Save money with sparse 3D printing

Fused Deposition Modeling or FDM 3D printing is an excellent and popular choice for 3D printing rapid prototypes, jigs, fixtures, tooling, and low volume production parts, due in part to its material choices. FDM allows you to build complex parts with the same tried and tested thermoplastics found in conventional manufacturing.

A lesser known fact is that with FDM technology, you can chose between different interior fills to increase your savings when requesting your next 3D printing job. Depending on the material requested and your prototyping needs, you can print the interior of your part in up to three standard options plus additional custom options. Today we are going to cover the two most popular options:  

  • Solid
  • Sparse

Regardless of the interior fill that you choose, the exterior of your part will always be printed in solid. We have completed jobs in which we printed the same part using both of the above-mentioned interior fills, and the parts looked identical on the outside! There was a noticeable weight difference when they were picked up, which helped to tell them apart. When choosing interior fills, there are a few factors to keep in mind. These are some basic guidelines; each project is different and should be evaluated on an individual basis.

When to choose a solid interior fill:

  • Part strength is a critical feature
  • Part is comprised of fine details & thin walls

Choosing a solid interior fill will produce the strongest part. If part strength is a critical factor for your prototype, then a solid fill is the way to go.  A good example of this is any part created to replace metal tooling, as these parts typically need to withstand high levels of impact and heat. Functional prototypes are another area in which you may not want to sacrifice strength.  If you are going to put your part through the ringer, and the interior needs to resemble the final product as closely as possible, you will want to keep it solid.

Another consideration is the amount of fine details or features that your part has. If your part has thin walls or fine features, you will want a solid fill. With thin walled parts, there typically isn’t enough room for a sparse fill.  Your savings would be marginal and it wouldn’t be worth any loss of strength.

Aerospace 3D printing

Polycarbonate (PC) form tool used in hydroforming machines

Medical Prototype 3D Printed with Ultem 1010 thermoplastic material

Parts that have thin walls are best printed in a solid interior fill

When to choose a sparse fill: 

  • Weight is an issue
  • You have a part with a large interior and strength isn’t a factor

Jigs, fixtures, and trade show parts are three great fits for a sparse interior fill. BMW was able to reduce the weight of one hand-held assembly device by 72 percent by using a sparse fill printing technique. When a worker uses a tool hundreds of times in a shift, the reduced weight can make a big difference. Large trade show parts that are shipped frequently can also benefit from a sparse fill; the reduction in weight can help reduce not only shipping costs, but the strain of setting up the parts for each show.

Perhaps the most popular way to use a sparse interior fill is on a prototype you are printing for concept design or for fit and form testing. In most of these cases, you do not need the maximum strength of the thermoplastic material for your part.  You need to hold the part in your hand, make sure it is the right size, make sure it will fit nicely inside of the final assembly, etc. It is a one and done part before moving onto manufacturing or making additional design changes. If this is the case, consider giving the sparse interior fill a try for your next 3D printed project.

3D printed ergonomic production jig

Hand held device printed in a solid interior fill to reduce the weight by 72%

aerospace 3d printing materials

Aerospace prototype 3D printed using a sparse printing technique

How much will I save with a sparse fill versus a solid?

This is a very popular question and the answer, like so many others, is that it is geometry dependent. If your part has a large solid interior, i.e. a dumbbell, then you would experience far more significant savings by printing in a sparse fill versus a part that is mostly hollow, i.e. a cup. Depending on your part geometry and your prototyping needs, this printing technique can save you a couple of dollars, or it can cut your project cost in half. If you have a part for which you would like a quote, simply upload your STL or native CAD files here and mention in the comments that you would like to try a sparse printing technique.

Finishing my 3D printed parts – sanding

Finishing my 3D printed parts – sanding

A couple of my friends asked about quick tips for finishing up FDM parts so they are smooth and polished looking.  I was more than happy to help, but thought that perhaps our industrial users may want an overview of some hints.

First, Stratasys sells finishing systems for FDM parts that include vapor polishing (where acetone vapor smooths the surfaces) and has a referral network to vibratory tumblers and media blasters for other types of smoothing besides sanding.  Power tool sanding equipment ranges from Dremel tools to palm hand sanders, but many users complain power tools take off material far too quickly for careful finishing, so most tend to tick to hand sanding.

The parts that adapt to hand finishing best are parts that have a long area of “plain” features.  For example, a part that is shaped like a cup would be ideal for hand finishing since there are not small cracks and crevices to try and dig into with a small tool to smooth out.  The sides can be smoothed out and if desired, the part can be finished by painting.

First off, remove any support material that remains from the build.  If the part will be painted later, you want to print in a color that is as close to your final color as possible.  For example, if you intend to have a blue part, print the part using blue filament and after finishing paint in blue.  You will find that your part may need little paint in those cases.  Starting with your clean part use coarse grit sandpaper to knock off any obvious edges and defects and gradually move down to the fine grit sandpaper.   (Start with coarse then move to fine line so – 100, 240, 400, 600, 1500, and 2000 and so on using what you have on hand.)  If you have a perfectly flat surface that you are wanting to sand, a sanding block out of balsa wood keeps uneven pressure from your fingers from causing a divot on the surface.  Between changes of sand paper washing or blowing off the surface with shop air will allow you to check your progress.

Once you have finished sanding and are looking for the final touches, you can polish the part with a plastic buffing compound.  Note that if you are using a wheel or Dremel pressing too hard may cause heat build-up on the part surface.  If you intend to paint the part, the part should be washed to remove all traces of grit, dirt or oil.

When painting the parts, make sure that the paint selected is compatible with the type of plastic you are coating.  And, thin coats are much easier to control for gloss and drips than attempting to do a thick coating and short cutting the process.

On PolyJet parts, because of the superior surface finishes, you usually do not sand for finishing.  On occasion, sanding is used to prep the surfaces for paint, but usually you don’t need to smooth and polish the surfaces.  Ensuring the part is free of oil and dirt by washing is a good insurance policy to help assure paint adherence.  Some customers prefer to paint matte surfaces and build with this finish and some gloss, but most are not painting.  If you have the new J750 machine for PolyJet parts – decoration and painting is not needed – you can get the CMYK colors in and throughout the build by using our latest machine.  Logos and colors can be transferred from VRML files and 3Dpdf files into the build data and the 3D printed parts look and feel like the product pieces.

Want more information on the J750 click here.

Just returned from AMUG

I just got back from the annual Additive Manufacturers Users Group in St. Louis where I met fabulous people, saw wonderful machines and technology and saw so many of my old friends.  I can’t begin to cover everything but I do want to share some highlights.

On Monday, I was privileged to be at the unveiling of the J750 Connex 3 printer.  This printer is an enhanced Connex printer with WYSK color capability, increased speed and better resolution of features/layers, an enhanced software suite for dealing with files plus the ability to build with 6 materials and 1 support on one tray at one time.  It runs in 3 modes including high quality, high mix and high speed and dispenses droplets that are ½ of the size of what the Connex machines did in previous generations.  In high speed and high mix, the resolution is 27 microns and in high quality the resolution is an incredible 14 microns.  The ability to mix the 6 colors at once allows the user to mix colors to achieve a full spectrum of color and with the PolyJet Suite (formerly called Objet Studio) you can compare what you are specifying to what the machine output would be on the color to fine tune to get just the right brightness and density as well as color saturation. 

The J750 represents the product line between the Connex 3 and the Objet 1000 for better speed, resolution, color use and part size.  Using the Connex 500 size build platform, the machine also features the “file cabinet” hot swappable material bays we first saw introduced in the Connex 3 color machines and a new print head design.

The print head allows the material to flow thru the nozzles by having two build materials come thru the nozzle dedicated to that build or support.  It is explained as follows:

Screen Shot 2016-04-13 at 10.44.33 AM

This makes the print head very reliable and robust.  This also makes the print very detailed with the color with well-defined borders.

Screen Shot 2016-04-13 at 10.45.46 AM

All in all, this new printer could indeed be the bigger, faster, better offering that customers have been looking for in color 3D printing equipment.

In the new Objet Studio software, the new user interface gives you a better experience since it has buttons and more interactions on print speed, color selection and mixing as well as more options on digital material selection.  Objet Studio also gives users a better interface that is easier to use with more feedback on materials and file set up as well as repeatability and customization. 

Screen Shot 2016-04-13 at 10.46.29 AM

Compared to traditional color application, the new machine plus the new software give the user time savings and more options than ever possible.

The three printing modes of the J750 means that the users get 3 build options and 26 base materials with over 360,000 color combinations  that give them both resolution and speed with different material selections.  Additionally the digital material selection for different material mixes gives them color thru rigid and soft durometer parts.

Screen Shot 2016-04-13 at 10.46.47 AM

If you would like more information on the J750 or the PolyJet Studio software, give us a call.

Irish Jig or Jigs and Fixtures? A quick summary of the DFW 3D Printers Users Forum Meeting on St. Patrick’s Day.

Irish Jig or Jigs and Fixtures? A quick summary of the DFW 3D Printers Users Forum Meeting on St. Patrick’s Day.

I just came from our first DFW 3D Printers Users Group meeting in Irving Texas, and I have to say, this was an outstanding event.  Attendees raved about the topics, visuals and getting to meet experts on applications, machine support and software, scanning and how to choose the right technology.  With tornadoes, large hail with wind guests above 75 mph plus flooding due to heavy rainfall, Mother Nature didn’t make it easy to present the event and materials, but our St. Patrick’s Day morning was a winner.

With thanks to Kris Matson, the Technical Application Engineer from Stratasys who flew in just to present to our group on materials and applications, to Steve Kersen, the Vice President from locally based NVision who spoke on scanning and converting scan data to CAD and STL files, to Justin McNamara from Engatech’s Houston showroom who outlined the differences between software that comes with FDM machines, and Janice Callahan the North Texas account manager who welcomed our group, it was a wonderful meeting.  I was privileged to speak about the differences between FDM and PolyJet processing as well as share some online sites with communities and tools that we found useful and free for 3D printing people.  What a group of distinguished pros to share the podium with!

It was a lively group, with plenty of questions about machines and materials.  And, the applications and parts were great conversation starters, including contributions from the audience with samples and specifics.  Well done everyone.

Let me share a couple of key phrases from our presenters. 

From Kris Matson the Stratasys Technical Application Engineer – 3D printing doesn’t replace traditional manufacturing, 3D printing gets your parts into high volume and more traditional manufacturing area faster with more economy.

From Steve Kersen at NVision – Scanning is more than just a scan, it is also the manipulation of the data and meshes that result from the scan so the information can be used.

From Justin McNamar from Engatech – Using all the features of Insight gives you the ability to make your 3D printed parts even better by managing how the material is laid down in each layer and in different build styles.

From Barbara Arnold-Feret from Engatech – FDM make great durable parts and PolyJet makes high precision and high finish parts. Whether one is better than the other is going to “depend” on what you use the part for.  Plus there lots of free tools on the web that can be helpful for 3D printing pros.

From Janice Callahan from Engatech – commercial 3D printing machines are reliable and made to produce parts every time.  Each machine has a different price point. 

These are quick highlights from each speaker on just a quick snippet of what was covered.  Imagine the value of this conference to your firm.  We will be setting up more of the Users Forums in other cities across the region so stay tuned for updates and information on events, seminars, webinars and more on our event page and emails.

3D Printing A Perfect Part – Part 2

3D Printing A Perfect Part – Part 2

Note: This is Part-2, Click Here To Read Part-1

Last time we touched on building from the foundation of a good CAD file, this entry deals with orientation of the part during the build as a factor in making a good part. This orientation may be different in PolyJet versus Fused Deposition Modeling and also varies on the end use of the part that you are building. However there are few good guidelines.

In general if you are building a part with a cylinder shape, hollow tube, or circular ductwork, you will want to build the part in a vertical orientation. In other words, you want to build the parts so that the open area of the tube faces upward. This orientation allows you to minimize the amount of support used, maximize the stress resistance from forces from the side and minimize the stepping that can be seen when the part is built on the side. This build orientation may be a factor when looking at whether you can get the part into the build envelope, but in general, if you can get the part into the build area vertically, try to go that route.

In parts where you using PolyJet and building the part out of Rigur or Durus, if the part is going to be flexed across a thin wall area (such as a prototype of a living hinge) you will want to build the part with the thin section in the x and Y axis with the longest side of the hinge area getting the longest paths on the material laydown. Try avoiding doing short pathways of material build where the layers will be at the flexure points.

Note that the parts with living hinge prototyping will not have the same lifetime as an injection molding part with the same feature due to difference in material tear strength.

In prototyping a flat part, if the flat area exceeds 4 inches, remember that getting a similar part in injection molding would mean developing geometry to assure flatness. In end of arm tooling, thin flat areas with tips that must be accommodating to robotics with precision placement should have “v’s” or ribs to assist in keeping the parts from defecting, much like an injection molding part. In contrast, in injection molding achieving a flat surface is difficult due to material shrinkage and internal stresses in the part due to material flow and knit lines where the material fronts meet together during processing.

In 3D printing, you can often get the desired flatness on the part, but then have problems reproducing the flat feature in the production part. In FDM Ultem for example, you can print low volume production parts that have the flat feature, but in injection molding would not be abler to produce the same flatness.

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