Introduction to 3D Printers
Whether you are a first time 3D Printer Buyer, An experienced buyer for a School or an Industrial buyer wanting rapid prototyping capability, there are good and bad products in every price range. So which are the Apple of the 3D world and which are the rotten apples?
With prices ranging from a few hundred dollars to many thousands and whether you are looking for desktop manufacturing or a larger size industrial 3D printer, our aim is to find the best and worst features of all the current top models and present them for you in a readable way, enabling you to compare and make your choice a little easier.
What is a 3D Printer?
Wikipedia describes a 3D printer as a process of additive manufacturing for making a three dimensional object using a 3D modelling . Layers of material being built up successively, programmed by a data source controlling a computer driven head extruding molten plastic. Most commonly PLA plastic and molten polymer deposition. Effectively then the 3D printer is an industrial robot
What is the current state of the 3D Printer Market
In April 2014 M3D lauched their 300$ “truly consumer” micro model, an indication of the maturity of the market. Consumers demand driving the price down as the 3D printers become more widespread. Most models that would be for professionals and higher education though are in the range 1000$ to 5000$ to be realistically useful. Lower schools are obviously recognizing that the technology is now widespread and there is a huge number of schools indicating that they want to have at least entry level machines to introduce pupils to the basics. Companies like the Dutch Leapfrog are offering courses and participating in schools corricula.
What are the Main points to consider when buying a 3D Printer?
1 Which materials will it print with?
2 Levelling the Build Platform
4 Maximum Volume of your print
1) 3D printers use a variety of plastic extrusion materials
ABS ( Acrylonitrile Butadiene Styrene ) If you use this, you would benefit from a heated build platform, During cooling, the edges of an ABS print, can become unstuck and tend to curl off the platform. ABS sometimes exudes a burning smell during printing so it is wise to use in a well ventilated room. For a school or industrial machine safe fume extraction, would be a requirement. As it is a petroleum based plastic, you have to consider carefully any contact with chemicals which might react with or break down the ABS composition. ABS is more prone to cracking and delamination than other materials but does not need cooling fans during printing. Everyone should be familiar with ABS based products like Lego bricks.The results have a little flexibility. The temperature used in extruders is between 220 and 240 deg C, to produce good flow. .Experience shows that maintaining an even temperature around the workpiece ( the environment temp ) is advantageous, so printers within a case or enclosure, fare better than the skeleton models when printing with ABS.
PLA ( Polyactic Acid) This is a starch based biodegradable plastic..This is more brittle than ABS, but does not need a heated build platform as it does not tend to warp nearly as much as ABS during printing. Cooling fans are recommended to speed up and strengthen layers
Open Source Material
Open Source is a term used to denote that a printer will operate with any source materials, not just the specific ones sold by your printer manufacturer. Note that this is sometimes specified because of reel type, or because the spools are contained within a cartridge. A thinner reel may tend to wander on its spindle and it is possible it will get tangled , ruining the work so be aware of this. The tension on the filament should be maintained constantly, to give a perfect print. Sometimes a simple cardboard tube used as a spacer or similar arrangement, will allow you to use materials from any source, rather than having to keep within your manufacturers offerings. Some users have noted that they are paying well over the average price for filaments from their own manufacturers, just because of the container or the method of attachment. Color matching between batches needs careful attention too, as it varies considerably.
2) Levelling the build platform
This is a hugely important part of the setup process. In entry level machines and most older models this is an entirely manual procedure. In most cases it isn’t difficult, but if not carried out properly it can seriously affect the finished product, worst case the workpiece can be ruined or become detached from the platform. Recent machines like the UP Plus 2 have an automatic levelling and platform calibration built into the very easy to use software. Most printers now have semi automatic methods, where you follow on screen prompts , levelling by hand as the extruder is automatically driven to the next position.
To raft or not to raft
With pieces which don’t have a good footprint, ie don’t have a large area of the work to place on the build plate, it is worth considering a raft, or low density matrix of material, for stability while printing the main object, this is discarded afterwards, with a dual extruder model like a Leapfrog, or XYZ ‘s Da Vinci model it can be printed in a different material, which is easy to remove later
Be sure to choose a realistic resolution most 3D printers will make a good workpiece at 100 micron, be aware of the time consequences of using a really small resolution and that increasing the printing speed will exaggerate any weaknesses of the machine design like overhangs where the printhead overshoots when decelerating too rapidly ( inertia of the head unit ) and inability to supply enough material when printing fast, breaks or “air printing “ in the product. Check out the rigidity of the unit when printing, any shaking of the enclosure during a print run will cause inaccuracies in the work. If the X-Y drives are by belt, it really needs to be tight or pre-tensioned , any sloppy drive belts will cause wobbly edges.
Setting the Z (vertical) resolution : This is a compromise between too low a resolution, which will result in stairstepping and too high, which creates so many layers it just takes too long to print.
An object which exhibits stair stepping is going to require you to hand finish with abrasive paper or chemicals later.
Even with a small volume printer, it is possible to produce your print in several pieces and assemble them later, of course this may introduce small errors, especially if the edge is thin, it may tend to warp, resulting in the pieces not fitting together well. The price though of some of the larger printers like the Lulzbot or Leapfrog, is considerably higher than the smaller models
There are many free open source softwares which certainly have their place and improvements come along all the time, it is worth keeping an eye on what is available as it is a rapidly changing area. What was expensive and with features only available on one software , will sometimes appear in the next version of all the free softwares. If your work has big overhangs ie parts with no support under them , like a bridge, it can be important to be able to introduce supports, thin walls , in the design or within the slicing function, to make sure you don’t end up with drooping bridges.
It used to be the case that design, slicing and printing were all separate softwares but increasingly all these functions are available in single softwares.
The constant in this mix is the STL file, the instructions to the machine for printing. To be useful , any design software really has to be able to import and export these types of file. Open source software is quite popular especially for the sub 1000$ category. With Open source, it means you would have the ability to add or take out lines of code, to modify the software for example to use a different printer with some extra feature like an extruder wiper. I have tried out several of these, including the Sketchup design software and the Cura software checkout my reports elsewhere on the website
Multi Extruder 3D Printers
Some like the Leapfrog or XYZ Da Vinci, can use different color materials or use different materials at the same time, so color changes can be done automatically during the print. Although it is possible to change color filaments with a single extruder, during the print, it can be an extremely tricky job and cannot be timed exactly as the print head obviously contains molten material. Also some software will not allow you to pause mid print to do this at all. So if multi color or multi material objects are a requirement, it would be better to start with a dual extruder type, to save that extra step, painting or assembling multiple parts together, after the printing stage.
Most of the 3D printers now have some sort of display on board, so the computer is only coupled when transferring the STL file. A useful status can be displayed during the print and it is also used to prompt the user when platform levelling is taking place. Not all printers though, have a display and so will rely on the coupled computer for these functions, so be prepared to tie up the laptop for long periods, if it does not.