Site updates coming soon!

Wow, it been nearly 2 years my last blog entry. What can I say?…The website and blog are something of a sideline for me. Even simple updates and posts take time away from actual work. Paying customers always come first! We have busy here at Dobson Technical Drawings working with clients to design their projects but are finally able to take a bit of time to catch-up on the website and blog.

That said, in the coming weeks we have a number of things planned:

  • Samples from recent projects
  • More of the best practices series
  • Perhaps even a completely new look

Check in often – Updates are coming soon

Inventor Best Practice – iProperties – Part 2

In this post, we are going to continue our look at iProperties, and how to use them to speed up your designs.

The Project tab contains much useful data for reducing your documentation time. As you can see in the image below, I have used the same notation as Part 1.

iProperties Project Tab

The list below highlights where the intended data use, as foundin the help file, and my own findings where it is actually used in the Default ANSI titelblock and Style.

  • Location – Storage location of the selected file on your drive – absolute path -not editable
  • File Subtype – Autodesk Inventor file type – Modeling, Assembly, Presentation, etc – not editable
  • Part Number – The file name is automatically assigned as the part number, unless otherwise entered – edit to suit your numbering
  • Stock Number – The stock number as used in parts lists, etc
  • Description – Part or assembly name as used in parts lists, etc
  • Revision Number – Part revision number – change to match your system
  • Project – Specifies a project name – Not Used
  • Designer – Specifies the designer for the project or model – Not Used.
  • Engineer – Specifies the engineer for the project or model – Not Used.
  • Authority – Specifies a signature authority – Not Used.
  • Cost Center- Specifies a cost center – Not Used.
  • Estimated Cost – Assigns a cost to the file. Must be a real number – Not Used
  • Creation Date – Date that Inventor created the file. Used as the drawn date, and can be changed.
  • Vendor – Manufacturer or supplier name for components – Not Used
  • WEB Link – Displays a Web site address – Not Used.

So there a lot of possibilities that are not taken advantage of in the stock ANSI title block. In my own customized title block, only use a few of the iProperties.

  • Part Number – The part number as following my clients number scheme
  • Stock Number – Industry standard format reference, unless defined by my client – often blank – more detail below.
  • Description – Part name as used in parts lists, as well as title block
  • Revision Number – Matches my clients system – typically 0 or –

Let’s consider the possible iProperties for a standard socket head cap screw, 3/8 course thread, 2″ long. it could use these iProperties:

  • Part Number:3/8-16 x 2 SHCS, Stock Number: bin/container reference to your stock, Description: Socket Head Cap Screw
  • These would work quite well with the default parts lists, etc. BUT so would…

  • Part Number: 91251A632, Stock Number: 3/8-16 x 2 SHCS, Description: Socket Head Cap Screw, McMaster#
  • If the shop ordered Standard Hardware from Mcmaster-Carr. It gets even less clear if you consider the other iProperties on this tab. the Vendor could be set as McMaster, and the Weblink to the product detail page.

    The bottom line is that be default Inventor doesn’t use many of the iProperties it has pre-defined…but you can. It all depends on your use. If perhaps, your company exported the finished Bill of Materials to MS Excel, having a link directly to the order site would be great for purchasing, and having the purchased cost on the date created would also be valuable.

    But at what cost…there in lies the balance, The vendor might change there website, so now the link is broken, the price will change, so then it’s bad data, and all this data is managed by your CAD guy, should it be? What’s right? Ultimately that’s up to you and your company to determine.

    Do you use iProperties in your company? How? Do you have better ideas? I’d like to hear any ideas you might have.

    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!

    Standards and Templates – Best Practice

    So in over the past couple of weeks, I’ve tried to write a number of posts and I kept getting way too deep into each subject. My problem stemmed from the fact we haven’t discussed standards and templates yet. In my opinion the use of standards and templates is the single largest contributing factor to making a good set of drawings, quickly, that accurate and concise and precise.

    To start, let’s be clear on what defines standards and templates. Any Inventor file can be used as template file. The only requirement is that they are place in your template folder so that they are on the list in the Create New File window. A standard is different. Standards are simply way of working that you repeat every time that condition is encountered. Many times standards are included in your template files, but not always. For now I won’t be including national or international standards – these will come up in a future discussion.

    Let’s consider the following example. You are working on a design for your employer, managed by a specific project manager. The design is large machine that does something. It is manufactured primarily from structural steel shapes, cut to length, and welded together. Some parts are purchased, while other are fabricated.

    Here’s a list of some of the items you could include in your template files.

    • Company name
    • Project name
    • project number
    • project manager
    • Parameters for Length, Width, and Thickness
    • Pre-selected material for steel
    • Pre-modeled block using the Length, Width, and Thickness parameters
    • Component manufacturer, part number, other ordering information

    So if items like these are included in every file, in a consistent manner, they become part of template, but also part of your standard. Other items, that are often standards within companies can not really be included. Items like:

    • All round holes are created using the Hole feature rather than round extrusions
    • Specific tolerance for dimensions controlled by your manufacturing equipment
    • Fully constrained sketches
    • All work features are on or off
    • All suppressed features are removed
    • All holes are in standard drill increments
    • No broken constraints

    Over the coming months I will pick individual ideas from the lists, for further discussion, showing you how to implement these into your standards and templates, and reduce your design time, while improving your design quality.

    Original 3D Printer

    Ok, I don’t normally post jokes or non-work stuff, but I couldn’t resist re-posting this 3D printer; it seems so appropriate.

    Original 3D Printer

    My thanks to the original poster. If this is your work, please let me know, I’ll credit accordingly.

    Hardware Recommendation – 3D Mouse

    So late last week I was working on my laptop instead my normal workstation and I realized exactly how much of a productivity increase adding a 3D mouse really made. The improvement is significant enough to call for the first (of very few posts) about computer hardware.

    About a year ago, when I was shopping for a new workstation, a friend recommended adding a 3D mouse. he said, “I know they are a bit pricey, but get one – even the basic model. You’ll never be without one again.” Once I began pricing 3D mice, they were less expensive than I had expected. I selected a Space Explorer by 3D Connexion. When comparing the feature sets, this model is about middle of the pack for features and price. There are others with more programmable buttons and features, and others with less.

    Within the first few seconds using it, I saw what all the hoopla was about. The speed increases were immediate. I’d estimate the reduction in modelling time is 30-40%, right out the box, with no tweaking or customization. Basically, a 3D mouse puts all view related movements in your left hand while you are free to make selections with your normal mouse on the right. The stock button assignments are pretty good, but with some simple tweaking the programmable buttons issue whatever commands you want. The assignment is flexible and changes based on the modeling mode you are in – Part, Assembly, Welded Part, etc.

    The higher-end the models have more programmable buttons which are even more beneficial for some, but this works for me.

    I’d give-up my left hand before being without a 3D Mouse again.

    If you are a using 3D CAD – any platform, almost any software – you need a 3D Mouse. Convince your managers. It’s money well spent.

    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.

    Reposting Best Practice Posts.

    After a few horribly frustrating issues with our site, it seems to stable again finally. We are beginning to repost the earlier blog entries. They will be re-posted one at time over the next few days allowing for some time between to make sure the site stays stable.