Friday, April 29, 2016

Adventures in 3D printing, and the end of the semester.

3D printing

As I mentioned in my last post, I ordered a 3D printer off Monoprice's Ebay page. They had a very nice deal: a prusa i3 clone for only $309, or, shipped and taxed and everything, 478 canadian pesos.

The printer. Monoprice Maker Select, or Wanhao duplicator i3, or Prusa i3 or...
This printer has more clones than Jango Fett! That is, surprisingly, a good thing. The development of this printer came out of the reprap community, and started in 2012, 3 years after I saw the very first mendel, and tought that 3D printing was super cool awesome, but would never be economical due to the price of non-printable parts, like motors and electronics. Welp...thanks china! We now have decent (ish) printers for $300 (on sale, but still)

When it came, I was expecting it to be essentially non-working...or to print like this:

Surprisingly, that's not what happened! Let's start by the beginning though, the opening. Here's the box. Beer for scale (because I didn't have a banana)

The manual, which is pretty much useless when you've been gorging on websites, blogs, subreddits, youtube videos, google groups, etc.

The power supply electronics box. Everything beside the 4 stepper motors, the limit switches, and the heated bed is in there. That's where most of the pixies are dancing. There's a micro-sd (WHY?) slot on the side, along with a micro USB (Which you can't even USE unless you go inside and remove a jumper. What the hell?) There's also a switch-you-must-never-touch to switch the power supply between 110 and 220 volt modes.

The heated bed and the y-axis. Everything is pre-wired....which is both good and bad. Good because wiring in general is a pain, bad because it makes it really hard to get out of the box by yourself. The butterfly on the bed is essentially their QA check I guess. Making the printer run before shipping it, and showing the customer that it did least before being shipped.

But I DID manage to get it out! Ignore the harry potter on the wall, that has been there for way too long, and i'm not supposed to stay much longer, so removing it is way too much effort for what it's worth.

Aaaaand assembled. That was actually really easy!

Then, the other box.

Electronic box cable, a USB cable, micro-sd card, a free complementary scrapper, spool holder, and allen keys. Metric allen keys. At this point I should mention this: EVERYTHING on the printer is metric. Most 3D printers are metric actually. I think it's a good thing, and might actually help americans switch slowly to metric. (Unless they're all using stratasys printers, then we're screwed)

While i'm here, I want to point out some weird design choices. Like, why is this belt pulley fixed only on one end? and with a BOLT? I mean, bolted connections aren't known (or used, EVER) for their strength in flexion. And why did they use a flat cap? had they used a socket cap I could've put a zip tie or something to help, and make the bolt (and zip-tie) force in shear...but nope, stuck with that. I'll need to go buy an M4...or 5, can't really know without taking it off, socket cap screw and zip-tie it.

 Enough whining, I only paid 478$ for it anyways, time for printing!

It works!

 It...oh, wait, it separated from the bed and got stuck to the nozzle...ooh.

I did manage to get something printed though (from the sd card) It's about high! I have a chair! a 3d printed chair for ants!

I don't want to print via SD card forever though. What happens if you try to print from the USB port is...the printer resets. You have to go in, open the electronics board, and remove a jumper. The one nicely labelled "Auto-reset" right above Arden of the Ardentissimo. Another bad point here, EVERYTHING is hot glued. I understand that for transport these days, with courrier services pretty much playing soccer/football/football with parcels, you want to connect things in a way that won't come undone. but i'm disapointed nonetheless. It's a bit overkill...and I will hate it if that board dies. Or if the power supply dies, as chinese ones often do.

Now that I can print from USB, the calibration can commence! I had a hard time to even print since that chair. Nothing would stick to the bed, and leveling didn't help. At that point, I found out my aluminium build plate gets a "nice" dome shape whenever it's heated. Thanks, thermal expansion! (not the minecraft mod) So until I get a glass plate, I can only print in the very center of the bed. Oh well, that will do for a few days. Then, things STILL wouldn't stick. So, I thought the raft looked pretty anemic. At that point, I thought I might not be extruding enough plastic. On to E Step calibration!

A nice calibration guide, for any printer, is this one here: Calibration guide

E-step calibration is pretty much the act of telling your printer's firmware how much steps/mm of filament it takes. For my printer, the default value was 96. What you do to calibrate it is to make a mark on your filament, 110 mm from the top of the extruder, then tell the printer, through a program that can send gcode like pronterface, to extrude exactly 100mm of plastic. the ratio of 100mm over what actually came out is the value by which you should multipliate your estep.

And that worked! got a 3D benchy to print. It's measurements are...okay. 32.1 wide, 59.85 long, and 49 high, instead of 32, 60, and 48. The 49 is what annoys me the most, the others are...pretty much spot on (for an out of the box printer) 150 off microns isn't bad when you think the best FDM printers claim 50 microns.

 Then I printed one of MAKE's 3d printer shoot out test models, the dimmensional accuracy one to be exact. My x and y are pretty spot on. You see a the top a small problem though! That is due to 2 things: poor cooling, and me not putting back the extruder setting to 200 degrees after messing around with it, before calibrating my e-steps. So the PLA might have been extruding at 225 degrees.

Because of those cooling problems, (which you can also see in the door's overhang on the benchy) I decided to print a cooler! the diii cooler. I'm doing longer and longer prints! That one took 7 hours.

Printing the diii cooler was a mistake though. I should've printed the cobra... the diii cooler has REALLY low visibility at the beginning of a print, and strings like to stick to it. oh well, I wasted what? 28 grams of plastic out of a kg spool. not too bad.

My next print took WAY longer. The diii cooler needed an adapter to use the stock 30mm fan, and, well, I wanted to get on reddit's 3d printer bandwagon and print The Pink Panther Woman. I won't share a picture, because it's not safe for work I guess.

The next print, which was going to be going for 23 hours, screwed up like this:
 I have no idea what happened. I stopped it and spent a few hours leveling the bed again. But then I noticed I could never get it level! I always had 1 corner that would be way too low, or way too high, and whenever I fixed it, the other corners would screw up. and another would become too high...the cause? my y axis slide-shafts aren't co-planar. Something to fix in the future. For now, I can print well on 3/4th of my bed. I'll finish printing a few mods, and then get down under the printer and fix it.

I've also started 3D printing rocket parts!

And obviously, parts for the printer itself!

I still have a few upgrades i'm planning on doing: Making an enclosure to print ABS, and switching the hot end for a micro-swiss all metal one. Also changing the print cooling fan since the first one crapped the bed. I'm also having a few under-extrusion trouble since a print failed catastrophically (but I don't have pictures, I was more panicking on cleaning the printer and making sure nothing exploded). While frenetically tring to fix it, I noticed the extruder stepper were getting a bit hotter than I like. I'll check the voltage reference, as a common problem on this printer is that it's set too high for the stepper, causing overheating and skipped steps.

End of the semester

I'm actually taking a break from studying for my last exam EVER (well, beside the order's ethics exam in 3 years or so). I still have one semester to go in my bachelor, but the 2 subjects I have left are my capstone design class, and a fluid lab both of which are reports-based. I've also found an internship for this summer, which is required in my program. I was getting worried I would be only missing that to graduate.

So i'm pretty much guaranteed to graduate for christmas! yay!

Monday, April 4, 2016

3D printing, molding and casting!

A few weeks ago (as of posting this, not writting) I received an e-mail from my student project director saying the Department of Electrical and Computer Engineering were planning on buying a few 3D printers, and wanted our opinion on the matter. They had received many sponsorship request to buy 3D printers, and, due to the demand, wanted to make one/some available to the whole Science and Engineering Faculty. They also had made a pre-selection of printers: The Form 2, which would be primarily used for research purposes, and a Stratasys uPrint SE.

The Forms 2 is a GREAT idea! it's not too expensive for research, it's high quality, and it's..."fairly" simple to use.

The uPrint came out in 2010. Just to compare; you know what else came out in 2010? The first Ultimaker. Oh, and the very FIRST Makerbot came out in 2009. Thingiverse started in 2008. Heck, the reprap project started in 2005! The uPrint SE is closer in time to the creation of the RepRap project than today! It's minimum layer height is 0.254 mm (oh, look at that, 10 thou, not even metric), a far cry of today's 0.1 and 0.2mm, (or even 0.02 if you actually believe ultimaker's specs) Not only that, but it costs 17 000$ canadian pesos. Well, ok, 12 000 for the printer, some for the wavewash...thing, and some for taxes, duties, formation, and so on. Still, for a printer not really better than the Printrbot simple, it's quite appalling.

So, I've tried to steer the department away from that printer, towards cheaper alternatives; Rostock max v2, Ultimaker, Makerbot, Printrbot simple, Lulzbot Taz5, Markforged, etc. For that 17 000$, you could almost buy all of them! It would serve the community better, and allow for unhindered growth instead of being stuck with 1 big and expensive printer for a while, until the next grant comes in...maybe. The main problem being that you also have to include time for set-up, calibration, and maintenance. On that point, the uPrint should be more more or less "Set and forget" While, for some other printers, the process can be...a lot more complicated. Finding the right tool-chain: Cura by itself? Cura + Pronterface? Slic3r? and so on. Then finding the right settings for every printers, then printing, maybe, and finally, well, maintenance is another thing you have to consider when you have to pay technicians to maintain these things.

All right, enough text, let's go to more interesting stuff! return season has passed, and I have some money to do stuff...humm, what can I do...humm, looking at all these 3d printers for actual research makes me mighty tempted. Uh? Monoprice has a printer? Uh? the old version is on sale and has better steppers than the new one? Oh? it's based on one of the newer reprap (The last I had heard of reprap before that, the Mendel just came out...2009) What's that? only $300?...welp, looks like I now have a 3d printer! (which, after a few mods, will still be better than that uPrint SE...) Delivery is expected this week! I already got the plasteeq too!

The next post will be an adventure in 3d printer calibration.

Mold Making and casting
Since I didn't buy the HTC Vive (because I think it would be worth 1000$, not the 1400 canadian pesos they're asking for right now) I finally bought all the smooth-on products required to do a mold of that part on dark repulsor that makes the whole build so hard.

ALL the smooth-on products, +Punished Props  would be proud

I've been watching Bill's (+Punished Props ) videos forever now. So I used what I learned to do a one part mold. Measuring cups are so usefull! And since they're flexible, if you mix your stuff well, you can just pull it off once it's cured.

I ran into a small problem casting the mold. I used contact cement to hold down my master on the floor. Thing is, contact cement is somewhat flexible...and the silicone got under the master and lift it up. I'll have to sand the bottom of both my finished pieces. Oh well, now I know not to use contact cement to glue down a master, and to be careful so the bottom of the master is somewhat water-tight.

Guesstimating the correct quantity of...well, everything, is so hard! I made double the urethane I needed. Oops =( Should've filled the mold with water first to see how much i'd need.

In any case! I got 2 pieces I can use out of it! I've wasted some material, and i'll have to do some sanding so the pieces sit flat, but for a first time, i'd say it's pretty good. I've failed at some thing, but then, success is built upon failure! As long as you learn from those failure!

I know I'm getting late on the Robot Combat rule translation. The construction specs are taking a longer time than planned to translate as they are way more technical than everything else. I've also missed a nice opportunity with the Montreal's Festival de Robotique being the past weekend. Oh well, it's coming soon (tm)