A special issue of the Rapid Prototyping Journal is out with an article by our very own Ben Weiss.   His paper entitled “Low-cost closed-loop control of a 3D printer gantry”  (Weiss, B., Storti, D. W., & Ganter, M. A. (2015). Low-cost closed-loop control of a 3D printer gantry. Rapid Prototyping Journal, 21(5), 482-490).   DOI


{ X Axis Sensor Mount Design. }


Purpose:   The purpose of this paper is to explore the improvements in speed and precision achievable using straightforward closed-loop control for the gantry motion in additive manufacturing machines. The authors designed and built an economically viable demonstration system to quantify the performance improvement.

Design/methodology/approach: The authors develop and evaluate a low-cost closed-loop controller for the X and Y axes of an entry-level three-dimensional (3D) printer. The system developed captures and compensates for the dynamics of the motor and the belt-driven stage and detects mechanical errors, such as skipped motor steps.

Findings: The system produces path-following precision improvements of 40 and 75 percent for two different sample trajectories. Correcting for skipped steps increases reliability and allows for more aggressive tuning of motion parameters; time savings of up to 25 percent are seen by doubling acceleration rate.
Research limitations/implications: The system presented provides an appropriate platform for further investigation into more complex, application-specific controllers and inclusion of more details of the printer dynamics that could produce still greater improvements in speed and accuracy.


Practical implications: The performance, low cost (40 USD/axis) and applicability to the majority of sub-2000USD 3D printer designs make this work of practical significance.

Originality/value: The CNC machining industry has for many years used similar approaches, but application to 3D printers has not been explored in the literature. This paper demonstrates the value of even a simple controller applicable to almost any 3D printer, while maintaining cost-effectiveness of the solution in a competitive market.


Acknowledgments: This material is based on work supported by the National Science Foundation Graduate Research Fellowship Program under Grant No. DGE-1256082, which supported the lead author throughout the research process. The authors also gratefully acknowledge the insight of Matthew D. Sorensen, as well as the helpful comments of the reviewers.


{ Y Axis Sensor Mount Design. View from under the carriage, inside printer. }

The release of this material is exciting especially because the performance implications are substantial!   Great work Ben!


ganter on September 1, 2015

Congrats goes out to the team of researchers:  John Klein, Michael Stern, Giorgia Franchin, Markus Kayser1, Chikara Inamura, Shreya Dave, James C. Weaver, Peter Houk, Paolo Colombo, Maria Yang and Neri Oxman.

This team has presented a working 3D transparent glass printing system!   While we know of three other teams working in this exact idea, this teams successful results are amazing!

And upcoming article in 3D Printing and Additive Manufacturing:

Klein, John, Michael Stern, Giorgia Franchin, Markus Kayser, Chikara Inamura, Shreya Dave, James C. Weaver et al. “Additive Manufacturing of Optically Transparent Glass.” 3D Printing and Additive Manufacturing (2015).

“Additive Manufacturing of Optically Transparent Glass

We present a fully functional material extrusion printer for optically transparent glass. The printer is
comprised of scalable modular elements, able to operate at the high temperatures required to process glass from a molten state to an annealed product. We demonstrate a process enabling the construction of 3D parts as described by Computer Aided Design (CAD) models. Processing parameters such as temperature, which control glass viscosity, and flow rate, layer height and feed rate, can thus be adjusted to tailor printing to the desired component, its shape and its properties. We explored, defined and hard‐coded geometric constraints and coiling patterns as well as the integration of various colors into the current controllable process, contributing to a new design and manufacturing space. We report on performed characterization of the printed material executed to determine their morphological, mechanical and optical properties. Printed parts demonstrated strong adhesion between layers and satisfying optical clarity.

Demonstration of this molten glass 3D printer and fabricated objects demonstrates the production of parts, which are highly repeatable, enable light transmission, and resemble the visual and mechanical performance of glass constructs that are conventionally obtained. Utilizing the optical nature of glass, complex caustic patterns were created by projecting light through the printed objects.    The 3D printed glass objects described here can thus be extended to implementations across scales and functional domains including product and architectural design. This research lies at the intersection of design, engineering, science and art, representing a highly interdisciplinary approach.”

Please check out other online pictures which are awesome.    Again congratulations!

ganter on July 9, 2015


{Pilchuck Glass School}

In Session 3 of the 2015 summer program at Pilchuck Glass School, a new class on Digital Fabrication was offered.  The instruction team consisted of Fred Metz,  Mark Ganter,  Josh Kopel,  Matt Sorensen,  Tim Belliveau, and  Julia Chamberlain.   The class consisted of hands-on exposure to the latest 3D CAD and 3D printing software as well as both plastic material extrusion (filament) and binder jetting (powder) 3D printing systems.    Our students were brave and fierce in their desire to absorb new techniques and technology.

{Class getting ready for a metal casting pour into Lost-PLA investment molds}

The class designed and 3D printed their hearts out for the fabrication of press molds for sand casting glass, and lost-PLA investment molds for metal and glass.


{Peeking into the lost-pla investment glass kiln to check on the kiln cast glass}

The instruction team also brought a 3D binder jetting printer (powder printer) to Pilchuck to directly 3D print molds and glass.


{3D printed hydroperm molds for kiln casting glass}

One of the very last events of the class, direct 3D printing of boro-silicate glass (compliments of David Winship).   David brought along some samples of recycled boro-glass and his ball mills for the production of glass powder.  He screened the powder for printing and we 3D printed it.


{3D printed boro-silicate glass via VitraGlyphic process}

This is a first in the 3D printing community (as far as I know).   This was the very first 3D printing of boro-silicate glass using 3D binder jetting.   It was a great success.

Overall, the class was a smashing success.   We came.   We designed in 3D CAD.   We 3D printed.   We made glass and metal artifacts.  We celebrated our success.  We had a blast.



ganter on June 19, 2015

Four sophomore students who were all members of the student 3D printing club:WOOF, set out to design and fabricate a large format printer (during one academic quarter of 2014).  They are the third team to undertake this task. The team was composed of  Jeff Bergeson,  Nicole Bentzen,  Daniel Palomaki, and Kim Sokol.



{Rendering of the overall design concept}

“Over the past ten weeks our team has designed and built a large scale, multi-format
3D printer. Our project began where another project left off, with a preexisting printer that was very limited in many aspects. Our goal was to create an entirely new printer with the ability to extrude a variety of paste materials while still maintaining a high quality resolution and large scale. In addition, we aim to make the printer easy to use, and easy to transport. We went through the entire process of redesigning, building, and testing a new KiloPrint.”



{KiloPrint with the design/fabrication team}

“KiloPrint has a maximum build volume of 21”x33”x32… The cost of building KiloPrint, taken directly from our Bill of Materials, is around $1300. Though KiloPrint has a smaller build volume than the Brand-X, it is literally 1/10th the cost. Furthermore, the price of KiloPrint would continue to go down if it was manufactured in bulk. In addition, KiloPrint is also mobile and can print in multiple materials… we have plans to retrofit it with the ability to print in plastic as well. KiloPrint is still in the first stage of development; therefore it is not yet refined enough for retail sale. With these things in mind, it is safe to say that KiloPrint is rapidly becoming more and more competitive in the large scale 3D printer market.” – 6/15/2014

{Printing acrylic latex caulking}

Over the course of the current school year, the KiloPrint team has been busy with their studies. However, they HAVE tested several versions of plastic filament heads on its gantry.   They printed several full size rocket bodies and other rocket assembly parts {a future post}.   Recently they added a volcano style extruder to KiloPrint with some very good results.



The word around the WOOF room is new Z-axis drive system for smoother layer to layer transitions.

ganter on May 25, 2015

It seems like everyone is getting on the DLP bandwagon in the 3D printing space as of late.  While we have known about DLP 3D printing (i.e. vat photopolymerization process – ASTM F2792 − 12a)  for some time, we had chosen to stay away mostly due to resin issues.   Over the past few years, many new resin formulations have become available and many are both low in odor with toxicity within reasonable limits (in fact several resin systems are open sourced).  When you combine the improved resin systems with substantial activity in crowd funding sites and IRC chat, we decided to jump in to see what all the flashing lights were about.  We purchased a couple of systems and have been exploring both overall print system and resin concepts.


{One of our tet-ty bears under production using a test DLP system}

The left image is the exposure phase (about 1 sec).  The middle image during the peel and re-position phase (about 1 sec). The right image is a completed tet-ty.   It’s exciting to see the speed and quality of this process – no wonder everyone is excited.

ganter on May 22, 2015

We have been experimenting with creation and printing of structured and unstructured tetrahedral meshes over the past several months.  Our work has just been for fun and experimentation.     It currently involves multiple steps through different software systems (we are working on reducing what’s required).  Please notice that the animals are completely filled with tetrahedral structures (it is not simply a surface shell structure).

We are pleased to present:


{ a tetra-saurus rex}

tet_bear2{a tet-ty bear}

We will be posting more tet-ty creatures as our work progresses.

ganter on May 15, 2015

The Open3DP site received the following this week:

Hi Open3DP,


We are happy to tell you that CGTrader community has named you The Best Website For 3D Printing News out there!


CGTrader asked their 180 000 community members to vote for the best 3D online resources, software, tools and designers.  Qualitative and quantitative surveys were answered by 662 designers and they chose their favorites in the industry.


For more information on this award and other categories please check out: CGTrader page

Thank you!

ganter on April 28, 2015

Dear Readers,

Thanks for your patience.

After a bit of work,  we are running on new campus level servers.   This mean MUCH better up-time and automatic backup — hopefully more reliable service for you.

For a short time, there will be a redirection page (but that will go away in the near future).

BUT the real reason that we moved to campus level servers was SECURITY.   We were just getting tired of folks on the internet attempting to break into our little server.   Our failed login file was about 2GB each day.     When that failed, they were running DNS and flooding attacks.   I believe that will be done very soon.

I hope you all look forward to more OPEN material from us.

Yours … Open3DP team.


The Autodesk Spark team has done something quite unusual in the world of commercial 3D printing companies (3D Systems and Stratasys, please take note).  The Spark team has brought out a DLP style printer called the Ember which employs photo-resin technology.


{from lemoncurry group}

The Ember system is a bit on the high end in terms of cost (coming in at about $6000).   It is a bit out of the price league for home consumers but possibly within the scope of prosumers and small companies.  Unlike almost all 3D printing companies, Autodesk promised that they would not use the “razor blade model” for consumables (according to Duann Scott).     They have come through!   Autodesk released PR48 under CC-SA.

Thank you!

To get all the details, please check out their post on the spark blog:




ganter on March 6, 2015

by Kat Steele

Seattle Handathon

Students join forces to hack 3D-printed prosthetic hands

 Seattle’s first-ever “Handathon” brought together students, faculty, and clinicians last weekend for a 24-hour, hackathon-style challenge to build better 3-D printed prosthetic hands.  The event included two dozen participants from the engineering and prosthetics & orthotics (P&O) programs at UW-Seattle, UW-Bothell, and Seattle Pacific University.

 TheBeginning  The Beginning

 Teams were challenged to improve the latest open-source 3D-printed hand design, the Raptor Hand – from functional improvements to crazy design ideas. All teams had access to a CAD lab, 3D-printers, tools, actuators, electronics (Arduino, electromyography, etc.), and enough pizza, coffee, and treats to keep them energized for 24 hours.

 At the end of 24 hours we were amazed at the designs and improvements the students had developed.

The winning team, Dexterity, had two P&O students on the team and focused on function and comfort. They modified the thumb to provide more degrees of freedom and allow multiple types of grasps. To improve comfort, they incorporated a neoprene sleeve.

TeamDexterity Team Dexterity

 The second place team, Myo, used an Arduino with electromyography to create a locking mechanism for the hand. The current hand design lets users open and close the hand by flexing and extending their wrist. However, if you want to hold onto something for a long period, you have to keep flexing your wrist. To reduce fatigue, Myo created a simple mechanism that could lock the hand into a specific position triggered by electromyography.

Congratulations to all the participants! Over the next few weeks designs will be uploaded to the E-nable community to let others continue to build and innovate on the open-source designs. From Seattle, we challenge more groups to take hackathons from programming to physical devices!

The Handathon was organized by Dr. Kat Steele, a UW assistant professor in mechanical engineering and students in her Ability & Innovation Lab, along with Mark Ganter, a UW professor of mechanical engineering; Sue Spaulding, a UW teaching associate in rehabilitation medicine; Pierre Mourad and Ivan Owen at UW Bothell; and Adam Arabian at Seattle Pacific University.


 Karla Vega incorporates the actuator for Myo’s locking mechanism.