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| When Zero Tolerance Means Zero Sense |
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My youngest son is eleven years old now. Like most boys his age, he likes video games. His favorite video game is Halo3, played on Microsoft's XBox 360.
He printed out several color screenshots of the weapons used in the video game, so he could take the pictures to school and show them to his friends at recess. The boys discuss these imaginary weapons at great length. Sort of a who is better - Superman or Batman? discussion.
Since this boy is my THIRD son, I am used to this stage of doodling cannons and rockets, army men, and war strategy. I consider it part of a normal boy's development.
Well, his teacher caught him and his friends poring over the pictures before the school bell had rung and confiscated the paper. Her reason? The school has a Zero Tolerance policy on weapons brought to school.
Keeping in mind that these were PICTURES, I laughed myself silly. I then fired off the following letter to the school principal:
Dear Principal Gibbs,
My son, Isaiah, is a sixth grader in Ms. Thompson's class. Yesterday Ms. Thompson confiscated several pictures from my son. They were computer generated images of fictional weapons from a sci-fi game. Ms. Thompson explained that graphical representations of weapons are not allowed at school due to the zero tolerance policy on weapons.
I am highly amused that your staff is unable to discern the difference between images of fictional weapons and actual physical weapons. I assume that the zero tolerance policy is meant for solid objects which might be used as weapons.
If this is not the case, I assume all history texts, artwork, novels, plays, songs, etc. which mention or depict weapons are banned from Rolling Hills Middle School. This would include the singing of the national anthem, since that song celebrates a battle victory and makes mentions of bombs, cannons, and other warfare.
Additionally, I would hope that none of your classes teach Macbeth (daggers and swords), Romeo and Juliet (swords and poison), Hamlet (swords and daggers), Steinbeck (rifles and guns), Hemingway (guns and rifles) or any of the other classics.
Given that a zero tolerance on fictional depictions of weapons would lead to a zero tolerance towards actually educating our children, I would hope that Ms. Thompson misinterpreted district policy and was simply being overzealous.
I am also mindful that confiscating paper because you do not like what is printed on it could be construed as censorship. The confiscated papers were in my son's private possession. They were not being distributed or circulated to the general school population. They did not violate any laws in that they were not pornographic, treasonous, or libelous. Thomas Jefferson, who founded and promoted public education, would be appalled.
When adults over-react to non-threats, it is difficult for our children and their parents to take them seriously with regards to other issues.
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Determining the UnderDefined Assembly Constraints |
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When you create assemblies in Inventor or SolidWorks, you apply assembly constraints.
I like the assy constraint tools in Inventor better. I think they work better. But, the real key for me is trying to deal with under-defined assembly constraints.
When working in 3D assemblies, the first concept a user should understand is Degrees of Freedom. All parts have six degrees of freedom - the three work planes and three axis of rotation. As you apply assembly constraints (mates), you eliminate the degrees of freedom. As you eliminate the degrees of freedom, you improve your processing time because your system doesn't have to keep track of how parts can move.
Some users resolve this by simply grounding or fixing their parts in place once they position them correctly. Applying a Ground or Fixed constraint eliminates all six DOFs in one shot. This method scares the heck out of me because 1) It is the Brute Force method. 2) It does not address how the part actually interfaces with any of the other parts in the assembly 3) If you have to change the part's position because parts change, etc., you have to unground/float it and then re-position it.
SolidWorks puts a (-) symbol in front of components that are not fully constrained. I find this helpful, but I like the DOF tool available in Inventor better. Go to View->Degrees of Freedom. A triad will appear on all underconstrained components showing what degrees of freedom are still available. Then you can determine how to constrain the parts.
This is better than SolidWorks because the most common missing constraint is axis of rotation for inserted parts, especially nuts and fasteners. I don't really need to remove the rotation on a bolt. I wish there was a way we could set an option to have the program ignore rotation on fasteners, so it doesn't bother calculating that DOF. |
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Using ETransmit to Keep the Xrefs with the DWG file |
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Skyler Mills, of Rhode Island, writes in response to my article on binding XREFs:
Another good way to send a drawing intact, including xrefs, is the etransmit command. Very useful!
Etransmit basically acts like Pack and Go. It will locate all the linked files and create an archive file for email purposes. While I agree, it is a good way to go when you don't want to bother binding all the xrefs, I have found that it is not 100% full-proof. That is because there are users out there that don't know how to use XREFs, can't locate files properly, and just are generally inept. So, I would recommend Etransmit if the recipient is a competent user.
How to ascertain if the user is competent is the $64,000 question as far as I am concerned..and to do it diplomatically is a real trick.
Recently, I sent an sat file to a vendor. The vendor didn't have a 3D model of his part, so I modeled it up based on the 2D spec provided. However, I wanted the vendor to look at it to make sure it was OK before I used it in my assembly. The vendor was using AutoCAD 2000. Now, AutoCAD 2000 can open an sat file and bring it in as a solid model. Just type ACISIN on the command line. The vendor did not know this. He thought I had sent him a "useless" file. |
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Tweaking the Gorillas |
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Greg Milliken, Alibre's CEO, can't resist making fun of his perceived primary competition - SolidWorks and Autodesk in his blog.
He basically says they both are behind the times and users who are futurists should jump over to his software.
He complains that users who don't like Alibre because it lacks the features or tools they want or need are short-sighted. I'm sorry, but I find this highly amusing. I thought most of us buy software based on the features, not because it gives us a warm, fuzzy feeling, or to feel cool.
CAD software is a tool. It is used to create models and test designs. Users are going to want the software that allows them to get their jobs done in the least amount of time at the lowest cost. Because there is a trade-off between the two (cost and features), users can choose which is more important to them...but they inevitably are going to need to be able to perform the bare minimum to get their job done. If Alibre can't even meet the bare minimum requirements, then it is not a tool, it is a toy. However, from what I have heard (I haven't actually tried the software) it is an adequate tool for the low-end user.
So, if you want to play in the Majors, get the right equipment and suit up, Greg!
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