Tuesday, June 21, 2011
Reprap at the NextGen Science Fair 2011 in San Francisco
After many misgivings about the direction of the event {it was the Cable TV channel TasteTV's first such event}, the NextGen Science Fair 2011 came off very well. The number of exhibitors was quite small, and the entry fee was substantial at $25. I expected a few hundred people at most. In fact, I think we got many times that. We had a thick crowd around the Reprap table virtually all day long.
I brought my Rapman and my nearly complete Sampo and Brook Drumm, who set up the RepRap/MakerBot Builders in Northern California, showed up with his Makerbot Cupcake and his nearly complete Mendel. He's used his cupcake to make Mendel parts sets for everybody in his group since January of this year. Brook has become an accomplished Reprapper in a very short amount of time..
Here you can see Brook Drumm {left} of the RepRap/MakerBot Builders in Northern California talking about his Průša Mendel.
You can see from left to right, a Makerbot Cupcake {to the left of Brook}, a Průša Mendel just below his hands, the nascent Sampo printer and a Rapman 3.0 at the far right.
Brook and his daughter/assistant Sydney with their Makerbot Cupcake in printing Mendel parts.
I brought my Rapman and my nearly complete Sampo and Brook Drumm, who set up the RepRap/MakerBot Builders in Northern California, showed up with his Makerbot Cupcake and his nearly complete Mendel. He's used his cupcake to make Mendel parts sets for everybody in his group since January of this year. Brook has become an accomplished Reprapper in a very short amount of time..
Here you can see Brook Drumm {left} of the RepRap/MakerBot Builders in Northern California talking about his Průša Mendel.
You can see from left to right, a Makerbot Cupcake {to the left of Brook}, a Průša Mendel just below his hands, the nascent Sampo printer and a Rapman 3.0 at the far right.
Brook and his daughter/assistant Sydney with their Makerbot Cupcake in printing Mendel parts.
Brook Drumm's Průša Mendel made from parts printed by a his Makerbot Cupcake.
A Darwin-derivative Rapman 3.0 monitored by Adriaan Higgs printing a y-axis drive belt gripper for the next generation Darwin-derivative Sampo printer just to the right.
Adriaan demonstrating the technology differences between the Rapman and the Sampo Darwin-derivative printers.
Showing the familiar Reprap banner at NextGen Science Fair 2011.
Labels: darwin, NextGen Science Fair, Průša Mendel, RapMan, reprap, Sampo
Friday, November 26, 2010
Random thoughts on hot-end design
I spent some time modding the bfb hot-end. Originally the hot end is very sturdy but with extremely soft filament (soft-abs from orbi for example) it is not able to print at low speeds (0.25mm layer 16mm/sec was on the limit, working but not consistent, 0.15mm layer 16mm/sec killed it)...
Labels: hot-end, RapMan, reprap
Saturday, May 15, 2010
Quick hot bed temperature controller...
I received some aluminum plates (one for my rapman and other for my mendel) and some 50W resistors (still waiting for the 100W ones) tied it all together and it worked just like Chris shown on his super cool blog :), anyhow using the max power (~12A ~500W) I can push to the bed it can overshoot the max temperature those resistors are specified to handle so I needed some way to control it. Initially I used the simple thermal switch (like you can see in TA oven) but as I want to be able to change the temperature from the motherboard I decided to replace it with small electronics.
I do not have a SSR lying around but I have bunch of "no name / no marking" 25A 600V triac's that are perfect for the job, I used the MOC3043 (optocoupler with triak output and zero crossing detection) to separate the electronics from the AC going in to heat bed (I'm using 41VAC), the microchip PIC16F819 is used to drive the LCD, read NTC and work as I2C slave. NTC is connected with 10K resistor to maximize reading range between 20 and 180C. NTC used is same one from BFB hot end's (GT-204).
I do not have a SSR lying around but I have bunch of "no name / no marking" 25A 600V triac's that are perfect for the job, I used the MOC3043 (optocoupler with triak output and zero crossing detection) to separate the electronics from the AC going in to heat bed (I'm using 41VAC), the microchip PIC16F819 is used to drive the LCD, read NTC and work as I2C slave. NTC is connected with 10K resistor to maximize reading range between 20 and 180C. NTC used is same one from BFB hot end's (GT-204).
"firmware" is written in PICC C, it takes ~70% ROM and ~40% RAM so there's room for more functionality if needed. I2C slave address is 0xAB but it can be changed, first 2 addresses (0 and 1) are read/write and contain target temperature for the heat bed while second 2 (2 and 3) are read only and here you can read current temperature of the heat bed. To avoid float math, the temperature is stored as *100 value. When turned on - the controller reads last stored temperature from the EEPROM (locatio 0 and 1), when both key's are pressed the current target temperature is stored in EEPROM. You can both change the target temp via i2c or using key's (whatever happens last).
Source (PICC C file) is available here.
Source (PICC C file) is available here.
Labels: controller, heated bed, I2C, Mendel, PIC, RapMan
Tuesday, March 30, 2010
Best of both Worlds
I'm using RapMan 3.0 for a while now and it is a great machine. I did tweak it a lot, but however I tweak it, and however I change more or less important parts or the way some things work on this Darwin based kit the few things I cannot change and they bug me big time. Major issue I have with it is size. And as I'm printing a lot of PP/HDPE there is no way I can use that big table (PP warps 10 times worse then ABS)...
now it would be cool if I only used this desk for printing but that's not the case. I found solution in Mendel, the second generation reprap machine. Mendel is super cool reprap, it has small footprint, it requires less power... but all the extruder designs I seen for Mendel are not comparable to those of rapman's designed and sold by BFB. Getting your nozzle to 260C and extruding at high pressure will render PFTE tube based extruder tips unusable, and standard extruder drive has no way of applying enough pressure. dr. Bowyer recently published YAGE that IMHO had potential to push with enough strenght (I did modify the drive a bit and added some very sharp 2mm pitch pulley as drive instead of that M4 inset) but still, the PFTE tube design and 260C don't really go together, not to mention glued PFTE and high pressure so I looked at the hot end piece of rapman's extruder. BFB sells hot end kit for some reasonable price, and as I have few spare and I know this hot end can take a beating (the first one extruded kilograms of different filaments and is still in prime condition) I decided to give it a go.
This is the left third (almost half actually) of my desk:
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| From RapMan |
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| From MENDEL |
I heated the hot end to 270C and let it be hot for 2h before I checked if the x-carriage (made out of PLA) is getting soft - and, to mine surprise, it was not. I was afraid I will have to print the x-carriage using ABS or HDPE and that requires heated bed that I still don't have.
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| From MENDEL |
Testing the extruder, it is bit slower then original bfb extruder (because bfb one is 1:1 and this one is 5:1 and because I'm using some second hand stepper of unknown manufacturer) but is pushing filament at more then 2-3mm/sec of filament (not the 0.5mm but the 3mm filament) per second and that's what I was aiming for.
Now I need to try to modify the bfb pcb to run Mendel so Mendel can also be stand alone printer and I can truly have best of both Worlds, but for now, Mendel is, with this new powerful extruder, ready to replace the dear chunky rapman from my desk (and rapman, as stand alone printer, can go to back room)
Labels: extruder, Mendel, RapMan
