Adventures in 3d printing Or "I Finally Built a RepRap!"

I've wanted a 3d printer for quite some time. A few years ago I stared building one that, to say the least, was poorly engineered and under constructed. It never actually worked at all. Some of the designs could have worked, especially in a large CNC machine, but were just not a good fit for a small 3d printer. I've been eyeing the RepRap i3 models for a while now, last week I bought a kit (less electronics).

RepRap i3 with cooling fans and filament spool.
Note spool is on backwards to allow for the sloped ceiling in my lab.

Assembly was quite straightforward, there is a partial guide, though it skips (or I missed) some key steps.

A few tips:

• Final alignment of the XZ (vertical) frame should be done after assembly. Just line it up so the extruder will reach the front and back of the Y frame and is square.
• I printed thumbnuts to fine tune the bed leveling, it makes it really easy to get it spot on. I used these "Easy Heated Bed Leveling Thumbnuts"
• The Z axis endstop was a pain, part of it was I used the wrong mount, but I printed this "Adjustable Z-Axis Endstop Arm" to make it easier

Fire in the Hole!

Everything I (and probably everyone else) build has some "teething" issues. I had (and am still having) a few. After I got it set up fairly good I started a print and it seemed to be working nicely, then the Sanguinololou literally caught fire (there were flames). The bug list for the Sanguinololou says the traces for the heated bed are too small, so I had reinforced them with wires before this point, it was the wires that caught fire. Turns out the mosFET shorted and the bed just stayed on continuously drawing ~16A. I salvaged the board and put a new mosFET (all I had on hand was a 12A logic level one) put it back together, set it to pwm at 50% and it lasted about 30 seconds before shorting too (I was watching this time). I swapped it again, added a reverse diode and ran it through an automotive relay (so the mosFET turns the relay on and off). That works really good.

Electronics, complete with rats nest

Now that the fires were out It was time to try some real prints. The filament won't stick to the bed. No matter what I do it won't stick. I tried cleaning really well, nope. gluestick helped, allowed me to print the upgrades I mentioned, but was hit or miss. I researched, tweaked settings, spent the better part of a day on it. Finally my brother was over and (looking on his tablet) said "they say here that Reprapper brand glossy black PLA won't stick to glass, use blue tape". Yep, I had Reprapper brand glossy black PLA filament, and yes, it sticks really well to blue tape.

A Sheep! Here's the first print that I took a picture of.

A few remain

Now I can print, I've still got a few issues left, mostly "dialing in" problems.

• Overhangs and bridging don't work quite right. I've been lowering the extrusion temperature and it really helps. I started at 200C and am down to 180C for the first layer and 175C after that. A box fan after ~5 layers helps even more.
• I printed some large parts and they warped, pulling the blue tape off the glass. The cooling fan bracket printed really nice with the 182C/177C and bed at 35C settings. this might be licked, but can't say yet. 
• The first layer of big parts will bunch up a bit during infill, leaving stuff sticking up that can catch the extruder. If it gets 3 layers or so it will bury the problem and will complete fine. I might still be a touch close on my z-axis start point or it might be something else.

Future plans

• Upgrade to optical endstop for Z-axis. It should be considerably more repeatable than a mechanical endstop, so I think it would be a big improvement. The X and Y axis are not nearly as critical, so I don't see any need to change those endstops.
• Upgrade the electronics so I don't need a computer hooked to it and add cooling fan support. I've got several options: MosFET board and sd adapter, MosFET board and android tablet, Panelolou (includes Mosfets on the interface board and SD on the panel). I'm leaning toward the tablet option. The software looks really cool. I need to try it sometime.

UPDATE: I printed a bracket to mount some 40mm cooling fans, but all my small fans are 50mm, so I printed a 50mm bracket. Seems I chose one bad fan (rattles) so I'll have to replace that at some point. It makes a huge difference. I'll do another post on integrating it with the electronics.

Links

http://www.thingiverse.com/thing:208137 - thumbscrews
http://www.thingiverse.com/thing:267927 - Z-Axis Endstop Arm

Underground Leak Location (Failed, but interesting)

My brother has a water leak in the plastic line between his house and the street. We don't know where the pipe runs and haven't been able to find a wet spot. It's not a huge leak, so he can just shut it off at the meter most of the time.

Cool Little Amplifier

The first problem is locating the pipe, we know where it is on both ends, but there's 400ft and a concrete driveway in between.

Options

• I found ground penetrating radar first, but it would cost way more than just running a new pipe to buy and it's well out of my capabilities to build. Maybe in a few years, but we don't have that kind of time.
• Metal detectors don't work on plastic pipe unless you put something metal in them (steel cable), which requires disconnecting the pipe. If we had a metal detector this would be a reasonable starting point. It's still on the table, but we have other options to try.
• A smaller wire could be pushed down the pipe and connected to a small transmitter. Then a receiver would locate the signal and pinpoint the pipe.
• With a ground microphone and an amplifier it's possible to listen to sounds under ground. A wrench or solenoid can be used to tap on the pipe, which will transfer down the pipe a ways and (hopefully) be audible near the pipes location. The leak may also be audible within a few feet.

Schematic - Pretty much exactly as in the source link

I've build a amplifier based on a circuit for an amplified ear I found on the internet. It seems to work good, but I'm having a real problem with the microphone. It will pick up sounds from all over, but nothing from the ground. I've tried several different ideas to transfer the sound, but so far I've come up dry. I think a piezo buzzer element is the key, and I managed to break the only one I had. I've got several more on the way, but it will be at least Saturday, probably Monday before I have them. We can't start digging before Monday (call-before-you-dig), so I'm hoping for Sat.

Prototype and RevA001 PCB

Results So Far

• It's a really cool little amplifier, Q3 varies the gain of Q1 so that faint noises are highly amplified and loud noises have little amplification. If I can sort out the microphone problem it should work really well. It would also work great as an electronic stethoscope.
• It doesn't seem to work as I intended to use it. I really need the digikey parts before passing judgement, but I think it should have a variable bandpass filter in it to isolate the desired noises. I can hear all kinds of stuff, but not what I'm listening for.
• I ended up connecting a piece of wire to a fish tape, shoving it down the pipe and hooking a arduino clicking a relay that shorts a (low output) battery charger across the wire to transmit a clicking noise. I only had a 50ft tape so I couldn't trace much of the line, but it looks like a bee line. I used 30 turns around a cool-whip container (approx 15cm diameter) connected to the microphone input to listen for the clicks. It (barely) picks up the clicks, but AC lines are VERY obvious (loud buzz). I think I found the pipe and the end of the tape, but gave up as I didn't feel I was accomplishing anything. I could divide the pipe into (up to) 8 pieces and find the leak, but that would mean 8 potential future leak points (and 8+ holes to dig of unknown depth).
• Unless the digikey parts are here tomorrow and I locate and fix the leak (unlikely) we're digging in a new line with a trencher on Monday. It's not looking good. I'm not shelving this project yet though, it would be very useful for locating noises in various equipment and it should work for finding pipes, if I can come up with a working mic. Perhaps I'll modify it for a bandpass filter too. 

Notes

• R1 is specified as 10K, but my mic element specified 2.2K and worked much better with that. For the piezo transducer and the wire coil I disconnected the resistor.
• The audio jack is connected with wires, I didn't have time to make a footprint for the one I had.
• I did the PCB in a hurry, and I really should redo it, I make no promises as to it's performance.

Underside of PCB

Links

Circuit source: http://www.redcircuits.com/Page38.htm
KiCAD Files: https://dl.dropboxusercontent.com/u/4806416/GroundMic.zip