Six Step Guide to Printing in 3D

1. The Printer

While 3D printing has been around for many years, the machines have typically been worth many 10s, even 100s of thousands of dollars.

This is now rapidly changing, with the maker movement starting and encouraging a trend towards sub $1000 3D printers, putting it well within the reaches of the average person, where the same machine just five years ago would have cost in excess of $20,000.

Once a concept reserved for the pages of science fiction, can now be found sitting in the living room. I estimate that within 10 years, a high proportion of homes will have some form of 3D printing device, and it will be in common use in stores like Harvey Norman and Ikea (in the way that the photo print booths are now). When you require a spare part, it is just as likely to be printed on demand as held in stock, or available as a file to download and print at home.

By and large, the sub $1000 printers that are now available are still relatively utilitarian, a mass of cables and components, retained within a basic shell, and often not even that. That matters little to those using these devices – window dressing is not a high priority when compared to functionality.

There are moves by some of the big companies, such as HP, and some speculation they will be joined by Apple and Google in releasing consumer-level printers, although it will be a while before they become particularly affordable.

There are three main forms of 3D printer.

Orthogonal 3D Printer.

The most traditional form, with linear (Cartesian) movements in the X, Y and Z directions. It may be that the print head makes these movements, or it can be stationery in one or more of those degrees of movement, and instead the object itself (or rather the supporting bed) makes the corresponding movement.

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The printer I have for example, has the print head moving in the X and Z directions, and the printer bed moves in the Y direction.

Radial 3D Printer

A very uncommon form (in fact, I have only seen a single example of such a printer), with the print heads (and base) using polar coordinates to reference printing points.

Delta 3D Printer

This is becoming a popular orientation, with three print arms each rising and falling on the Z axis, causing the head to be pulled one way or another, covering the base area.

The orthogonal / delta discussion is very likely to retain supporters on both sides. It won’t ever reach the levels of PC vs Mac, but there will be evangelists for each concept.

There are a number of common components to 3D printers, starting with the printer head.

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While the consumables will be covered in greater detail in step two, the solid plastic tube (called the filament) feeds into the print head. On a direct printer setup, the motor and associated gearing that grips the filament is situated on the print head, and it pulls the filament from the storage reel and pushes it into the hot end. The combination of stepper motor and gear used to push (and pull) the filament is called the extruder.

There is another setup where the extruder is located away from the print head in a stationery location. It pulls the filament from the reel, and feeds it through a PTFE tube (Teflon) to the print head. This is called a Bowden feed, and has the advantage that the printer is not having to deal with the added weight of the extruder on the moving print head.

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The hot end is where the magic happens. Such a simple concept, you really have to wonder why it took so long for it to come to fruition.

The filament feeds from the extruder down a short length of PTFE tube which is in a cold section – this is either air or water cooled so the filament inside does not begin to heat too early and cause a blockage. It then passes into a hot block where the temperature quickly transitions up to and beyond the melting point of the filament. Cold filament pushing from above forces the molten filament to continue down and out of the nozzle. Starting and stopping printing is achieved rapidly by the extruder motor being run forward and reverse as required. Being a stepper motor, its rotational position is accurately controlled.

The nozzle has a diameter typically between 0.2mm and 0.8mm, with 0.4mm being a very common size. A larger nozzle can extrude filament faster, but with a rougher (textured) finish. A fine nozzle produces a smoother, more accurately dimensioned object, but with dramatically increased printing times. 0.4mm appears to be a reasonable compromise between these extremes.

The hot block has a heating element (controlled by the printer), and a thermistor to provide the printer feedback on the temperature of the hot end. Temperatures up to 300C can be achieved on some printers.

The other stepper motors that make up the printer control the position of the print head relative to the part being made. For the X and Y directions, the stepper motors turn a pulley attached to notched drive belts. The Z direction is a threaded rod, and the whole gantry slowly moves up as each layer is printed.

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The item being made is deposited on the printer bed. Ideally, this can be heated, especially if printing ABS and other plastics that tend to warp if cooled unevenly. The heated bed should be able to achieve around 100-110C.

Every component on the printer plugs into a controller, which is commonly arduino-based. It in turn is fed the “G Code” either directly from the computer via USB, or from an SD card. The G Code is created by the slicing program, discussed further at step 4.

2. Printer ‘Ink

The ‘ink’ used in these printers is just a little different from your standard computer printer. Instead of being a liquid dye, or an ultra-fine powder, a 3D printer has a roll of solid plastic. This is melted and deposited in layers on the printer bed, slowly building up the object layer by layer, 1/10th of a mm at a time.

A basic printer can normally handle PLA and ABS thermoplastics (the latter being what Lego is made from), with the right printer components, more demanding plastics can also be used, such as nylon and polycarbonate.

3D printing isn’t just reserved for plastics either. There is a type of wood filament, somewhat akin to printing with MDF that a reasonably basic level machine can print. There are already food printers, able to make creations in extruded sugar or chocolate, and top end (industrial) machines are around that can even print titanium components.

Plastic filament comes in a wide variety of colours, and if you want to get more exotic, there are phosphorescent filaments and heat sensitive filaments available that change colour when held or with environmental temperature changes.

You are not restricted to printing a component in a single colour either. In addition to some filaments that change colour along their length, a dual head printer can switch back and forth between a couple of colours. If your controller can handle it, there are four head units available, and even one that allows two different coloured filaments to be mixed in the printer head as the filament is extruded.

More advanced models can be made, not only by printing support structures, but by printing these support structures with a dissolvable material (polystyrene).

While early generation printers used to exclusively use 3mm diameter filament, 1.75mm diameter printers have become the norm.

Each material has its advantages and disadvantages, so you choose the material that is most suited to the job at hand.

PLA is easy to print with, and is a sugar (rather than an oil) derivative. It melts at a relatively low temperature, with a printing temperature around 195C, and does not need the printer to have a heated bed. In saying that, I do find that heating the bed to 40C helps with bed adhesion. It is stiffer than ABS, and not as strong. A parts fan is ideal while printing, and the filament will absorb moisture and become difficult to print. It can be used as a dissolvable filler when the body of the print is ABS.

ABS is also easy to print, although a heated bed is mandatory. Needing a slightly higher print temperature of around 230C, and a heated bed temp of 90C, it doesn’t melt so much as soften and flow sufficiently to be printed. It is more prone to warping during printing, but the stronger, flexible result is often worth the slight increase in hassle.

3. Objects in Space

There are a number of ways to get an object ready to be printed. The easiest (and by far the most common) is to have someone else do the work! What is nice about the 3D printing community, is its willingness to care and share with each other. Not only are there plenty of people on forums ready and willing to help troubleshoot any issue you may have, there is a massive library of three dimensional objects that people have created and are then shared for free.

A very popular source of these files is a website called Thingiverse (www.thingiverse.com). Here you can find thousands of objects, ready to download and send straight to your printer.

The file type normally used for 3D printing is .STL, otherwise known as STereoLithography.

For the more creative, there are a number of 3D programs available to create objects from scratch. These include Photoshop (the latest edition supports 3D printing), AutoCad, 3D Studio Max and a host of others. Even Google Sketchup can be used, if an STL plugin is installed.

The last method is to mimic reality. With the right tools, an existing object can be scanned into the computer in 3D, manipulated, then printed.

4. Slicing

Once you have a computer-based 3D object, the next step is to prepare it for printing. This is done using a slicing program, which works just as it sounds. It takes the object you have provided, and slices it into individual layers, including working out all the tool paths required to achieve it.

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Given each layer can be around 0.1mm high, it is rather handy that the computer can automatically handle this step! The slicing program takes the parameters you have provided (thickness of outer wall, percentage of infill, printer head and hot bed temps, operating speed etc etc), and produces the G Code that gets sent to the printer controller.

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Percentage of infill

There are a number of free slicing programs available, and some costing between about $50 and $150. Programs include Cura, Sli3er, KISSlicer, Simplify3D and Repetier-Host among others. They have different advantages, and some support multiple head printing, and multi-material printing.

 5. Printing

Finally, it is time to turn the computerised object into something tangible. The required filament is fed into the print head, and the print bed prepared to ensure print adhesion. Having a print separate from the print bed is one of the most common failures. Kapton tape, blue painters tape and hairspray are all techniques that are utilised. I find using a glass bed and a gluestick quite effective, but am still experimenting to find my preferred option.

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It is important that the printer bed is level relative to the print head, particularly so the first layer is laid down properly. Too much gap, and that portion of the print will not adhere to the bed, too little, and the print head can be blocked and under-extrude (or worse, back up in the print head).

If a particular design has a low surface area on the bed, the slicing program can have other options enabled, including printing a ‘raft’ that the print is then attached to which is easy to remove at the end.

As the print is molten plastic, it needs to be supported until it hardens. While that happens very quickly, only so much overhang or unsupported area is possible. A print fan that rapidly cools the resulting print helps, but the main way to span large areas is to print supports. These are cut away once the print is finished. Some designs come with supports built in, otherwise supports can be turned on in the slicing program, which will calculate the supports required for a successful print.

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Printing on these small-scale printers is not exactly the fastest process. The “Planet Express Ship” used 22 metres (65 grams) of filament, and took 3 ½ hours. A Terminator model head, 130mm X 110mm X 175mm takes 95 metres (284g) of filament, and takes 18 hours to print.

An object the size of a GoPro case (specifically “The Frame”), uses 13 grams of filament, and takes 45 minutes to print. The Frame retails for $65, and takes 23 cents of filament to print.

An iPhone case retails for about $35. A printed case takes about 45 minutes, and 18 cents of filament. Gives you pause doesn’t it!

 6. Finishing

It is pretty common to take the finish of the part straight from the printer, so much work goes into refining the setup and settings to maximise this quality.

There are as many variables that can be tweaked as components in the printer, and settings in the firmware. While printers will come reasonably well setup, I have also seen when someone with a gift sets up the same machine, and gets their prints to sing with the quality of the result.

There are other finishing steps that are possible, from using a high speed grinder to clean up prints, sandpaper, through to acrylic paint, and, for parts printed with ABS, acetone smoothing is available to achieve a high gloss, smooth result.

Parts assembly (or repair) where required can be achieved by a number of methods as well, from using glue, to friction welding, again using the high speed rotary tool to hold and spin a short length of filament (5-10mm). When touched against the object, the friction causes the printed plastic, and the spun filament to melt together as a plastic welding technique.

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Conclusion

3D printing has been a long time coming, from the first 3D print in 1982, and the first 3D printer in 1984. Like a classic example of exponential growth initially slow over an extended period, when it gets sufficient momentum the explosive growth is near impossible to comprehend. That is where 3D printing and the whole additive manufacturing process is rapidly heading.

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We are seeing the start of the final growth phase now. 3D printing of houses, body parts, Formula 1 car parts, the first parts printed in space, and soon military supply lines and disaster relief operations are likely to be supplemented with the same. At home, it is still very new, but it will not take long at all to become part of the landscape. It is making its way into schools and universities, and while it may be too late to wrest large scale production back to this country, boutique manufacturing and prototyping, and manufacturing on demand is a fascinating opportunity.   It is a great time to get involved, and start to become familiar with the technology…..and its idiosyncrasies.

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In a decade, the machines we are printing with now will look like the Wright Brothers plane compared to the latest A380, and although it will be very interesting to see how the printers change over the next decade, it is even more interesting to be involved in some small way in the development process.

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A logical conclusion

Using the same steps discussed in the last entry, I have taken a vector drawing of a Celtic Cross (created by “CarveOne” on the Vectric Forum), and produced a 3d rendering of the design.

This is the first time I have really tried using multiple paths on the same object.

The first pass was a roughing pass – used to remove as much of the unwanted timber as possible with a strong router bit, and higher feed rates to perform the task quickly.

DSC05816For this I used the 46294 3D carving bit from Toolstoday.com  It has a Zirconium Nitride (ZrN) ceramic coating, so this bit is also appropriate for routing in aluminium, brass, copper, cast iron and titanium alloy.  It makes very short work of the camphor laurel!

DSC05818There wasn’t a lot of material that needed to be removed, but it is still a worthwhile step to minimise any unnecessary load on the finishing step (and router bit).

DSC05820The final design was then carved using the 46282 3D carving bit.  This has a 1/16″ diameter tip, so can really get into the details.  Even so, there is a bit that is even finer, if even more detail is required (with a 1/32″ round nose tip).

I was using these at around 80mm/sec.

Once the design was cut, I swapped over to a solid carbide 1/8″ upcut bit to first cut around where the gaps were meant to be inside the design, and then to cut around the outside, down to about 12mm deep.

DSC05822For a sense of scale, the cross is about 300mm high, and 200mm wide.  Straight off the router bits, there is no need for sanding where the carving bits have been.  There is a bit of feathering on the outside of the cut out, but that is both a function of the timber, and insufficient router bit speed.

I deliberately didn’t cut all the way through the timber, so there was no need for tabs to hold the cut pieces in place.

To release the cross from the surrounding material, I turned the whole thing over, then ran a basic flattening profile on the back, taking off 2mm at a time with a surfacing cutter – using the RC2248 replaceable tip cutter.

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Once this cut down to the required depth, the cross was released.

Each project presents different challenges, so I get to know more and more about how to use the CNC router effectively, and how to incorporate it as another workshop tool.

I had a look back at some tests I did on the CNC Shark using 3D carving bits – the finish I am achieving here is chalk and cheese compared to my early experiments.  I don’t know if I can attribute it all to the platform, but having such a solid, heavy duty CNC router certainly is not harming the finish that I can now produce!

 

3D printer in action

First quick video of the printer working.

Had a few teething problems, mainly around getting the print to adhere to the bed.

Removed the aluminium bed and replaced with glass. A quick wipe of the surface with a glue stick, and we were away laughing!

skull1Print completed

skull2

Ready for removal

skull3

Skull box completed, ready for a brain

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Hooks to hold the lid closed.  The rear hanging point has since been removed (bandsawn and sanded).

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Ouch!

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Flip top lid!

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BRAINS!!!!!

Original files sourced from Thingiverse

Time to don those 3D glasses

We are moving into a new dimension.

CNC machines are not restricted to 2D patterns and simply cutting in to produce a raised (or recessed) pattern.  Nor are they restricted to 2.5D, which is how patterns that are cut in 2D then built up to produce a 3D image are classified.

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True 3D means the cutter is moving through all 3 dimensions as it is cutting.  This can still produce something like a bas relief image, but irrespective of how complicated, or simple the result, the motion of the cutter throughout the cut is the defining parameter.

Finding 3D patterns to send to the CNC machine are not as easy to find as I expected.  The 3D printing community openly creates and exchanges their creations, including the required files, and open source development programs, whereas the 3D CNC community charges significant fees for each and every pattern, and the software to develop your own costs $thousands.

I did download a sample file from VectorArt3D.com who also provide the code generator program (for free, but it only works with their files) called Vector Art 3D Machinist.  Bit of an experiment-was not sure if it would work on the CNC Shark, but it was fine.

va3dm-1-largeThe program produces the required G-Code for the CNC machine control program, but has an interesting additional output, that of a roughing out pass.

Given how much material the can be removed to create a 3D object, it is good being able to first run a heavier cutter to take a few quick passes to remove the bulk of material before the fine, final cutter moves in to refine the design.

Rather than just use any router bit to attempt to machine a design, I turned to the precision Amana Tool bits that are specifically developed for 3D CNC routing.  These come from Toolstoday.com, and are Zirconium Nitride (ZrN) coated router bits.  I know it says coated, (which to the layman suggests painted or dipped) but I suspect they may be produced using one of the physical vapour deposition techniques.  This is an important distinction.  A coating can rub off over time.  A vapour deposition has characteristics somewhat akin to welding, where the coated layer fully penetrates into the surface of the base material, effectively creating an alloy at the surface.  Localised, controllable, surface alloying is a particularly effective modern technique for producing exceptional products.

6225_7_The bits are all up-spiral, pulling material up and out of the cut, while the cut itself is not a chipping action, but a slicing one.  They are particularly sharp, and smooth.

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The first pass was a roughing pass, using the largest bit seen to the left here.  It quickly scallops away the bulk of material, leaving the finer router bits to produce the detail, without having to push through tonnes of material.

Photo 8-02-2014 16 45 58Once that pass was done (4 minutes), the bit was swapped over for the one making the final passes for detail.

Photo 8-02-2014 17 00 10The final result looks a bit rough – more refinement by me I think.  It is definitely not the router bit – the ZrN bits performed superbly.

Photo 8-02-2014 17 24 24Final pass, which was about 16 minutes for this size pattern.

The additional benefit of these router bits, is their ability to handle other materials, such as aluminum, brass, copper, graphite, phenolic composites, plastic, sign board, & wood.  The ZrN surface is particularly useful in preventing buildup of the material being cut, such as plastic and other gummy materials.

The benefit of having a set of bits is having the right ones available when you need them (and less costly than purchasing individually).

The set of 4 covers a good range.  If you are heavily into 3D CNC woodworking (and as a business), consider the 8 piece set.

Episode 47 3D Drawing Board and the Smartpen

Episode 47 3D Drawing Board and the Smartpen

A quick demonstration of two technologies – one useful for quick visualisations of ideas in 3D, the other with the ability to transfer handwriting and drawing into a realtime digital form.

Contact page for drawing boards http://www.3dboards.com.au/
Contact page for SmartPen http://www.smartpen.com.au/
Original Stu’s Shed review article 3D Drawing Boards

3D Drawing Boards

At a number of Working with Wood Shows, I’ve seen in passing a display for 3D Drawing Boards.  At the time, I hadn’t really perceived the benefit of the system, especially since I have had a fair few years of technical drawing and draughting experience, and the boards seemed to be pitched at people with little to no drawing experience.

I have since had a chance to actually have a good look (and use) the system, and I’ve gone from being somewhat apathetic, to being a definite fan.

That does seem to be a strange way of starting a review of a product, and for that I apologise. However, what I am trying to highlight with this bit of an honest insight, is that because of our preconceived ideas and perspectives, there may be some great products out there that we really haven’t ‘seen’, and for me, this is one of them.

So let me take you through my experience of this drawing system.

Storage Case

Storage Case

When I first opened the package on my doorstep, I found the enclosed storage case, and before even opening it, I had a good feeling that I was onto a good thing. Presentation and attitude of a company towards their own product is king.  If they seem enthusiastic about their product, it is a good start!  I love this case, as simple as it is – it keeps everything together and is neat, and I’ve taken it with me almost every day and shown the drawing board off to a number of (interested) people so I have found myself rather enthusiastic as well.

This drawing board is not just for novice draughters, and in fact I’d say the more draughting experience you have, the more you’d get out of this – incredibly convenient method for achieving drawings in 3 point perspective.

The principle behind a 3 point perspective drawing is to attempt to achieve the most realistic representation of a 3 dimensional object in 2D.  Every single object you look at which has parallel lines, to our eye is not actually parallel – they trend towards a single point on the horizon.  This is known as a vanishing point.  Think of looking up at a tall building – the walls are not straight up and down – they lean in towards each other, and if you continued to build higher and higher, it would look like the very top floors were approaching a single point – that vanishing point.

To draw an object in 3 dimensions so it is visually accurate, you need a vanishing point to the left, and right, and one for verticals. This is known as 3 point perspective, and is what this board is designed to facilitate very very easily.

The Package

The Package

Inside the case was a whole collection of goodies.  There is the drawing board itself, with the unusual curved tracks, a perspex straight edge, which has its own onboard storage location (the two holes in the top-left corner), a pencil case with a pencil and liner pen, an elipse template, an optional 3D calculator CD Rom, and an exercise book.

You can tell the inventor of this product is a teacher – and I gather is a draughting instructor at a tertiary institution in NSW.  The exercise book is designed for those with little to no experience, and each exercise builds on the last, going from constructing a simple cube using some pre-supplied lines right through to a final project.  Not everyone will need the book, but it will definitely get novices easily up to speed with the system.

The 3D Calculator runs on Windows, and allows calculations to be translated into scale for the perspective drawing.  Measurements in perspective is complex at the best of times, so although it is available, I would tend to say that it isn’t something that is needed to get the most out of this board.

It is most useful for pre-visualising, and initial conceptual design rather than producing a set of dimensioned drawings to then build from.  Even those who use a compute drawing package (AutoCAD, even Google Sketchup) will find it beneficial to be able to quickly sketch up an initial concept before creating a digital masterpiece.

The Ruler and Vanishing Point

The Ruler and Vanishing Point

The heart of the concept are these curved slots that the straight-edge runs in. The centrepoint of the curve is the vanishing point, and this again is where this is so much easier than the traditional method.  In that method, you draw (lightly) a horizon line, then choose two vanishing points as wide apart as possible (when drawing average sized objects).  The bigger the drawing board the better, and less distorted the object appears.  This system allows the vanishing points to be very far apart, and yet the board itself is a convenient size.  The vertical vanishing point has a track with a very large radius indeed.  Often, this sort of drawing is done using two valishing points because the third is too difficult to achieve given the distance required, but this board solves that problem.

There is also available a larger version of this board for A3 sheets (the one pictured is for A4) (I don’t know if the US versions of the system are the same, or are for US paper sizes).

There is also a separate system available called the Archi-board with completely different vanishing points for people who are creating architectural drawings.  One idea I had would be to have the drawing board made from thicker stock, and the architectural vanishing points on one side, and the standard ones on the other, so you can use whichever side of the board suits the current project. For those that wanted that, it would save buying two complete drawing boards. Speaking of mods, I’d also like to see a couple of straight slots cut, probably under where the straight edge gets stored, as somewhere to put the pen and pencil when not in use (and deep enough so they don’t affect operation).  I keep finding when drawing, and switching from one to the other, that I put the pencil down on the chair, and then loose track of it.  If there was somewhere on the drawing board for storage, that would be even better.  Also, if under the straight edge, that would help retention of the pen/pencil during transportation, as the straight edge would keep them there!

The two boards are also referred to as the BEV (Birds-Eye View) (the one seen here), and the ELV (Eye-Level View) for architectural drawings.

Ruler Tracks

Ruler Tracks

As you can (just) see here, you flip the straight edge from track to track as you are drawing.  It is very quick and easy.  The bottom of the straight edge is not straight – has bumps along it.  I don’t know why they are there, but at a guess it is simply so you don’t mistake which side of the straight edge you are meant to use!

Paper Location Points

Paper Location Points

Cut into the surface are some marks for aligning the paper (which you stick down with some sticky tape – 3M magic tape would work well here, as it is easily removed afterwards).  The main marks are for aligning the paper in landscape orientation, and the small dots are if you want the paper in a portrait orientation.

Perspective Circles

Perspective Circles

Drawing circles in perspective is a bit of a trick, as you can’t simply use a compass.  A template is provided to assist with ellipses.  Personally, I also have a set of French Curves from my draughting days which I also use. (Did I ever mention I used to work as a draughtsman for a shop fitting firm in London while touring Europe in my pre-Uni and Navy days?)

Basic Perspective Cube

Basic Perspective Cube

It is a bit hard to see in the photo, but hopefully you can make out a simple cube that I’ve drawn here.  You do all your sketching in pencil, then go over the final correct lines with a fine-liner pen.

Adding and Subtracting Solids

Adding and Subtracting Solids

Taking that simple cube further, here I have added and subtracted some solids – added a cylinder to the top and a cube to one side, and subtracted a cube from the other.

More Complex Visualisations

More Complex Visualisations

When I first got the board, I sat down that evening, and in a very short time (about 15 minutes) while learning how the board worked, I sketched this workbench up, complete with drawers, and tapered portions on the bottom of the legs.

As I mentioned at the start of this article, I am rather enthusiastic about this product – having a package that I can use in the shed, or even in front of TV in the lounge to sketch up some concepts is great, and I am REALLY enjoying getting back to using a pencil, rather than a computer in project creations – I didn’t realise it, but I really missed that relationship that you have when drawing yourself, rather than the modern digital solutions.

There is a very comprehensive set of instructions on their website which are worth reading (and watching).

http://www.3dboards.com.au/

You can purchase the product directly from this site – costs $A140 for the standard A4 board detailed here.  If you are in the US / Canada, there is a link for ordering from a US distributor, and costs around $US60 (will confirm price shortly)

(I just had a look at the site to get the pricing, but it is going through some maintenance on the ordering page, so in the meantime you can ring them directly on 1300 363 352, or email merrick@3dboards.com.au). Merrick (who created the product) is more than happy to chat to anyone who wants more info about the product, how to use it etc.

Bottom line – awesome product which I am really enjoying using, and another great Australian product to boot!

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