OK so I'm doing more work :(
Where I'm at so far..... I have figured out the theory behind the X axis drive. The mods to the stepper motors is a given but not unrealistic. What is bugging me is the quality of the output. Looking at the Geoweaver's mess, I'm hoping for a proper model. Whilst on the subject of the Geoweaver, the distance between the extrusion and the layer is enormous, allowing for cooling and virtually no bonding. It really is an experiment! I'm looking for a proper model as an output. This then brings me on to warping. This is something that occurs often in models and is primarily to do with the heating and cooling between layers. Compensaters such as heated beds and fans seem to work as does printing with PLA rather than ABS, due to the material property. So when I am printing in the unlimited X axis, I will find that I will start to warp longitudinally rather than vertically. It is possible that this could be overcome by operating a heated fan in front of the hotend (this would mean having four fans for heating plus the cooling one!) but the truth lays firmly in the overall temperature gradient throughout the model. I've read about people putting their printers inside of fridges to print, also people putting their printers inside sealable bags to keep the heat in depending on what it is they are doing. I can not do this if I am to print on the floor! So now I'm not sure whether this is a departure from my project or not. The fact that I have produced a theory that, to all campers and dolphins (intents and purposes), will move the datum outside of the machine envelope just has to be built to be proved. Is this worthy of an MSc? Or do I build it AND have it make a decent model? Time to fire up my handlers!
So at long last, I have done a bit more work!
having looked at the design of the delta system that I had thought of, I realised that it will need two controllers; one for the drive and one for the printhead. Both of these controllers will have to be controlled.
I therefore revisited the gantry based design and suddenly was aware that if I used a single axis bed machine, I could remove the bed and instead use the stepper motors as a drive (the hotend would need a Z axis). All that would be needed is to change the size of the bed in the GCode software (Repetier, Kisslicer etc). This means that although the model would be limited in the Y and Z axes by the machine size, the X axis would be limited only by the quantity of filament carried and the supply of power. So, long, thin models!
My next stumbling block is that of layers. If I have to produce a model one layer at a time, this would mean the machine moving a long way for each layer. This in itself is not a problem apart from the battery life. The main problem is that of the temperature gradient experienced by the part causing warping. This usually occurs in the Z axis as most entry level machines have a relatively small bed size (relative to my proposal) and have compensated this with heated beds and / or high temperature deposition for the first couple of layers. These layers will then be able to accommodate any subsequent expansion / contraction through the model's Z axis. However, my concern is now that the temperature gradient will be found in the X axis rather that the Z, producing long, thin warps along the length of the model.
Therefore I am now looking at whether it is important to redesign models to allow for the material's thermal coefficient by introducing thermal breaks and also whether these can be overcome before a redesign is necessary.
Thursday 7th November 2013
I skipped Uni today and instead visited the 3D Printshow at the Business Design Centre in Islington. What a show! There was a myriad of stands all demonstrating their wares. It primarily focused on 3D printers, 3D scanners, 3D software & filament makers. There were all manner of printers even though my research so far has shown that there are primarily only two types within the entry level FDM sector.
The Delta Tower machine put up a good show and I had a long chat with the man on the stand. He said that. It might be feasible for the company to help out with my project. I will contact them next week! The most help I had was from a company based in China. They supply all the components for manufacturing desktop printers. After an in-depth chat with the technician, it was decided that, yes, it was feasible for my project to work! That was really good news albeit I should contact a robotics specialist.
Another bonus for going was the answer to one of my primary questions : 'Does the build bed have to be perfectly level?' The answer is NO! The Delta Tower machine has a calibration system that determines the angle of the build bed and prints with compensation! Wow!
The filament maker was the only one there at the show. This intrigued me as recyclability is a big issue with the rise of home market printers. The Ethical Filament Foundation had a stand. This showed the start of the use of recycled plastics currently taking place in India. It promoted the sourcing of filament directly from waste picker groups in developing countries. Excellent!
I managed to attend just one seminar. The speaker is Richard Hague, a professor in Innovative Manufacturing from Nottingham University. The subject was 'Exploring the potential of Additive Manufacturing and the move to Multi Functionality'. Great speaker! Lives and breathes the subject. There was a great section on topology optimisation and fluid optimisation. He discussed re-optimised engineering and flow control where using additive manufacturing has the ability to put the path around the flow rather than conventionally putting the flow into the path. Great stuff! I thought I could catch him out with the 'printing in voxels' question but he already had an answer.... We already are! His vision of the future is jetting. He already has a machine with four jet heads capable of spraying four different metals! The heads heat up to 2000 degrees. Apparently, the bonding process is excellent when spraying multi metals. The beauty of this is the fact that the machine is capable of producing objects made from semi-conductor materials. Combine this with Jennifer Lewis batteries (super small - grain of sand sized; can be jetted!) and we are printing electrical systems.
The future looks promising!
Levels of importance for 3d printing
Low - up to £3000
Medium - up to £ 15,000
High - £50,000 upwards
I intend to set my project in the Low level. This is based on the fact that if one throws enough money at something it can always be achieved.
I intend to find out if it it is feasible to add another axis to an entry level 3D printer enabling it to print large objects. This has been done at the high level with a conveyor belt method. It has also been done with a novel printing method with micro - folded parts.
Q: Can a 3d printer become mobile? Look at Foster's vision of building on the moon.
Q: Can the build size become infinite and does it need to?
Q: Why can we not build a model in one go rather than in smaller parts?
Q: Do I need to look at the space program to see if this is needed?
Q: What if the unit uses GPS or Google Earth to determine the datum?Q: In other words, can the machine datum be moved to the build rather than the build envelope?