Wednesday, September 29, 2010

RepRap: close to a full bed of parts...

Now that my quality is up and I have my spool working properly I wanted to try a full bed of parts. Here are 20 bar clamp parts needed for a Mendel. These parts took 7 hours to print.

Sunday, September 12, 2010

RepRap: Mendel calibration through gears...

The best way I've found to calibrate a RepRap printer is by printing gears. Any flaws show up immediately. Also, if one of your gears break after several prints some of your bad calibration prints could work enough to print a better gear. This weekend I was able to print all the Mendel gears, as well as all the Wade extruder gears. Pictures follow.

I am satisfied with the quality. Now I am ready to print a full bed of parts.

RepRap: Spool Extensions...

The spool I printed up a few days ago works, but has occasionally jammed as a result of the filament coming off of the ends of the spool. To fix the problem I designed some extension tabs in OpenSCad

printed, and installed.

I think this will be a solid solution. Now I just need to upload it to Thingiverse so others can benefit from it as well.


Thursday, September 9, 2010

RepRap: Walk Away Mendel...

Now that my extruder is consistent I decided to focus on a filament spool for the Mendel. Thankfully, thingiverse users already designed a mendel spool, so I just had to print it.

This is the biggest part I've printed yet. It took most of my Mendel bed.

Here it is installed.

With a consistent extruder and a filament spool I really want to try a time intensive, full bed, print. First, I need to play with Skienforge a bit more to increase the quality of my print.

Tuesday, September 7, 2010

RepRap: Tiny Open Violin...

A friend has been asking for me to print the open violin ever since the xkcd comic. I've been holding off for a better print than my Darwin is capable of. Now that my Mendel is working decently, and after getting some brown PLA in the mail from ultimachine for free with a large order, it was time to fill the request.

First, I printed the original violin, but I don't think my friend realized how small the original one was!

So I blew it up to a size you can't easily lose and printed again.

Opensource hardware is just fun!

RepRap: RepRap host, or Skeinforge...

With my Darwin RepStrap printer I first attempted to use the RepRap host to generate my GCode before deciding to go with Skeinforge. With my new Mendel I took the same path. First, before pulling out Skeinforge, I spent a few days playing around with the RepRap host. First, I have to say that I was impressed with all of the improvements. The prints are quiet, and really pleasant to listen to. The default settings also use some interesting concepts, like homing the axes before each layer, and building up a wall to catch the first bit of filament before starting the next layer. It's also really easy to lay out multiple parts and position them before generating the GCode. You can even easily rotate parts, which is a very nice feature! However, the quality of the generated GCode is still not comparable to Skienforge.

Here are some pictures of a Mendel bar clamp, first printed using the RepRap host, and then using skeinforge.

Here are the parts side by side. The one on the right is using Skeinforge.

I still don't have my settings perfect, but Skeinforge is where I will be spending my time.

Monday, September 6, 2010

RepRap: Mendel extruder, take 3...

After my second extruder broke an idea came to me that I think is pretty original. I don't think I've seen an extruder designed like this before. I took some 1 inch diameter PTFE rod I ordered a while back and some aluminum square and made the following parts. If this design is able to hold together over time I will post it to the reprap wiki.

The benefit this design has over the last one I tried is that in order for the hot end to push out it would have to pull the two steel rods through the PTFE. I don't think this will happen. A benefit of this design over my first design is that the only part that comes into contact with the PLA drive mechanism is PTFE. Because of this I don't think it will melt out.

The first print worked beautifully, but then it failed because of the firmware! I had to completely disassemble the extruder to remove the clog due to the PID algorithm in the firmware allowing the hot end to spike over 300 degrees Celsius. It's suppose to keep it regulated at 190 Celsius.

This design is not easy to take apart, but I don't know one that is. I'm now under the impression that some of my other designs could have been fine, but that it was the firmware that allowed the extruder designs to get too hot.

Sunday, September 5, 2010

RepRap: Extruders are really hot...

I had some backup materials laying around from my original darwin extruder. To save me some time I decided to just use these, even though I knew the primary weakness.

I glued the PTFE into the drive mechanism like Adrian describes here.

I crimped and shrinked on the nichrome wire.

I also turned down the end so that it flattens the filament better.

I soldered up the thermistor and taped it all together.

I also used some ceramic tape for insulation.

It worked beautifully on the first print. However, as it cooled down the pressure stripped the PTFE, pushing the hot end slightly closer to the bed. On the second print the hot end dug into the bed and destroyed itself.

I am still learning that patience is a virtue.

RepRap: Extruders are hot...

I finally released my video on the making of my Mendel a few weeks ago. It's very exciting to finally be done. It's not very exciting to have my extruder break only days after getting it working. The extruder I went with was a variation on Ardian's hot tip.

It worked perfectly for a few prints, at which point the wood transfered enough heat to the bolts that the nuts melted through the PLA and the whole hot end fell off.

I think I will revisit this design at some point. I think where I went wrong was the length of the bolts. If the PTFE thermal barrier was a bit longer, allowing the bolts to be longer, I don't think they would have transferred enough heat to melt out. For now, I'm just going to use what I have and see if I can rig something functional up.