3D PrintingTips & Tricks 5

ABS GLUE
ABS glue is a great addition to any 3D printer operator’s tool box.  This slurry of acetone and ABS has many practical uses such as:
Bonding small parts together to create larger or more intricate ones (it’s just a bit easier to apply than straight acetone)
Improving the surface finish of your part (simply paint it on or dip your part into it)
Mending cracks in your parts (if you don’t feel like reprinting/redesigning them)
How to make ABS glue:
Use a small glass jar with an air tight lid.  You can find these at most hobby shops.  Empty nail polish bottles work too, but they’re kind of small.
Fill about half way with straight acetone (or however much you’d like if you’re using a larger jar).
Add ABS.  ABS takes time to completely dissolve in acetone, so the smaller bits you use the quicker the results.  We like to simply print a 1-layer thick square sheet (or just start any print and stop it after the first layer), and then cut it into pieces.  Snipping small pieces off the end of your filament works too, but it’ll just take more time to dissolve.
Wait and stir.  Repeat until all the ABS is dissolved.
There’s no perfect ratio of ABS to acetone.  Just use less ABS to make a thinner solution (great for surface finishing) or more ABS for a thicker solution (great for bonding or mending parts).

PRINTING LARGE OR UNIQUELY SHAPED PARTS
If you need to make parts larger than the printing area of your printer or parts that have intricate projections, here are a few choices in order of popularity:
Fuse smaller sections together using acetone.
Design smaller parts to be attached together (without hardware).
Design smaller parts to be screwed together (with hardware).

EXTRUSION TEMPERATURE FOR ABS
The optimal temperature for extruding ABS usually ranges between 215-240C.  These are some factors that can influence the optimal temperature:
Color
Hot-End design :  How accurate is the temperature reading vs. the actual temperture of the hot-end?  Some factors to consider:
distance between tip & heater resistor, thermistor & heater resistor, and thermistor to tip
Plastic compound
Moisture in the Plastic
Temperature of the printing environment
Elevation (from sea level) of the printing environment

CRACKING ON TALLER PRINTS
Problem: “There are layer cracks on the sides of my taller prints.”
This cracking phenomenon can occur with taller prints.  The reason is because at higher layers (say from ~30mm on a typical Reprap), the part cools quicker and has less “help” from the heated bed.  Therefore, subsequent layers cool down faster and faster which causes poor layer adhesion.  Try increasing the extruder temperature by about 10C.  Also, try increasing the bed temperature between 5-10C.