Monday, March 12, 2018

"Velocity Painting" experiment

Velocity Painting is a method of incorporating surface patterns into an 3d printed object by varying the print speed only. The Velocity Painting software tool post-processes the g-code output of your sliced object, applying speed changes to produce a surface pattern. The technique was conceived and developed by Mark Wheadon ( https://www.velocitypainting.xyz/ ), and Application created by Guillaume Vigneron.

This technique works best if applied to hollow, single walled objects, but as an experiment I applied it to the prosthetic hand I had previously printed for demo purposes in support of Enabling the Future local Chapter . Transparent plastic is also recommended for best outcome. 

I chose a pattern (craftsmanspace.com) and using the Velocity Paining tool, applied it to the "hand" g-code ( Flexy-Hand 2 by Gyrobot ), which was pre-sliced. The process is well documented here.





 
(Above - post-processed g-code preview)
The results were interesting in that while surface patterning was visible (below), the transparent plastic also allowed you to see the internal channels in the "hand" design.

The pattern is visible on the surface, but not very pronounced. I reduced the infill considerably (5%), in the hope of increasing contrast by allowing more light through. Strength loss due to reduced in-fill may make such a part too weak for purpose though.


An unexpected side product of using the transparent material was that the internal channels within the Hand became very visible. Combined with the surface patterning it produces an unusual aesthetic.

(  Ran out of transparent filament, hence the truncated print!  )


I expect it's quite subjective as to whether the effect is considered aesthetically pleasing of not.
Thought the experiment worth sharing.

Ivor


Saturday, March 3, 2018

Printing in support of local e-Nabling the Future Chapter...

Some 3d printing in support of the local e-Nabling the Future Chapter...

This design (above) is found here: https://www.thingiverse.com/thing:380665

This design if from here: https://www.thingiverse.com/thing:2576916/#files

These prints were done as demonstration pieces, in support of the a local e-Nable Chapter. 
https://www.facebook.com/groups/344234809356338/

Ivor

Sunday, April 23, 2017

Clay 3D Printing with Jonathan Keep...

When an opportunity arises to join a clay 3d printing workshop with Jonathan Keep, it should not be passed up! Jonathan describes himself simply as an artist and potter, but as evidenced by his own website, he is much more than that simple description. The breath and depth of his lifetime of work in ceramics, makes a workshop with him something much greater than a instructional 'how to' 3d print in clay. You just know it's going to be something special!

In more recent years Jonathan's exploration of digital technology, from an artists perspective, brought him to learn how to model and code in programs like Blender and Processing, creating patterns, shapes, even vessels in a virtual world. A next logical step for him was to explore how to bring the shapes to life in clay and fire into wonderful ceramic works. Learning from what the RepRap movement was sharing about 3d printing in plastics, Jonathan went about adapting a RepRap design (Rostock Delta) to print in clay, creating and sharing his own clay delta 3d printer with the world (2013).

His "Ceramic Delta" broke new ground, with it's simplicity of design and ease of construction, even with limited DIY tools and materials. The printer, specifically for printing in clay, was easily constructed, making it an attractive option for other artists, designers and potters to build themselves. The printer he launched and the desire for people to create their own clay 3d printers continues to be supported via a Google+ Community called  Make Your Own Ceramic 3D Printer.

The workshop...
What I'd like to convey here are some observations and explanations of the clay printing process, complemented with photos and videos from the two day workshop I attended. It was interesting from my perspective to be comparing the clay 3d printing process to that of printing in plastic, as I'm very familiar with plastics, but never before printed in clay. There were many parallels and some differences which I'll try capture. Also, this post is not meant as an instructional document, more a log of key processes followed and some notes along the way.

The Workshop took place at Fab Lab Limerick, which is equipped with a variety of 3d printers. One of these, the Wasp, has a 3d print-head and related air pressurised chamber for clay delivery. This is what was used for the workshop.
Jonathan setting a clay print on the WASP printer.

A simple hollow cylinder always forms a good test print for tuning in the printer.  Photo: Johanna Aaspollu.
Cylinder Diam 50mm approx.
It's all in the preparation...
What immediately stood out about printing in clay was the time given to preparation. In plastics the only setup time is in changing a roll of filament or waiting for the heated bed to come up to temperature. In clay, the preparation of the clay is everything. Softening the clay with the addition of water is a skilled process. The judgment of how soft to make it also requiring careful judgment and experience. Too hard and the the clay won't flow easily from the pressurised chamber. Too soft and the printed object won't support it's own weight and simply collapse. The best way I can convey the mixing process and final consistency of the clay is the share a video of the process in it's entirety.
Clay is cut in thin slices using wire, and dipped in water for an initial wetting. A fork is used to increase the water contact area with the clay. The complete softening process is illustrated in full in the video below (20min).
Video courtesy of Johanna Aaspollu, Fab Lab Limerick.

Note: Some clay preparation guides illustrate the use of  ethyl achohol (ethanol) as a softener, mostly in place of water. The ethanol will decrease the viscosity of the clay also. It will evaporate during the drying stage and may make softening the clay an easier process, but in discussion during the workshop it was collectively felt that for health and safety reasons we would stick with water. Good ventilation and masks would be required to work with ethanol.

Loading the clay...
My observation of clay printer designs is that there's a chamber of some sort to hold the softened clay. This cylinder typically has a piston type insert and is pressurised by air or perhaps mechanical means to force the clay out of the cylinder, through a pipe, to the print head. The clay may be directly fed to a nozzle, or delivered in a more controlled manner via an auger screw driven by a stepper motor. The WASP has a motor driven screw to move the clay through the nozzle. The movement of the print head in three dimensions on a clay printer is no different to equivalent style plastic printers.

In our workshop session Jonathan took the clay and carefully loaded it into an aluminium cylinder, adding large scoops and careful to avoid trapping any air while loading. The clean inside of the cylinder received a light coating of silicon spray lubricant before loading any clay.


There isn't a single "right way" to load clay. The important point is to avoid any method that might get air pockets trapped in the clay. The piston, in the WASP design, has two rubber "O" ring gaskets. It's important to ensure they are seated well and free of clay from any previous use.

Both end-caps of the cylinder were screwed back on, hand tight, making sure the threads were clean. The air valve was opened slowly until the pressure rose to about 4 bar, and clay began to flow through the 12mm teflon tubing, connected to the cylinder via a pneumatic style push-fitting.
Above shows the air pressure control valve which keeps the piston under force against the clay in the cylinder.
Above: Jonathan opens the air valve, increasing the air pressure to about 4 Bar. Clay begins to flow at a slow but steady pace from the connected pipe. This pipe then gets connected to the push-fitting in the extruder printhead assembly.

Slicing and tuning...
With a presumption that you are able to get a 3d model of your object to STL format, the next key step for 3d printing is to 'slice' the object. This generates a 'gcode' instruction file for the printer. There are many slicing packages to choose from, and everyone has their favorite. The fact that we were printing in clay was is some ways irrelevant to the slicing process.

If anything, configuring your slicing software for clay printing is a lot easier. You have no heated bed, nozzle temperature or cooling to consider or manage. Typically also your are printing a 'vase' or 'vessel' style single walled object, so infill percentage or pattern is not a factor. A 'spiral' or 'vase' setting is usually chosen, and that was the primary choice in our workshop also. With this setting it's usual not to have any top or even bottom on your object. If a base was desired on our objects then Jonathan quickly showed us how to press a solid disk in clay and print onto that. This over-sized base could be easily trimmed to shape later once the object was printed and allowed to dry for a while. This also saved on printing time and gave good solid bases to our prints.
Above: Jonathan shows a clay base placed on an MDF disc.

The WASP printer only came with a .5mm nozzle for the clay extruder. Jonathan's preference was for a 2mm or even 3mm nozzle for clay printing. A new nozzle was fashioned from some threaded rod and drilled out to 2mm by Michael in the Fab Lab, and it worked excellently, as visible in some of the photos below.

With experience and confidence showing, Jonathan soon has the printer working well with the new nozzle, choosing to just get it printing then play with the flow setting via the printer control panel.

An easy way to tune in the printer was to print a simple cylinder, with a .6mm layer height and ~ 1.5mm wall thickness set in Cura and see what happened. Jonathan adjusted the flow rate on the machine's control panel until a visually satisfactory result was obtained. Corrections could always be made back into Cura settings later to negate the need for any control panel changes when printing in future.

This approach taken by Jonathan may be in contrast to how you might carefully research and select settings for your particular machine when printing in plastic for the first time. But clay from a 2mm nozzle was far more forgiving of 'loose' settings. Once the Z height was reasonably dialled in the clay would take nicely to the base, and soon begin to grow the object as it spiraled around.
Above: Jonathan tuning the flow via the printer control panel.
Above: Test cylinder printing in 'spiral' mode, continuous rise in Z direction.
Video courtesy of Johanna Aaspollu, Fab Lab Limerick.
This cylinder was drawn in Blender and sliced in Cura,  Jonathan has shared  Cura settings on a Google+ ceramic printer group

Printer bed surfaces...
Jonathan recommended that an absorbent surface rather than a smooth surface was best for clay printing. An absorbent surface would absorb moisture, drying the base as the rest of the object also dried. A smooth surface under the base would prevent drying at the same rate as the rest of the object. Uniform drying of the clay is very important, I've learned. 

The Fab Lab laser cut some 200mm discs from MDF (9mm), and these proved ideal for printing on to. The printer was "zeroed" to the height of two discs, and as Jonathan explained in the following video, this meant we could choose to easily print our object with or without a base with no printer z-height adjustment needed. The discs were simply held in place with some 'blobs' of clay, and that gave a quick and efficient swap out of finished prints, welcome in our workshop scenario.

Above: Making a clay base for your print.
Video courtesy of Johanna Aaspollu, Fab Lab Limerick.

First prints...
The beauty of printing in clay, was that if your first layer wasn't good due to poor initial flow or even z-height setting, you could easily start over with a simple wipe-down and print again!
Above: Restarting a print job after poor initial clay flow.
Video courtesy of Johanna Aaspollu, Fab Lab Limerick.

Above: 5min in Blender, allowed Jonathan's experience to draw this object and move quickly to get something printing to demonstrate the process end-to-end early on in the workshop. Good strategy. Impressive result.
By the end of the two day workshop, everyone had produced some prints. Keeping in mind that many of the attendees had never 3d printed in any medium, the results were very impressive, and the workshop a great success. With the majority of the participants being from a ceramics background, students and professionals, this introduction to 3d printing in clay had everyone very excited about a new direction to explore with their clay medium. 
Above: A mix of objects printed during the workshop. The majority original creations, the lower two from Thingiverse thing:969262 and thing:1063915.
A big part of the 3d learning curve, whether you are printing in clay of any other material, is 3d modelling. Some of the workshop discussion was given to this topic, since many of the participants had no computer based 3d modelling skills. While the power and potential of Blender was demonstrated, we reverted to Autodesk Tinkercad, and in my case 123D Design to begin drawing some objects we could later print. (Sadly, both programs are now being retired by Autodesk.)  Identifying and learning a 3d modelling program that meets your needs is one of the biggest obstacles and challenges in exploring 3d printing in any material.


Above: Once fired the object is transformed in strength and appearance.

To conclude, a big thanks goes out to Jonathan Keep for giving the workshop, to the Future Artist-Maker Labs exhibition and events program for funding and organisation, to Fab Lab Limerick for hosting and providing the equipment and venue, and to the Ceramics dept. at Limerick School of Art and Design (LSAD) for firing the printed pieces. Should you care to view them, some more photos of the fired prints are posted to Ceramics at LSAD Facebook page.

Thanks for viewing.
Ivor

Wednesday, June 15, 2016

"IvorBot", the early days...

I found some short videos of early days testing of my core-xy movement (stacked, fishing-line, rectangular format). Worth sharing I thought, as even a short video shows so much more. In the first clip you see it plot, probably doing about 40mm/sec. It was my first experience of a core-xy movement and was pleasantly surprised at how precisely it plotted, and how accurate the repetition of the same drawing was. Fitting a pen holder to an x-carriage is always a practical way to get an initial feel for movement and dimensional accuracy, in x/y directions at least. See video below.
(In the audio you can hear the poor quality groove bearings beginning to grind, which was it's ultimate downfall. The stepped nature of the circle is just the way it was drawn.)


Driving it at higher speeds didn't help the failing bearings, but you could really open the throttle on this chassis. Having no weight at all on the x-carriage helped. In this other short video clip (below) you can see the movement running at faster speeds. I used an old Gen6 board to drive the experiment, which it did without issue once I updated Marlin firmware for the core-xy support. The tests were controlled from Repetier Host. If you don't have an extruder fitted and want to trick the printer into working you need to set a dummy thermister "998" in Marlin Configuration.h, and un-comment #define DUMMY_THERMISTOR_998_VALUE 185". You can then slice something and send the gcode file, which it will pretend to print, or plot if you have a pen fitted, and no Z mechanism.



I learned a lot from this 'prototype'. I was able to draw on my existing body of knowledge and understanding of 3d printing, and build on that to construct this experimental chassis. The plans were drawn up in Sketcup primarily, which I use quite a lot for design visualisation. With some plug-ins I can export for printing (STL), and export for laser cutting (SVG).



I've also found Autodesk 123D very good also, and move to it for more complex components.














By building the physical working model I was able to get a true sense of scale, construction challenges, and mechanical performance. I was then able to modify design and rapidly improve through iteration, swapping out both printed parts and laser cut framework. I'm constantly keeping an eye to my primary design goals of compact size for given print volume (200x300x250 approx), along with dual extrusion capability with room for experimentation.

More detail of the journey to follow.
Tks for viewing.

Sunday, June 12, 2016

Code named "IvorBot"! (Part 1)

I've been lax in blogging of late. Sometimes it seems there's always "just one more thing" to do or make or print before a new blog post is worth writing. Then the weeks and months pass and the motivation to post historical work just isn't the same after a time. Lets see if I can do a bit better on the blog front going forward!

I'm always keeping an eye on 3d printer developments, innovations and direction, as things continue to evolve at some pace. Digesting these influences, I've regularly found myself subjectively noting the 'desirable' and 'best' features of the changing printer vista, with one eye, as always, on building my next printer.

A design is always given focus with some constraints, and for my "next printer" I imposed some goals that formed the general basis of the prototyping and experimentation that followed, for some time now. Key enhancement objectives included such goals as faster print speeds without loss of print quality, dual extrusion, moderately larger print volume, but minimum increase in outer printer dimensions. Secondary goals might be a flexible carriage system to allow for easy print head swap-outs for greater flexibility.

The choice of movement system and filament feed mechanism was left open in the early research. Also, I wanted to explore and experience bowden vs direct drive, 3mm vs 1.75 and the pros and cons of these now common machine choice variables. My new printer would give greater opportunity for testing and learning, reconfiguration for experimentation.

The attractions of CoreXY has stood out for some years, and has enjoyed much adoption in both experimental machines and commercial printers of late (FABtotum, Airwol3D Axiom, SmartrapCore). I quickly settled on this as key design feature and pushed on with some basic plans.

Armed with Sketchup, my trusty Mendel90 and access to a local Fab Lab laser cutter I was quickly able to stand-up a basic core-xy chassis. For a fast and relatively accurate movement system I also took inspiration for RichRap's use of Spectra line as in his Sli3RD Printer, and even Nicholas Seward's CoreXZ printer. The following fishing line CoreXY "plotter" was put together (Photo below.).

Using fishing-line allowed compact and flexible "belt" paths. By routing the line over small groove pulleys it was possible to position the motors below the x/y plane resulting in space saving and more compact external dimensions. (Illustrated in photos below)





Access to a laser cutter was transformative in terms of flexibility of chassis design, manufacture and build speed. It allowed me to iterate quickly, and a very low cost. I worked in Shetchup, exporting to SVG via a plugin for laser cutting comparability.

Above is one of my printer frame work revisions being cut from cheap plywood on the Trotec laser cutter at Fab Lab Limerick. Back at home (below) the next revision was quickly constructed and motion testing resumed.

The prototype printer, pictured below (actually just a plotter at this stage), made many trips to the Fab Lab - Thursday evening sessions over the Winter, for peer review and valued feedback. It was during one of these visits that it earned it nick name, the "IvorBot", which has stuck!














Testing with the fishing-line core-xy chassis ran it's course. It was functional and with the addition of an extruder might even have done some printing, but it didn't have the robustness I was striving for. Also, my choice of cheap grove bearings was a mistake and they were grinning and failing as I'd push the speed and tension on the fishing-line. 

The next major revision of the design was a move to belt drive, and brass pulleys. I designed and printed a whole new set of motor mounts, corner brackets and x-carriage ends. I chose 9mm GT2 belt, matching brass pulleys with double inserted bearings, LMS8UU linear bearings. I ran a "stacked" cord-xy belt path so there was no cross-over in the design. I felt the wider belt and pulleys wouldn't lend itself to the cross-over belt path that typified some core-xy layouts.

Another frame was cut, this time with more z-height, and when E3D started selling the 200x300 heated bed from their BigBox printer separately, I jumped at the opportunity and matched printer frame size to accommodate this larger print bed.


Above, "IvorBot" current revision. It prints reasonably, but there were many changes to get it to this stage as you might appreciate. I recently got it tuned up for dual colour printing, which was a new personal mile-stone, and gave me the incentive to resume some bloggin. There's lots more detail to share, and much planning going into changing and refining my design, but for now I'll sign-off and get this much published.

As always, comments and questions welcome!
Ivor

Wednesday, May 27, 2015

A day out for my Mendel90!

I'm involved locally (Limerick, Ireland) in a maker group, that has both a virtual presence (  https://www.facebook.com/groups/MidWestMakers/  ) and meets once a week in Fab Lab Limerick http://fablab.saul.ie/. The formation of this group has been a great way to meet other makers in the region, and the level of activity has grown steadily over the past year, perhaps much to the determent of this particular blog, but with an invitation to speak about our maker group and fab lab, at an innovation day hosted by Dell Solution Center, Ireland, I thought it would be worth sharing a few photos here on my blog also.

It was an excellent opportunity to take my Mendel90 out-and-about. As always the printer got lots of attention and questions. A few photos of the event are featured on our maker FB Group page , some of which I'm reproducing here (Photo credit to Lucia in the maker group)
Prints in the foreground are by one of our maker group members, Dara, (medical illustrator)  (on an Ultimaker 2). There's an interesting musical instrument by Ed Devane , in the picture also, which he calls a "pluck wheel lute". It's utilised in instrument building music workshops he runs. He makes some parts of the kits in the Fab Lab. 

Talkin' the talk, at Dell Solution Center, Limerick, Ireland.

My Mendel90 printing Heatwave Vase from here: http://www.thingiverse.com/thing:126567 Always a good show print!

Thanks for viewing!
Ivor

Sunday, February 8, 2015

Minor updates to my printer (Mendel90 scratch build)


Quick post showing some minor printer updates I've made in recent times:
Moving to the newer Mendel90 x-ends, with their 4-screw bar clamps, has made a good difference to my printer. The older design, (second photo below) was unable to clamp the bar tightly enough and I was loosing belt tension over time. The clamp was also beginning to split along layer plane. The newer design doesn't have this issue as the layers are in compression because of the clamping direction.
Newer x-end installed above. Nophead relesed this design back in Oct 2013, and has been incorporating this design in the kits he sells since then, but if you have an older printer it's worth updating. Full detail on this and other design improvements he has made to the Mendel90 can be found here: 
This is the older x-end design, with it's weaker x-bar clamp arrangement.

I'm trying out an E3D V6 hotend at present, swapping it out for a J-Head which, by the way, I've never had an issue with. I just want try some printing in some materials that require higher extrusion temperatures, beyond that supported by the J-Head.

 To mount the E3D Hotend on Mendel90 without loosing any Z-heignt, I took inspiration from the hot-end clamping idea devised by Ralph Hilton which he shares here: http://www.thingiverse.com/thing:371252. I applied this hot-end clamping approach to Nophead's original extruder, importing the original STL into Sketchup and hacking away there until I got it as I wanted it. It's not pretty, but anyone is welcome to the Sketchup original if you think it's of use. (just give me a shout on the RepRap Forum under user name NumberSix).
Screenshot of extruder modified to clamp E3D V6 hotend in a way that does not result in loss of Z-height. The keen of eye may also observe I've moved the left extruder clamping hole. I want to be able to attach/detach the extruder to the x-carriage without having to remove the E3D fan assembly so have also made an x-carriage with an enlarged hole. See screenshot below.
X-carriage with wider opening to allow E3D hotend to be inserted/removed without taking it's cooling fan off, or detaching it from the extruder block. (one in picture not in my current colour, just test printing it)

One thing leads to another, and if you swap out the j-head (on a Mendel90) for an E3D hotend you'll soon realise the original work cooling fan doesn't fit over the larger heater block of the E3D. So that lead me to Daniel Bull's Fan Duct  which he drew in in Autodesk 123D Draw. A fine job he mad of it too, but it's distance below the x-carriage is set for the E3D fitted to an original (M90) extruder and in a much lower position.
The screenshot above shows my modified version of Daniel's fan duct. I've lowered the mounting points, and adjusted things to make room for the x-belt. It was a struggle but a good way to learn more about 123D Design. Daniel provides a great starting point in his shared fan duct. I added the little cross you'll see in the middle of the duct to help with bed adhesion on this narrow circle. The cross is cut away after printing.


That's it for now! Thanks for viewing.
Ivor.