Major Design Change again...

I've been trying to write this post for the last five days but have been unable to find time due to work and chores round the house. So first things first, I did manage to draw a reasonably accurate illustration of the design. It helped me think of a few things I hadn't thought of yet such as the X slide motor on the I beam would need to be mounted on a plate from the front so it doesn't dragged across the angle material of the Y slide. After this point though I basically abandoned finishing the drawing. This was because I felt the canter-leaver of the X slide would be hard to secure onto the Y slide. This joint is shown with a circle, in the picture below.

To over come this I had a small brainstorming. During this I found there was a new MendelMax (version 2). This gave me some good ideas. I wanted to still use the carriage design as I thought the current design worked quite well (more later on in this post about the carriage), so this would need to be kept in mind.

I then came up with a design fairly similar to the MendelMax version 2 above and mixed with a wharf/cargo crane.

When I first drew this design out I thought it would be great if the whole frame could move above the work as this would save on the footprint of the printer and so save space. (This was sort of one of my aims - to have the printer so it would fit on a desk, with my desk being 600mm deep so hopefully able to fit on that with out encroaching over the edge.) I might have to abandon the frame moving idea but I'm not sure. I can use the aluminium extrusion bars mentioned in relation to the very first design, for tracks for instance but I have not evaluated this yet. The other option is to design it like the MendelMax with the work moving for one of the directions. This might seem like a back flip for my ideas, and in a way it is but all in all, the project is a learning one so its no surprise that I end up with a design similar to others. I could make sure the sliding frame would work if I didn't use aluminium and used steel for example instead but I would prefer it to be light enough to move if needed which steel would parts would not help with.

In this design the slide between the two sides could be the carriage design and the Z slide could be the same again or just use track like the bottom. I had also when first thinking of this design, to not bother with diagonals for the uprights but after looking at the MendelMax2 I thought this would be a better idea.

I then started designing the carriage that I think is a good idea in Inventor. I haven't finished it yet but here are some pictures showing my ideas. I also haven't finalised on dimensions or locations so some parts are out of place. The four wheels that roll along the centre part of the I beam will have holes cut into the rectangular hollow so they have enough room to spin while also allowing the material to protrude in enough that the wheels in the upright position have somewhere to mount on both sides.

The diagrams above also have a very key part missing, that is the mechanism that joins the wheels to the aluminium. I'll attach them as shown in the following image.

This is a change from what I had previously designed. This is due to the previous design only being attached in one place and at 90 degrees so if there managed to be forces in the wrong location is was much more prone to damage.

Recently while trying to think of other uses for the printer I've worked out I could potentially use the printer for CNC drilling which would be great for doing circuit boards. Out of this same idea I thought the extruders could also be used for solder as it runs about the same temperature as PLA.

I've now gone back to having a look at the electronics. I've had a quick look at the stepper motor driver. I've attached some LEDs to each of the leads. This means that if neither LED is on for a coil then its off, same when both are on and if only one of the two for each coil is on then it should be positive or negative 12V. At the moment though it seems to have both on for one coil and both off for the second coil and hence why the motor does not spin. I'll write a test program that turns on each pin separately on the ATMega and see of I can get it to go to each state. If this doesn't work I'll have a look at the wiring and maybe redo it. If this still doesn't work, I managed to solder the SMD stepper controller on Friday with just a normal soldering iron and so can try that out.

With regards to the display, I'm going to try the serial connection which I said before. This looks to be much easier than I2C but does mean I can't use serial for anything else. This isn't such a concern as I can use SPI for connecting the controllers together.

This next week I have more time to work on the project as I'm not at work for two full days so should be able to spend more time on it as it seems like ages since I did anything even though its only been 4 or 5 days.