"Hains" Prusa Mendel RepRap: Finished!

Houston, we have plastic.

Last night was the night for finishing up the wiring and plugging it all in. With a small complication in late hour, and a fairly major soldering crime that followed, I was final able to put the finishing touches on the machine and turn it on. It is now finished.

In the video you will see me pitch the segment to the main camera twice, then, panic as the extruder starts smoking, consult the community chat room who say that's normal the first time, then finally get some gooey mess to come out of the extruder, which they say is also normal for a first time extrusion. Then I finally toast the occasion with a sip of single malt scotch.

Success!


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"Hains" Prusa Mendel RepRap Update: Final Stages

Build Tasks

1. build frame
2. add y axis
3. build x axis
4. add x axis w/ z axis
5. add top print plate
6. build extruder
7. make hot end
1. make heat core
2. make thermistor
3. assemble hot end
8. connect electronics
9. install software
10. test reprap
11. calibrate reprap
12. PRINT!

The hard parts are all done! The machine is essentially built. Not only that, but even though I haven't officially completed steps 9 and 10, I have skipped ahead a bit so I could figure out what I'm doing. I filmed the moment when I first got the motors to turn, which you can see on YouTube.

I got the netbook computer running. I'm using it right now to write this post. That was a major point of anxiety for me because I wasn't sure I could resurrect it and it's going to be the main interface for this machine until I get the SD card thing working. I'm relearning Linux and learning the new Ubuntu OS for the first time.

With the netbook working (which has a web cam built in) I've started live streaming the build. You can check out my UStream channel to see recordings of live parts of the build, and even maybe catch me live while I finish the build and start printing. I'm broadcasting all of the rest of the build and will keep it going while I print for a little while.

The software has also been sorted. Up until a few days ago I was still more or less in the dark about the software process, and frankly, it was the part I was most worried about. I hadn't seen much in the way of tutorial or video about the software, not even so much as someone to outline the process from electronic 3D model to printed plastic.

Here's what I wish I had known from the start, so I could be more confident about completing this project.

From Electronic File to Plastic: A Software Overview

Before you make your first print you need to first load the firmware onto the RepRap's motherboard. The application for that is Arduino IDE. It can be obtained through the Arduino web site.

There are three steps to making a plastic print on a RepRap.

1. Create a 3D model. Produce an .stl file.
2. Skein the .stl file. Produce a .gcode file.
3. Load the .gcode file into the print host application and print.

Create a 3D Model

I recommend Google Sketchup. There are a series of helpful tutorials by Google that will help you get started. You'll need a plugin for Sketchup to export an .stl file.

Skein the .stl File

The model needs to be sliced into layers, and for each layer a tool path, the plot the extrusion head will follow, needs to be generated. This is called the skein. Skienforge is the program to use for this step. This application is also where you set up all the calibration information for the printer. Skeinforge can be picky about the .stl file, so you might need to run it through an automated repair service at netfabb.com.

Load the .gcode File Into Print Host

The application that actually talks to the electronics on the RepRap is called a print host. Use the application called Pronterface. With pronterface (usually not capitalized) you can manually control the printer too. So with pronterface connected you can move the print head around, which helps with configuration and testing. When you're ready to print, load the .gcode file and hit the print button.

All of this software is free. All of it is available for Windows, Mac. Only Google Sketchup is not available on Linux. I will be creating videos and screencasts of each step, as well as a summary overview, to make things easy for you. Stay tuned.

RepRap Milestone - Fame and XYZ

The "Hains" Prusa Mendel RepRap in progress.

Updates on this project have slowed, but it's been in favor of getting work done. But the project reached a significant milestone yesterday that deserved an update. The frame, X, Y, and Z axis and print platform are complete. This constitutes the main body of the machine and most of its mechanical parts. All that's left is to build and mount the extruder, then the electronics.

While I will go back and continue to blog the build process, step-by-step, I want to take this opportunity to give you a few highlights and insights from the work so far. The project has not been without challenges and opportunities for discovery. Filming has added an extra dimension, and I've realized that I tend to drift off in the middle of a sentence while I'm working, so I need to speak THEN do.

The quality of the printed parts matters a great deal, more than I would have thought. Last week I broke a coupler, the part that connects the 5mm motor shafts with the drive bars for the Z axis.

One coupler was well made, the other one wasn't. It's 5/16" end was too big, which made it necessary to route out material between the clamps, and by the time I got it to grip on the drive shaft it flexed too far for the plastic to take. 

I tried a few ideas for building new, DIY couplers. The IRC #reprap channel gave me the idea for the rubber tubing version. I made a couple wooden variations of couplers that are commercially available.

I couldn't machine the wood so that the drive shaft would align with the motor well enough to use, so I wound up going with the tubing.

Besides that, it was a big challenge to get the Y axis smooth rod to line up. That one almost broke me. I think that one was related to the quality of the parts as well, since it seems the variation in the width of the bar clamps affected the measurements for getting the bars parallel. In fact, the hardest parts of this build have been the parts that need a lot of fine adjustment, like the parallel Y axis smooth rod, the parallel Z axis smooth rod, and the level print platform. I was surprised by how much attention these processes would need and failed to appreciate how minute changes can dramatically affect the performance of the machine.

Fasteners have been a problem. It could be the parts list, my ability to shop, or the sales person at Fastenal not being able to understand me, but the parts I got were not universally the parts I needed. It will be fairly important to detail exactly what I got and what I should have bought in this blog, because I have had to cut some screws, use the wrong size screws, and otherwise make do in not just a few cases. Some parts remain completely unused.

But regardless, I've made it through and now I'm on the back nine and feeling good. The next steps are to build the mechanical part of the extruder, then the hot end, and then finally the electronics. Those few steps accomplished it will just be a matter of getting computers to talk to the machine to turn plastic filament into stuff.

Today I film the build of the extruder (the test run pictured above,) and I'll start the hot end. Since I've already given it a try to work out its issues, today's event should go off without a hitch. Tomorrow I'll try to finish the hot end and maybe start to set up the test of the electronics. If I get a test by tomorrow night (not likely) then next Wednesday I'll try to mount the electronics and start to dial it in. If that goes perfectly then I'll maybe try printing something next Thursday. If that happens I'll put up a UStream live video stream of the maiden voyage/calibration print. That's the soonest I could print something. I'll be going to GenCon the first week of August, so that's going to knock a week and a half long hole in my calendar and printing will most likely start the weekend of the 12th of August or the weekend after that. At least I have a decent estimate now, though. 

RepRap: Frame Complication

{Before and after photos above.}

In the process of building the Y axis for the Prusa Mendel I discovered a problem with how I built the frame. The visual instructions I am following directed me to put three washers and a nut in between the Y motor bracket and the front pulley. This, though, made it necessary to position the pulley gear on the Y motor out  about four millimeters past the end of the shaft. It's not the end of the world, but I was afraid the strain of uneven support on the gear might cause it to break eventually.

On the wiki for the construction of the Prusa this step had a big red note attached. It mentioned this problem and suggested that if the motor shaft is too short to accomodate the spacing washers they could be left out, along with the nut, as well. The two versions are illustrated here.

The shaft, as I said, was about 4mm shallow of flush with the end of the gear. Two washers were just over 3mm, and I had maybe another 1mm wiggle room in how close to the Y motor bracket I could shift inwards. Too close, though, and the extension of the 10mm long screw out of the gear would impact the Y motor bracket. Instead of taking the whole machine apart to remove two washers I removed the motor, got the Y motor bracket out of the way, and used a cutting tool on the Dremel to cut off the washers, carefully.

Quick and Dirty 2x4 Project for My Mom

Away from home visiting my mom and she needed an adjustment to her chair to make it higher. She's fresh out of surgery and until her leg heals she's going to have a hard time getting in and out of normal chairs. So, a quick trip down to Lowe's and a few minutes of fiddling and presto, her chair is a little better than five inches taller.





Not a lot to say about this except that the iPad and iPhone came in handy, as always. Used the iPhone to take pictures of my measurements as visual notes. Transferred the photos over to the iPad via "Camera for iPad" app. Drew up a quick plan in Adobe Ideas on the iPad to work out the measurements and get a count on the hardware. The plan came in handy at Lowe's when I had them cut most of the pieces to spec for me. I love that they cut stuff for me. The idea I had about using the tie-down tape worked out neatly, which made me happy. The only thing I wish I'd done differently is pack a hack saw or a Dremel to take care the long nails I used when at the last minute I added a support sticking out the back of the frame when I started thinking the higher center of gravity might be dangerous if she reclined.









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