Girl Gang Garage: Custom Car Rebuilds + 3D Scanning + 3D Printing

What do you get when you cross a 1961 Volvo PV544 retro-look car with a sleek 2019 Volvo S60 T8 Polestar Engineered sedan – and why would you ever do that?

You get a custom head-turner hybrid vehicle designed to get people talking, especially about women in automotive trades. That’s because this blended vehicle project is being disassembled, redesigned and rebuilt by an all-female team based at Girl Gang Garage in Phoenix Arizona.

Bogi Lateiner and Shawnda Williams, co-owners of Girl Gang Garage, stand next to the stripped-down body of a 1961 Volvo PV544 that will soon be retrofitted on the chassis of a brand-new 2019 Volvo S60 T8 Polestar Engineered sedan. The rebuild project provides a rare hands-on learning opportunity for women of all ages and skill levels, from around the U.S., to come and learn (or improve) skills in welding, cutting, transmission work, body repair/painting, electronics, upholstery and more. (Image courtesy Girl Gang Garage.)

Girl Gang Garage founder and co-owner, Bogi Lateiner, TV host of Motortrend’s All Girls Garage and Garage Squad shows, is well on the way to transforming these vehicles as the third major public project she has undertaken. Along with co-owner Shawnda Williams, Lateiner offers women of all ages, experiences and skill levels the chance to lend a hand, learn a tool, and possibly discover a new career-path in the automotive trades.

The front showroom of Girl Gang Garage (Phoenix AZ). At the left is the group’s second all-female build dubbed High Yellow 56, displayed at the 2019 SEMA Show. Partially hidden in the center is the first (2017) Girl Gang build, the Chevy Montage with its BMW engine, and at the right is the early-stage PV544 rebuild slated for showing at the 2021 SEMA Show. (Image courtesy PADT Inc.)

Lateiner and Williams apply well-honed old-school skills but have been increasingly interested in the possibilities offered by today’s digital workflow. That’s why early in 2021, after conversations with the fellow re-build team at Kindig-It Custom Car Fabrication, Lateiner reached out to Stratasys to see how they might work together to incorporate 3D printing in the PV544 project.

At Stratasys, Pat Carey, Senior Vice President Americas Products & Solutions, and Allen Kreemer, Senior Strategic Applications Engineer, were immediately onboard with the chance to help Girl Gang Garage move into the digital world while widening their circle of women with automotive skills and interests. They loaned the team an F370 FDM 3D printer and accompanying support-removal SCA tank and offered to supply filament material for a two year try-whatever-you-want time period. Moreover, they pulled together a volunteer team of women across the country who could support the effort on multiple fronts.

Every 3D printer looks better with a cool scooter in front: the Stratasys F370 FDM printer, installed at Girl Gang Garage. (Image courtesy PADT Inc.)

A Virtual Team and a Digital Workflow

The team includes engineers whose day-time jobs have them working at Stratasys, Link3D, Autodesk, Xerox, Collins Aerospace and Ford Motor Company or as independent consultants. Printer installation and local support is handled by PADT Inc, a Stratasys reseller and 3D printing/design/simulation company located just 16 miles away from Girl Gang Garage. In addition, members of Women in 3D Printing offered to coordinate many of the publicity efforts and even sponsor a related design competition targeted at young women in high schools and colleges who are learning CAD skills. (More on that to come.)

During the first few Zoom meetings that introduced Lateiner and Williams to the technical capabilities of the different team members and the printer, the basic rebuild plan was presented: strip the PV544 down to bare metal (removing every mechanical and electrical component), disassemble the S60 down to the chassis, engine, drive-train and hybrid motor system, and figure out how to make the two sections fit!

Traditionally, that workflow depended strictly on the classic tools of the trade, from cutting wheels and a Sawzall to hand-grinders and pneumatic drills. Those components are still coming into play on the current project under the skilled eye of the Girl Gang Garage leaders, but now complementary digital processes are being added.

It Starts with Scanning

Using the GOM Tscan Hawk hand-held 3D laser-line scanner to digitally capture reference points, surface curvature and details on the PV544 body. (Image courtesy PADT Inc.)

PADT recently became a reseller of GOM 3D scanning hardware and software tools, and the timing was perfect to bring the new handheld Tscan Hawk system on-site. Operating with both red-line and blue-line (different wavelength) laser scanners plus stereo cameras, the Tscan Hawk captures millions of spatial 3D-point-coordinates (termed clouds of data) which are converted into a standard STL mesh file format for several end-purposes. The red lasers generate measurements across medium to large surfaces while the blue-wavelength sensors capture fine detail, with accuracy down to 20 microns.

GOM Inspect software records reference points, captures the individual coordinate data and allows interrogation of that data to provide dimensions, such as the distance between the engine frame mounts or the diameter of the hole into which the headlamp fits.

 (Images courtesy PADT Inc.)

These three images show a) the reference-point data that appears on the laptop screen as the shape of the PV544 vehicle’s underside is captured, b) the completed scan showing the 3D details of the as-built sheet metal and c) a report page from GOM Inspect software with dozens of dimensions extracted from the scan, such as the length of the trunk opening and the width of the opening available for the engine mount. The scan data, if exported as an STL file, could be sent directly to a 3D printer – though for this project the team is not printing the full body. Instead, subsets of the scan are being used for reverse engineering, where the data works as the basis for creative design elements to be printed and perhaps painted or plated.

To do so, the scanned data is be brought into a surfacing package such as Geomagic Design X or Innovmetric PolyWorks. Those software tools let users convert the STL mesh into an IGES surface, which can then be brought into a CAD package as the basis for a new solid model.

Not for the real build but as a fun example, here is a possible headlight-rim with the letters “Girl Gang Garage” cut out as a circular repeat pattern, that could be backlit with LEDS to customize the build. The design and dimensions are based on the maximum inscribed circle fitted by the GOM Inspect software inside the given opening. (In future blog posts, we’ll show examples of the CAD team’s actual 3D printing results.)

Scanning has many other purposes and capabilities. If CAD data were available for the actual vehicle, those files could be imported, overlaid on the captured data, and compared, alerting the user to deviations between intended and actual dimensions – a very common use of GOM Inspect software.

Next Steps

Every Thursday through Sunday, volunteer women come to Girl Gang Garage and learn to use cutting tools, welders, sanders and more, making daily progress toward the completed hybrid PV544. (All women are invited to come help and learn, at no cost – just sign up to get involved and get yourself to Phoenix.) Here are a few glimpses into the work as of early April – much more has been done but stay tuned for the next blog post as we show off elements of the S60 sedan, scan data being used for reference, and details of the design contest.

Views of the PV544 Volvo with work underway on a rear fender (also shown as scan data from the Tscan Hawk, with Bogi Lateiner in her Girl Gang Garage location). (Images courtesy PADT Inc.)

PADT Inc. is a globally recognized provider of Numerical Simulation, Product Development and 3D Printing products and services. For more information on Stratasys printers and materials, contact us at info@padtinc.com.

The Many Flavors of 3D Printer Maintenance, and Why it’s So Important

Just over a year ago, PADT, like most every other engineering company, shifted rapidly into minimal on-site-operations mode. As the PADT 3D Printing Application Engineer, I worked from home while requesting support from our manufacturing group for running benchmark parts on our Stratasys fused deposition modeling (FDM) filament and PolyJet resin printers.  Whether those parts were created on the F370, F450, F900 or J55 printers, they spanned a wide range of part size, function and material. It was an interesting time, but software tools like GrabCAD Print made remote part set-up possible, and the on-site team kept everything running under some often-challenging conditions.

I’ve been back in the office for about a month, so I’m tending to tasks that were, out of necessity, put on a backburner while our company did high-importance projects such as printing a ton of PPE visor frames. Now it’s time to do some printer maintenance that got a little delayed beyond the recommended run-time schedule.

For our Stratasys J55 full-color PolyJet printer, while all the standard components were cleaned and checked after every print, we stretched the recommendation period for replacing the wiper blade, the roller-waste collector, and both filters in the compact ProAero Air Extractor that contributes to making this printer truly office-friendly. Now I’ve checked those off as done.

Bring in the Printer Maintenance Experts

Other steps should only be done by a professional from the Service Department at your reseller or from Stratasys. When they come on-site to perform Preventive Maintenance for your printer, do you know what goes into this, and the kind of tasks that keep your system humming along?

It’s similar to practicing good automotive ownership: checking the air in your tires, changing the oil every 5,000 miles or so, replacing brake pads before they’re so thin that you have to turn the rotors, etc. Some jobs you do monthly, some yearly and some on general principles to avoid future trouble which inevitably occurs during the critical stage of a project.

Stratasys F450 Print-Head Gantry Assembly (Image courtesy Stratasys)

Here are some of the tasks our PADT service technician performs from the 12-month Preventive Maintenance Checklist for a Stratasys F450 industrial FDM printer:

  • With the printer powered off, clean the canister drives, gantry fans and electronics bay ventilation fans (kind of like cleaning out the ventilation area under the front of your refrigerator – which we all do regularly, right?) Also, inspect the head cable and heat shields, verify X-Y belt tensions, and replace the vacuum filter.
  • With the printer powered on, verify voltage levels, fan speeds and Z-Zero calibration, inspect the flicker brush assemblies and clean and lubricate the Z-axis leadscrew.

When the two-year point rolls around, these tasks are repeated plus another set is added, such as:

  • With the printer off: Replace the filament guide tubes, Kapton seals, X and Y bellows seals, oven lamps, air-pressure regulator diaphragm and all compressed-air system filter elements.
  • With the printer on: Adjust the air pressure and airflow, verify the oven blower operation and perform filament load-time tests.

And at the four-year mark, all of the above are completed plus such tasks as “replace the X and Y belts.” At every service appointment, too, the technician verifies that the current version of the printer control software has been installed, and that the user has the latest application software, whether Insight or GrabCAD Print. All in all, we’re talking more than 50 check points and tasks that keep the printer running smoothly.

High Expectations from Good Maintenance

I have to admit that when I get into my car, I expect the engine to idle smoothly, the air-conditioning to generate chilled-air, and my driveway to be free of oil spots. However, that expectation is only realistic if I or my mechanic has done due diligence with regular inspections and taken action when certain conditions show up. Checking for dirty spark plugs or a cracked distributor cap will maintain engine performance. If the serpentine belt is showing signs of wear, I’d better replace it rather than risk losing both power steering and air-conditioning on some far-off road in the desert on a beastly summer day. And worn rings, pistons or gaskets could all contribute to that oil leak.

And so it goes with 3D printers. First, the importance of avoiding down-time is huge for most manufacturers and factors into both production planning and a smooth workflow for printing prototypes. Second, if you’ve paid for a Stratasys-authorized Service Plan, you get guaranteed response time when something does go wrong (say you accidently melted filament into the print-head because you didn’t mount the tip correctly – life happens). Third, with a PM contract, a trained technician steps you through every aspect of the printer’s operation, inspection and cleaning whether done daily/weekly/monthly by a program engineer or by the system operator.

Stratasys offers three levels of contract service for almost all of its 3D printers, now covering the gamut from FDM and PolyJet to SLA, DLP, and the new Selective Absorptive Fusion (SAF, a polymer powder-bed fusion technology). Those levels are Sapphire, Emerald, and Diamond which can each be purchased for multi-year coverage.

Generally speaking, service offerings include:

  • On-site technical service
  • Spare parts
  • Priority service scheduling
  • Discounted user-training
  • Discounts on printer heads

Customers also win with hardware updates, optional backup printing services, predictable maintenance expenditures for easier budgeting, and more.

It’s not in my budget to buy a new car every year or even every couple of years, so regular, professional automotive inspection and maintenance is critical to me. It is to customers in the additive manufacturing world, too. So, to paraphrase that diamond-jewelry advertisement, “Now you have a friend in the 3D printer business: Stratasys.” Find out more about service contracts and the details of preventive maintenance by contacting 3DPSAL@PADTinc.com.

PADT Inc. is a globally recognized provider of Numerical Simulation, Product Development and 3D Printing products and services. For more information on Stratasys printers and materials, contact us at info@padtinc.com.

GrabCAD Print (the App): Making Work-from-Home Actually Work

I am so lucky in a zillion ways to be able to work from home while functioning in my position as a 3D Printing Application Engineer for PADT Inc., a Stratasys 3D printer reseller and engineering consulting/manufacturing company in Tempe Arizona.

Three things are making this possible:

1 – Awesome management and co-workers

2 – Great high-speed internet connection

3 – GrabCAD Print software, and more specifically, the GrabCAD Print phone app.            

Of all the apps on my phone, next to my gmail account, this is the app I check most often, because it is so handy!

First off, I can instantly see the status of the nine PADT printers we have on our Tempe network; I can also check other networks and accounts in other locations for which I have permission. That means I know the status of printers I’m running or want to run, and can tell how long someone else’s job is going to take – a very useful bit of information when it comes to telling a customer or our sales group what printer is open for running a part.

For example, this screen tells me:

–  a job is ready to start on our full-color PolyJet Objet500 Connex3,

–  one print just finished on our Fused Deposition Modeling (FDM) Fortus400,

–  my job is 43 percent complete on one of our FDM F370s, and

–  another of my jobs has just begun on the second F370 system.

I can even see that a print got cancelled on our older F250; in this case, I was expecting that, but it’s good information in case I wasn’t. But there is so much more…

Say I want to confirm the file name of what’s running on that first F370, and get some data about its status. I click on that printer’s name and the app shows me this screen:

Now I see that the print has just gotten to layer 2 of 123 slices total, it started at 1:58pm and it will finish at 6:12pm this evening. It also displays the file name of the part and shows that I’m the owner.

If I slide the image of the printer to the left, I then get the camera view, since an F370 has a build-chamber camera that updates about every ten seconds. Because this print had just started, you can’t really see much beside the build plate (brightly lit at the top), but I can come back to that as often as I like to monitor a particularly challenging geometry – say, perhaps a tall thin part where I added some extra support structure.

At this point I can access several more windows. If I click Job Material Usage, I see

This information is useful if I need a reminder of how much model and support material this print will consume.

The next line offers the bigger picture: clicking through, I see how much material remains in each canister, for both the model and support; it also shows what, if any, material is loaded in the second set of bays. Stratasys printers with double bays will do an automatic hot-swap as needed – a nice feature over the weekend or in the middle of the night.

Here’s another possible status screen: a paused build, where I had planned ahead, inserting a Pause Build instruction in the GrabCAD job set-up. In this case, I wanted to stop the part and remove it, to create a sample piece that exposes the hexagram infill I chose for lightweighting. Another reason to pause and resume an FDM print is to add hardware such as a flat washer to reinforce a deep hole.

The GrabCAD Print App also sends me email alerts (with a chime on the phone) when the status of a print job changes, such as the message below telling me the job has indeed paused as planned:

(I don’t get notifications for other people’s jobs, so I don’t get inundated with messages.)

This real-time information lets me keep track of all my print jobs from my 3D Printing Command Center deep in the heart of suburban Phoenix. I can do 98% of what I need to remotely.

Of course, I depend on the engineers in PADT’s Manufacturing group – essential workers who’ve been in the office non-stop throughout this crazy 2020 work-year. They change filament, load clean trays, run calibrations, remove parts, and put finished prints in our Support Cleaning Apparatus tanks (a PADT-developed system spun off to Oryx and OEM’d to Stratasys since 2009.) That step dissolves the soluble support. (For several of the engineering filaments I run, the support is break-away, and my team takes care of that, too.)

The GrabCAD Print App is available as a free download from the Apple app store. And all of this is in addition to how you can view and interact with GrabCAD Print itself from any computer, setting up a part to print as you sit in one city then uploading the print-ready file to a system across the state or across the country.

Got any questions about the app? We’d love to answer them.

PADT Inc. is a globally recognized provider of Numerical Simulation, Product Development and 3D Printing products and services. For more information on Stratasys printers and materials, contact us at info@padtinc.com.

Example of full color part with mapped image, created from 3MF file format brought into GrabCAD Print and printed on a Stratasys PolyJet 3D printer. (Image courtesy GrabCAD)

3MF Printing Format Comes to GrabCAD Print

Example of full color part with mapped image, created from 3MF file format brought into GrabCAD Print and printed on a Stratasys PolyJet 3D printer. (Image courtesy GrabCAD)

Example of full color part with mapped image, created from a 3MF file-format brought into GrabCAD Print and set up to print on a Stratasys PolyJet 3D printer. (Image courtesy GrabCAD)

What is the 3MF format? How does it differ from the standard STL format? And what can you do with it, especially if your 3D printers run GrabCAD Print software from Stratasys?

For most designers, engineers and users involved in 3D printing, regardless of the 3D CAD software you use, you save (convert) your model to print as an STL format file. A lot has been written about it, including a PADT post from back in 2012 – and STL-wise, things really haven’t changed. This format approximates the native CAD solid model as a closed surface comprising small triangles of various shapes and sizes. STL has been the standard since the AM industry began, and although different CAD packages use different algorithms to create the mesh, for the most part, it’s worked pretty well.

A Sample STL File Segment

However, an STL file is simply a large text file listing the Cartesian coordinates for each vertex of the thousands of triangles, along with info on the normal direction:

Sample code from saving a CAD model in STL format.

A modest number of large triangles produces relatively small files but doesn’t do a good job of reproducing curves (think highly faceted surfaces); conversely, big files of many small triangles produce much smoother transitions but can take a long time to process in slicing software.

And, perhaps the biggest negative is that an STL file cannot include any other information: desired color, desired material, transparency, internal density gradient, internal fine structure or more.

What is 3MF?

In early 2015, Microsoft and a number of other major corporations including Autodesk, Dassault Systèmes, HP, Shapeways and SLM Group created a consortium to address these issues. They decided to overhaul a little-used file format called the 3D Modeling Format (3MF), to make it support highly detailed 3D model information and be more useful for 3D printing and related processes.

Logo 3MF Consortium

This ongoing consortium project defines 3MF as “a set of conventions for using XML to describe the appearance and structure of 3D models for the purpose of manufacturing (3D printing).”

In developer language, 3MF is a standard package or data that follows a core specification and may include some task-specific extensions.

In user terms, a 3MF file contains some or all of the following information in ASCII format:

  • Metadata about part name, creator and date
  • Information on the mesh of triangles (yes, it still creates and uses these, but does it better for a number of reasons, one of which is that it cannot create non-manifold edges (i.e., triangles that share endpoints with more than one triangle, which confuses the printer))
  • Color information (throughout the complete part body or in sub-sections)
  • Ways to define multiple materials combined as a composite
  • Texture information – what it is and where to place it
  • Ways to assign different materials to different sections of a part
  • Ways to duplicate information from one section of a part to another section, to save memory
  • Slicing instructions

Without getting into the nitty gritty, here are just two examples of XML code lines from 3MF metadata sections:

Example code of saving a solid CAD model in 3MF format.

Meaning, information about the part number and the part color rides along with the vertex coordinates! For a deep-dive into the coding schema, including a helpful glossary, see the 3MF github site; to learn how 3MF compares to STL, OBJ, AMF, STEP and other formats, check out the consortium’s About Us page.

Exporting 3MF Files

Now, how about using all of this? Where to start? Many 3D CAD software packages now let you save solid models as 3MF files (check out your “Save As” drop-down menu to verify), but again, they can vary as to what information is being saved. For example, a SolidWorks 3MF file can generate data on color and material but does not yet support transparency.

Here are all the options that you see in SolidWorks when you click the arrow next to “Save As”:

Second step in SolidWorks for saving a file in 3MF format: check off “include materials” and “include appearance.” (Image courtesy PADT)

“Save As” window in SolidWorks 2019, where step number one is to select “.3mf” format. (Image courtesy PADT)

You can select “.3mf” but don’t Save yet. First, click on the “Options” button that shows up below the Save as File Type line, opening this window:


Second step in SolidWorks for saving a file in 3MF format: check off “include materials” and “include appearance.” (Image courtesy PADT)

You need to check the boxes for “Include Materials” and “Include Appearances” to ensure that all that great information you specified in the solid model gets written to the converted file. A good, short tutorial can be found here.

Another interesting aspect of 3MF files is that they are zipped internally, and therefore smaller than STL files. Look at the difference in file size between the two formats when this ASA Omega Clip part is saved both ways:

Comparison of file size for STL versus 3MF formats.

The 3MF-saved file size is just 13% the size of the standard STL file, which may be significant for file manipulation; for files with a lot of detail such as texture information, the difference won’t be as great, but you can still expect to save 30 to 50%.

Working with 3MF files in GrabCAD Print

Okay, so CAD programs export files in 3MF format. The other half of the story addresses the question: how does a 3D printer import and use a 3MF file? Developers of 3D printing systems follow these same consortium specifications to define how their software will set up a 3MF file to print. Some slicers and equipment already act upon some of the expanded build information, while others may accept the file but still treat it the same as an STL (no additional functions enabled so it ignores the extra data). What matters is whether the system is itself capable of printing with multiple materials or depositing material in a way that adds color, texture, transparency or a variation in internal geometry.

GrabCAD Print (GCP), the cloud-connected 3D Printer interface for today’s Stratasys printers – both FDM and PolyJet – has always supported STL and native CAD file import. However, in GCP v.1.40, released in March 2020, GrabCAD has added support for 3MF files. For files created by SolidWorks software, this adds the ability to specify face colors, body colors and textures and send all that data in one file to a PolyJet multi-material, multi-color 3D printer. (Stratasys FDM printers accept 3MF geometry and assembly structure information.)

For a great tutorial about setting up SolidWorks models with applied appearances and sending their 3MF files to GrabCAD Print, check out these step-by-step directions from Shuvom Ghose.

Example of setting up a textured part in SolidWorks, then saving the file in 3MF format and importing it into GrabCAD Print, for printing on a full-color Stratasys PolyJet printer. (Image courtesy GrabCAD)

Example of setting up a textured part in SolidWorks, then saving the file in 3MF format and importing it into GrabCAD Print, for printing on a full-color Stratasys PolyJet printer. (Image courtesy GrabCAD)

At PADT, we’re starting to learn the nuances of working with 3MF files and will be sharing more examples soon. In the meantime, we suggest you download your own free copy of GrabCAD Print to check out the new capabilities, then email or call us to learn more.

PADT Inc. is a globally recognized provider of Numerical Simulation, Product Development and 3D Printing products and services. For more information on Stratasys printers and materials, contact us at info@padtinc.com.

Varied Infill Options for CAD models brought into GrabCAD Print software for 3D Printing. (Image courtesy PADT)

GrabCAD Print Software, Part Two: Simplify Set-ups, Save Time, and Do Cool Stuff You Hadn’t Even Considered

(Edited 3 August 2020 to reflect GrabCAD Print V1.44)

You haven’t really lived in the world of 3D printing until you’ve had a part fail spectacularly due to open faces, self-intersecting faces or inverted normals. Your part ends up looking more like modern art than technical part. Or perhaps the design you have in mind has great geometry but you wish that some parts could have regions that are dense and strong while other regions would work with minimal infill.

In Part One of this blog post about GrabCAD Print software, we covered the basics of setting up and printing a part; now we’ll look at several of the advanced features that save you set-up time and result in better parts.

Behind the Scenes Repairs

Stratasys GrabCAD Print software, available as a free download, is crafted for users setting up solid models for 3D printing on Stratasys FDM and PolyJet printers. Once you’ve started using it, you’ll find one of its many useful advanced features is the automated STL file-repair option.

Imported STL file, with GrabCAD Print ready to automatically repair errors. PADT image.

Most people still create solid models in CAD software then convert the file to the industry-standard STL format before opening it in a given 3D printer’s own set-up software. Every CAD package works a little differently to generate an STL file, and once in a while the geometry just doesn’t get perfectly meshed. Triangles may overlap, triangles may end up very long and very skinny, or the vector that signals “point in” or “point out” can get reversed.

Traditionally, the 3D printer set-up program reacts to these situations by doing one of two things: it prints exactly what you tell it to print (producing weird holes and shifted layers) or it simply refuses to print at all. Both situations are due to tiny errors in the conversion of a solid CAD model to a tessellated surface.

GrabCAD Print, however, gives your file a once-over and immediately flags sections of the model in need of repair. You can see a color-coded representation of all the problem areas, choose to view just some or all, and then click on Automatic Repair. No hand-editing, no counting layers and identifying sections where the problems reside – just a click of the virtual button and all the problem regions are identified, repaired and ready for the next processing steps.

CAD vs. STL: Do So Much More with CAD

GrabCAD Print also uniquely allows users to bring in their models in the original CAD file-format (from SolidWorks, Autodesk, PTC, Siemens, etc.) or neutral formats, with no need to first convert it to STL. For FDM users, this means GrabCAD recognizes actual CAD bodies, faces, and features, letting you make build-modifications directly in the print set-up stage that previously would have required layer-by-layer slice editing, or couldn’t have been done at all.

For example, with a little planning ahead, you can bring in a multi-body CAD model (i.e., an assembly), assemble and group the parts, then direct GrabCAD to apply different parameters to each body. This way you can reinforce some areas at full density then change the infill pattern, layout, and density in other regions where full strength is unnecessary.

Here’s an example of a SolidWorks model intended for printing with a solid lower base but lighter weight (saving material) in the upper sections. It’s a holder for Post-It® notes, comprising three individual parts – lower base, upper base and upper slot – combined and saved as an assembly.

Sample multi-body part ready to bring into GrabCAD Advanced FDM. Image PADT.

Sample multi-body part ready to bring into GrabCAD Advanced FDM. Image PADT.

Here was my workflow:

1 – I brought the SolidWorks assembly into GrabCAD, assembled and grouped all the bodies, selected an F370 Stratasys FDM printer, chose Print Settings of acrylonitrile butadiene styrene (ABS) and 0.010 inches layer height, and oriented the part.

2 -To ensure strength in the lower base, I selected just that section (you can do this either in the model tree or on the part itself) and opened the Model Settings menu at the right. Under Body, I chose Solid Infill.

3 – Next I selected the upper base, chose Hexagram, and changed the Infill Density to 60%.

4 – Lastly, I selected the upper slot section, chose Sparse, and changed the Infill Density to 35%.

5 – With all three sections defined, I clicked on Slice Preview, sliced the model and used the slider bar on the left to step through each section’s toolpath. For the screenshots, I turned off showing Support Material; the yellow bits indicate where seams start (another parameter that can be edited).

Here is each section highlighted, with screenshots of the parameter choices and how the part infill looks when sliced:

Upper base set up in GrabCAD to print as Hexagram pattern, 60% infill; sliced toolpath shown at right. Image PADT.
Upper slot section set up in GrabCAD to print as Sparse pattern, 35% infill; sliced toolpath shown at right. Image PADT.

So that you can really see the differences, I printed the part four times, stopping as the infill got partway through each section, then letting the final part print to completion. Here are the three partial sections, plus my final part:

Lower base (solid), upper base (hexagram) and first part of upper slot (sparse), done as partial prints. Image PADT.
Completed note-holder set up in GrabCAD Print, Advanced FDM mode, weighted toward the bottom but light-weighted internally. Image PADT.
Completed note-holder set up in GrabCAD Print using advanced infill features, weighted toward the bottom but light-weighted internally. Image PADT.

Automated Hole Sizing Simplifies Adding Inserts

But like the old advertisements say, “But wait – there’s more!” Do you use heat-set inserts a lot to create secure connections between 3D printed parts and metal hardware? Planning ahead for the right hole size, especially if you have different design groups involved and fasteners may not yet be decided, this is the feature for you.

Sample part set up for easy insert additions, using Advanced FDM in GrabCAD Print. Image PADT.

Sample part set up for easy insert additions, using advanced, automated hole-resizing features in GrabCAD Print. Image PADT.

In your CAD part model, draw a hole that is centered where you know the insert will go, give it a nominal diameter and use Cut/Extrude so that the hole is at least the depth of your longest candidate insert. Save the file in regular CAD format, not STL. Next bring your part into GrabCAD Print and go to Model Settings in the right-hand menu.

This time, click on Face (not Body) and Select the inner cylindrical wall of your hole. Several options will become active, including Apply Insert. When you check that box, a new drop-down will appear, giving you the choice of adding a heat-set insert, a helicoil insert or creating a custom size. Below that you select either Inch or Metric, and for either, the appropriate list of standard insert sizes appears.

Automatic hole-resizing in GrabCAD Print, for a specific, standard heat-set insert. Image PADT.

Choose the insert you want, click Update in the upper middle of the GrabCAD screen, and you’ll see the hole-size immediately changed (larger or smaller as needed). The new diameter will match the required oversized dimensions for the correct (melted into place) part-fit. You can even do this in a sidewall! (For tips on putting inserts into FDM parts, particularly with a soldering iron, see Adding Inserts to 3D Printed Parts: Hardware Tips.)

Note that this way, you can print the overall part with a sparse infill, yet reinforce the area around the insert to create just the right mass to make a solid connection. The Sliced view will show the extra contours added around each hole.

Sliced view showing insert holes with reinforced walls, done in GrabCAD Print. Image PADT.
Manufacturing notes automatically created in GrabCAD Print when insert holes are resized. Image PADT.

To document the selected choices for whoever will be doing the insert assembly, GrabCAD also generates a numbered, manufacturing-footnote that lists each insert’s size; this information can be exported as a PDF file that includes a separate close-up image of each insert’s location.

GrabCAD Print keeps adding very useful functions. Download it for free and try it out with template versions of the various Stratasys 3D printers, then email or call us to learn more.

PADT Inc. is a globally recognized provider of Numerical Simulation, Product Development and 3D Printing products and services. For more information on Stratasys printers and materials, contact us at info@padtinc.com.

New Options for 3D Printing with Nylon Filament, Including Diran

NOTE 10/28/2019: See updated information regarding Diran extruder heads, below.

Does the idea of 3D printing parts in semi-aromatic polyamides (PA) sound intriguing? Too bad it has nothing to do with making nicely scented models – but it has everything to do with reaping the benefits of the Nylon family’s molecular ring structure. Nylon 6, Nylon 12, carbon-filled Nylon 12 and now a new, smoother Nylon material called Diran each offer material properties well-suited for additive manufacturing on industrial 3D printers.

Stratasys Nylon 12 Battery Box
3D printed Nylon 12 Battery Box. (Image courtesy Stratasys)

Quick chemistry lesson: in polyamides, amine sub-groups containing nitrogen link up with carbon, oxygen and hydrogen in a ring structure; most end up with a strongly connected, semi-crystalline layout that is key to their desirable behaviors. The number of carbon atoms per molecule is one way in which various Nylons (poly-amines) differentiate themselves, and gives rise to the naming process.

Now on to the good stuff. PA thermoplastics are known for strength, abrasion-resistance and chemical stability – useful material properties that have been exploited since Nylon’s discovery at Du Pont in 1935. The first commercial Nylon application came in 1938, when Dr. West’s Miracle Tuft Toothbrush closed the book on boar’s-hair bristle use and let humans gently brush their teeth with Nylon 6 (then called “Exton”) fibers.

Today’s Nylon characteristics translate well to filament-form for printing with Stratasys Fused Deposition Modeling (FDM) production-grade systems. Here’s a look at properties and typical applications for Nylon 6, Nylon 12, Nylon 12 CF (carbon-fiber filled) and Diran (the newest in the Stratasys Nylon material family), as we see their use here at PADT.

When Flexibility Counts

Nylon 12 became the first Stratasys PA offering, filling a need for customized parts with high fatigue resistance, strong chemical resistance, and just enough “give” to support press (friction-fit) inserts and repetitive snap-fit closures. Users in aerospace, automotive and consumer-goods industries print Nylon 12 parts for everything from tooling, jigs and fixtures to container covers, side-panels and high vibration-load components.

3D Printed Nylon 12 bending example. (Image courtesy Stratasys)
3D Printed Nylon 12 bending example. (Image courtesy Stratasys)

Nylon 12 is the workhorse of the manufacturing world, supporting distortion without breaking and demonstrating a high elongation at break. Its ultimate tensile strength in XZ part orientation (the strongest orientation) is 6,650 psi (46 MPa), while elongation at break is 30 percent. Users can load Nylon 12 filament onto a Stratasys Fortus 380mc CF, 450mc or 900mc system.

As evidenced by the toothbrush renaissance, Nylon 6 has been a popular thermoplastic for more than 80 years. Combining very high strength with toughness, Nylon 6 is great for snap-fit parts (middle range of flexing/stiffness) and for impact resistance; it is commonly used for things that need to be assembled, offering a clean surface finish for part mating.

Nylon 6 displays an XZ ultimate tensile strength of 9,800 psi (67.6 MPa) and elongation at break of 38%; it is available on the F900 printer. PADT customer MTD Southwest has recently used Nylon 6 to prototype durable containers with highly curved geometries, for testing with gasoline/ethanol blends that would destroy most other plastics.

Prototype gas-tank made of Nylon 6, printed on a Stratasys system, using soluble support. (Image courtesy MTD Southwest)
Prototype gas-tank made of Nylon 6, printed on a Stratasys system, using soluble support. (Image courtesy MTD Southwest)

Both Nylon 12 and Nylon 6 come as black filament that prints in tandem with a soluble brown support material called SR-110. Soluble supports make a huge difference in allowing parts with internal structures and complicated overhangs to be easily 3D printed and post-processed.

Getting Stronger and Smoother

As with these first two PA versions, Nylon 12CF prints as a black filament and uses SR-110 soluble material for support; unlike those PAs, Nylon 12CF is loaded at 35 percent by weight with chopped carbon fibers averaging 150 microns in length. This fiber/resin combination produces a material with the highest flexural strength of all the FDM Nylons, as well as the highest stiffness-to-weight ratio.

Nylon 12 CF (carbon-filled) 3D printed part, designed as a test brake unit. (Image courtesy Stratasys)
Nylon 12 CF (carbon-fiber filled) 3D printed part, designed as a test brake unit. (Image courtesy Stratasys)

That strength shows up in Nylon 12 CF as a high ultimate XZ tensile strength of 10,960 psi (75.6 MPa), however, similar to other fiber-reinforced materials, the elongation at break is lower than for its unfilled counterpart (1.9 percent). Since the material doesn’t yield, just snaps, the compressive strength is given as the ultimate value, at 9,670 psi (67 MPa).

Nylon 12 CF’s strength and stiffness make it a great choice for lightweight fixtures. It also offers electrostatic discharge (ESD) protection properties better than that of Stratasys’ ABS ESD7, yet is still not quite conductive, if that is important for the part’s end-use. (For more details on printing with Nylon 12 CF, see Seven Tips for 3D Printing with Nylon 12 CF.) The material runs on the Fortus 380mc CF, 450mc or 900mc systems.

Just announced this month, Stratasys’ Diran filament (officially Diran 410MF07) is another black Nylon-based material; it, too, features an infill but not of fibers – instead there is a mineral component listed at seven percent by weight. This filler produces a material whose smooth, lubricious surface offers low sliding resistance (new vocabulary word: lubricious, meaning slippery, with reduced friction; think “lube job” or lubricant).

Robot-arm end printed in Diran, a smooth Nylon-based filament. (Image courtesy Stratasys)
Robot-arm end printed in Diran, a smooth Nylon-based filament. (Image courtesy Stratasys)

This smooth surface makes Diran parts perfect for applications needing a non-marring interface between a tool and a workpiece; for example, a jig or fixture that requires a part to be slid into place rather than just set down. It resists hydrocarbon-based chemicals, displays an ultimate tensile strength of 5,860 psi (40 MPa), and has a 12 percent elongation at break.

Close-up of Diran's smooth surface finish. (Image courtesy Stratasys)
Close-up of Diran’s smooth surface finish. (Image courtesy Stratasys)

(Revised) For the first time, Diran also brings the benefits of Nylon to users of the Stratasys office-environment, plug-and-play F370 printer. The system works with the new material using the same extruder heads as for ABS, ASA and PC-ABS, with just a few material-specific requirements. 

To keep thermal expansion consistent across a model and any necessary supports, parts set up for Diran automatically use model material as support. A new, breakaway SUP4000B material comes into play as an interface layer, simplifying support removal. The higher operating temperature also requires a different build tray, but the material’s lubricious properties (just had to use that word again) make for easy part removal and allow that tray to be reused dozens of times.

Read more about this intriguing material on the Diran datasheet:

and contact PADT to request a sample part of Diran or any of these useful Nylon materials.

PADT Inc. is a globally recognized provider of Numerical Simulation, Product Development and 3D Printing products and services. For more information on Stratasys printers and materials, contact us at info@padtinc.com.