Just Another RepRap

So close!!! So close, and yet, so far. I keep thinking “wow, am I actually almost done?” then I remember a whole host of things I need to do.

…but I am damned close..

So first off, right last week’s post I determined the cause of my recent motherboard problems – the cheap ATX power supply I’d bought from MakerBot in late October had died after 3 uses. I grabbed one out of an old PC, and everything was working again. I quickly recorded these three short youtube videos demonstrating at least some limited X, Y, and Z axis motion:

X-axis motion!

Y-axis motion!

Sickly almost Z-axis motion

While that was fun to do, and showed me that at least the hardware could move (and that I still have a problem with the Z-axis), that wasn’t the ultimate test of the electronics, because I’d only started doing the electronics modifications required for all of the circuit boards, and they’d have to be retested later. So, I dug into that task, and proceeded to make all of the circuit modifications necessary to all of the boards.

If you do something enough times, eventually you get good at it.

What a strange new skill I’ve aquired – removing RJ45 connectors from circuit boards. I’ll never use that skill again, but I’ve become pretty good at it.

Again, I’ve found it helps to pull the still-soldered-in wires to the front of the plastic RJ45 enclosure (out of their slots), use pliers to break off the black plastic tabs holding it to the circuitboard, grab the RJ45 connector with the pliers and then bend up 45 degrees off the board (on the wires), then down, left/right, etc, then you can get it off first – and desolder the pins later.

Far tougher was the molex power connectors.. The whole bit in the instructions about melting one bit of solder, prying that part of the connector up a bit, letting the solder harden, then moving to the other side really did work.

Here are the three stepper driver boards, with everything removed.. (the one on the left already has its new 3-pin header for the opto-endstop connection, which I used for last week’s post).

So it turns out the 2-way screw connector I obtained for power for the stepper driver boards had 4 pins instead of 2. There’s no harm in that, it just means I have extra (live) pins hanging in front of the board. I decided not to order new ones and wait, but rather press on with these.

In my eagerness to solder something on, despite careful attention to other details, I can’t believe I actually soldered on this screw terminal backwards:

That meant that now once again I had to use that same melt-one-bit-of-solder-then-pry-that-side-up-and-let-the-solder-cool-to-add-tension-then-move-to-the-other-side trick that I’d just learned on something that I just soldered onto the board. Here is the fixed board with the screw terminals facing the right way (the blue silly-putty looking stuff behind it is called Blu-Tack, a silly-putty-like reusable “adhesive” that I’d never heard of before the RepRap project, which I found myself using to hold circuit parts in place before soldering them, which mostly worked well except the putty would get hot).

Here’s the final state of the modified stepper controller board. In the 3rd picture you can see the two live pins hanging over the end of the board, which I’m not too worried about.

The screw terminal I bought for power for the extruder controller board had 2 little plastic pegs on it that also were going to get into my way. I cut those off.

Here’s my modified extruder controller board. On this one basically I replaced the RJ45 jack with a screw terminal and a 2-pin header:

One of the toughest things for me to get off was the ATX power connector on the motherboard. I’d read that I needed to use forceps to reach in and pull out pins as I melted the solder on the other side of the board. The closest I could find to forceps one night while driving home was two different tiny tweezers. Neither could reach the pins well. Then I realized that I didn’t care about the ATX connector at all, so why not just butcher it with my dremel, cutting around the entire side all around, so I could expose the pins more. That worked out well.

Here was the resulting butchered plastic after I successfully removed all of the pins:

With all of the circuit board modifications complete, I mounted them all onto the two pieces of MDF that would hold them.

The bottom MDF also holds the power and USB connectors. I mounted those next.

I then mounted those boards onto the Mendel.

Unfortunately, I’ve now come to realize that it seems that two of my three stepper driver boards aren’t functioning properly. The three videos at the beginning of this post were all done with one stepper driver board being connected to one stepper motor after another. The other two boards won’t cause any motion in a stepper motor at all. Their green power LEDs come on, but that’s it.

That’s left me in a state of debugging. Here are some messy pictures, with wires everywhere, of what my Mendel currently looks like, with the boards mounted and cables running everywhere.

And on THAT note, I’m done with this post, and aside from any remaining RepRap work I may get done today, I’m probably done with progress for the next 16 days or so, as I’ll be otherwise occupied. So close! Certainly way closer than I thought I was a while back. Which statistically probably means I’m not as close as I think this time either. 😀 Either way, this is a fun ride!

This entry was posted on Sunday, May 2nd, 2010 at 1:55 pm and is filed under MyRepRap. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.