Earlier we looked at "eyeballing" objects together (Worksheet 4. Simple Assemblies); this process is fine for basic drawings but most of the time we need to be much more accurate. Pro/DESKTOP allows us to place an object precisely in relation to another and this worksheet is aimed at showing you how this is done.
We will make this simple assembly:
Open a new design. Save it as Base Block.
Draw a block 150 x 100 x 50mm.
Click on Select then Faces. Select one of the long sides of the block.
Click on Workplane, New Sketch, then OK.
Draw a circle of 20mm diameter on the long side that you have selected.
Extrude this circle through the block to create a hole.
Open a new design. Save it as Top Block.
Draw a block 50 x 50 x 50mm.
Open a new design. Save it as Rod.
Click on Workplane, New Sketch, then select the Frontal Workplane before clicking OK.
Draw a circle of 20mm diameter.
Extrude this circle to create a rod 120mm long. You should end up with three files like this:
Open a dew design. Save it as Assembly 1.
Click on Assembly then Add Component. Find the Base Block file and double click on it. It should appear in your design.
Repeat for the Top Block and the Rod files until all three are in your design. They will probably have "merged" with each other - don't worry about this.
Click on View then Half Frame.
Click on each part in turn to select it then move it away from the others so that you get something like this:
Select the base block - do this by clicking on Select then Parts then selecting the base block.
Click on Assembly then Fix Components - this will fix the block in place. You will find that, while you can select and move the other parts around the page, the base block is immovable.
Click on Select then Faces. Select the outside face of the rod. Hold down Shift and select the inside face of the hole through the base block. Both should be highlighted.
Click on Assembly then Centre Axes. The rod should align itself with the hole. If you click on Select then Parts then select the rod you will find that you can only move it in relation to the hole. This process is really useful for circular components.
Click on Select then Faces. Select the top face of the base block. Hold down Shift and select the bottom face of the top block.
Click on Assembly then Mate. The top block can now only move so that its base is always on the same plane as the top face of the base block. Confused? Roll the drawing so you are looking at it from the side and try moving the top block.
Click on Select then Faces. Select the long edge of the base block. Hold down Shift and select the nearest vertical face on the top block.
Click on Assembly then Align - the top block can now only be moved along one edge of the base block.
Click on Select then Faces. Select the short edge of the base block. Hold down Shift and select the corresponding vertical face on the top block.
Click on Assembly then Align - the top block is now fixed in position in the corner of the base block.
Experiment with these tools. They are worth getting to know well as they form the basis of being able to create animations in Pro/DESKTOP.
© Jim Rowley 2005