Repetier Host currently comes with Slic3r 0.9.7 and Skeinforge 50 bundled with it. Skeinforge 50 is a bit different from Skeinforge 39, which comes in the Solidoodle download. The main difference is that it calculates flow rates automatically, much like Slic3r.
The settings for this are in the Dimension tab.
Measure the filament in several places with a caliper and enter the average in Filament Diameter. Filament Packing Density is like Slic3r’s extrusion multiplier, but in reverse. Higher values mean less flow. I’ve found that 1.18 gives me accurate thread widths, based on the extruder being set to 109 steps/mm in firmware. Start here, and find a value that works for you based on the test in Setting the Flow Rate.
Even though the flow rate is now handled by the Dimension tab, the Flow Rate setting remains in the Speed tab. Set the Flow Rate to the same value you are using in Feed Rate.
Be careful about switching back and forth between Skeinforge 50 in Repetier, and Skeinforge 39 in Pronterface. Both of them keep the current settings in the same place. If you have Feed and Flow both set to 50 for Skeinforge 50, they will both still be 50 when you open Skeinforge 39 and you will have to change the flow rate back to its original value. And in reverse, when you go back to Repetier and Skeinforge 50, if you don’t change the Flow Rate back to 50, you will barely get any extrusion.
Once you have determined the correct steps/mm for your extruder, you don’t need to re-flash the firmware to update it. You can do it with a gcode command-
M92: Set axis_steps_per_unit
So if you need to change your E steps to 109, you would enter M92 E109 into Pronterface or Repetier. This is a good way to immediately check the new value. If you are satisfied with it, you can change it permanently in firmware, or add the command to your start.gcode so that it is always active.
If you are using Repetier, you can set it permanently in the EEPROM. Go to Config-Firmware EEPROM Configuration. There are fields there for X,Y,Z and E steps/mm. These values actually override the firmware, so if you set them there, you won’t have to go change them back every time you update.
Josh Smith ran across a excellent ABS post processing machine at Walmart, in the kitchen section. It is the Presto Part Finisher, aka the Presto Kitchen Kettle Multi-Cooker Steamer.
He outlined his results in a post to Soliforum. In short, pour a small amount of acetone in the bottom of the pot. Place the prints in the basket, and turn the heat on just until the light comes on, maybe a little more. The acetone vapor will begin to fill the pot until it begins to condense on the lid. At that point, turn the heat off and pull the basket out of the pot, having left the prints in the vapor for about 30 seconds. They can be touched after a few minutes, but will be a bit soft for 40-60 minutes. I put screws into the bottom of the basket so it would sit higher above the acetone, and covered the bottom with Kapton tape to make a smooth surface.
Like my needlessly complicated DIY version, use this outside. Also wear a respirator, or you are likely to have a sore throat for the rest of the day. I put together a short video of me making a knob for my printer door, using Crysta-Line Topaz ABS from 3Dprintergear and http://www.thingiverse.com/thing:30335, using the Presto at the end.