Inventor Best Practice – iProperties

This weeks Inventor Best Practice is about iProperties. Inventor iProperties are the little bits of information that make life easy, and quick when you are documenting your design. According to Autodesk’s help pages you can:

Use iProperties to track and manage files, create reports, and automatically update assembly bills of materials, drawing parts lists, title blocks, and other information.

I’m going to highlight a few ways that you can use iProperties to improve the quality and consistency of your drawings while reducing the time required.

This post was originally started in nearly a year ago, but I decided to put the post on hold to re-examine the work flow I was proposing. After much trial and error, I decided to go back to basics to explore more of how Inventor uses iProperties by default.

To find the iProperties for a file in Inventor you can use the Home Menu (the Big I) then select iProperties, or you right click on any part name in the browser bar, the select iProperties from menu. The right click method will work with an Assembly, Part, or Drawing open, so long as you click on the file name in the browser. I prefer to right click, it’s faster and lets me immediately jump to any part in the assembly. This opens the iProperties window, to the General tab.

iProperties General Tab

This tab shows all the info you would normally see in Windows Explorer for most any file – filename, location, size, etc. All interesting to note, but not all that useful. The practical stuff is on the other tabs.

The Summary tab contains some useful data for reducing your design documentation time. As you can see in the image below, I have already completed the properties values following the Tab:iProperty schema. This will let us examine more closely exactly which iProperty is used where in the default template files.

iProperties Summary Tab

Taking a few minutes to complete each of these iProperties will save you time later. The list below tells you a bit about each iProperty and how it affects the default ANSI title block. This list is compiled from my own findings and Inventor’s own Help Information..

  • Title – The drawing title – TITLE box – single line with no work wrap.
  • Subject – Defines a Subject for the file – Not used
  • Author – File creator – DRAWN box – overridden by Application Options/General/User name.
  • Manager – Defines a Manager for the project – Not Used
  • Company – Company – Unlabeled company field – centered single line no word wrap
  • Category – Specifies a catagory for the file – Not Used
  • Keywords – Defines Keywords for a file – Not Used
  • Comments – Defines Comments for a file – Not Used

Overall not very useful – here is how I use these values. First and foremost please understand that I do not use the default ANSI title block. I have created a custom title block for each client. However, the iProperty usage is common to all.

  • Title – The end user or ultimate customer of the design if know – otherwise blank
  • Subject – The project’s common name
  • Author – that’s me of course
  • Manager – Name of the project contact
  • Company – My client’s company name
  • Category – Job Number/Project Number – the number associated with the project
  • Keywords – Classification of equipment designed – fixture, end effector, bench, etc
  • Comments – Unused

I complete all of this information in my template file before I start a single part. It takes about a minute or perhaps two to gather and enter this information, but it is then carried forward into every part created with that file. I complete the same information in an assembly file for use as a template as well. Since most clients are repeat customers, the savings is even greater since it takes less time to change these values before starting the next project.

In the next part of this series I’ll cover the Project tab, and how I make it work!

Inventor Best Practice – Manufacturability

It doesn’t matter if you are creating a design in 2D on paper or in 3D as a virtual prototype, the entire purpose of the design is manufacturing. In this best practice, I’ve highlighted a few ways that you, as a designer, are in nearly complete control of the cost to build the design.
So, how can you, the designer, affect the cost? Here’s some examples or ways to lower the build cost of a design:

  • Design parts out of the least amount of material needed.
  • Always think about the manufacturing process as you design.
    • Reduce the number of manufacturing steps.
    • Remove unnecessary features such as fillets, radii, and chamfers.
    • Reduce the tolerances where every possible.
    • Reduce or remove surface finishes when not needed.
  • Start with standard raw material shapes.
  • Use the least expensive material specification you can.

Those of you with lean manufacturing experience will recognize the items above as waste removal. Waste on many fronts…Waste of Engineering, and Waste of Manufacturing time are the first two that spring to mind. When starting a machine design, ask yourself a few questions:

  • Do you need a high-end, feature riddled design or will a basic, functional design suffice?
  • What are the problems that you are trying to solve?
  • What features add real hard and true value to your product?
  • As a customer, what requirements would you be willing to pay for? Which features wouldn’t affect your user experience, and by extension are not adding value?

Take the problem back to the root cause…sometimes this leads to a very different set of specifications than initially thought of.

My last thought for this best practice…consider the cost of tolerances. Have you every actually tried to hold +/-0.001″ when making something? It’s not really all that difficult given reasonable manufacturing parameters, it just takes care and caution. Two very expensive commodities in the world of manufacturing. Now, I’m not saying that you shouldn’t do high precision, tight tolerance work. I am simply saying think about the tolerances you apply.

Lets consider the manufacturing process for cutting bar stock to length.

  • Tolerance: +/- 1/16″ – Simple process; Measure with a tape measure and start the saw.
  • Tolerance: +/- 0.005″ – First step is to cut the length to +1/16″ same as before, plus then a machining operation. Probably milling, with a setup and care precision to get it to tolerance.
  • Tolerance: +/-0.001″ – The first two steps are the same, as before, except that you must leave the part at the plus side of the tolerance, and this time, set-up a secondary machining operation – possibly grinding, with its own set-up and care and caution to produce the part.

I know we can argue the details of this process over that, but in general terms, the more precision that you, as designer need, the higher the cost to manufacture that part. There are cases where any of these different tolerances are be necessary, but the trick to controlling cost is understand when to apply each.

Give me some feedback, what types of things do you do when working in CAD to cut the manufacturing cost of a design? Are there other best practices you’d like to discuss? Leave your comments below.

Inventor Best Practice – Sketches

Ever been working on a model only to have everything, well for lack of a better term, blow-up? Components have moved to improper locations, while others have changes shape and size?

I know I have…always at the most inconvenient time. I often find complex sketches, or incompletely constrained sketches are the cause much of the trouble.

In order to prevent these issues, it is best to think simple when working with sketches. Each sketch should have only a few geometric and dimensional constraints to full define it. I have my best results when working by:

  • Allowing Inventor to automatically apply constraints.
  • Creating most of the lines for shape, verifying and adjust geometric constraints
  • Adding dimensions after the shape is geometrically defined
  • Purposely reviewing (again) the geometric constraints before finishing the sketch.
  • Keeping every sketch as simple as possible
  • Use Inventor’s Feature tools to pattern, fillet and radius features

Let’s consider the part shown here. It is a steam chest, used to supply high pressure steam to a steam-cylinder, and guide the control valve. The Inventor part files are found here – Steam Chest.
Steam chest

It is a sample of a part that ended up way more complicated than it needed. When I modeled it, I was working from a 2D drawing for the part. I started by modeling exactly what I saw on the source drawing, one feature and dimensions at a time. The result is a model that while accurate, it is horribly difficult to work with.

  • The dimensions are a mess
  • The sketches are hard to edit
  • Very unpredictable results if edited

Since first modeling this part, I have recreated it to take advantage of this Inventor Best Practice making it easier to work with.

  • Each sketch is a simply shape
  • Patterned features build the part
  • Editing is much faster and more predictable.

I’ve cheated a bit and not completed the Best Practice part, but it still shows the benefits of keeping things simple and clear, especially when combine with some of other of my other Inventor Best Practice recommendations.

If you had a project to revise this part to fit a new larger model, which would you rather work with?

Inventor Best Practice – Parameters

Imagine this scenario…

A local manufacturer has contracted you (or your manager has asked you) to make an engineering change to a product that is several years old. You have never seen the real product, only the designs and a few photos. The original designer is long gone, and there are no design notes available – only the CAD files. You open their files expecting a quick and easy edit only to find the Parameters have their stock names…d1, d2, d3,…d274. Which parameter controls the overall length? The mounting bolt location and pattern can’t change, which parameters are they?

You spend hours studying the model. You try many trial and error tweaks – some correctly and some not so correctly.
Why is this so difficult? There must be a better way!

One of the best practice ideas I have ever heard is to name parameters. The feature exists in every 3D modeling package I have used. Simple identification – such as “OAL” for the Overall Length, or “MountHolePitch” to show the mounting hole pitch saves huge amounts of time when it comes time for future editing.

Naming parameters is dead simple in Inventor. There are a few different of ways to carry out the task. Here’s a couple of the easiest.

  • Anytime you are creating a dimension or adding a value, simply enter the parameter name = value. This will automatically rename the parameter to the name you entered.
  • Open the parameters list, and edit the parameter names in the list. I find this is a bit clumsy, since you need to know the default name (d3, d4, etc) for the parameter you want to name.

Naming parameters takes a bit of time, and may slow your creative processes a bit, but it is time well spent when you have you have to edit the model.

The moral of the story:

Always name your parameters You might be the unfortunate person editing the files later!

Do you know other ways to name parameters in Inventor?
Have you found a work flow that work well for you that you would like to share?
Please post your comments.

Inventor Best Practice – Introduction

In January, Paul Munford at the CAD Setter Out posed the question “What does a good set of drawings look like to you?” . His question and it’s responses have had me thinking…the drawing is only the result of the design process – it’s the bit everyone sees and uses to build the product but isn’t it as important to build good data files? The data files are the roots of the drawing.

  • Flexiblity
  • Accuracy
  • Precision
  • Stability
  • Editable
  • Relays Design Intent
  • Efficiency in Design
  • Completeness

Aren’t these some of the features we should build into our models? I believe so. I’ve started this – Inventor Best Practices – series of posts to put forward some of what I believe is important in CAD work. In general terms, these posts will discuss the idea and form a simple tutorial for how to carry out the idea in Autodesk&#174 Inventor. My intention is that I will add a new post every week or so. There is no formal outline for the series, so things will not necessarily follow any specific flow, or order.

I’d like your help as well. Have I included everything you think is important in creating and documenting a product design? What other features are important in good design? Any time you have something to add or share, please post your comments below or email me your thoughts.

Kevin