Mobile 3D Printing (Out of the Box)

We offered a new laboratory exercise in our Compute Aided Engineering class — Kiln Glass Casting.   We have been playing with direct 3DP molds for a little over a year now.   The way to know if you really understand something is to let students give it a go.

This lab allows you to experience direct mold printing (via 3DP) and kiln casting glass.  Your mold will be used once(it will be
distroyed during the Kiln casting process).

You will not need draft and you can have undercuts (if you have undercuts, you will likely need  vents due to trapped air).  
Also, if you have significant undercuts, there may be issues of de-powdering your mold.

Constraints:

You will not be constrained by mold boxes BUT you may use only 12000 mm^2 (~18.6 in^2) or less of plate cross-section and the max
height is 70 mm (about 2.75 inches).

No part of your resulting glass object can be more than 1 inch (25.4 mm) thick.

Mold must be 16mm (5/8 inches) thick everywhere.

Design Guidelines:

• Consistency of honey.
• Features on a surface (min 3-4mm).
• Smaller features might break off in depowdering (similar to previous labs).
• Some smaller features might not completely fill out, but they will leave an impression.
• Extruded and thinner features must be greater than 3/8″ with proper gates to allow flow and air to escape.
• Edges of smaller features will not be crisp.
• Must be able to access all parts of the mold to depowder it.
• Features on the top surface (especially open-faced) on the edge of the mold will be rounded because of the meniscus of the glass.

They designed!  We printed molds.  We set the firing schedule on the kiln to cast glass, loaded up the kiln, and pushed start…

The result was a 50% yield.   Even after all of the reading that we had done on kiln casting (and successful runs), the thicker parts were not annealing and cooling correctly.  We even had one explode with such force that it destroyed its mold!   Time for more research and reading.  After much more reading, we learned a new phrase — “lower strain points“.   While one could employ finite element analysis to run an annealing/cooling analysis to determine a furnace curve (perhaps another time), much of art glass is explored empirically.   We found an amazing book of furnace curves by Graham Stone called “Firing Schedules for Glass – The Kiln Companion”.   Biblical in firing schedule nature!  With several new firing schedules in hand, time to reprint molds and try again…

Yes, we know that you REALLY shouldn’t open the kiln when its glowing hot (so don’t) but we couldn’t resist taking this picture.  Our resulting firing schedule is a mixture of schedules from Bullseye Glass, Spectrum Glass, and Graham Stone’s Book.   We were casting regular (not premium) Spectrum Furnace Nuggets (a System 96 soda-lime glass) which is typically used in glass blowing furnaces (it is economical for class use).

Rate (F/hr)  Temp (F)   Hold Time
=================================
200           850       0.5 hour
500          1050        1 hour
500          1650        6 hour
9999          960        6 hour
  8           800        1 hour
 16           700        1 hour
OFF  to cool to room temperature

This schedule seems conservative and produced 100% casting success.

We believe that this curve works for objects of 2 inches (100 mm) or less in thickness.  (How one determines maximum thickness is completely another issue to be discussed another time).  

Results…

Our students had a great time (although if we’re not careful this could become the “shot glass lab”).  We still have a few more pieces in the kiln… We can’t wait to see them.

Wow, it seems clear that the general populace is very interested in 3D printing.   I based this conclusion on the close of the recent Kickstarter Project PrintrBot.    If my facts are correct, the PrintrBot project comes in as the second highest funded project of all time (the highest funded project is the TikTok watch at $942,578). Just like 3D printing has the possibility of changing the future so to does the Kickstarter project!  This is amazing!

The final total = 1808 project backers with total contributions of $830,827.
Here’s a rough funding history (as emailed to project supporters).

We’ve been busy working on new works for Emerge 2012.

However, one of our alumni (Nick Lewis) of the InkShield project and RepRapBreeding checked in the other day.  He told us to check out the action on Kickstarter in 3D printing & DIY CNC.

As of today, we checked Kickstarter search: <3D printer>, there were 12 projects!  Of the 12 projects, 9 of the 12 projects were funded!  That’s a great success ratio.

The current project: <Printrbot-Your-First-3d-Printer> by Brook Drumm

“I designed the Printrbot to be the simplest 3D printer yet.  There are some great kits out there – the Makerbot, the Ultimaker, the Prusa Mendel, and others – but none as small and simple as the Printrbot.  This all-in-one 3D printer kit can be assembled and printing in a couple of hours.  Other kits will not only take you many more hours to build, they will also have hundreds more parts, and they will cost more.  My design also does away with the finicky calibration and adjustment from which most 3D printers suffer.   This is the printer a kid could put together. We assemble the electronics, we assemble the hotend, and we put the connectors on all the motors and components… no soldering required!”

The PrintrBot project currently has 635 backers as of 11/28/2011 @ 10:00 am PST.

The best part of the PrintrBot project is … a pledge of $499 or more gets you a Full Printrbot Kit (according to the project post).

The PrintrBot project closes on Dec. 17th.  Imagine a nice PrintrBot for the Holidays! Wow!

Again, we checked Kickstarter search: <CNC>, there were 16 projects!  Of the projects, 12 of the 16 projects were really DIY CNC projects!  Out of the 12 projects, 7 of the projects were funded! That’s a good success ratio.  There are no current project DIY CNC projects.

Bottom line, if you’re looking for something interesting to do with Cyber Monday money, please consider helping out your fellow inventors, artists, designers, and budding business owners via online funding sites.

“3D Systems to Acquire Z Corp and Vidar”

Once again, 3D Systems has been shopping.

===== Updates =====

We’ve included a couple of nice overviews from the web from yesterday.  There’s some great historic information being presented.

http://blog.rp-editorialservices.co.uk/2011/11/3d-printing-landscape-changed.html

http://www.plasticstoday.com/articles/3d-systems-buys-z-corp1121021102

In a bit of fun, we took the Skull Coin from Thingiverse and used it to produce a mold.  Last night, we did a kiln cast glass run.   The results were very nice glass dubloons (not quite the glass coins we envisioned).

{glass skull dubloons}

It was bound to happen, SLA for everyone.    RobHopeless over at Instructables.com has recently posted a quite complete description of a DIY stereolithography (SLA) system. SLA was one of the first systems commercially available to early makers.  SLA is part of a group of technologies often called “rapid prototyping” and recently being called Additive Manufacturing or Additive Fabrication.

”

Several people, we know, have been asking if we know anything about a book that has shown up on the various internet sites called “Printing in Plastic” by J.F. Kelly & P. Hood-Daniel.   It is a companion book to “Build Your Own CNC Machine“.

The P-in-P book is 446 page manual taking readers through the process of building a “White Ant” printer (fabbed mostly out of wood).   The White Ant is YARR (Yet Another RepRap) plastic printer.  The book has a nice chapter dealing both hand tools and power tools needed to fab a White Ant as well as overall construction advice (including safety).  A step-by-step build process is presented that might really be helpful for people from novice to mid-level maker skills.  Further, the book is linked to the Build Your Own CNC site (there are more pictures and construction videos).   The one of the links, provided in the book, points to a zip file of all of the wooden part drawing (these are quite well done). Other resources provided are a Skeinforge configuration file and an XML Gen4 configuration file

Kelly and Hood-Daniel have recently release their own set of White Ant electronics.   More electronics suppliers are always a good thing especially during recent times of controller board shortages.   Lastly, in Appendix B, the authors present a straightforward conversion of the White Ant into a basic small CNC mill.

Overall:  A thorough book with clear writing, many pictures & illustrations, and many web site links.

Dear Open3DP readers and members of the Maker Community,

This is a question that was send to us recently from a local high school and we are reaching out to you (the reader community) for a better answer.

{ Image by Rewster from CNCZone.com}

Question:

“I have been working with #### at ### HS with Model making and we have been thinking how great it would be to have a material we could cut with a cnc and then be able to recycle it, forming it back into a block that could be cut into another model. Schools have zero budget for materials and so the hope is to be able to recycle much like they now recycle with machinists wax. For fast cutting on  small cnc the machinists wax is so dense you have to go to slow.. The density of 2lb per cubic foot extruded styrene foam or 10lb polyurethane is nice but not recyclable.

You have so many amazing materials. Can you imagine a combination of materials that could first create the block and then be able to grind or reduce back into components that could then become another block?    Thanks…###”

Our response:

“###, I would experiment by making your own cutting wax.   I would add a filler to standard paraffin to reduce the density (making cutting possible).  Also, you should likely add *Stearic acid to your wax as it will raise the melting temperature slightly and make it harder (and less gummy).  Basically any material could work but something that doesn’t melt in the temperature range of paraffin (thus allowing you to remelt the wax to reform your machining blocks).   Adding fillers will allow you to adjust the density and material properties of your wax.     You might try something as simple as wood flour (finely powdered wood dust or dry clay body).   Please keep me posted. “

Related Link:

http://www.myheap.com/chapter-1-materials/overman-charity-waxes.html

If you have a better suggestion, please respond via comments.   Thank you for your time.