Notes on the cost of 3D printing

This post sets out to address the cost of plaster 3D prints - also variously known as ZCorp, Sandstone and Colorstone. 

All 3D print technologies have different pricing parameters so the points below do not necessarily translate to other processes. Plaster printing does not need supports to be printed as the part is fully supported in the bed of plaster powder as the print progresses. Unlike the SLS process which is also powder based, all of the unused powder can be reused in the next print.  

In addition to the powder used to make the part, a greater expense in binder fluid, cleaning fluid and printheads needs to be factored into the material cost of the print. Despite this it is usual (but not universal) to charge per cubic cm (£/cc) of material used.

For many parts including most architectural massing models consideration needs to be given to whether or not a part can be hollowed out to reduce the amount of material used and ultimately to save cost.

Parts need to be cost effective for the long term success of a bureau and hollowing parts is key to this.

For many heavier 3D printed parts there are 3 possible outcomes to treating a 3D print:

• Print solid
• Print hollow and leave unused powder trapped inside the part
• Print hollow and leave an opening to remove unused powder

Buildings usually sit on the earth and are consequently not viewed from the underside. This makes it possible to hollow most building massing models leaving the underside open to remove unused powder.

Hollowed 3D print

Solid models may be needed for vac forming etc and in some parts just have the wrong geometry for hollowing and need to be made solid.

Other parts can be hollowed but a hole or other opening is unwanted and then unused powder may be left trapped inside the part. Consideration needs to be given in such circumstances as to whether it would be desirable for powder to leak out if a model were broken. 

So let us take an example of a cube measuring 100 x 100 x 100mm.

• Solid this occupies 1000cc
• Hollowed with a 4mm wall thickness it occupies 221cc
• Hollowed with a 3mm wall thickness it occupies 169cc

This sheds some light on those stories of horrendously expensive prices sometimes quoted (and sometimes paid) for 3D printed parts. Be careful of this when getting quotes for parts online, software is not likely to pick up on the fact you are asking to print a lump of material that could do with being hollowed. A human is usually better able to spot this kind of thing.

In the case of our 100 x 100 x 100mm cube it is worth noting that the difference in volume between the 4mm wall thickness and a 3mm wall thickness is 52cc. Which priced on a cubic cm basis could be a 23% difference in price. 

Choosing an appropriate wall thickness depends on various things. The size and strength of the part, its purpose, whether it needs to travel and even on very tight deadlines the time available to remove it from the machine and get it to the customer.

Generally we hollow parts for customers as part of our file optimisation service at Lee 3D. To do this we use Magics RP, the industry standard software for preparing models for 3D print. This allows us to hollow complex parts with a uniform thickness.

For more information about 3D printing at Lee 3D please visit www.lee3d.co.uk

Optimising CAD models for 3D printing in plaster or sandstone

This post is geared towards customers planning to use the Lee 3D online quoting and ordering service. However, it should be useful to anyone modelling for 3D printing using these materials. Please note - optimising is not the same as fixing. If you are considering using an online service it is assumed that your data is print-ready. Optimising is about getting best results.

The Material

Plaster printing using ZPrinter (renamed as Projet x60 series) is sometimes called sandstone, colorstone or similar. Whatever you choose to call it, the material is predominantly plaster of Paris bound with a water based binder in the printer and most commonly hardened afterwards with cyanoacrylate (superglue).

When freshly printed, the models do not have their full strength. We sometimes use the analogy of concrete vs steel to describe the material properties of unfinished and finished parts. Concrete is great under compression but poor under tension, whereas steel is strong under both compression and tension. 

So, parts fresh from the printer have limited strength in tension and therefore thin parts are liable to fail and more especially, thin cantilevering parts are liable to break off. 

Finished parts, hardened with superglue have good all round strength.

Part Orientation

Part orientation affects surface finish and strength of parts.

Strength of parts due to orientation only needs to be considered for thin parts. A thin column printed horizontally is stronger than if printed vertically. Thus, part orientation will affect minimum part size (fig. 4).

Scale

Architectural models rarely get printed at 1:1. If you are modelling in software at 1:1 and you want to print at scale, you need to think in advance about the size of the final model.

If you are printing to scale and want to use an online quoting service you must think about the size of parts as they will be printed. 

Remember that you are making a model. Columns may look weirdly thick in software but when they are printed at 1.2mm diameter they will be thin!

Hollowing

Hollowing parts reduces cost. However, if you hollow parts and leave the powder trapped in the model we will have to charge for the unused powder as we cannot remove it. This may lead to your order being rejected. 

So, consider how unused powder will be removed from voids and remember that powder does not flow out like water - it needs to been blown out with an air brush. Small holes are not adequate for removing large quantities of powder.

It is not easy to model complex structures with consistent wall thicknesses. If you are not careful, weak points can appear as illustrated below (fig.1).  From the outside, these can be difficult to see without viewing the part in section. Thin parts, if they do not break, can become translucent once glued giving the part a patchy finish.

It is usually better to model parts as solid in design software and then use Materialise Magics (or similar) to hollow the part effectively. This will produce a uniform wall thickness which will produce uniform strength and finish. 

fig. 1

Minimum Part Thickness

Everyone asks what the minimum size we can print is, to which I usually answer that it is geometry dependent. It is also usually worth considering the end use of the part. If the part is likely to be handled a lot, then make it strong. If the part needs to fly to the antipodes, make it strong. 

If its useful life is for a single meeting in which you need to make a crucial decision, then perhaps take some risks to make it look great for that meeting. If the model will spend the rest of its days inside of a Perspex display case, make it detailed (it may take us a little longer though).

Below are some rules of thumb to determine minimum thickness for various features:

1.  Freestanding wall features

The fig.2 below shows a fine wall detail well supported by the core of the model which is hollowed to about 3mm. The table shown in fig.3 contains suggested minimum wall thickness for differing wall heights.

fig. 2

fig. 3

2.  Column features supported at both ends

As shown in fig. 4, these features are strongly dependant on print orientation. Some files cannot be oriented so that all fine details are horizontal and in this case all parts need to be thickened for printing horizontally. Table fig.5 shows suggested column heights for parts printed in either orientation.

Please note that free standing columns are much less sturdy than columns supported at both ends and need to be made significantly thicker.

fig. 4

fig. 5

3.  Shadow gap and surface relief size

Fig. 6 shows shadow gaps on the surface of the model. The smallest readable shadow gap is of the order of 0.3mm. Bold shadow gaps should be 0.5mm or greater.

Some thought needs to be given to depth of shadow gaps. It is difficult to remove powder from gaps narrower than 1mm, so there is little to be gained from making these deeper than a couple of mm.

fig. 6

Relief details are readable from 0.2mm at the minimum. To clearly see surface relief, a minimum size of 0.5mm or more is recommended.


4.  Hollowing

Hollowing thickness depends on the size and strength of part required, usually 3mm or more.

Walls need to be of adequate thickness after hollowing to give the part sufficient strength for us to remove it from the printer.  

You cannot make a part the size of the build volume with a thickness of 1.5 or 2mm - it will collapse. We will check every part and will need to modify or reject parts that are too thin. 

fig. 7

For further information about the Lee 3D online quoting and ordering service see Optimising sandstone or plaster models

For more information about Lee 3D go to www.lee3d.co.uk 

Wiktor Kidziak - Colour 3D prints

These two guys were designed by Wiktor Kidziak while studying at UCL, 2014. 

I am not sure what they represent. The forms remind me of trees growing on an exposed hillside, leaning away from the prevailing wind. They also appear to be walking in the image below. As for the colour they remind me of marble mosaic cubes swept up in a vortex or whirlwind.

Wiktor has worked closely with 3D printers in the past and his confidence in the media shows in the ambition of the project. 

The parts were generated using parametric design tools including SoftImage XSI. 

There is something very edible about these prints. Certainly they we very satisfying to make and proved quite photogenic too.

For more information about colour 3D printing at Lee 3D please visit www.lee3d.co.uk

A smashing new art work!

When Adam gave us the brief for his new work titled "You & Me", I was not just taken aback, I was simply shocked. 

He showed us a sketch of the piece and explained that we would print two identical parts but one would be broken up and stored in a large glass vessel. The two parts "You & Me" would then stand together making up the whole artwork.

I spend all my working life trying not to break the work, from consideration of print files to careful handling of parts, our mission is not to damage, not to break, to deliver the cleanest, smartest, most blemish free part that we can. This even goes to the extent of mentally rehearsing the whole process on the way in to work each morning. So it really goes against the grain to make a piece and then wilfully break it.

It goes further, each of these pieces are over 700mm tall and require four full machine builds to make. Making parts of this size that fit tightly together, retain good colour and generally avoiding defects is a real challenge. It really, really goes against the grain to make a piece as monumental as this and then break it.


You & Me from Adam Nathaniel Furman on Vimeo.

For a time I tried to persuade Adam to consider less violent alternatives but I quickly saw that he was resolved on the matter. 

Over several weeks we did the work and made the parts, finished and assembled the two sculptures. Then the time came the artist stood lump hammer in hand, paused, took a deep breath and demolished one of the pieces.

Despite my reservations the end result proved a real treasure. Standing next to the rather majestic whole piece, the glass vessel came to life when filled with bits of its broken other. The pair stand well together.

This kind of high stakes poetry is not you average 3D print job but then Adam Nathaniel Furman is not your average customer.  You & Me is in many ways the culmination of years of Adam's output of amazing and colourful 3D printed designs, many of which we have had the pleasure of helping to bring into being. As a physical object the ambition of this piece and the final result are beyond anything that I have been involved with in this business. But this is the work of a poet and an artist too, the title, the initial sketch, the idea, the design and the execution. A work of poetry encapsulated in a work of art, recorded in a moment of theatre. Bravo Adam!

You or Me? Detail of upper parts.

Two sculptures together

After the action

You & Me

You & Me was exhibited at London's Hospital Club in 2014.

For more information about Lee 3D's colour 3D printing service visit www.lee3d.co.uk

Design Studio 13 - 2014

This year we printed a number of models for architecture students at Westminster University and in particular for diploma Design Studio 13. 

The project was set in a development zone in Shenzhen. The brief seemed pretty open, located within an area with no existing context and produced a wide range of proposals. Three of the DS13 projects are featured below. There were many other 3D printed models on display across the show and many of them interesting in their own right. 

Perhaps the most intriguing was the Anything Factory designed by Bryan Ratzlaff whose scheme calls for a multi-storey block split into 3 parts dividing logistics, data services and production. Interestingly Bryan previously worked as a 3D print production engineer and understands commercial 3D printing workflow, he also know to model details to the exact capability of the ZPrinter which shows in the detail of the model.

The premise for the project is the notion that 3D printing can shift manufacturing from far flung factories to local made on demand products. So the design speculates on a future where large machines are centralised in corporate additive manufacturing centres. Presumably an array of technologies producing parts that are assembled locally or sent out for assembly. 

Models printed using limited colour; white, grey and black. 

A 2D illustration of the concept

Image showing the surface texture modelled to the capability of the printer with a 1mm black rail representing the conveying line weaving between departments delivering consumables to machines and bringing creations back for inspection and shipping. This black rail is carefully modelled to pick up support from the structure enabling the 3D printer to produce this fine detail running through the core of the building.

Buildings will undoubtedly be built specifically to house additive manufacturing which often requires specialist environmental servicing in a similar way to conventional factories and labs. What would a suitable building typology for additive manufacturing look like? What kind of products would such a centre produce? What materials would they need to store? Could an additive manufacturing centre design and build itself? Will it require human intervention?

Certainly a project that asks as many questions about the future of additive manufacturing as it answers. Quite where this leaves the personal 3D printer is not addressed. It would seem to me that large multi material commercial 3D printers will always out compete the capabilities of the personal printer but that does not mean there will not be a place for both. 

Alexander Sun, who we bumped into at the opening night of the China Design Centre, printed a 1:2000 space frame as part of a huge shipping terminal - the 8th Wonder Cruise Terminal. Ambitious to the point of gratuitous engineering, an overwhelming city entrance or modern day triumphal arch, a proclaimed "international spectacle" and a statement of Chinese confidence.

The geometry of this model would usually cry out for printing in Nylon on an SLS machine. So this is not your typical plaster printed model but the result looks great. Personally I prefer the opacity of plaster models compared to the light absorbing Nylon material but I certainly acknowledge the increased strength and resilience of Nylon. In this case Alex did not have time to get the model made on SLS and opted for plaster. The part size of the structural members was 0.9mm diameter. 

The red ship was printed by Alex on a filament extruder. He also showed some very small scale master plans printed on his home machine. For student work or for any architect these machines can make a convincing contribution to presentations.  They are slow and cannot print all geometry but I expect to see a lot more extruded building models in future.

Ryan Kingsnorth's law court designed to promote openness and transparency in the functioning of the law in China. An example of British meddling in other people's business? An ironic statement on British law and trial's held in secret? From my cynical view I see this "transparent" building quickly surrounded by security fencing (for the best of reasons). Is architecture really able to influence human behaviour in this way.  Humans have a way of  shrugging off buildings that do not fit their requirements and replacing them or moving (back) to ones that do.

Anyway from a presentational point of view this model exhibits a nice use of minimal 3D printing in a less costly but highly effective context model. We often have clients requesting 1:200 models because that gives the level of detail they expect from sketch models made in the office from card and foam. I am not suggesting that 1:1000 is always a good scale for detail models but with 3D printng the smaller scales can show a great deal of design detail. 

Lee 3D was proud to contribute towards DS13's final show along with PLP Architecture, Allies and Morrison, Urban Future Organisation, Dust Architecture and Base Associates.

For more information about Lee 3D please visit www.lee3d.co.uk

3D Printing the KREOD pavilion

KREOD produced a trade pavilion for the London Olympics and plans to do the same for Brasil 2016. Lee 3D produced a model of KREOD's London pavilion which will initially be exhibited at the new China Design Centre which launched on the 1st May 2014. 

The 3D model of the pavilion was made using tools such as Rhino, Grasshopper and Evolute. This very neat structure naturally lends itself to 3D printing with the finest of margins. In this case the main construction is made up of elements that are 0.7mm in thickness. This allows a good amount of light to pass through the model expressing the geometry and the design intent.

The pavilion is made up of three moveable pods

The pavilion in the closed position

The ZPrinter 650 used to build these parts even picks up the floor detailing with gaps of just 0.125mm. Of course it is not all down to the machine. These parts are very fragile until they hardening resin is applied and require delicate handling and a certain amount of experience to remove powder from the surface of the parts with out breaking the models. Once hardened the parts can be handled with ease. 

The pods connected end to end

Interior view

KREOD's Chun Qing Li was suitably impressed and I think a little bit relieved when he came to pick up the model on the day before the China Design Centre launched. Lee 3D is now looking forward to working with KREOD to produce models of the proposed Brasil pavilion which will first be shown at the Clerkenwell Design Week later this month.

The China Design Centre showcases the unique design vision emerging from a country with a long history and rich culture, and whose dynamic economy is generating a new wave of talent in Architecture, Art and Craft, Furniture, Products and Materials. 

Terry Farrell speaking at the grand opening
of the China Design Centre in London

China Design Centre - chinadesigncentre.com
KREOD - www.kreod.com

For more information about Lee 3D visit www.lee3d.co.uk

3D printed art - a pointless exercise?

Making art pieces using a 3D printer may in some respects seem a pointless exercise. "won't it just get 3D scanned and copied?" is a common response. If you can copy it then it is not unique and it has less inherent value.

In theory yes you could scan and 3D print a copy of a 3D printed artwork, but there are a number of reasons why this is not a likely outcome. Some reasons for this are:

• A functional prototype is finished to a different standard to an art work. In one the physical attributes of the part are key where as the other surface finish is key. Achieving quality surface finish is likely to be achieved more with human labour than with the 3D printing system alone. All 3D printing currently requires post processing which usually involves physical human input and additional processes that make parts unique. With colour 3D printing, parts needs cleaning up and a strengthening resin applied and possibly further finishing to protect the part. Not all colour 3D printer technicians use the same techniques and finishes and each produces parts that have a distinct appearance to the trained eye.
• 3D Scanning an artwork is likely to be difficult, the presence of occlusions would mean that it would take a lot of time would be needed with the piece. Some areas of parts may not be possible to scan. You could not just scan an artwork while wandering around a gallery. The quality of scans makes it difficult to reproduce a part to to the same standard as the original. 
•  3D Print technology is constantly changing after 5 to 10 years it would be difficult to find an original 3D printer running the right materials to reproduce a part. After 20 years it would be almost impossible. 

It would certainly be possible to make an imitation 3D print, but it would be as difficult to make a true copy of a 3D printed art piece as it is of a traditional print or even a contemporary painting. It could be done but it would not be easy. It would take an amount of time and expense that would raise the bar to a counterfeiter undertaking this work. Considering that most art pieces take many years to rise in value it may become more difficult to achieve as pieces rise in value and technology becomes obsolete.

Techniques that may be used to make more difficult for counterfeiters include adding signature or watermark voids into the part that cannot be seen without special equipment, adding unique chemicals to binders or resins, inserting RFID tags etc. 

Many of the 3D printed pieces that we made for Adam Nathaniel Furman's "Identity Parade" will be on public view at the Hospital Club from 22nd April for 2 months. You can make up you own mind how easy or difficult it would be to reproduce this amazing collection.

The Hospital Club
Endell Street
London
WC2

For more information about Lee 3D visit www.lee3d.co.uk