Thursday, August 29, 2013

How to Export Solid Models from NX and Import into Blender

This blog post details how to import solid bodies into Blender from NX. As always there are many different ways to skin a cat, but I was only able to find particular combination of files types and tools to maintain solid body definition after the import into Blender. The assembly model I wanted to import from NX had over 50 different bodies and over 500 surfaces. Even trying to select all of the surfaces associated with a body and creating a group or linking them would be impossibly tedious and wasteful. Hopefully this information will save you time and effort as well!

I'm going to use this part with two bodies, a cube with a square cutout and a cylinder, as an example and walk through the process.

1. Export the model from NX. I'm using NX7.5. File -> Export -> Parasolid

2. A new Export Parasolid dialog will pop up. Select the desired bodies to export or Ctrl+A for all bodies. The desired bodies should be highlighted and the OK button should become green/selectable. Click OK.

3. Browse to the desired output directory and name the output file. 

4. Download and install CAD Exchanger. Unfortunately this is not freeware or open source, but there is a free trial period (no idea the duration) and it was the only file converting utility I could find that could go from parasolid to x3d.

5. Open CAD Exchanger. Before we get started we need to enable "Merge Face Sets" in the X3D exporter options. Go to Tools -> Options. Click on "X3D exporter" in the left hand list. Check "Merge Face Sets". Click OK.

6. Start a new file, File -> New.

7. Import the recently exported parasolid file, File -> Import.

8. You can see a preview of the model and solid bodies in the tree to the left.

9. Export the model, File -> Export. Select X3D files (*.x3d) in the dropdown menu). Name and save the file.

10. Open a new file in Blender and delete the auto-generated cube. Your screen should look something like this. I'm using Blender 2.68.

11. Import the newly exported X3D file using File -> Import -> X3D Extensible 3D (.x3d/.wrl).

12. Browse to the X3D file, select it, and click "Import X3D/VRML2".

13. After rotating and scaling this is our cube and cylinder! Done!

Hope someone finds this helpful, I know it would have saved me quite a few hours of trial and error. Please post successful results or questions in the comments as well as if you find a free/open source file converter.

Thursday, August 22, 2013

Nissan Altima P1491 Check/Replace the Vacuum Cut Valve Bypass Valve on a 1998, 1999, 2000, 2001

This post describes one of the diagnosis steps for the P1491 codes on a 1999 Nissan Altima. Specifically the testing and replacement of the vacuum cut valve bypass valve. This applies to all second generation Nissan Altimas which are 1998, 1999, 2000, 2001.

The vacuum cut bypass valve is installed in parallel with the vacuum cut valve on the EVAP purge line that runs between the fuel tank and the charcoal canister.

Nissan EVAP Diagram

The purpose of the vacuum cut valve (white part in the pictures below) is to prevent the intake manifold vacuum from being applied to the fuel tank. The vacuum cut valve bypass valve is energized (opened) for diagnostic purposes to bypass the vacuum cut valve to apply the intake manifold vacuum to the fuel tank. This verifies the intake manifold vacuum.

The vacuum cut valve bypass valve (what a mouthful!) is located just inside of the passenger side rear tire, next to the gas tank and spare tire compartment. You can locate it by looking for the charcoal canister which is a large, black square box on the drivers side of the gas tank, and then following one of the lines until you see a white cylinder with four tubes coming out of it. That is the vacuum cut valve. The vacuum cut valve bypass valve is located on the same metal bracket as the vacuum cut valve. Here is a picture of the bracket/valve assembly after it has been removed.

In order to check the vacuum cut valve bypass valve we need to first remove the assembly.

Make sure your car is off, disconnect the battery and block the tires.

1. Slide the two hose clips away from the white vacuum cut valve and carefully remove the hose from the vacuum cut valve tubes. Twisting sometimes helps.

2. Remove the two 10mm bolts that hold the metal bracket assembly to the chasis. Be careful to no strip these bolts. I had one of mine strip and had to use mechanic wire to fasten the bracket in place. I suggest using PB Blaster well in advance of doing the actual removal and letting it soak. 

3. I like to save the electrical connector for last so that you can have the assembly dangling low for easy access. Push the green tab "in" and pull "out" on the exterior. You should be able to hear/feel a click when you get the green piece pushed in far enough.

4. Unbolt the vacuum cut bypass valve in order to diagnose it using the below steps.


Perform the exact same battery energizing test that I used on the similar EVAP purge solenoid valve. If you don't hear the solenoid valve click/move (or air passage) when power is applied then yours is bad!

For additional diagnosis steps for the vacuum cut valve go here.

I was only able to find a replacement over at Quality Resale Auto Parts (the website is a bit sketchy but they shipped the correct part, as described, and quickly) for $38 shipped. It's hard to beat that. Here's a comparison shot of the old vs. new solenoids. Why don't they encase/seal these parts better? Darn you northeast salt!

The steps to replace the assembly is just the reverse of the removal. 

Hopefully this write-up was helpful. Please feel free to comment about successes, or suggestions for improvements!

Friday, August 2, 2013


A friend snapped this picture and I couldn't help but laugh at the indifference of the pug compared to the excitement of Laura holding the dog. I then couldn't help but create the next internet meme: