CAD Craft

A resource to CAD Craft specialists, and a showcase of my work — in both material and virtual worlds

Archive for machining

Part 2: Configurations & Modular Design

Following on our discussion in Part 1, I used a Gear Assembly to show the creation of size configurations for the Gear. In Fig. 1 below, you can see in the Configurations Tab that there are currently two configurations: the Default, and Medium. (I’m using screen shots because some of the feedback I received expressed concerns that the video went too quickly.)

 

Gear Wheel configuration tab #1

Gear Wheel configuration tab #1

 

In Fig. 2, I am creating a third configuration, Large. Note at the bottom there are two check boxes, the first of which Suppress Features, is very important. It provides a setting so that any features I create for this configuration are automatically suppressed in the other configurations, instead of me having to do it manually. You can also designate acolor for each configuration, which makes it simpler to recognize different configurations at the assembly level, which is particularly handy when the difference(s) between configurations is not immediately obvious. This applies at the part & assembly or subassembly level.

 

Gear Wheel configuration tab #2

Figure 2: Gear Wheel configuration tab #2

 

Fig. 3, the sketch for the primary extrusion of the wheel disk is open, showing me modifying the diameter dimension. You will note that on the dimension dialog, there is a tab selected, opening a flyout allowing me to specify which configuration this diameter is to apply to.

 

Gear Wheel configuration tab #3

Figure 3: Gear Wheel configuration tab #3

 

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CAD Tips: Sweeps

In engineering design of machined parts, there is often a misunderstanding of meaning when someone uses terms like ‘economical or low cost design’. Conditioned to think of cost in terms $$, many often overlook the factor of time, most significantly in the context of machining steps — operations, iterations, repeated passes, etc. Whatever we can do as designers to reduce the number of operations & iterations in the machining process saves $$$. This is what time study engineers do — analyze ways to streamline a task process. For instance making a series of circular features concentric — even when this may not be crucial to the design — can significantly assist those in the machine shop & inspection area to more swiftly and effectively complete their tasks.

One of the features which sometimes befuddles folks is the Sweep(in SolidWorks), whether an extrusion or cut. I will address some tips in this area. However, it is important to keep in mind that it is a mistake to presume that just because you can design a 3D model, it can be machined. It is also true that a feature you apply in a CAD design may not be able to be machined in an analogous process. For instance, a sweep along an edge of a circular part is a fairly simple lathe operation. However, a sweep along a polygonal part is more complex.  For some machining systems, working their way around a 4, 5 or 6-sided part is not so challenging.  For others, it is a harrowing issue. Allow me to reiterate: CAD is not a stand alone tool/premise/concept — it was always conceived as a partner in CAD/CAM = “Computer-Aided Design” & “Computer-Aided Manufacturing(or Machining)”.  Once you have completed your model and submitted it to the shop, they must go through a process of conversion to their CAM software to program their CNC machines to actually do the work.

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