arduino, robots, cameras, and life

The other day I saw a tweet from sparkle labs saying that they were ‘participating’ in American Express small business saturday. The jist of that event is that Amex will give you a $25 statement credit if you register your card on their sbs site and then use it to buy more than $25 from a small business on November 26th.

I did a little sleuthing and it seems like Sparkfun also qualifies. They show up on the sbs page in a search for Boulder, CO. There is no sure-fire way of knowing if it will work, but all signs point to yes.
If you want to give it a shot, be sure to actually register your card on their site, buy some stuff, and have (spark)fun supporting small businesses!

Please note: This has nothing to do with sparkfun themselves, and I doubt they even know about the programs existence. Don’t bug them with questions. Call up Amex if you want to ask someone. Either way you end up with cool stuff. One way you get a $25 credit for buying it. Oh yeah, it also seems like you can get the credit for every Amex card you have with them that you register(!)

It’s been a busy start to the summer! I was able to go to Maker Faire, and now that I’m back I’ve spent every spare second on my bike or at the new hackerspace in town. One benefit of being a hackerspace member is that I finally have a place to keep my big /noisy / messy projects!

Here’s a pic of where it stands right now. I have everything together, but it’s not wired up yet. I’m also replacing the clonedel parts as fast as I can. They are causing more trouble than they are worth right now.
Here’s a link to solid state depot’s wiki on my prusa.

Here’s a pic of my monster e-stop button. It came out of a printing press. It is wildly overkill, but it looks cool. It is currently wired up to the psu, so if the switch is tripped, it cuts power to the machine. dead stop.

I’ll update more when I do more. I’ve been learning how to use a lathe in order to drill out some hot ends. It’s been exciting so far…

1) Last weekend I completed drilling out my clondel kit and started bolting things together. Here’s a list of things I realized.

2) Having precisely cut threaded rods is nice, but not necessary provided they are longer than spec.

3) Drilling out the metrix createspace clonedel kit is difficult verging on impossible to do exactly. The vertex pieces that require precision don’t have flat, 90 degree sides. Also, some of my pieces varied +- 3mm in thickness. That is a big problem when the piece is 15mm thick, and it’s off in the – direction. I had to do a fair bit of eyeballing on those undersized pieces or else the drill bit would have just ripped through one side. This kit is a lot better than nothing, but the first thing to print is definitely replacement pieces. I also think I have one of their earlier versions judging by the way my z motor brackets look, so potentially they have improved since the first few batches.

4) I scavenged some 8mm rod from two desktop printers. That gave me enough for the z and the y axis. To get the long rods needed for the x axis I think I will probably need 2 more printers to destroy. I’ve been toying with looking into the rods from ikea filing cabinets to see if they are even vaguely straight or consistent. I doubt it.

5) Looking at the printers made me wonder if dc motors could be used with opto-encoders for this project as a replacement for the steppers. I’m not sure what would be the best way to do it, but I’m considering making a “stepper driver board” out of an arduino to see if I can get it to behave as a drop in replacement.

6) It appears like the thin and thick sheet are unnecessary for a prusa. Well that’s nice.

7) I’m looking into using my xylotex 3 axis kit as the stepper interface for this prusa. I think that just means I need to put the mosfets, end stop pins, and thermistor circuits on a shield for my mega and I ought to be good to go.

8) I’ve got 3 nema 23 260 oz/in steppers that would be delightfully overkill for this. I’m wondering if it is worth the trouble of building new brackets for everything. I know that torque does not necessarily equal speed, but I would like to see how fast those would print. I would try the extruder (possibly) and the x and y with those monsters. The z axis doesn’t need that kind of speed.

9) I ended up buying some 8mm linear ball bearings from ebay. 12 for $15 isn’t too bad considering they will last a lot longer than the pla.

10) Using the testing setup of repg from Ben Jackson I have been able to connect to a mega 1280 and a 328. I can’t do much else before it crashes, but at least its a start. Repsnapper seems to work flawlessly with the 1280, untested on the 328.

I can’t believe it took this long, but I finally had a bad filament tangle last week, and a few aborted prints because my old setup wasn’t working. I really needed to get my filament spooled so that it would nicely dispense, and not jam, tangle, or unspool.

I really love the way the official makerbot kit looks, and I bet it really works smoothly. I just don’t have $90 sitting around. I’ve already spent that on ABS, relays, arduinos, and prusa parts!

I went down to the old Home Depot and picked up a cheap ($8) extension cord spool and a few feet of nylon water tubing. My extruder hasn’t had any trouble with its grip, so this creation has the extruder just pull the filament off the spool. I drilled out the handle and carefully spooled the ABS on the spool. THAT took a while, but it’s way better than having to constantly babysit the machine.

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It all came down to this…

When I assembled the extruder (makerbot mk4) the allen wrench that came with the kit never felt right. Regardless I tightened the set screws on the gear until the allen wrench felt like it was about to strip it, and then I went on my merry way. After watching my extruder not work for the last few weeks I finally:
1) rebuilt my hot end
2) put longer leads on the thermistor and nichrome so I could move the extruder board out of the way
3) put a light on my table next to the maker bot, and
4) noticed that the motor shaft was spinning but the gear was not!

So I disassembled the extruder, found the RIGHT sized allen wrench (1.5mm maybe?) tightened everything down, and I was on my way! It’s frustrating that it took so long to figure it out, but I’m so glad that I finally did. I spent the morning printing out an accessible wade’s extruder and playing around in skeinforge.

I wasn’t able to print out the small gear on the wades extruder no matter what I tried. It always ended up getting eaten by blob monsters. I eventually figured out how to use the multiply feature in skeinforge and printed out 9 of them. With no raft to boot! The no raft thing was only cool because I figured out how to do it, but in the end three or four of them broke free and were garbage.

That last pic is what I was really surprised with. I have never printed without a raft before, and I was really happy with how flat and smooth the surface was. One more thing pushing me towards building that heated bed!