SolidWorks Legion has a contest going on for the month of April 2010. The basic idea is to simple. To enter the contest, leave comments for any new articles on SolidWorks Legion, and any SolidWorks Legion articles that I link via Twitter with my fcsuper account for the month of April 2010. For full rules, see the announcement article. Available to win is a CSWP test voucher, “signed” book by Sir Richard Branson, and a insulated SolidWorks mug. Have fun!
How to use sticks safely on PCs (USB Safety part 2)
Do not plug a stick in to a computer that does not have updated and active virus protection software.- Do not use a stick for both home and work. Keep these uses on separate sticks.
- Do not plug your stick into unknown computers.
- Do not plug unknown sticks into your computer.
- When first plugging a stick into a computer, a prompt should come up with options of how to view the items on that device. Always choose the Cancel button. This should prevent malware from running automatically.
- To access a file or start legitimate software, simply navigate to the stick using My Computer or Windows Explorer and LMB double-click on the item.
- If you suspect that a stick is infected, you may be able to use virus protection software to clean it. However, I will err on the side of caution by simply destroying the stick. Of course, this option is not as practical in the case of large external hard drives.
Malware and your USB stick (USB Safety part 1)
For us old-timers, there is a memory of the old days when we passed around floppy disks (floppies) to share computer programs, data files or images. Floppies where great because users could easily read and write to them. It didn’t take long for viruses and other malware to begin spreading through the sharing of floppies. In fact, floppies from unknown sources where often handled with suspicion. People would frequently scan floppies using anti-virus software. These days, the floppy disk has almost completely disappeared, along with the issue spreading malware on them.
A whole generation of people has grown up without an easy-to-use read/write exchange media similar to the floppy disk. For a long time, sharing data was in the form of CD-ROM and DVD. These require special software to create and read. They also don’t allow new information to be added to them once they are created. It is very difficult for malware to spread via these formats for that reason.
With the advent of the USB memory stick or thumb drive (sticks), we now have a new easy-to-use read/write exchange media. Usage of sticks has increased drastically in the past couple of years. Us old-timers have looked upon these sticks with the same suspicion we use to reserve for floppies. I never allow sticks from unknown sources to be plugged into my computer. People who are new to the realities of the Information Age (particularly, younger people or others who have just started using computers within the past few years) don’t have this same prohibition. I’ve witnessed people gleefully passing around sticks to share files or run software on various systems. I’ve watched as people would use their sticks for both work and personal purposes (back in the old days with floppies, this was an absolute no-no). As a result, industry is now witnessing computers and networks get infected, just like the old days.
Such usage of sticks has rebirthed the spread of malware. According to Trend Micro, sticks and other types of external drives are highly common sources for the spread computer virus infection. The problem is getting worse very quickly. Companies and private users are now faced with this new onslaught of malware.
Rounding of numbers
On most computer systems, decimal numbers that have 5 as the last digit are automatically rounded up when removing a decimal place. This may create a problem.
Some people have a rule that SolidWorks drawings should not have overridden dimension values (Override values). I generally agree. Yet, there are several legitimate reasons to use Override values. One major reason is for proper rounding of linear dimensions for removed digits after the decimal. Currently, SolidWorks offers no option that allows the user to automatically round dimension numbers in a way that is consistent with current industry standards and practices.
SOLIDWORKS 2015 now has several rounding options that follow the rules below. More information, please see SOLIDWORKS What’s New Rounding article.
Rounding rule for dimensions
On most computer systems, decimal numbers that have 5 as the last digit are automatically rounded up when removing a decimal place. For example, the number 1.425 rounds up to 1.43. This creates a problem. Most standards require that such numbers are rounded to the nearest even number in the last decimal place. For example, that number 1.425 should be rounded to 1.42, and 1.435 should be rounded to 1.44.
ASTM E 29 states:
6.4.3 When the digit next beyond the last place to be retained is 5, and there are no digits beyond this 5, or only zeros, increase by 1 the digit in the last place retained if it is odd, leave the digit unchanged if it is even. Increase by 1 the digit in the last place retained, if there are digits beyond this 5.
NASA’s Engineering Drawing Standards Manual states:
When the first digit discarded is exactly 5, followed only by zeros, the last digit retained (i.e., the digit preceding the 5…) should be rounded upward if it is an odd number, but no adjustment made if it is an even number. For example, 4.365, when rounded to three significant digits, becomes 4.36. The number 4.355 would also round to the same value, 4.36, if rounded to three significant digits. This procedure is known as odd-even rounding.
It is my understanding that this rule helps reduce statistical bias by allowing different numbers to be rounded up or down. Using the computer default rule (5 is always rounded up) only allows for the upward rounding of such numbers. This can create greater statistical errors, particularly when compounding rounded numbers to derive further rounded numbers.
Rounding as it affects tolerances
No rule is absolute. There are other considerations when rounding. A number should never be rounded so that it increases the original limits of a dimension. Although this rule mostly applies to inspection techniques, it can also apply to specification. For example, if there is a feature whose size limits are 1.255-1.275, the specification cannot be rounded so its limits are 1.25-1.28. In such a case where rounding occurs, the specification limits should be 1.26-1.27. Fortunately, this isn’t something that often occurs in mechanical design (though it does pop up when trying to apply dual dimensions).
Usually, rounding the limits is something that more often happens in quality assurance during incoming inspection of products. In such cases, Interpretation of Limits rule from ASME Y14.5 declares limits are absolute. For example, 12.25 MAX is the same as 12.2500000000000000 MAX. If the feature measurement is 12.2540, that measurement should not be rounded to 12.25, as it is still out of tolerance because it exceeded 12.25.
SolidWorks should supports more rounding options
Right now, SolidWorks does offer one rounding option for dimensions. In documents options, there is a setting to round numbers to the nearest fraction, but only if fractional numbers are in use. I would like to see other rounding options supported, but not a document option. SolidWorks should have a setting added to the dimension PropertyManager that allows the user to establish a rounding rule for a particular dimension. For each dimension, users should have a choice to use the odd-even rounding rule, nearest fraction rounding rule (only when fractional numbers are in use) or always round 5 up rule. This shouldn’t just be for drawings. It should also be available in the model because they are often used as part of the product definition and because dimensions in the model can be inserted into a drawing.
For now, one can use Override values on the drawing. The drawback to this is that Override values do not automatically update if there is a change to the associated model geometry.
So, this sounds like this issue should be yet another Enhancement Request.
As of SOLIDWORKS 2015, there are several options for numerical rounding which are available.
- Round half away from zero, where the only digit being removed is 5, then round the last remaining digit away from zero.
- Round half towards zero, where the only digit being removed is 5, then round the last remaining digit towards zero.
- Round half to even, where the only digit being removed is 5, then round the last remaining digit so that it is an even number.
- Truncate without rounding, where any and all digits being removed have no effect on the last remaining digit.
There is also an option to only apply alternative round methods to dimensions, with the setting Only apply rounding method to dimensions. When this setting is checked, round half away from zero method is applied to all system and properties values, but the alternative rounding method (round half towards zero, round half to even or truncate without rounding) is applied specifically to dimensions. Without this option checked, the chosen rounding method applies everywhere in SOLIDWORKS.
To account for dual dimensioning issues, tolerance rounding includes an option to fit the secondary unit’s tolerance range so that it does not extend outside of the primary unit’s tolerance range. To use this capability, goto Tools > Options > Document Properties > Dimensions and click on Tolerance button. In the Tolerance dialog, check the option Inward rounding of secondary unit tolerance extents.
Office2PDM review (E!PDM for MS Office)
The power of SolidWorks Enterprise PDM has given many users streamlined solutions for CAD file management from within the CAD applications. Enterprise PDM is also capable of managing documents which are not CAD. Unlike its support for CAD applications, Enterprise PDM interface is not available within other types of applications, such as Microsoft Office. Office2PDM by Extensible CAD Technologies has changed this. Office2PDM is an add-in for Microsoft Office
With Enterprise PDM, beginning a change to a MS Office document usually involves closing the Office application (or at least closing the document to be changed), opening the standalone Enterprise PDM application, navigating the vault to the location of the document and then reopening the document from the vault. Office2PDM allows this to occur within the MS Office application. A side pane includes information about the MS Office document’s local version, revision, status and workflow. Many Enterprise PDM functions are also available, including access to any version of the document.
Enterprise PDM vault functions are also accessible from the menu ribbon within each MS Office application.
Additionally, each document’s data card is also accessible from within the MS Office application.
Within MS Outlook, Office2PDM includes a lite version of the Enterprise PDM Dashboard. This add-in is not limited to documents handled via Office2PDM. It shows information about all documents in the vault. One example for its use may be a manager who wishes to see what documents are currently in a workflow. Also, reports about document status may be generated and emailed without the use of an Enterprise PDM license.
Speaking of licenses, for each user of Office2PDM, one Enterprise PDM Contributor level (or above) license is also required. However, this license is only used temporarily when specific tasks are underway. This helps keep Enterprise PDM licenses free and readily shared among more users.
For all this functionality, the price per Office2PDM license seems like a good value. For 15 concurrent licenses, its at about $200 per user for the first year; maintenance each year after would be under $50 per license.
If a company wants to leverage their Enterprise PDM install to cover non-CAD documents, Office2PDM appears to be a safe bet to save money. It will streamline use of the Enterprise PDM vault for MS Office documents. It may also allow small companies to put off investment into bloated PLM applications until a later time. Use of Office2PDM in a larger company may allow its Engineering Department to control their internal documents, such as test protocols, procedures, and reports without getting tangled up in the corporate PLM. Though Office2PDM isn’t for all situations or customers, companies that can use it will benefit.
Plug for Enhancement Requests
In past articles, I’ve mentioned some enhancement requests (ER’s) for SolidWorks. Most (All?) of the enhancement requests I’ve made are now SPR’s, which are slated for some action at some time in the future. To get the ball rolling on these requests, I’d like to invite others to vote for these changes in the Customer Portal. I’m not going to provide links to my requests, as they wouldn’t work anyway with the Customer Portal’s java script. I will mention a brief description of each change, and bold keywords which may be used to easily find the open SPR’s in the Customer Portal. These are my requests, many of which I’ve talked about prior to submitting them to the ER system.
- Support new ASME Y14.5-2009 symbols on drawings and models.
- Option to force captilization (note the misspelling) of annotation notes on drawings (original article).
- Add CR (Controlled Radius) symbol (original article).
- Support External Threads as an actual feature similar to Hole Wizard (original article).
- and a new one (no SPR yet), the ability to auto insert angle dimensions and values in sketch mode, just as we can already do with linear dimensions. (This was inspired by a recent article by Deelip Menezes, in which he apparently misjudged SolidWorks dimension capabilities in sketch mode, but ended up finding a good candidate for an ER anyway.)
I have other SPR’s, but these are the ones that are actually enhancement related (as opposed to bugs or workflow annoyances). Please visit the Customer Portal soon. Choose “Enhancement Requests”. In the ER search field, enter the bolded keyword(s) for each of the requests above. Then pick and vote for the associated SPR.