3D environment is all relative. In other words it does not matter about the position of the cursor or an object in absolute 3D coordinates. All that matters is the position and orientation of objects relative to each other. The only absolute snapping you can do is to align an object centre line with one of the 3D axes (see axes snapping). All other snapping is relative to other objects (see object snapping).
 

Why don't I get intersections between objects?

First of all when you position an object in the 3D design area it has an 'outline' form. This means it is simply drawn as an 'extruded' shape, with parallel ends, that has no intersection with other objects. To compute and display the intersections you must use the 'Cut & Weld' comand in the 'Compute' menu (or press F8 as a shortcut). However if you have more than one object in the design and they physically intersect each other you may still not get an intersection result. This is because by default Sheet Lightning will only compute a intersections between objects that you have linked together. Forming links is the primary purpose of the 'SNAP' command. If having created one object then to create another that is linked to it you must use SNAP and set the cursor sliding along the object you wish to link the new one to. As you create a new object from this sliding cursor the link will be formed. Try 'Cut & Weld' again having created the design in this way and you should get an intersection. Note that Sheet Lightning can be enabled to intersect objects in space but generally the links are important in defining what typeof intersection occurs (i.e.bend, tee or junction). You can also form links between exisiting object using a combination of the 'DRAG' and 'SNAP' commands together.
 

How do I define links as bends, tees and junctions?

Whether you create a bend, tee or junction link depends on the position of the sliding cursor when you create the new, linked object. If you have got the cursor sliding on an object centre line (using SNAP) the next time you press the left mouse button the cursor will be set free from the slide and will begin stretching out a new object centre line from this point. If at the point of pressing the left button the cursor is positioned at the end of the object slide a 'BEND' link will be formed between that end and the new piece. If on the other hand the cursor is positioned at a central position along the object slide a 'TEE' will be formed between the slide object and the new object. Executing a 'Cut & Weld' command on the design will show up the difference in intersection results. To form a junction link the two objects must first be created with no link. One object should then be picked up and dragged using the 'DRAG' command. The SNAP command will then allow you to sap the cursor to the other object centre slide and slide up and down it whilst still dragging the first object. The next left mouse button click places the dragged object in position and a link is formed between the two. The type of link formed depends on what point on the dragged object centre line it was dragged from, and what point on the slide object it was finally place. If neither points are at the object ends a junction is formed. If one point is at an object end and the other not then a tee is formed. If both points are at object ends then a bend is formed.
 

How do I change the shape and dimensions of an object in the 3D CAD environment?

Initially an object is created in its simplest form, a pipe or cyclinder. Both ends are therefore circular. To change the object shape and size choose the 'SECTION' command in the left hand design menu. You may have to page through the 3 pages using 'previous' and 'next' to find it. There must be at least one object in the design for this command to operate. The command will come up with a page of section selections. Some of these sections will set the shape and dimensions of just one end of the object you select (next), others will set both ends. The simplest section available is the 'CIRC' or circular section. Try selecting this section. Note that when you selected CIRC the SNAP command was highlighted. This indicates that your next move must be to snap the cursor to an object, just as if you would if you had used the SNAP command directly. Snap the cursor to the object whose section and/or size you wish to change. Now, having snapped to the object the cursor will be sliding along the object centre line. If you only wish to change just one end then push the cursor to that end of the object and press the left button. The object section becomes active such that up and down movement of the mouse causes the object end section diameter to 'grow'. At this point you only need to begin pressing numeric keys (or press F5) for numerical input to be accepted for the active parameter. If section 'ADAPTEND' had been chosen three successive dimensions would have been required. Each of these can be entered by either pressing numerical keys or F5. To fully define an ADAPTEND numerically you would have to type in the three dimensions of 'Height', 'Width' and 'Diameter' successively. If after snapping to an object you choose a position on the object other than an end then both ends of the object will become active. See the user manual for further details.
 

How can I input values other than the selection appearing in the number menu?

Various commands require numeric input. Some of these commands automatically activate the 'number menu' so that a number can be selected using the mouse. If the exact value cannot be obtained simply begin pressing numeric keys or press F5 to enter new values.
 

Can I design in  inches or some other units than millimeters?

Sheet Lightning is not restricted to working in millimeters or any other units of measurement.
 

How do I quit the program?

ALT-X is the quickest and easiest way to quit the program. Otherwise select 'Quit' in the 'File' menu of the 3D CAD environment or the 'Quit' button in the parametric environment.
 

Can I assemble designs together?

Use the append command in the 'File' menu to load designs from disk together with the existing design in the 3D CAD environment.
 

Why do objects move after a drag operation?

When you drag select and object to drag it only that object is seen to be dragged but when you place it all objects linked to it are displace by the same amount. In effect they catch up with the drag operation. If you want to drag linked objects apart you will have to unlink it using the 'UNHOOK' command. You can do this by selecting UNHOOK commad during the drag operation or by selecting it when the cursor is sliding along the centre line of an object. If the cursor is positioned at the end of the object in question then only that end is unhooked.
 

How do I transfer designs from the 3D CAD environment to the Parametric environment?

Via the 'File/PARAMETRIC' menu or by using the ALT-B key to take a short-cut to the menu. The 'Parametric Mode' command will take you directly to the empty parametric environment. The 'Transfer Design' command will transfer the design in the 3D CAD environment through to the parametric environment. The analysis that takes place on transfer automatically attaches dimensions to a transferred design. If the design is complex with many links there is likely to be a large number of dimensions. It is up to the user whether to use it in the raw form or filter out the dimension required to produce a useful template.
 

How do I query the dimensions and links to an object in the 3D CAD environment?

When an object is active (in the process of creating it, or when it is reactivated through the LIVE command) its dimensions are displayed at the base of the screen. The relative dimensions between the object and others that are linked to it can be examined by selecting the 'DIMENSION' command in the design menu. If more than one is linked then the object selector will allow one of the linked objects to be selected so that the relative dimesions between it and the object in question can be displayed. Alternatively transfer the design through to the parametric enironment to examine its dimensions. Moving an object by dragging it will prove any links, because unlinked objects will not catch up.
 

Why do I keep getting 'Error:6 Element Active' when I select a command?

If you see a centre line rubber banding from the cross cursor in the 3D design area this indicates that you are in the process of creating a new object. A number of commands issue an error if you try to execute them while in this state. To re-enable the commands you must complete the object creation by pressing the left mouse button in the 3D design area to place the new object, or by using the DEACT command in the left hand design menu to deactivate the object creation process.

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