Well, we're still working on finishing up the bits and pieces of the Mendel. Mainly, we need to get the PCBs done for the stepper controllers. My partner in crime ordered some stepper motors and those should be coming in today or tomorrow, and we'll be using those with the stepper controllers to get this thing running.
In my previous post I was talking about the Stepper Driver 3.0 that we were going to be building. Well, I got a short email dialogue with Zach Hoeken and he informed me that the modifications that Nophead suggested were made on the newer revision of the board, which he directed me to. (the XLS file is out of date, schematics are up to date)
So, the only problem is that I ordered all 1206 parts, when the new revision changes up a lot of components for 0805 parts (SMT part sizes). This causes an issue cause the parts I ordered are too large now to fit on the revised board's pads. So, I need to order all new parts, which I did yesterday. Hopefully the LEDs will be nice.. I got a good variety.. Deep Red, True Green, and Hyper Blue. RGB are my favorite colors to have on things.
We got the PCB boards and developer in, and we're going to make some Cupric Chloride to etch the boards. It's much safer than the Ferric Chloride, and better for the environment too. I spent last night working a little in Eagle. The light version won't let you panelize the board because it's too big, so I exported each side of the board as a PDF and then imported it into Inkscape. From there, I created an outline the same size as our board to help me in positioning the sides, then used align tools to create top/bottom layers. Now I can mirror the top layer and print them onto transparencies. We're building a UV light source with a lot of LEDs to see if that will expose better than fluorescent lights. It seems to be pretty sensitive, the package says to expose for 60-90 seconds under "exposure unit" which we're assuming is a UV source. or 6-10 minutes under a normal fluorescent lamp.
I got around to redoing the H bridges on the extruder controller, because I had hooked it up backwards to 12v at one point and blew the H bridges. So now I have a new set of H bridges on the board, so we should be good to go. However, I'm still going to be using the Stepper Driver 3.2 on the board. I may use the 3.2 boards I'm making for the X and Y axises, and the normal ones for the Z and extruder, as they require less precision. The 3.2 boards are tunable via 4 potentiometers and also have selectable microstepping. That will be an interesting feature to experiment with.
I'll try to get some photos or video of the etching process, as I think it would be a cool thing to watch!