The first thing that needs to be completed is kind of the core to this process.
Normally we would begin in an assembly file, but for this exercise we need to go mess around with Autodesk’s artwork. We need to edit the Thread.xls file. You see, the Bolted Connection Generator as well as everything else in Inventor derives it’s threads from this file. This file contains a beautiful collection of thread data, including Inch, Metric, and tapping threads. Unfortunately the facts that bring us here today is that:
a) there is nothing available for ANSI/ASME B18.6.1 Wood screw threads; and
b) The Bolted Connection Generator only reads data from the first 3 thread tables in that file (ANSI Unified, ANSI Metric, ISO Metric).
What we need to do is to add a new row for the B18.6.1 thread for a #6 screw. The new row needs to be added in the ANSI Unified Screw Threads Table. Why? Because if we don’t, the Bolted Connection Generator will not use it. I know this is in bad taste, but it will get the job done. I have no doubt that the table restrictions in the design generator is coded in XML, and that I will eventually find and exploit it. For now, this is the only way.
Navigate to the following VISTA path:
C:\Users\Public\Documents\Autodesk\Inventor 2009\Design Data\Thread.xls.
Open this file with Excel and navigate to the ‘ANSI Unified Screw Threads’ Tab. Select the first #6 thread entry row header, Right click and select Insert. You should see an empty row appear. Add the data from the highlighted row in the table shown below.
Close and save the file. Let’s start the next step by opening a new Inventor assembly.
Sample Part Modifications
As I continue through this process, I will describe rows and fields to add in Inventor, that are for the purpose of authoring information in later steps, and the reasoning may still not be evident. I will mention that they are ‘for authoring’ but will leave the explanation for the later segments when we will apply the information.
We need a sample item to use as a template. We could create it from scratch, and you will on later projects, but for now we need some assistance. Not only is it already part of the way to what we want to publish, and the iMates are installed, but also that the content and data containers are already represented from a published family.
Using the Place From Content Center, select a sample item to use for a starting point. The thing I want to point out here is the ‘As Custom’ radio button. This will allow us to save the part OUT OF the default library Location (listed in the Application Settings), so that we can edit the part.
I chose a 100° Countersunk Self Tapping screw from the Sheet Metal Screws Category, something that was similar to what I needed, but the countersink angle is not what I wanted. (I will correct it as I go through.)You may want to use the 82° which is titled the same, but without the head angle listed. When prompted, save the file to a temporary location that you can use during the authoring process.
Edit the part by double clicking the part in the browser. At this time we need to make any physical changes to the part. I have added a square drive to the head recess (I will not describe the method). The thread feature is incorrect and needs alteration. Right Click on the Thread feature, and select Edit Feature. In the Location Tab, make sure the Length is set to the User Parameter GEL. In the Specifications Tab, ensure the Thread Type is ANSI Unified Screw Threads (remember, Bolted Connection Generator will only read the first 3 tables). Change the Size pull down to read 0.138, and new 6-18 thread we added previously will come up in the Designation list. Click OK to close the Feature Edit dialog.
Note: The thread feature does not send it’s modifications to the User Parameters. Instead it creates a custom field in the part. We need to make sure the thread is modified in the parameters as well.
Open the parameters, and scroll down to the User parameters. For this example we need some custom size changes, they are as follows:
NLG…Nominal Length = 1.625 in
GEL…Thread Length = 1.0 in
KOH…Head Diameter = 0.244 in
KOH…Head Height = 0.083 in
SEWI…Countersink Angle = 82 deg (the angle correction)
TPU…Thread Pitch = 18 ul
Next, we need to create 2 User Parameters for authoring, as follows:
KGL…Grip Length for Authoring = NLG-GEL
BDM…Shank Diameter for Authoring = NND
Close the Parameters, update the part, and save.
…more to come