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Monday, August 15, 2022

Using Fusion 360 to Create Parts for a B-17 Restoration

A portion of the original print used to 
create the model.
 For many years, I've created models in Fusion 360. On occasion, I've 3D printed a few of my Fusion 360 models as "desk ornaments". 

But a few weeks ago, I had a fantastic opportunity to create a model that would be used to make a part for the restoration of a B-17 Flying Fortress. 

The part was a "friction washer" for use in the throttle quadrant. And the team needed geometry that could be cut on a water jet.

It started with a reproduction of the original Boeing print. Having the original dimensions made the modeling easy. It was interesting to note that even though standards have changed in the nearly 80 years since that print was created, it's not too different from the prints I work with today. 

The model of the friction washer, created in 
Fusion 360

Next, was to place the view on a drawing. The first goal was to dimension the drawing as a way of verifying all the dimensions were correct. Second, the drawing is what creates the 2D DXF file for the water jet. 

Once the drawing is created, delete any information that isn't required for the waterjet. This includes borders, title blocks, dimensions, centerlines and centermarks, etc. You might even consider creating a second page in the drawing for this purpose. 

Also, make sure to save the drawing before you export. I learned the hard way when I realized that the first file I exported still had all that extra geometry. Save the file before export!

The dxf geometry sent to the waterjet

Once I recovered from my snag. I sent the files off to my colleague for cutting. 

A few days later, we had our part and it fit perfectly, making for a very satisfying little journey. 




And while this little project was well worth a victory lap, there were three minor challenges that are worth mentioning. 

1) Drawing standards have changed over the decades, and while the drawing wasn't hard to interpret, some information wasn't where I'd expect it to be. Modern 3D modelers have spoiled us. We can "slap down" a new view in seconds. For the drafters of old? Adding the simplest view would take minutes. A more complicated one? Hours. 

The number of views was kept to a minimum. A part of single thickness, such as this one, will likely have the thickness dimension called out in a note. 

2) Not only have drawing standards changed, industry standards have changed. That material specification called out in 1943? It's been long superseded by a new standard. It's even possible that the standard that superseded the 1943 standard has, in turn, been superseded itself. 

Be prepared to spend a few minutes Googling the updated standards. Thank goodness for the internet! 

3) Finally, how does one interpret the tolerances called out on the drawing? Symmetric, +/-.005 for example, is easy. Model to the nominal. But what about a tolerance such as +.010/-.000? Do you "split the difference"? Do you aim for nominal? 

In my case, I decided to aim for the dimension as it was called out on the print. I figured that was the target dimension, after all. 

And in my case. It worked! Fusion 360 gave me an excellent dxf file that the waterjet used with no issuee, and the part fit perfectly into its intended position.  

It was a wonderful opportunity to contribute to a restoration. And a wonderful learning opportunity!

Acknowledgements

Print Reproduction via my Aircorps Library Subscription

Models and drawings created in Autodesk Fusion 360

Tuesday, June 07, 2022

My Tool Won't Fit! A Design Lesson From Life.

A typical aircraft brake disk.
There's not much room for a socket!
Hands on experience is often the greatest teacher. 

And, while helping work on a friend's change tires on a light aircraft. 

In looking at the brake disk, bolted to the tire rim, I saw that there was no way one could get a socket, the ideal tool for the job, onto the bolt. 

Fortunately, my friend, having run into this case many times before, had a wrench he'd cut to fit inside the disk. So in the end, it was job that was still very easily accomplished. 

But there lies a lesson for those of who sit behind a desk and design the machines we use every day. 

Just because the fastener fits, doesn't mean the tool will! So when designing, think of ease of maintenance. 

The maintainers, who are sometimes your customers, will thank you for it! 

About the Author:

Jonathan Landeros is a degreed Mechanical Engineer and certified Aircraft Maintenance Techncian. He designs in Autodesk Inventor at work, and Autodesk Fusion 360 for home projects. 

For fun he cycles, snowboards, and turns wrenches on aircraft. 

Friday, June 03, 2022

All PLA Prints the Same, Right? WRONG!

I print a lot of Polylactic Acid (PLA) in the 3D printer at work. I've found it's a great material to work with. It prints easy, and generally gives great results. 

A sample of a different PLA print. 
Usually a great material to work with.
Sorry, the actual print is proprietary.
Almost without exception, I have great results.

At least until all of a sudden I start having problems with it! 

When printing new color, silver from Amazon the PLA started peeling off the bed. 

It didn't matter how much glue I put down on the bed, It would peel up after a few layers. 

So what to do? 

My first step was to try a few troubleshooting steps. 

First, I raised the temperature of the bed from 50 degrees Celsius to 55 degrees Celsius. No luck there. 

Next, a thorough cleaning of the bed with isopropyl alcohol. I definitely had a cleaner bed, but still, the problem persisted.

Finally, I found a trick that solved the problem. Move the nozzle .05mm closer to the bed. Success!

The Z setting adjustment in my slicer.
I moved the nozzle slightly closer to the bed.

What is it about the silver filament? I'm not sure. But during my troubleshooting, I did notice that the gray filament did appear to be laying down a thinner layer. 

My only guess is something with the dye used to color the filament. But that's just a wild guess. 

So what's the takeaway? 

Keep an eye on those layers, and remember that not all filament of the same material prints the same! 

Resources used for this post: 

3D Printer: Fusion3 F400
Slicer Software: Simplify3D

About the Author:

Jonathan Landeros is a degreed Mechanical Engineer and certified Aircraft Maintenance Techncian. He designs in Autodesk Inventor at work, and Autodesk Fusion 360 for home projects. 

For fun he cycles, snowboards, and turns wrenches on aircraft. 





Tuesday, May 10, 2022

So Solidworks Happened at Work Today - A Musing

I've spent just over 20 years working with 3D CAD programs. That experience has been nearly exclusively with the Autodesk manufacturing product line, starting with Mechanical Desktop (shortly after the earth cooled), and followed by Autodesk Inventor. 

We've all seen the ubiquitous, 3D model, floating in space.

A couple of years ago, my company decided to experiment with switching to Siemens NX.

That experiment, unfortunately, failed. Siemens NX, while a good program, wasn't the right program for the needs of my employer. 

A few months ago, my company announced that we would be going to Solidworks. 

Other than dabbling in it a few times, I've never touched Solidworks. This could be an enormous change for me. 

Or not, perhaps? 

CAD Tools - Is it just
a Virtual Toolbox?

I completed an abridged "transfer training", where we were shown where all the buttons were and how Solidworks ticks. After that, we were released upon the world. 

And what did I find? Were my eyes opened to a brand new world? Was Solidworks so much better that I wondered what I was missing? 

Did I wail and gnash my teeth because Inventor was far better and I was being forced to use this inferior product?

No. I left that training and thought, "Wow! They're really similar." 

Sure, Solidworks has an Extrude and and Extrude Cut button, while Inventor has the same options combined within one Extrude command. But they both add and remove material in the end. 

There's functions where I think Inventor has it down better, and others where I have to give it to Solidworks. 

In the end, I see it as an opportunity to learn a new skill, enrichen myself, and be more marketable in a competitive world. I think that's going to take me further in the long run. 

So I suppose the point of my writing this is to muse about how CAD programs are tools. They're not the endgame, there the means to create our designs, drawings, and help us build our products. 

And there's nothing wrong with learning a new set of tools. It can only make me a more marketable designer. 

One Final Note

If you're using Fusion 360, you can change your Pan, Zoom, Orbit shortcuts to reflect Inventor or Solidworks, among other programs? 

I've switched mine to Solidworks, it may not be the same as having Solidworks at home, but it does makes it easier when I switch from one to the other at work! 

The Pan, Zoom, and Orbit options in Fusion 360