Documented on thingiverse: here.
Wednesday, December 1, 2010
Sunday, November 21, 2010
Filament spool
With the printer becoming more and more reliable, longer prints are made and a filament spool was needed. The spool was made using a metal tube with printed PLA endpoints glued to it and some cardboard. The filament is kept resting on some M6 threaded rods.
The spool is hanging in a huxley frame. I may replace the frame with something else if I need to finnish the huxley, for now the rapstrap is working fine.
Today a 2 hour print and a 5 hour print were done without any help in the middle. Should order more PLA now...
The spool is hanging in a huxley frame. I may replace the frame with something else if I need to finnish the huxley, for now the rapstrap is working fine.
Today a 2 hour print and a 5 hour print were done without any help in the middle. Should order more PLA now...
Tuesday, November 2, 2010
Z opto endstop
The new z-axis is very stable and I am confident enough to take the z-axis opto endstop into use for calibrating the height automatically at the beginning of a print. A very simple bracket to hold the opto endstop was printed and fixed to a vertical rod. The endstop is mounted with bolts with springs to allow for easy calibration. Three nuts are trapped in the plastic. The bracket looks like this:
The final endstop installed looks like this:
The printing procedure now is to set the extruder in the middle of the area where an object should be printed, with height close to zero (0-2 cm high). The extruder than will be lowered 2 cm, but the movement will stop when the opto endstop is activated. This is the point where the height is calibrated to zero and the extruder can move up 2 cm to warm up and do a test extrusion.
The final endstop installed looks like this:
The printing procedure now is to set the extruder in the middle of the area where an object should be printed, with height close to zero (0-2 cm high). The extruder than will be lowered 2 cm, but the movement will stop when the opto endstop is activated. This is the point where the height is calibrated to zero and the extruder can move up 2 cm to warm up and do a test extrusion.
Sunday, October 31, 2010
Extruder crontol
The original makerbot MK4 extruder worked well until it broke, but like most extruders the starting and stopping of the plastic flow was not very accurate. When printing simple objects this is not a problem, a few loose strings here or there are easily removed with a sharp knife. The extruder motor did reverse a bit after extruding to try to reduce oozing out of plastic, but the gear motor was not really suited for that purpose. I read that now in the the latest version of ReplicatorG the reversing is not switched on by default to reduce the strain on the motor. One of the reasons for building the new extruder based on Wades's design a while back was exactly the extra control over the flow of plastic which a stepper motor would provide. The new extruder has been working fine so far, but one thing I had not done yet: the new extruder was running all the time using a separate Arduino processor and was not controlled at all by the printing software. This works ok, but of course it produces a large amount of strings between the different parts of a model, like in this part of the new Z axis support:
The part is fine after some cleanup with a knife as can be seen here.
The current standard software for the mendel includes support for a stepper motor in the extruder, but the control circuit which is used by default is a double motor steering on the extruder mother board which is not very good for this purpose. I think there are several pieces of software being developped which look promising for the near future (e.g. here), but I don't have a standard solution right now. So in order to get control over my extruder now, I hooked up the output of the extruder mother board which used to go to the MK4 extruder gear motor to my arduino board which is controlling my stepper motor. Since the extruder board is sending 12V signals I reduced the signal voltage with some diodes and resistors so it is safe to connect to the input of the arduino.
The arduino will now detect the extruder motor state from the 2 signals and determine if the motor should go forward, backward or stop. There are some limitations, but it works!
I printed this nice puzzle, a Philippe Dubois burr from thingiverse, which consists of 6 different parts. All parts where printed at the same time and the extruder stopped and started during moves between the different parts for each layer (first layer 1 for all parts is printed, then layer 2 for all parts etc.). As you can see the amount of strings is very little; strings are not completely gone, but no comparison to the z-axis picture above!
The puzzle looks like this when assembled:
The puzzle is much more difficult than I imaged. There is a good website describing the different forms of the puzzle and also includes animations of the solutions. This particular puzzle is what is described on the website as a level 6.4 burr puzzle. This means it takes 6 (!) moves before you can remove the first piece, after that it takes 4 moves before you can remove the second piece. After this the other pieces fall apart.
The part is fine after some cleanup with a knife as can be seen here.
The current standard software for the mendel includes support for a stepper motor in the extruder, but the control circuit which is used by default is a double motor steering on the extruder mother board which is not very good for this purpose. I think there are several pieces of software being developped which look promising for the near future (e.g. here), but I don't have a standard solution right now. So in order to get control over my extruder now, I hooked up the output of the extruder mother board which used to go to the MK4 extruder gear motor to my arduino board which is controlling my stepper motor. Since the extruder board is sending 12V signals I reduced the signal voltage with some diodes and resistors so it is safe to connect to the input of the arduino.
The arduino will now detect the extruder motor state from the 2 signals and determine if the motor should go forward, backward or stop. There are some limitations, but it works!
I printed this nice puzzle, a Philippe Dubois burr from thingiverse, which consists of 6 different parts. All parts where printed at the same time and the extruder stopped and started during moves between the different parts for each layer (first layer 1 for all parts is printed, then layer 2 for all parts etc.). As you can see the amount of strings is very little; strings are not completely gone, but no comparison to the z-axis picture above!
The puzzle looks like this when assembled:
The puzzle is much more difficult than I imaged. There is a good website describing the different forms of the puzzle and also includes animations of the solutions. This particular puzzle is what is described on the website as a level 6.4 burr puzzle. This means it takes 6 (!) moves before you can remove the first piece, after that it takes 4 moves before you can remove the second piece. After this the other pieces fall apart.
Thursday, October 28, 2010
Contest won, glow-in-the-dark ABS on the way!
A few designs in the previous blog posting were submitted to the Makerbot halloween contest. This week the result was published and the bat mobile design was one of the winners! Makerbot actually choose 2 winners, the other winning design was this great spiderweb.
The price for the contest is a roll of glow-in-the-dark ABS plastic from the makerbot store which is on the way to Finland now.
The Bat mobile will definitely be printed again in this new ABS and I'll post some pictures of the bat mobile with the lights off.
For now just a fresh picture of one of the bats with the lights on:
The bat was created using tricks described in the wiki of EvilMadScientist here, originally intended for the eggbot. One final step in the creation process is the conversion of an SVG file of the source image into gcode. For this I wrote a little script which I had intended to document later. A newer version of skeinforge however apparently has now a built-in way to import SVG files and create gcode from that so I won't be working on the script anymore (I have not tried the new version yet). Of course if someone is interested let me know and I'll share what I have.
The price for the contest is a roll of glow-in-the-dark ABS plastic from the makerbot store which is on the way to Finland now.
The Bat mobile will definitely be printed again in this new ABS and I'll post some pictures of the bat mobile with the lights off.
For now just a fresh picture of one of the bats with the lights on:
The bat was created using tricks described in the wiki of EvilMadScientist here, originally intended for the eggbot. One final step in the creation process is the conversion of an SVG file of the source image into gcode. For this I wrote a little script which I had intended to document later. A newer version of skeinforge however apparently has now a built-in way to import SVG files and create gcode from that so I won't be working on the script anymore (I have not tried the new version yet). Of course if someone is interested let me know and I'll share what I have.
Thursday, October 21, 2010
Recently printed objects
This is just an update with some objects printed during the last weeks.
Cryptex
In the book -the Da Vinci Code- a cryptex plays an important role. The cryptex is a cylinder with an important document in it, protected by a code word which can be set by turning rings around the cylinder.
Design files and more images here.
Elliptical Gears This is just toy downloaded from thingiverse, no real life use!
2D single line objects made as entries for the makerbot halloween contest.
- 2 halloween cards:
Pumpkin
Grim Reaper
- Bat Mobile
The bat mobile and the cards are designs from images which where converted first to gray scale and then to a dotted image where dark areas are represented by more dots and lighter areas represented by fewer dots. A special algorithm then tries to find the shortest single line though all the dots which results in an image which is made of a single circular line. A good writeup of the procedure can be found here. This line image is than coverted directly into gcode as gcode is basically a description of a line too. Printing a few identical layers on top of eachother gives the object some strengh.
Cryptex
In the book -the Da Vinci Code- a cryptex plays an important role. The cryptex is a cylinder with an important document in it, protected by a code word which can be set by turning rings around the cylinder.
Design files and more images here.
Elliptical Gears This is just toy downloaded from thingiverse, no real life use!
2D single line objects made as entries for the makerbot halloween contest.
- 2 halloween cards:
Pumpkin
Grim Reaper
- Bat Mobile
The bat mobile and the cards are designs from images which where converted first to gray scale and then to a dotted image where dark areas are represented by more dots and lighter areas represented by fewer dots. A special algorithm then tries to find the shortest single line though all the dots which results in an image which is made of a single circular line. A good writeup of the procedure can be found here. This line image is than coverted directly into gcode as gcode is basically a description of a line too. Printing a few identical layers on top of eachother gives the object some strengh.
Monday, October 11, 2010
New z-axis installed
The new z-axis base was installed and commissioned this weekend. The new base pieces are working fine and the printer is looking less cluttered with the old wooden motor supports replaced (more info about the old configuration here). Only one motor is doing the work now with a belt connecting the 2 vertical threaded rods; left and right won't get out of sync anymore.
A small reconfiguration was needed for the software since the motor has an 8 tooth pulley and the rods have 20 teeth. I still use standard replicatorG software; changing the following line in the machine.xml file from:
<axis id="z" length="200" maxfeedrate="100" scale="320"></axis>
to:
<axis id="z" length="200" maxfeedrate="100" scale="800"></axis>
did the trick.
The printer looks like this now:
A small reconfiguration was needed for the software since the motor has an 8 tooth pulley and the rods have 20 teeth. I still use standard replicatorG software; changing the following line in the machine.xml file from:
<axis id="z" length="200" maxfeedrate="100" scale="320"></axis>
to:
<axis id="z" length="200" maxfeedrate="100" scale="800"></axis>
did the trick.
The printer looks like this now:
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