Tag: prusa

Doing the RepRap #14: Updates and upgrades

Here’s something that I didn’t think about. I had skipping on extruder as well as Y & X, but hadn’t thought that the pulley grub screw needed a flat surface to press against. Here I was thinking that the heat was melting the inner bore and allowing slippage (which might still be happening) but filing the motor shafts flat hadn’t occurred to me. Lucky me there’s an instructional video on the process, which seems straightforward enough.

→ Filing flat a motor shaft: http://www.youtube.com/watch?v=DBnKPEnt9a4

Regardless, I’m still getting metal pulleys, and having looked at how coarse the T5 belt is and how it’s jumping on my printed pulleys, I’m probably moving to T2.5 belts. Now if I could only find a local source of the stuff which didn’t cost a fortune, I’d be set. On IRC I spoke with some guy in Poland who was buying and shipping the stuff, but couldn’t get a quote from him. And the pulleys had to be hand drilled, which seems a bother if there are pre-drilled ones available. Suggestions are welcome; the ones I’ve found so far seem too expensive for what it is, I mean, how much can diecasting pulleys cost?

Someone is starting to assemble a guide for beginners into the art and magic of building a RepRap, and it’s off to a good start. If you want an overview of the build process, check out reprapbook.appspot.com. I wish that page had been live when I started out, but you know what? Back then we didn’t have fancy e-books but read the wiki and begged in chats, and we would count ourselves lucky!

Doing the RepRap #13 — Printer finished

It’s been a long road, but my Reprap Mendel Prusa 3D printer is finished and I’m printing stuff. There have been so many problems and fuckups along the way, that when I finally started printing stuff a week ago I didn’t think much of it, but with hindsight it was a Grand Moment™. I’ve joined the ranks of 3D printers. You may now commence the “oohing” and “aahing” I understand are my dues.

So far, with the exception of a frog and a replacement LM8UU Y axis holder, I’ve mostly been printing calibration cubes. These are shapes intended to troubleshoot your printer and give you an opportunity to get your Skeinforge/Sfact setting correct. As you can hear in the video there’s some rattling going on on the Z-axis, and I have some trouble with Y-alignment on some prints, but with lowered acceleration on Z and Y, and perhaps tightening of the belt on the latter, I think I’ll be able to print halfway decent parts.

Sara came over for a few days, and as any good boyfriend I set about making her feel comfortable helping out with the build. It was much appreciated as it often seems I have three hands too few to get something assembled. Making the print bed was slow going, and as I’m using plexiglass for print surface we broke off a couple of pieces before getting a more-or-less square one. The plexi is actually good for printing on cold, at least once the PLA starts sticking to it, but if your hotend gets too close the PLA fuses with the surface, and you’ll inadvertently run the head through the board which will create pockmarks in the surface, and possibly plug your nozzle with plexi — which is the reason I’m printing with the 0.5mm nozzle instead of the 0.35 I started with.

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We were leveling the print table for a good two hours, and found that the design with springs between the lower and print bed wasn’t optimal, since the springs were unevenly springy. I had bought a whole kit with the suckers but none seem to fit well enough and give enough force to work. It’s a good design on paper, but we found that it was just easier to use two sets of nuts per fastener bolt. Protip: Get spanners which fit instead of fiddling with adjustable ones or pliers; it’ll save you so much time and temperament it’s worth the expense.

At this moment thanks might be in order. A great amount of those go out to Traumflug for design and massive help with the electronics, and Kliment, Triffid_Hunter, Action68 and everybody else who’s been quick to lend support in #RepRap on IRC or on the reprap.org forums. When you’re as ignorant of a subject as I was about the RepRap, you rely on the help and input of friends and strangers, and without the support of everyone from awesome girlfriend Sara to KKV electro to that guy who barely spoke English but cut me some metal rods, this project might have fallen over and not gotten up after any of innumerable stumbles.

Of course, thanks to the people here in Turku for providing an incentive to start this, as well as the means and time to finish it. Ultimately, bigup to Adrian Bowyer for getting the RepRap project started, as well as all those who keep improving upon it. I have a public presentation of the project on Thursday 6th October at 1800 in Gallery Titanik in Turku, and if you’re nearby I’d love to see you there.

Doing the Reprap #12 — First extrusion

Last Friday, while Pilvari Pirtolas had his opening here at gallery Titanik, I was sitting in an adjacent room and fiddled with my machine. I had managed to get the extruder to heat up and the thermistor to register in Pronterface — a previous day of troubleshooting revealed that I’d connected the hotend to the wrong two pins of the Gen7 board — and now it was heating up with no problem and only a slightly worrying amount of smoke. Once it was mounted on the Accesible Wade’s extruder I was good to go for extrusion test.

I got some visitors from the opening next door, and it was fun to see some people react with curiosity and others with disinterest to the machine. To the uninitiated it looks mostly like a heap of metal and plastic, so the awesome disruptive power isn’t always readily apparent, so I got to practice my pedagogical skills on young and old, tipsy and wasted alike. Once I realized that all motors had the wrong polarity in relation to the Teacup firmware, I pressed “reverse” instead of “extrude” and lo! there was extrusion and much exaltation all around!

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Doing the RepRap #11 – Frame & motors

I got the frame of the Prusa more or less assembled, even though I still need to make sure that it’s straight and so forth. The motors are mounted and connected to the correct rods or belts, and they are stepping at 1/16 nicely, although the LM8UU bearings don’t seem as smooth as I’d like them to be; I will probably re-assemble the Y-carriage whenever I add the hotbed, seeing as that might be cause for some misalignment and grinding.

Robin from the forums popped by the studio and we compared builds and I got some advice which is always welcome; where to source materials, in what order to assemble specific parts, why patience usually pays off better than a flamethrower, etc.

The long M3×60 screws for the adjustable extruder have proved elusive, so I’ve gone for an M3 rod I’ll put wingnuts on. Once you get warmed up and understand how things are supposed to fit together and what functions they perform, you relax enough to improvise. It’s a good feeling. The Makergear hotend shipped with a mounting plate which doesn’t fit my Accessible Wade’s Extruder so I schlepped the studio bike around looking for 4mm plywood to drill a replacement. Once that’s done and the hotend built, I’m pretty close to testing to print.

Perhaps I’ll be able to melt som plastic into a horrible blob in time for tomorrows opening of the new show here at Titanik and impress Sara who’s coming over for a few days. That would be most excellent.

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Doing the RepRap #10

Before you can print from your STL file you need to convert it to gcode. Think of it as Postscript for 3D-printers and 2D routers. The tool of choice for people working with RepRap has been Skeinforge, which has acquired tons of functionality at the expense of usability: It’s ugly as sin and has more features than are properly documented (or documented at all) so I’m happy to see that there are alternative versions cropping up, like SFACT.

Also, putting the printer together I ran into some issues with the otherwise excellent documentation put together by Gary Hodgeson, namely the parts using the LM8UU linear bearings instead of printed bushings. Because I don’t have any spare parts I’m terrified of messing up those I bought from Greg Frost (shipped all the way from Australia) so am anxiously browsing the RepRap wiki and forums in search of instructions. I’ve already managed to put the Y-motor bracket in every position possible, and finally had to email Greg to get a picture of how to do it properly. I’m documenting every step, but so far it’s more of a blooper reel…

I finally found an excellent description of how to fit all the parts together: How to build up a LM8UU Linear Bearing Prusa. It does exactly what it says on the tin, and with the exception that I’m going for a three bearing bottom plate, I ought to be able to finish the build in no time. Now, if I could only settle on which lubricant to use for the rods, I’d be set. “Light machine oil” or “PTFE spray” is the question.

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Update from the comments. In the video below I’ve inserted the pins from the wrong side. The black plastic bits should go on the underside of the Polo, so that it’ll sit flush with the mounts. As it stands, the Polos work for me soldered this way as well, but it’s more finicky and there’s a risk that you’ll have too much solder left and won’t be able to push the pins far enough into the mounts.

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