Next-Make 3D Printer

I’ve found out what was wrong with our steppers!

Yesterday, Dan Lorenc from Simmons (who also built a 3D printer) brought over one of his motors (supposedly the same as ours), and – lo and behold – it worked perfectly with our electronics.

So, this whole time, it hasn’t been our electronics causing any problems. It’s been our motors.

This morning I’ve investigated further, and it turns out that either the manufacturer’s datasheet is incorrect, or our lot of steppers happened to have messed up on the wire colors. Once I figure out what the proper wiring should be with a multimeter and some trial and error, we should be home free!

Marcel’s been tidying up the mechanical structure, and it’s looking a lot better – most of the damage from moving the printer around has been fixed, and it’s looking like a RepRap should look.

I got the software running on my laptop – it wasn’t working on Vista (something about Java crap – I have multiple RXTXcomm.jars running around and I’m too lazy to clean all that up), but it works fine from Ubuntu (which I haven’t used too often prior to this, so it’s a fresh start). I’ve been controlling the heater, and it works just fine

So, all in all, I’d say we’re a few days away from a working printer!

Stay tuned,

–Aaron

First off, I’d like to apologize for the lack of pictures and other media – most of my stuff’s in storage so I’ll have to swipe a camera from someone.

I’ve reached a 3D printer milestone – the extruder stepper motor is now working! As I type this, it’s happily humming away its exerciser program.

The extruder stepper is different from the other motors (the extruder motor is a NEMA-17 stepper, whereas the axis motors are NEMA-23), which have been giving us the most grief – they refuse to be driven and instead just vibrate rather than rotate. I suspect that perhaps we got a bad lot of steppers? I’m borrowing a NEMA-23 stepper from a friend to check whether or not it exhibits the same vibrating behavior as our own NEMA-23s.

If we’ve found the source of our problems we could be days away from a working 3D printer!

–Aaron

Hi everyone! So here’s where the situation currently stands with regards to the 3D printer:

At the end of last semester, leading up to finals week, the stepper motors still weren’t rotating properly (which had been the major issue since late March) – they just vibrated angrily. In addition, while testing the extruder, the material holding up the extruder began to creep due to the heat, and the extruder head began to droop – then the epoxy holding the extruder barrel to its mount failed, causing the barrel to fall out. Somehow the thermistor leads shorted out and melted off.

Fast forward to yesterday – Marcel and I took the printer out of Metropolitan Storage, where it was living for the summer. We rolled the RepRap over on a cart, and the printer did not like the vibrations at all; by the time we got to Next the machine was out of square and everything was loose, so we’ve got our work cut out for us.

Yesterday I set up the power supply, Arduino, a stepper board, and a stepper for debugging, but so far haven’t done much work on it beyond setting it up. An interesting thing I noticed, though…the stepper board has 2 bipolar LEDs that rapidly change between red and green when the motor is stepping, and it creates an orange color. Sometimes the LEDs did weird things, like one LED stayed red and the other LED was off. Something’s not right…

On the hardware side, I got a lot of work done on the extruder. The leads going to the heating element had somehow worked themselves loose and were dangerously close to fatiguing off, so I bought some high-temperature epoxy and applied it around the leads for strain relief. Hopefully that fixes that. Also, at the end of last semester, Marcel machined a new barrel mount for the extruder (the part that had been drooping due to heat) out of aluminum. This mount has setscrews to hold the Teflon barrel in place, instead of relying on epoxy. I just hope the aluminum doesn’t steal enough heat away so that the extruder can’t melt the filament…

I still haven’t fixed the thermistor leads (by attaching new wires), but once that’s done the extruder toolhead will be all set and ready to go! Pictures will be up soon, as soon as I take them.

I think I fixed image uploads. Here’s a test:

Cool, guess it works! It turns out that the uploads directory on our server was not writeable by WordPress, so effectively it couldn’t save anything we uploaded. Should work fine now.

Upload lots of pictures you guys!!!!!!!!!!!!

ACTIONABLES:
1. I can’t seem to upload images here – Steve and Joe, could you look into this?
2. WEI AND MARCEL! STOP IGNORING MY EMAILS!!!!!11111shift+one
2.a. The power supply needs to work -> Wei
2.b. I need to know when the thermoplast pincher sleeve is going to get made -> Marcel
3. Test stepper boards -> Aaron
4. Fix stepper connectors -> Paul

I’ve soldered together the stepper boards over the weekend, which must have taken me around 15 hours total – I soldered two boards on Saturday working from 4 pm to 5 am, then Sunday from 1pm to ~6pm. Gaaaah…it was tough because we’re making double layered boards, so I had to be careful about making sure that the traces on the top layer ended up making connections where they were supposed to with the bottom layer. Steve O. is checking the boards now for shorts and other obnoxious things; as I understood, he was up late Sunday night checking the boards (until 8:30ish am).

In short – we’re working damn hard to make sure this thing gets done.

Wei brought in the modified power supply unit last week, but I tested it yesterday and it wasn’t working. No response from Wei, who was in charge of making sure I could plug this thing in and have it work perfectly. I researched the problem, and there were/are 3 issues: 1, a certain cable has to be tied to ground for the PSU to latch in the ON state. This cable was not connected to ground. 2, the 5V sense line was not tied to the 5V line (though the 3.3V sense line was tied to 3.3), which would have prevented the PSU from latching on. 3, and this is my hypothesis, is that the PSU needs a load to latch itself in the ON state. Right now when I plug it in, even after fixing 1 and 2, nothing happens – the fan doesn’t even turn on. After doing some research on the interweb I’ve found that some PSU units use an 80 ohm, 10(!) Watt resistor to give the PSU a load to latch it on. I don’t really like that solution. I’m hoping the reprap will be enough of a load to keep it latched on.

I’ve tested the temperature sensing board and the PWM driver board; both are confirmed working.

I can’t seem to upload images…

Tonight, I plan to test out at least one stepper circuit, and Roberto will be finishing up the thermoplast extruder (ohh yeaaaah).

–Aaron

I’ve installed the GUI software on our next-make computer. Java3D is giving me some strange errors, but I don’t think that they will affect the actual printing (we just may not be able to see the STL on the screen in 3D before we print it). To use the software, log into the computer (email me for the username/password), and double click the large, obvious “3D Printer” icon on the Desktop. The machine is running Ubuntu.

Cheers!

So I realized today that the stepper motor for the thermoplast extruder is too big. The new extruder design calls for a NEMA-17 sized stepper, but I just assumed it was the same as the NEMA-26(?) motor that the other axes use. Argh, I wasted 25 dollars on it and I had to absorb the cost on a new NEMA-17 stepper for fifteen dollars.

I also had to purchase a ball bearing from McMaster-Carr for the extruder, since I wasn’t able to scrounge one up and the deadline is looming…

On the brighter side, Wei finished the power supply modifications, which is awesome.

We’re getting awfully close to CPW…

Here’s where the project modules stand thus far:
Cartesian Robot: Almost done. We just need to put on a few more cross braces and attach the belts.

Thermoplast extruder: We can’t find furnace cement. We’ll have to order it online, I guess.
Control Software: No idea.
Electronics: We’re hustling to finish up the boards. It’s been tough since everyone’s busy…

Hey everyone, we’ve got three week’s worth of 3D printer goodness coming up with lots of media and stuff. Stay tuned!

This blog now has MIT certificate authentication, meaning that if you register, you can log in with nothing more than your MIT certificate – no user names or passwords to remember! So, if you would like the ability to post to this blog, let either Joe or I (Steve) know, by emailing us or next-make-web@mit.edu so that way we can add you to the list of allowed people.

Cheers, and happy building!