Trouble in paradise

After last time's success with calibrating, I was hoping to get at least to primitive printing, but no luck. First I had to slice a piece off the plate under the extruder to not have it stuck on the edge of the Z frame. That's bother enough to take on and off. Then I made some little cardboard pieces to hold the roller skater bearing under the Z rod in place, but they still move back and forth. I think the rod is warped.

Most worrisomely, when I tested the Z stage with these new bearing holders, it moved erratically, as if it was skipping half the steps randomly. At first, I though it was a problem with the new holders, but it persisted when I took them out again. And when I tried on the Y stage. And the X stage. And when I unplugged everything but the X stage. And when I swapped out the power supply. And when I tried a different driver, or no driver.

Only when I took off my homemade shield and connected directly with little bits of wire did it work nicely again. While trying to set that slightly differently, I accidentally removed the ground connection, and it did the jerking skipping motion again. Aha! It's caused by not being properly connected to ground. As opposed to the simply switching rapidly back and forth in place, which is caused by wiring Step and Dir wrong. Luckily, FabLab has a set of small but high-quality wires compatible with the Arduino, instead of the random little bits I've been using that keep falling out. So until I get a properly constructed shield from Fritzing, I will have to make do with setting up wires every time I want to use it. So, in the end, I got very little progress today.

Progress in the 3rd dimension!

I have declared March to be "get the RepStrap running in 3D" month. With some help from Buro Detours, I have assembled the third stepper motor driver, and subsequently cut and drilled the pieces for the Z stage. It helps a lot to have a good hacksaw and a drill press, this one has gone a lot faster than the first two.

One difference between the Z stage and X/Y stages is that there is a plate under the rails that anything sticking too far down will hit. I had to change the spring-loaded wheel holders a bit to be as flat as possible, including cutting the bolts down to minimum size.

I should have a flange today or tomorrow so as to mount the whole thing together. The next interesting part is what to put on in order to hold a head, and how to avoid the whole movable part falling out when there is weight on it.

Progress: Stepper driver, X stage, endstops

With some help from a Norwegian friend, I have made significant progress.

I have the rails for the X frame bolted onto the end pieces.
I have the X stage acrylics mounted with nut and sliders (though I need to wrap some teflon around the sliders).
I have tested and fixed a soldering issue on one of the stepper drivers, it now works for all I can tell.
I have gotten an Ethernet cable that can actually communicate with the opto endstops.
I have tested the opto endstops, and found that they work... on and off. And not in the manner I expected.

I still need some way to connect the threaded rod to the motor, I figure duct tape will do for testing purposes. I am also out of solder.

Success!

So I swapped out the power supply I hadn't been able to get to work for one my brother had lying around, and voilá -- success! My car bulb lit up, as did one of my stepper motor driver boards. The other board has a short, it lit up briefly and then went out, after which the 12V line was dead until I unplugged the power supply and plugged it back in. However, the 5V and 3.3V lines were fine and under load from the 10 ohm 7W resistors put in -- which got quite hot in the process, as my fingers can attest to after trying to remove one:)

Pictures of the board with the short:

http://www.flickr.com/photos/51741439@N00/3625937412/
http://www.flickr.com/photos/51741439@N00/3625124543/
http://www.flickr.com/photos/51741439@N00/3625122231/

On the down side, I found that the acrylics should be about 1/4" thick (which is 6mm, mine are 3mm). To not waste the drilling I just did, I'll try to glue two pieces together.