ABS Raftless Printing
Since I finished building the excellent heated build platform from MakerGear, I'm been trying to get raftless ABS printing working. I decided to try out the Raftless skeinforge plugin. This requires the latest beta version of skeinforge to work which unfortunately completely changes the whole interface and a number of settings compared to the current version. It also means you unfortunately can't use SkeinFox on OSX. Here's what I did to get the butterfly above to print on my bot.
First of all, your platform needs to be perfectly level. Printing ABS without a raft is much less forgiving than when you use a raft which tends to even things out for you. Then you want to make sure it starts the first layer pretty close so that it get's smooshed on the platform almost like you used to smoosh the first base raft layer (maybe a little less smooshed) I found this large print bed tester object to be very helpful when getting it level and the right about of smooshiness.
I turned off the intro line in raftless plugin for the butterfly. It kept catching when it did the perimeter and pulled it off. Might work better with smaller objects or things with less complex perimeters.
I have kapton film on the ceramic platform and lightly sanded the kapton on top. Since I haven't built a plug for the platform thermistor yet, I'm not using the new heated platform enabled extruder firmware, so I just plugged it's heater in port C and used the fan checkbox in replicator G to turn it on/off and the temp stickers I put on it to see the temp. I found the best temperature to be around 90C, which happens to be about as hot as I can get it to go. I also found it best to just leave the heater on during the whole print. Rick suggests on his operating instructions to heat it up and then turn it off after the first few layers, however I found that to not work as well as leaving it on the whole time, but I might need to test it some more. Hopefully I won't burn it out or something, but leaving the power on for a long time and it never gets much hotter than 95C. One of the nice things about printing raftless on hot kapton is that you get a super smooth flat shiny finish on the bottom. So smooth it's actually like a mirror finish.
I found that if you leave the piece on the platform, turn off the heat, and then cool it down (I used a small cpu fan), around 30C you can hear it start to snap and crackle as it detaches itself from the platform. You can then reach in and just pick the object up! No more scraping things off. That was pretty awesome, however since it takes about 15 minutes to heat it back up for another print, it's not very practical. You can however use a putty knife and carefully work it under a corner while it's hot and it still pretty easily slides off. No real need to take the platform off to get prints out.
Update: SkeinFox 1.50 now includes the latest skeinforge and raftless plugin, so the below is not entirely necessary.
Now for the hard part, skeinforge. I downloaded skeinforge-tools from TeamTeamUSA's github and followed the installation instructions in the readme (copy the raftless.py to right place, edit extrusion.py, etc). Before I ran it, I backed up my ~/.skeinforge directory and then deleted it so I could start with fresh settings. Unfortunately, these default settings I'm guessing are optimized for a RepRap Darwin or something and not a MakerBot. I made the following changes from the defaults:
CarveLayer Thickness (mm): 0.375ChamberActivate Chamber: False(right now I'm controlling my platform with the fan port and haven't enabled control with the second thermistor or new extruder firmware)CombActivate Comb FalseCoolActivate Cool FalseFillGrid Rectangular TrueLine FalseInfill Perimeter Overlap (ratio): 0.2Infill Solidity (ratio): 0.15RaftActivate Raft FalseBase Layers (integer): 0Interface Layers (integer): 0Temperature Change Time Before First Layer (seconds): 0.0Temperature of Base (Celcius): 220.0Temperature of Interface (Celcius): 220.0Temperature of Shape First Layer Infill (Celcius): 220.0Temperature of Shape Next Layers (Celcius): 220.0Temperature of Support Layers (Celcius): 220.0Temperature of Supported Layers (Celcius): 220.0(I had changed base and interface to 0 before I got the raftless plugin, probably not necessary since we're turning the raft plugin off anyway, also I'm not entirely clear what the proper way to set the extrusion temp is with the raft plugin turned off when there is no temp setting in the raftless plugin, I guess it's up to you to set the temp before you print or in the start.gcode file)RaftlessActivate Raftless True1st Perimeter Feed Rate over Feed Rate (ratio): 0.931st Perimeter Flow Rate over Flow Rate (ratio): 0.68Add Extrusion Intro: False(the default is .5 feed rate, but that was way too slow and no matter what I set the flow rate to it just kept extruding way too much. This might be due to the fact that I use a high feed and flow rate by default. These settings seemed to work the best for me.)SpeedFeed Rate (mm/s): 28.0Flow Rate Setting (float): 255.0Orbital Feed Rate over Operating Feed Rate (ratio): 1.0Travel Feed Rate (mm/s): 55.0
They also changed the location and name of the start and end files. They're now at skeinforge_tools/alterations and are called start.gcode and end.gcode. Here is what I use. I like to start and end with Z at 50 so that it's out of the way and less likely to crash into anything you make at the end.
start.gcode:
(***************FIRST SET Z TO 50*********************)(homing routing)M104 S220 T0 (Temperature to 220 celsius)G21 (Metric FTW)G90 (Absolute Positioning)G92 X0 Y0 Z50 (You are now at 0,0,50)(You have failed me for the last time, MakerBot)M108 S255 (Extruder speed = max)M6 T0 (Wait for tool to heat up)G04 P5000 (Wait 5 seconds)M101 (Extruder on, forward)G04 P5000 (Wait 5 seconds)M103 (Extruder off)M01 (The heater is warming up and will do a test extrusion. Click yes after you have cleared the nozzle of the extrusion.)G0 Z0 (Go back to zero.)(end of start.)
end.gcode:
(end of the file, cooldown routines)M104 S220G90G1 X0 Y0 Z50 F3300.0
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