I want to keep track of some of the modifications that I do to my Printrbot LC since others might find them useful. Also it will be interesting to see how what I do changes over time.
1:
The first modification that I did was to place little pieces of silicone fuel line as washers under the printbed to allow it to be leveled. This tubing is the type used for R/C models to connect the fuel tank to the engine (which I had laying around). The tubing can squish down a bit so you can vary the height of each corner of the platform. This seems to work OK, however I still cannot get the bed perfectly level.
2:
I noticed that the heated printbed takes forever to reach 90C and will almost never reach 100+. It is a bit cool in my apartment, so that might be part of it, but I also think this might be a sub optimal design for the printbed. So to try to make it a tad more efficient I placed a layer of aluminized mylar film under the wooden platform. Maybe this will conserve a bit of the heat. Ideally this would be directly under the heated plate, however I did not feel like taking it off, so we shall see how this works.
3:
I decided that mod 1 was not working well enough for me, so I switched to using springs instead. I was originally thinking of making these however I have springs laying around so that was a simpler solution. Essentially it accomplishes the same thing. I was able to get the printbed very level which greatly enhanced the quality of the print so far.
Sunday, December 23, 2012
Saturday, December 15, 2012
Printer is printing
So, last time I addressed a few of the things I learned and was still struggling with on my Printrbot LC, but now I have had my first fully successful print, and another less successful so I will address some of the things that I have learned so far.
Most of my problems have been with extrusion which unfortunately can have numerous causes. One of the biggest issues I had was actually that the idler itself was not freely moving. The ball bearing was actually rubbing up against a piece of the wood extruder frame, and causing a ton of resistance. I did not look at this until well after playing around a ton with the idler tension. This lead to lots of frustration and cleaning of the hobbed bolt.
Because I draw I happen to have kneaded erasers laying around, whereas my Xacto knives were in my garage leading me to try using one to clear out the plastic from the hobbed bolt. I discovered that this is a very good way to get them cleaned out very quickly. For those who are not familiar with a kneaded eraser they are designed to pull up charcoal but not destroy themselves like a plastic eraser. They can be shaped very easily. What i did was roll mine into a rounded cone and just dab the hobbed bolt with the tip. Spin and repeat. The advantage here over the Xacto knife is that it doesn't leave a bunch of little bits of plastic all over the place. Also you are not destroying a blade by rubbing it on a piece of metal.
With the issues of the idler being stuck and the bolt being clogged solved, I was able to get a very beautiful print of Mr Jaws. During that print the second nut on the hobbed bolt came off, and apparently when I put it back on I tightened stuff up a bit too much. This lead to a ton of frustration since it seemed like the extruder was clogged even though I could manually feed filament through the print head. So it is critical that this not be too tight.
Additionally I would say that it is critical to apply locktight to both of the nuts on the Printrbot Wooden Extruder kit. On a longer print of a 40 mm cube for calibration the inside nut actually tightened up sufficiently to cause extrusion issues again. Luckily I was able to identify this and correct it, however it leads me to think that locktight or a single nylock nut should be involved in the situation to prevent this.
Most of my problems have been with extrusion which unfortunately can have numerous causes. One of the biggest issues I had was actually that the idler itself was not freely moving. The ball bearing was actually rubbing up against a piece of the wood extruder frame, and causing a ton of resistance. I did not look at this until well after playing around a ton with the idler tension. This lead to lots of frustration and cleaning of the hobbed bolt.
Because I draw I happen to have kneaded erasers laying around, whereas my Xacto knives were in my garage leading me to try using one to clear out the plastic from the hobbed bolt. I discovered that this is a very good way to get them cleaned out very quickly. For those who are not familiar with a kneaded eraser they are designed to pull up charcoal but not destroy themselves like a plastic eraser. They can be shaped very easily. What i did was roll mine into a rounded cone and just dab the hobbed bolt with the tip. Spin and repeat. The advantage here over the Xacto knife is that it doesn't leave a bunch of little bits of plastic all over the place. Also you are not destroying a blade by rubbing it on a piece of metal.
With the issues of the idler being stuck and the bolt being clogged solved, I was able to get a very beautiful print of Mr Jaws. During that print the second nut on the hobbed bolt came off, and apparently when I put it back on I tightened stuff up a bit too much. This lead to a ton of frustration since it seemed like the extruder was clogged even though I could manually feed filament through the print head. So it is critical that this not be too tight.
Additionally I would say that it is critical to apply locktight to both of the nuts on the Printrbot Wooden Extruder kit. On a longer print of a 40 mm cube for calibration the inside nut actually tightened up sufficiently to cause extrusion issues again. Luckily I was able to identify this and correct it, however it leads me to think that locktight or a single nylock nut should be involved in the situation to prevent this.
Wednesday, December 12, 2012
Starting in 3D printing.
The other night I finished assembling my first 3D printer, a Printrbot LC. I am very excited about this, and for the most part had an easy time assembling the printer. One issue I did have is that the instructions are video, and not completely up to date, however it seems like they are starting to also produce some instructions using Dozuki or some similar system. I think that this combination is great.
The first issue that I did run into however when getting everything configured is the wiring of the motors. The big thing to realize is that the printer does not use the standard Cartesian coordinate layout. Instead it seems as though the Y and Z coordinates are reversed, such that the Y coordinate instead of the Z coordinate controls the location of the printbed. Consequently the Y coordinate controls the height of the extruder above the printbed.
The symptoms that lead to this realization was that it was impossible to get the bridge assembly to rise very far above the printbed. This is because those motors must turn more for a given distance with the leadscrews. So if you are experiencing the same issue, go ahead and switch Y and Z motors and endstop connections.
Another issue that I am dealing with is with filament not feeding well into the extruder. I am noticing that I am unable to get a good 5mm test extrusion; the last little bit will not flow and the motor will meet lots of resistance. I believe that there are two issues going on leading to this. First, I think that the temp. might be a bit low, so I brought the extrusion temp from 200 to 210 in the _Filament_ section of the control software. Additionally I think that the idler is too tight, squishing the filament and causing the hobbed bolt to grind away material and become clogged. So I have cleaned that out and loosened the bolts for the idler. Hopefully this will lead to a good extrusion.
In addition to getting this going on the physical side I have been playing around with some of the digital side of the equation as well. I have been using Autodesks 123D Design program to learn the basics of 3D design and CAD. One good place to start is to try out some of the simple examples on the inhale3d site related to designing electronics enclosures. Additionally I have been looking into being able to generate STL files from Processing. So watch for a modification of the Menger Sponge class for a version that can generate an STL file for printing in the coming week.
The first issue that I did run into however when getting everything configured is the wiring of the motors. The big thing to realize is that the printer does not use the standard Cartesian coordinate layout. Instead it seems as though the Y and Z coordinates are reversed, such that the Y coordinate instead of the Z coordinate controls the location of the printbed. Consequently the Y coordinate controls the height of the extruder above the printbed.
The symptoms that lead to this realization was that it was impossible to get the bridge assembly to rise very far above the printbed. This is because those motors must turn more for a given distance with the leadscrews. So if you are experiencing the same issue, go ahead and switch Y and Z motors and endstop connections.
Another issue that I am dealing with is with filament not feeding well into the extruder. I am noticing that I am unable to get a good 5mm test extrusion; the last little bit will not flow and the motor will meet lots of resistance. I believe that there are two issues going on leading to this. First, I think that the temp. might be a bit low, so I brought the extrusion temp from 200 to 210 in the _Filament_ section of the control software. Additionally I think that the idler is too tight, squishing the filament and causing the hobbed bolt to grind away material and become clogged. So I have cleaned that out and loosened the bolts for the idler. Hopefully this will lead to a good extrusion.
In addition to getting this going on the physical side I have been playing around with some of the digital side of the equation as well. I have been using Autodesks 123D Design program to learn the basics of 3D design and CAD. One good place to start is to try out some of the simple examples on the inhale3d site related to designing electronics enclosures. Additionally I have been looking into being able to generate STL files from Processing. So watch for a modification of the Menger Sponge class for a version that can generate an STL file for printing in the coming week.
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