How To Make Laser Cut Interlocking Acrylic Designs

The Importance of Radii

We’ve written about using ‘nodes’ with 3D objects made from wood before, but suggested it may not work for acrylic because it is more brittle and tends to be less forgiving.

However, after working with Drownspire to develop their Vambit toy into a product for a giveaway at Makerfaire, it soon became apparent that you can successfully use nodes when making with acrylic.

Nodes in Acrylic: Two tricks to getting it right

Firstly the nodes need to be a bit smaller; something in the realm of <0.15mm/0.006″ on each side. This means they won’t cover the same range as when used in wood but they still remain a good option.

Secondly, how you treat the end of the slot is the key. If you have a sharp corner, which is typical in a laser cut slot, the acrylic will always fracture at that point. See this example:

Effectively a sharp corner is creating a weak point in the acrylic. Not such a good thing when this is an important structural part of the design! A small radius in that corner can do wonders to transfer the forces from one face of the hole or slot to the other, and reduces the risk of the material splitting at the corner.

How large should they be?

The larger the radii the stronger it will be so you will need to make an aesthetic decision on how big you can go. On the Vambit the radii was tiny, at just 0.26mm, and it was enough to make a noticeable difference. We suggest aiming for 0.5mm and greater if your design will allow it.

Where to place the nodes

Another trick to keep in mind is putting the nodes on a part of the design where you can guarantee the length. That way you don’t need to bet on the thickness changing and the range of variation is a lot smaller. This occurs when you have 2 edges that are cut by the laser that are the friction edges. This works if you are using tabs but is not necessarily the case if you are using a slotting joint.

For example, in the design of this spinning top Dan put the nodes on the tab as opposed to on the slot.

The tabs on the triangle parts fit into the slots on the circle part. Dimension X and Y will be the same each time as cut by the laser, therefore he put the nodes on these parts. Had the nodes been positioned on the slot for the handle (as in diagram below), the friction points would be against the surface of the material, a part that can vary if the thickness varies.

Other types of connections

An alternative joint is the t-slot joint which is popular with people who make more engineering-type products. This joint uses tabs to locate pieces then a t-shaped slot with a captive nut. This type of joint is great. You can slightly oversize the holes to allow for oversized material and the bolt will hold it snug together. If you use the radii on the corners of the cut outs you greatly reduce the risk of cracking the acrylic by over tightening the bolt.

If you want to go another step, rubber washers can also reduce the chance of over tightening and maintain tension in the bolt so it won’t come undone through vibrations etc.

Hopefully these tips will help you with your next laser cutting project, or perhaps give you the extra tools you need to finalize a design you’re working on.

We’ll be interested to hear your experiences using radii too, and any other advice you might have for people wanting to make 3D designs using acrylic. Let us know below!

This handy advice from Dan Emery was sourced from the Ponoko Support Forums.

A new hi-res desktop 3D printer announced today.

Formlabs announced today the release of the Form 1, their “prosumer” desktop printer that uses stereolithograpy to produce highly detailed models.

“The Form 1 marries high-end stereolithography (SL) technology and a seamless user experience at a price affordable to the professional designer, engineer and maker.”

A common complaint of current desktop printers like Makerbot, Ultimaker, and RepRap that use FDM extrusion technology, is that the print quality is too low. The Form 1 tackles this head on and the high quality results speak for themselves. Another printer in the “at home” printing market is great news for consumers too. The Form 1 promises to be “An end-to-end package. Printer, software, and post-processing kit that just works. Right out of the box.”

The price is affordable though the regular retail price has not been announced. At $2499 it is comparable to the price of the Replicator 2.

They have a kickstarter campaign to manage pre-sales and generate funds to ramp up production. The machines are selling fast! They have reached their goal of 100K in 2.5 hours.

Formlabs is a Boston-based start-up founded by a trio of MIT grads with impressive backers like Eric Schmidt and Mitch Kapor. They’ve also enlisted Dragon Innovation, a manufacturing consultancy, to assist with the production of the printers and hopefully avoid the kinds of hurdles we’ve seen other successful kickstarter campaigns face.

Nice work guys. I’m excited to see the results!

More on Formlabs and Wired

Glossy new 3D printing materials for your Personal Factory!

ABS gets glossy

We’ve just added 2 new 3D printing materials for your making pleasure. And for those who like acronyms, the process is Fused Deposition Modeling or FDM and the material is ABS — the same stuff legos are made out of.

These new glossy materials have high durability, decent detail and accuracy, but a rough surface.

Check ’em out:

Durable Gloss Plastic – Black

Durable Gloss Plastic – White

New materials for your making pleasure!

Oh, shiny!

In the USA we have –

Orange Tint Acrylic – great for electronic housings, jewelry, tableware, decorations or a novelty SF Giants World Champions trophy.

And for NZ we have the often requested –

Silver Mirror Acrylic – great for custom mirrors, jewelry, and finding out if your friends are vampires.

and the slightly obscure –

Clear Mylar film – great for PCB stencils, food packaging, or laminating a fake ID for your cat.

And now the sad news, Crystal Blue felt in 5mm/0.197″ material is removed from the USA catalog

We are no longer able to get Crystal Blue felt in 5mm/0.197″ so we’ve had to remove it from the USA catalog.

It is available now available in 3mm/0.118″.

Why 2D plus 3D excites us so much

and the origins of Dan’s Exclamation LampPonoko Personal Factory 4 opens up a new world of possibilities by combining more than one digital fabrication method as well as open source electronics.

Dan’s Exclamation Lamp on our home page is a fantastic example of this fusion, and we cannot wait to see what other designers will do with it.

We talked with Dan about how his lamp design came about, and why it is such an ambassador for the combining of fabbing methods:

Each fabrication method has its own strengths and weaknesses.
You can make a lamp using only laser cutting, but you are constrained by having to try and interconnect flat materials. You can make a lamp using only 3D printing, but you are limited in the material charactaristics available to you and the cost may be prohibitive.
Combining the two gives you the best aspects of both techniques.


How to reduce burn marks on acrylic

Or how to avoid “smudgy yuckyBurn marks are an inherent part of the laser cutting process – we are cutting things with a highly focused beam of fire after all. There are some tricks to minimizing this issue for different materials, and this post deals with acrylic.

Most of the acrylic sheets we use come with protective paper on both sides. It’s possible for us to leave this paper on when making your design, which we tend to do where it will not interfere with your engraving. The main downside to this is needing to peel paper off both sides of the acrylic, which can be time consuming and tricky if your design is intricate.

Generally our rule is: cut with paper on both sides if there is no raster engraving in the design, or if all raster engraving is of the heavy variety. Heavy raster engraving burns through the paper without any trouble, as does heavy and medium vector engraving. If the file has medium or light raster engraving, however, we will remove the protective paper from the top of the material unless otherwise requested.

It is possible to use medium engraving through the paper, but due to the dot matrix nature of the raster engraving not all the paper is burned away. A slightly sticky residue may be left on the plastic if you ask for this option – which may need to be cleaned off before you use it.

Below are some typical examples of what you get when laser cutting acrylic. It should be noted that it is most obvious on black hence using it as the example material. Also the images have been zoomed in to great detail and emphasizes the effects more than might be obvious to the naked eye.

Cutting – Paper Left On vs Paper Removed
On the left through the paper and on the right without paper. The right shows a clear example of the smudgy burn marks that are left on the acrylic after cutting. Clearly the shapes cut through the paper is cleaner than not.

Heavy Raster Engraving – Paper Left On vs Paper RemovedOn the left through the paper and on the right without paper. You can see that engraving through the paper produces a crisper result. The vaporized acrylic builds up around the outside of the letters when the paper is not use and produces this slightly ‘inflated’ look. This would probably polish off should you have the desire to do so.

Medium Raster Engraving – Paper Left On vs Paper Removed

On the left through the paper and on the right without paper. Again engraving through the paper is a little crisper in the letter forms, but as mentioned earlier there may be sticky residue left over from the adhesive of the paper.

So what does all this mean?

If you want us to leave the paper on, you should only use heavy raster engraving. If you use medium or light raster engraving, we will make your design with the paper removed.

If you would like to specify how you want your job cut, make a note in the Special Shipping instructions.

Other tips for engraving & cleaning acrylic:
How to improve your engraving results – Part 1
How to improve your engraving results – Part 2
Tips for cleaning acrylic

Kudos to @deleifd and @skruff for the awesome type design.

DIY is not so threatening.

Highlights from the IDSA 2010 Conference

The Industrial Design Society of America held it’s annual conference in Portland last week. I had the great fortune to present Ponoko’s response to “DIY: Threat or Opportunity”. Of course we love DIY here at Ponoko and we strive to bring powerful manufacturing technologies to people of all making abilities. We believe if you minimise the barrier to making your ideas real then all sorts of amazing projects will be produced that might not have been otherwise. We see these show up in the Showroom all the time!

I also think DIY and making are at the very core of being a designer. The workshop is where we learn about the properties of materials, the abilities of tools and how to creatively engage both to make awesome stuff. The nature of the tools might be changing, getting more digital and “hands off”, but the experiential nature of making stuff is just as important as it was 100 years ago.

Some highlights in no particular order:

Chad Jennings from Blurb presented his interpretation of the DIY revolution as a 3 phase development. 1: Mass customization (Nike iD) 2: People Powered Products (Moo, Blurb, Ponoko, Shapeways), 3: Towards people powered businesses. Blurb allows people to publish their own books with the same quality as mass published books and that has allowed individuals to compete with the big publishers. He also highlighted the power of your social networks when trying to sell your products. Someone who posts their Blurb book to Facebook through a widget experiences a 300% increase in page views and a 80% increase in sales. He suggested goal for making a living was get 1000 fans who love what you do so much they will spend $100 a year on your products. Sounds easy, right?

Jay Rogers talked us through how Local Motors is co-creating unique cars. Designers submit their concepts and a voting system decides which cars are then developed (open and collectively) and built by Local Motors. He explained how they are building flexible manufacturing facilities close to the customers that want to buy them as this makes more sense than shipping large objects around the world (sound familiar?). It was also interesting to see how they combine custom parts with some off the shelf components (like engines and lights) to reduce the price of the end product, keeping it realistic. The coolest thing about Local Motors is that it gives designers, who may never have otherwise had a chance, to design cool cars with a chance of production.

Tine Latein provided us with a personal insight in the process of designing, manufacturing and market her awesome 3D printed Einzeller necklace. The design and manufacture was the ‘easy’ part for Tine and the marketing was where it got hard. The traditional route was what worked for this product. Combining traditional press articles with the sales and distribution network of a local gallery proved to be the best option. The gallery also understood the manufacturing story really well and were able to pass this to the customers. I think is an important point to note; if customers understand how something is made, from the designers story to the manufacturing, they are more likely to get involved on a personal level and spend the money. Even better if you are manufacturing with a rad new technology like SLM (selective laser melting).

Martin Van Tilburg walked us through the design and development of the Toideloi Stackhouse, a modular kid’s playhouse. Frustrated with not being able to make stuff well by hand, Martijn bought a small Shopbot router to aid in the development of the playhouse. What was interesting to note here is that having direct access to the machine (desktop manufacturing anyone?) allows you a lot better understanding of the process and quicker development time. The trouble he faces now is finding a manufacturer who can produce the same quality on a larger scale.

Ben Hughes from Central Saint Martins College in London provided the only counter point (sort of, that I saw anyway) to the view that DIY was an opportunity. He claimed the Reprap DIY 3D printer was like a blunt tool to his students. Digital manufacturing machines are tools, yes, but blunt tools? That depends on how you use it. A tool is only going to be as good as the person controlling it, be it a hammer and chisel, 6 axis CNC machine or a 3D printer. Sure there are some limits to what the DIY 3D printers can make right now but it is only a matter of time before that gets better and people start to push the design possibilities. He was surprised that 80% of the things on Thingiverse are parts for the machine itself and not more people sharing other (design) objects. The analogy we like to make is that DIY 3D printers are where personal computers were in the 70’s. They were still in the garage and in the hands of engineers. There is development needed to get them to the same easy to use level that computers were at when they became mainstream. The open source DIY 3D printer community is working together (though geographically separated) to continually improve the tech to make it easier for the next generation of users to get onboard and make cool stuff.

All in all it was an inspirational and fun week. Thanks to IDSA and Ziba for hosting a great event.

How to make snug joints in Acrylic.

The importance of radii

We’ve written about using ‘nodes’ with 3D objects made from wood before, but suggested it may not work for acrylic because it is more brittle and less forgiving.

However, after working with Drownspire to develop their Vambit toy into a product we could give away at Makerfaire, I discovered that you can successfully use nodes when making with acrylic.

There are, however, some tricks to it.


3D Printers at Makerfaire

So many to choose from

We have posted about the various DIY 3D printers on Ponoko before so it was great to be able to see them in action at Makerfaire.

The Makerbot guys were showing off their new Frostruder and a couple of new ABS colors. The red was super cool, it kind of glowed. They had a new design for a container for the plastic spool which was good to see. The spool can get out of control if not properly looked after. Also on the horizon is a new Plastruder design (the part that melts the plastic). The new design looks a lot more robust which will be fantastic.

You can also check out the presentation given by Bre Pettis at Makerfaire about the Makerbot project and the cool stuff they are doing.

It was also nice to see custom cases showing up. Like this fluoro pink Bot by Eddy Vromen and of course the Vambot we had on display.


Open source laser cutter

The Lasersaur
With all the excitement around open source 3D printers, Nortd Labs is looking to do the same for laser cutters. With 30 days left in the Kickstarter project they have more than reached the target funding. Cant wait to see how this turns out. Check out the Kickstarter page for more info.