using a derived part

[dzinn]

I have modeled a sems screw (screw, lockwasher, flatwasher) by creating a derived part.

I put the screw, lw, & fw in one directory, and I put the derived part in that same directory.

Now when I insert it into an assy, there is a single part in the bom.

What are the pitfalls, if any, of using this method? Recommend or despise?

 

[handleman]

It depends on what you really want to do. There are two other ways I can think of immediately to get the end result of one line in the BOM:

If you don't expect to have to change the individual parts in the future, you can put them together in an assembly and then save the assembly as a part using Save As. This has the advantage of not needing the individual piece parts any more. You will get some level of better performance out of this method. The disadvantage is that the part becomes a dumb solid with no feature history.

Another method is to keep it as an assembly. Then, in the Configuration Properties of that assembly, you can check the box marked "Don't show child components in BOM when used as a subassembly." This makes your little assembly much easier to modify in the future. For some types of components (pneumatic cylinders spring to mind) this is really the only method that achieves the single BOM line without a major loss of model functionality.

 

[Eltron]

I tend to do the latter, handleman. It keeps everything in a more realistic format, and I don't end up losing any functionality.

Dan

http://www.eltronresearch.com

 

[dzinn]

oKay, Handleman said:
"There are two other ways I can think of immediately to get the end result of one line in the BOM:"

But what about the merits of my method? My method keeps the parts as an assembly without dumbing down, and it is a single entry in the BOM no matter how you set up the BOM.

Dave Zinn
Mech. Des.
Currently residing in Massachusetts

 

[Eltron]

To be honest with you, I think it's a little more complicated than it needs to be. I don't know about you, but I need to keep my folders as simple as possible because I may not revisit the model for several months. If I have some derived parts I have to try to remember what I was thinking, or what I was doing. So I try to keep everything as clutter-free as possible...

Hulk brain hurt when Hulk think...

Dan

http://www.eltronresearch.com

 

[handleman]

I don't really have a comment on the "merits" of your method. Your method does not keep it as an assembly. It keeps it as a part file made up of derived bodies. It is more difficult to rearrange or reorient bodies in a part file than parts in an assembly file. This can be good if you want it to be a little more difficult for yourself or someone else to accidentally screw it up. This can be bad if (again, like a pneumatic cylinder) you want be able to easily change the relationship between the different parts that make up the subassembly. Using the actual assembly method also keeps the subassembly as one entry no matter how you set up the BOM. It's a configuration property of the subassembly.

I'm not going to say your way is better, worse, or indifferent to the two other ways I mentioned. I didn't say those were better ways, just other ways that I have used. Personally, I have never used your method, but everyone has different preferences. Each one works differently. Everyone's situation is different. What is an advantage to one person's situation is a disadvantage to another person. I'm glad you found a way that works well for you. If you like it, keep using it.

 

[J-C]

The way we do SEMS is to model it all in one part file since that is how they are purchased. Using a Derived part for this is too much overhead for something that may have lots of instances around an assembly. It's not too hard to add the washer features to the screw file.

Jason

SolidWorks 2007 SP4.0 on WinXP SP2
SolidWorks 2008 SP0.0 on WinXP SP2

 

[dzinn]

If I may be so bold, what is the purpose of a derived part?

Dave Zinn
Mech. Des.
Currently residing in Massachusetts

 

[CorBlimeyLimey]

Derived Parts
You can create a new part directly from an existing part. The new part, called a derived part, has the original part as its first feature, and it is linked to that part by means of an external reference. This means that any changes you make to the original part are reflected in the derived part.

Often used for purchased parts which are then modified. Changes made to the derived part will NOT be reflected in the original. Also used for castings where the derived part would be used to create the machined part.

 

[ShaggyPE]

If I may be so bold, what is the purpose of a derived part?

In addition to the modified purchase parts, derived parts are commonly used for cast parts that are later machined.

I agree with Gildashard concerning your method of creating the sems fastener. You buy a screw with a couple of washers built onto it. It should be modelled that way.

-Dustin
Professional Engineer
Certified SolidWorks Professional

 

[ShaggyPE]

Oops, I missed the 2nd half of CBL's post.

-Dustin
Professional Engineer
Certified SolidWorks Professional