Acrylic Snowman

While the MDF snowman worked out nicely, and it looked ok painted up, I wanted to get back to trying my hand at making some models from acrylic.

Given that Christmas is rapidly approaching, I thought I’d tackle the snowman again, and see just how well the CNC, along with a new set of router bits specifically for plastic from toolstoday.com would work out.

Just an aside for a second.  I have just gotten an iPad Pro, and while writing the article, have used one of the pro’s features of being able to run a second program simultaneously, and on screen at the same time.  Awesome feature! 

  
I also found a better supplier of plastic sheet goods, so that will be great (and dangerous to the wallet).  They also sell acrylic ‘glue’, and it is a vast improvement over using Superglue.

I still have some processes to work out to make things run smoother on the CNC process of working with acrylic, but for the most part it went very well.  Acrylic is pretty flexible when it gets thin, even worse than MDF it seems, if that is even possible.  So I found myself supervising the whole job while it was machining.  I was using an upcut bit, and perhaps that also has a lot to do with it.  While chip clearance is important (especially with a material that can melt), lifting the piece is not the best way of ensuring it is stable.  I still don’t have revolution speed control, so am still running the bits slower than I would like, and again that is probably a real factor.

Still, the result is a great snowman. Looks awesome (especially with Kara Rasmanis wielding her camera)  

 Next one to tackle – an acrylic AT-AT (Imperial Walker) in greys and black plastics. And there will be video, just once I have a better idea of just how to manage this material!

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.

3D-2.jpg

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.

SONY DSC

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.

SONY DSC

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.

SONY DSC

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.

SONY DSC

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.

SONY DSC

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.

SONY DSC

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.

SONY DSC

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.

SONY DSC

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.

SONY DSC

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.

SONY DSC

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.

SONY DSC

Death of a Vacuum

It was almost 4 months ago to the day, that I built a vacuum table for the CNC router.

While it worked well, I was sure the lack of overall airflow would result in the vacuum carking it very quickly.  Job after job, and it kept going.  It was encased in a rubbish bin with noise absorbing material stuffed around it to drop it’s horrendous noise down to bearable levels (it was a ShopVac, and it always was a screamer). It ran warm- the exhaust was always hotter than was healthy.

Went out to the shed tonight to check on a job, and although the CNC has indeed finished, it was a lot more silent than usual.

Instead of the muffled sound of the vacuum, there was a familiar smell of burnt plastic and ozone.

Carefully switching it off then unplugging it from the wall, I went on dealing with the job at hand, and then went over to the garbage bin, and started unpacking.  Partway down, and the normally white insulation material started coming out black.  Desite being some time, the vacuum itself was still very warm.  A complete meltdown.

Not as bad as the last vacuum though.  Years ago, I had a household vac for dust extraction, and it also failed in spectacular fashion, actually melting until it literally fell apart, and the motor fell out of the housing.

So the machining tonight has stopped, slightly prematurely.  I haven’t added up the hours the vac did in those 4 months, but it would legitimately be into the hundreds of hours.  Hundreds of hours, in a MDF laden atmosphere, with poor airflow. I think it did a pretty good job in the end!  Not even sure what the designed duty cycle of the vac was, or the model’s MTBF (mean time between failure).

So now the decision is “what next”?

Another cheap vac?  A vacuum pump?  If so, which one?  There’s a bunch on eBay, all different cfm, and I have no idea what cfm I’d actually need, let alone my current table would leak like a sieve, so would never actually be able to maintain a vacuum.  And that means the vacuum pump would be running continuously, unless I make some real mods (rebuild) to the table itself.  What do commercial machines do for a vacuum table, and the pump for them?  Too many questions, not enough answers (yet).

The Works of Kerry Strongman

Please note – all photographs used in this article were taken with permission of Kerry Strongman, and the works themselves are copyright.

It isn’t often you have an opportunity to meet and discuss woodworking with a Maori Shaman, but while visiting New Zealand a couple of weeks ago, I got to do just that, in a small town called Te Hana.

As you drive north on State Highway 1, you pass through a number of NZ towns, some larger, some smaller.  They all have a similar look and feel (and for those who grew up in NZ, very familiar, green hills, gentle winding roads (or not, if you are only used to the Australian dragstrip of the Hume! (and by that I mean long and straight, not fast))

After passing through Wellsford (and making sure you stop at “Jester’s” – their pies are unreal.  Especially the Miss Muffet- a chunky chicken pie with Camembert cheese and cranberry sauce.  Not available in Jester’s in Australia (and only then in WA), but it is unbeatable), you come across a small settlement, and on the main straight you see a mounted chopper motorbike.

Have a closer look though

Strongman-28

It won’t be going anywhere in a hurry, being made out of timber.  But even then, this timber has been around a while already – 25000-45000 years, and is swamp Kauri.

Strongman-29

Swamp Kauri is not the species, it is a description of how it has been found.  The ancient Kauri forests that grew in New Zealand (and there are still trees today) lived for upwards of 2000 years.  They were (and are) the giants of the forest, and are similar to the giant Sequoia trees in California.  They don’t have the same girth or height, but as the trunks don’t taper anywhere near as much as the Sequoia, they consist of a lot more actual timber.  Some trees from 25000-45000 years ago at the end of the last ice age were encapsulated in peat, and were buried in swamps, and there they stayed.  Protected by the anaerobic conditions in the swamp, it develops deep, shimmering streaks of iridescence and amazing chatoyancy.

As a master carver, Kerry Strongman makes incredible use of this stunningly beautiful timber, with carvings that are awesome in their own right, and magical when combined with the beauty of swamp kauri.

But Kerry doesn’t always stop there, and the use of clear and amber coloured resin in voids, often embedded with objects such as shells, minerals and kauri gum is a regular theme in his work.

The designs typically use the traditional forms of Maori carving – the Tanwha, the Koru, the Hei matau (fish hook), the Hei-tiki.

Another aspect of Kerry’s work is scale.  Sure, you can have a carved piece of his (or his students’) that is small and worn as a necklace,

Strongman-7

but the pieces that really blow you away are the ones made 6′, 8′ even 12′ tall.  You do need deep pockets for one of those stunning pieces (or a corporate credit card!).  These are known as “Jewelery for Giants” to coin Kerry’s catchphrase.

Strongman-1

Strongman-2 Strongman-3

One of the first pieces you see when entering the showroom is this fish hook (I assume) of Maui (the legend is this warrior from Hawaiiki – the mythical ancestral homeland of the Maori, cast his line into the waters and when he and his brothers heaved upon the line, they caught Te Ika a Maui (the fish of Maui), these days known as the North Island of New Zealand.  The South Island is known as Te Waka a Maui (the waka (canoe or watercraft) of Maui), and Stewart Island as Te Punga a Maui (Maui’s anchor) which held the waka as Maui caught the giant fish.)

Not only encrusted with kauri gum, it still has the rope attached at the top end.

In the third photo is Kerry himself.  Around his neck is another of his carvings, although I sadly don’t have a close up of it, it is a ornate carving in mammoth ivory (or bone?).  250 million year old mammoth!

The rest of Kerry’s showroom is filled with elaborate carvings.

I was fortunate enough to also be given a full tour of the workshops and storage areas – an area many times larger than the showroom filled with works in progress, works yet to commence (raw materials) and everything in between.  We are also both toolophiles, so were able to have a great chat about the tools used in the process of carving these works, and Kerry does not restrict himself to just using the traditional tools either.

Strongman-19 Strongman-20 Strongman-22

 

It is hard to do the work justice here, so if you ever happen to be in the vicinity of Te Hana (or any of the corporate offices around the world featuring his work), take some time to have a good look.  You can also check out the website at kerrystrongman.com

Strongman-27

Not only was Kerry very generous with his time giving me a full tour, (and my daughter now has some stunning necklaces), Kerry has offered me a pallet of timber for me to ship over to my workshop.  Can you imagine a pallet of timber from someone who really understands and appreciates the true quality of timber?!  And if some was the magical swamp kauri…..well….!  This is just a small example that I got years ago, just to give you an idea of what we are talking about.

There is no fate

At least not till next year, as the school fete has come to an end.  After 8 or so hours, a bit weary, but it was fun.

Quite an interesting learning curve – got a lot right enough, but there is always more than can be refined, if I ever intend to do this again!  I do have one other planned fete coming up in November, but that is about it.

Fun seeing the kids’ reactions.

The display stand with the black cloth covering it, is the Centipede XL which I just got back after lending it at the start of the year.  It is perfect for this sort of thing.  I made a top from 6 panels of MDF which were cable-tied together to create one overall top.  This allows me to take the top off and fold it up for storage/transportation.  I made it from 3mm MDF as that is what I had to hand, but 6mm or 9mm MDF would have been better.  As the MDF only has a few holes drilled right at the extremities for the cable ties, I can still then use the pieces on the CNC machine :)  It worked very well – easy to transport, easy to set up, and stable.  (Does that make it a stable table?).  In comparison the vacuum-formed tables are reasonably easy to transport (they weight quite a bit more but have much less surface area) and quicker to set up (if you factor in attaching the top).

That gets me thinking – I could come up with a segmented top for the Centipede, which engages with the holes in the leg caps.  That would remove the need for cable ties and make a really rigid (crossbraced) system.  Make a good way to use it as a workbench as well.  Alternately, I could recess out the area where the top of the leg touches the top, so the whole top piece can still be stored perfectly flat.  I’ll work on that, and let you know what I come up with!

Sales were ok, not unreasonable, not as high as I would have expected.  I did a quick gender comparison – ie assuming some models would appeal to one gender more than the other (and those that would appeal more to both).  It is a really rough tool – for example, I chose a swan to be oriented towards girls, and a cobra to be something that would appeal more to boys, and a turtle to be neutrally biased.  That might infuriate some people, but the reality is that if you got a bunch of primary school students and gave them the choice (with no observers, or chance that classmates etc would ever know the choice made), that certain toys would be selected disproportionally higher for one gender over the other.

The analysis is very loose – I did not record the gender of who was making the purchases, or who they were purchasing for, so already there is a lot of interpretation built into these stats.

Toy Variety

Girls liked a lot less variety than boys in the toys chosen.

Of the total variety of girl-oriented toys, sales were concentrated around 41% of the range available.
Of the neutral toys, 53% of the variety available were purchased.
For boys, 75% of the range had at least one sale made.

Kits vs Preassembled models

This data is not very relevant, as the models were only able to be collected at the end of the day, whereas kits taken straight away.  Additionally, there was only one of each type assembled, and between 0 and 10 kits available.

Girls’ purchases were 71% kits
Neutral purchases were 53% kits
Boys’ purchases were 78% kits

Total Sales

Of all the purchases available:

Total sales of girls-oriented models: 20%
Total sales of neutral-oriented models: 23%
Total sales of boy-oriented models: 56%

As very few types sold out completely, this data was not heavily influenced by particular models becoming unavailable.

Other interesting observations – quite a few people looking (kids and adults) – “Wow, these are really cool”, then after checking the price “Wow, these are really cheap” (the vast majority being around the $5-$7.50 mark).  However even after uttering both those comments, the person looking around would then wander off.  Interesting that something that is regarded as “cool and affordable” still does not necessarily result in a sale.

I would have sold more if there was no restrictions on whether the person could buy and take the pre-assembled model, so having two or three of the most popular kits pre-assembled would be beneficial.

It may also be better if there was less variety of kits available, and so people could select the ones they want for purchase, rather than having to ask for them.  While this makes perfect sense (and is how we shop most of the time), it is a lot harder to do this in a market-like scenario with limited space.  Especially with bulky products that have a degree of fragility to them.  Again, if I was doing this on a regular basis, I would be able to justify the additional investment in the multiple storage containers needed to keep everything sorted.  For a one (or two) off, that is less practical.

All in all though, it was a fun evolution, and I’d do it again.

Occasionally!

Episode 118 Lancaster cut video

A quick video of the Lancaster Bomber being cut out.  I don’t want to think how long it took this video to actually get done – so many delays, so few windows of opportunity to work on it!  I decided to cut my losses and just put together what I had, rather than stress too much about really refining it.

Plans from MakeCNC.com

Uses the 45705 V-Groove 60º x 1/2″ Dia. x 1/4″ Shank Router Bit and the 46200 Solid Carbide Spiral Plunge 1/8″ Dia x 1/2″ Cut Height x 1/4″ ShankDown-Cut, both from Toolstoday.com

For better or worse, here ’tis.

What I have been working on

For my next article in The Shed magazine, I have been designing and building this water wheel

water wheel-1 copyThe whole thing is about 1100mm high, and it can kick along at a fair rate of knots, even just with a hose as the water supply.

I’ve designed it to use either water weight (quantity, slow moving), as well as water velocity (smaller quantity, flowing at speed).

It has a square drive on one side of the shaft, so it can be used to do real work, and at some stage I’ll add some traditional gears to do just that.

water wheel-1-2No glue used in this project – it is all coach bolts.  About 170 or so in all.

Follow

Get every new post delivered to your Inbox.

Join 2,109 other followers

%d bloggers like this: