As I said before I've now installed inventor and so ready to start making proper designs. Unfortunately uni work has to come first so that has taken priority. In the mean time I'll write a short post on the the printer that is giving me the most ideas as well as ideas I have conjured up.
The printer I have most respect (and is DIY) is the RepRap MendelMax. One of the features of this model is that it has an aluminium frame. I think this is a great idea as it is strong, light and aesthetically appealing. I've done a very quick look on the net and found a maker in Australia that makes these aluminium profiles (Maytec). These would be great and have the advantage of being able to use the slots in the profiles as guides for the axis as long as they are accurate. Talking of accuracy, two other thoughts came to mind. One was a higher accuracy stepper motor such as this Nema 17 - 58 oz.in, which has twice the accuracy of the stepper on the MendelMax. The second thought was to use a ball screw to position the printer jet as is accurate and could also move faster than traditional threads due to the lower friction. The only problem with this is they seem to only be made of steel and are hence quite heavy. I tried to find one made out of aluminium but couldn't find one.
A further functionality is the addition of perspects or similar to be used as an enclosure as done in the commercial models. This helps with the printing as it keep the model while being built at much more of a constant temperature (assuming there is also a base heater) which allows the product to cool down as a single unit rather than cooling down in phases/layers and thus could cause cracks and deformations.
A final idea for this post which I haven't decided on yet is the possibility to have each stepper motor controlled by its own microcontroller. One of the reasons for this is practicalities due to the cables that come with the motors being short and thus being hard to route all the way back to the master controller for the printer. It would also mean its cheaper to fix/replace due to the individual boards being replaced and not the entire controller. The down side of this is the latency of the master controller deciding what needs to happen but then rather than telling the motor directly it sends the commands to the slave controller, ie it adds another step into the scheme of things. So I haven't decided the best way to do this yet but I'll keep thinking about the pros and cons of each. I'll also have a look at the MendelMax and see how its done for that but I think its controlled directly.
