Thursday, May 29, 2008

STS#2g - Part Configurations



Due to the sheer number of posts on this subject, here's a handy guide to all of them.
#1 - Associative Copy/I-DEAS Baseline
#2 - Derive Component Part
#3 - Top-Down Design
#4 - Blocks
#5 - Design Library
#6 - Assembly Cut
#7 - Part Configurations



Any experienced SolidWorks users who have been reading along have probably been scratching their heads at the hoops I seem to be jumping through to accomplish the goal. Just use part configurations, they say. It is "The SolidWorks Way". I stated from the beginning that I consider part configurations to be unacceptable for this scenario, and I will get to the reasons why in another blog post soon. However, in the interest of fairness after showing methods that probably aren't the way the software wants to work, let's take a look at how it "should" be done.

PART CONFIGURATIONS



There is only going to be a single part file here, so it really doesn't matter what I call it. But, let's stick with "source" since that's what I've been doing so far. Actually, I should recap what I'm trying to accomplish. I have a single extrusion profile/cross section, and I want to be able to represent the as-purchased model (long stick), and a couple of variations on machined cut-to-length models. So I need different extrusion lengths, and then I will have different cut operations.

Let's begin with my source part.



I'm going to edit my extrude feature, just to show what options are currently (un)available.



Length, direction, basic stuff. What I'm interested in is different values for the extrude length. In order to do that, I need to have some part configurations. To create them, I'll select the Configuration Manager.



Right-click on the top, then Add Configuration.



Give it a name.



There are a couple of options here that are interesting. First is what identification is displayed when this item appears in a BOM. If we would use part configurations, I'm reasonably certain we would name the configurations with the appropriate part numbers, and then use the configuration name in BOMs. The suppress features option will cause any new features to be automatically suppressed in this configuration. I'm not sure how I feel about this option. My gut says it is a bad idea, but I can see arguments in both directions.

I'll create one more configuration, so I now have a total of 3: default, Cut Length 1, and Cut Length 2.



Now let's return to the options for the extrude, and see what's new.



I now have some options regarding the extrude length. Does the value apply to all configurations, only the current one, or specific other configurations. I'll type in a new length and apply that to the Cut Length 1 configuration. I don't want the new length applied to my current configuration, so I'll deselect it.



I'm presented with an error message informing me that I cannot deselect the active configuration. So what this is telling me is that I cannot set up everything I need from here. (well, I suppose I could, but it would be convoluted) What I need to do is activate another configuration, then come back and edit. Activate, edit, activate, edit, etc. Fair enough, I'll switch configurations and try again.



I'll switch the to the 3rd configuration and repeat.



I don't know of a handy way to display all 3 at the same time for the sake of the screenshot, but rest assured I do indeed have a total of three different cut lengths.

Now I need to perform my machining operations. I have 3 features that I need to add. One of these features is exactly the same on both parts, one has the same size but different location on both parts, and one only exists on one cut length option. Let's start with the common one. I have three small holes that need to be cut out.



The dimensions are exactly the same for both cut lengths, most notably the locating dimension to the end of the part, so the individual dimensions will not need to change. The holes will simply move to follow the appropriate cut length in each configuration. But, I want to make sure that this cut does not appear in my raw extrusion configuration. To do that, I will need to configure the feature by right-clicking on it.



I'm presented with dialog box.



What this form is allowing me to do is choose in which, if any, configurations that this feature will be suppressed. Nothing is checked, so this feature is everywhere, which is not what I want. I will check the box for the default configuration.

Now for the next feature.



The diameter for this hole will be the same in both configurations, but the locating dimension is different. I'll complete the extrude, and configure the feature so that it also does not appear in the raw configuration.

In order to get the different value that I'm looking for, I'll need to switch to the other configuration, then edit the sketch for the feature. I will select the dimension in question.



Here I have basically the same options that I had for configuring the extrude. I can type in a new number, then I need to hit the Configurations button.



Here I can specify which configurations this dimension value applies to, and I will use the current one. I have one last extrude to perform.



Remember that this one is only supposed to appear in this configuration. You can select multiple features to configure at one time, so let's grab all of them to make sure things are set up properly. I have renamed the features for ease of use.





Here I make sure that all of the cuts are suppressed in the default configuration, and one of the cuts is suppressed in one of the cut length configurations.

So let's recap what I have now. I have a configuration representing the as-purchased full length extrusion.



I have a cut-to-length configuration with 2 machining operations.



And finally, I have a cut-to-length configuration with 3 machining operations.



This is all contained in a single part file. Whenever you place a part with configurations into an assembly, you are prompted to choose which configuration you want to use.

I don't really have anything to conclude here, as my conclusion is the blog post I need to write. I can see why people like part configurations, and I think we might use them for certain categories of parts. But there are plenty of potential downsides, and to me they outweigh the benefits, thus discouraging their wholesale use across the board.

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