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3D Printer

Revision as of 17:21, 7 June 2015 by Matt P (talk | contribs) (updated that ultimaker is now in place)

Currently there 2 printers available for Hackspace members use. A Prusa I2, able to print in ABS plastic, and typically prints reliably at a rather slow rate of 55mm per second.

A kit has been ordered to raise the maximum speed of this printer.

In addition, the Space has an Ultimaker + printer which is ready for member use. It has an RFID card reader and requires members to show their cards to use, an induction is required before the system will activate. Using this tool will not be charged. It will print reliably at around 80mm per second.

Happily the same software can be used to control either printer, and is freely downloadable from;-

There are 3 main steps to using either printer; choose your model; choose your material; and finally slicing a 3D model into "g-code" readable by a printer, and feeding it to a printer. This is typically done via an SD-card for maximum speed, although a computer or laptop can do this when connected to a printer by a USB cable.

Step 1 – Get your model ready to print

First stage of using a 3d printer is finding or making a 3d model from scratch. The TYPE of file that is easiest to deal with are .STL or .OBJ. Conversions from other formats to either of these is necessary in order to print. Well known public depositories of models for free usage are;- (needs registration, some models are pay per download);- (usually links to above 2);- (can go ANYWHERE with this one, caution recommended)

For a further more indepth list of depositories;-

ALWAYS LOAD and SAVE your model as an STL with Cura prior to printing. You may also need to scale it in one or more dimension if perfect accuracy is important. The reason for this is that STL models need to be perfect "meshes" in one piece prior to slicing. If not, they don't slice properly. A freely downloadable tool to fix STL meshes is Nettfabb, you can get a free version of it at;-

In addition, if you want to find out HOW to build an open source 3D printer, then models are available usually from the designers on github (sometimes the manufacturers if they offer open source plans), or a (somewhat out of date) list at;-

If you want to design models yourself, then 2 “free to use” pieces of software to use are Blender and OpenSCAD. Blender is GUI based, OpenSCAD is command line based. Using either requires patience and practice, but give you freedom to come up with your own designs. There are other possibilities, like an educational license (free for a year) for Autodesk Fusion 360 or if you have funds, the highly complex but capable Solidworks. There are plenty of other programs and I do not mean to cause offence by saying other software can not be used.

Step 2 – Work out your material

Both the Reprap Prusa I2 and the Ultimaker take 3mm sized filament. Members are encouraged to source their own filament, although for small project there is a limated amount of PLA available in the space to print with.

Both types of printer can be controlled via the Ultimaker Cura software. It can be downloaded for Windows, Mac and Linux from;-

Some suppliers sell “3mm” filament as “2.85”. This is actually a more accurate measurement of the same material – it extrudes hot at 3mm but shrinks to about 2.85 at room temperature. Either will feed on either printer. Technically the smaller 1.75mm filament will also feed on either printer but this has not been tested yet. Sources of filament are;-

Ebay – although caution is recommended with any particular sale! (Dutch) (Czech)

You can also get filament which is PLA with other additives, for instant bronzefill, woodfill (Laywood), brick effect (Laybrick), soft iron for electro magnetic cores, carbon nanotubes, carbon fiber and stainless steel. Caution is recommended when dealing with different filaments with unknown properties – each requires slightly different temperatures and may cause a nozzle to clog.

It is also highly recommended to MEASURE a new filament to get an average width. Putting this value into the slicing software that converts a 3D model into printer g-code enables the right amount of material to be laid down. If your filament has a different diameter for some reason, the software has to know this!

One great thing is – you can download a model into Cura and it will tell you roughly how long a piece of filament it will need to finish a print.

Rough guide to temperatures – PLA will print between about 177 for the software transparent or translucent varieties up to about 208 for the harder coloured varieties, especially black or white. Setting a bed temperature of 60 Centigrade or slightly higher will give the plastic a good chance of sticking to the bed. After the first couple of layers the heated bed can be turned off – this helps to reduce curling or warping on smaller prints, as does reducing print speed and printing temperature.

ABS requires a much hotter bed, MINIMUM 105 Centigrade or preferably 110-115. It needs a hot surface to stick to.

It is hoped the Prusa I2 will have other extrusion options available soon – for a start, printing from pellet or ground up plastic, and also paste extruders for materials that are printed cold but harden and cure on exposure to air. One basic requirement is for a quick change mechanism to be fitted so that different materials can be used without reaching for a set of spanners and screwdrivers. Printing in ABS is a gateway to that end goal.

Step 3 – Choose a printer and print – REPRAP Prusa I2 only, NOT Ultimaker

As there isn't an Ultimaker around currently, these steps are only for the Prusa I2, although there is some similarity between them.


This is THE most important stage. It is fiddly to learn and takes practice to get right.

The surface that models print onto is a square mirror, with a hole cut in each corner. This is clipped onto the aluminium heated bed, and needs to be prepared for the first layer to “stick” to it properly.

If a model is printed straight onto glass – it can be impossible to remove without breaking the mirror.

A coating material has to be added to a clean mirror, to give a surface for the hot extruded material to stick to. When printing with PLA, the best all around material for this is PVA wood glue, smeared thickly enough to be opaque, and then left to dry to a transparent layer. Masking tape is also useful for this and can give very good results.

For ABS, Kapton tape is a better bet. A large roll of this is kept in the Reprap spares box in the Members Room. Again, putting it on the mirror takes a bit of practice to get right.

Once a clean mirror has been coated, it should be clipped back onto the bed, and the heated bed turned on, either via the built in controls on the printer, or via a control program like Pronterface.

Pronterface is again an Open Source 3d program, part of “Printrun”. It is a Python script, and is very useful for manually controlling a printer, to make sure the travel over the bed happens right (no dips or rises), and also that the “home” positions of all the axes is correct. Pronterface can send G-Code to a printer, but does not have the capability to make G-code from a 3D .STL model. Cura or the alternative Slic3r software can do this. Slic3r is not so user friendly as Cura but does make better g-code, in general.


The adjuster for this is closest to you, and is a switch mounted vertically on a smooth rod. The switch should be clicked automatically when the nozzle is JUST above the HOT bed. The exact position varies slightly, which is why heating the bed up to begin with is the second most important part of preparation.

Happy that the printer homes and all the heaters work? Good, if your filament isn't already loaded, heat up the nozzle to working temperature, undo the screws on the extruder, and take out the filament that you don't want to use, and feed in the filament that you do want to use. (Video of this to be positioned here in the text at a later date). Then tighten the screws on the extruder, and use Pronterface to “Extrude” until you are sure the printer is squeezing plastic cleanly. It is wise to feed at least 40mm of fresh plastic through a nozzle prior to a print, to make sure that it is feeding and extruding hot plastic properly.

Once you are sure the printer is ready to go, it is time to feed it some G-code. Close Pronterface and get your g-Code onto an SD-card;-

Slicing G-code with Cura

Load your model into Cura. Scale and rotate it to fit the bed.

Choose a sensible “Layer Height”. This is the height each layer of the model is printed at. With a .35mm nozzle, a layer height between 0.175 and 0.28mm is sensible. Less layers = quicker print but weaker layers. So thin is good but slow.

Next, select “Save g-Code” from the Cura Menu. Give it a name, try to put Cura into the title, with a .g or .code suffix, and save the G-Code.

Transfer the G-code onto a SD-Card and insert into the printer. From the Menu (press the button), select “Print From SD card”, select your model, and watch it slowly being printed in front of your eyes.

Not happy? Leave a model to print for at least 3 minutes before aborting it (easiest way to abort is just turn the power off on the printer). Some models start rubbish but settle down to print well. Others start well but go badly – it is a good idea to shut down the heated bed after the first couple of layers, also smaller parts print better when printed slowly, as they need time to cool down.

Further info on using Slic3r;-

(To do - add Cura and Slic3R machine profiles to download for both Reprap and Ultimaker machines, add pictures, edit for clarity)

3D Printer Videos

Some videos which explain the basics of 3D printing and getting started

Element 14 videos (required login)